Power profiles in multifocal contact lenses with variable multifocal zone

BACKGROUND The power profile of multifocal contact lenses has been demonstrated to report important information that could be used during the fitting process. The aim of this work is to describe the power profile of a recent set of gas permeable multifocal contact lenses as a function of the pupil radius. METHODS The measured multifocal contact lenses have a centre-distance design, and are available with five distance-vision diameters (XS, S, M, L and XL) and two different additions: Type A (up to +2.00 D) and Type B (up to +2.50 D). The optical device NIMO TR1504 (Lambda-X, Nivelles, Belgium) was used to obtain the power profile measurements. The optical lens power distribution as a functi…

Short-Term Changes in Light Distortion in Orthokeratology Subjects

Purpose. Quantifying adaptation to light distortion of subjects undergoing orthokeratology (OK) for myopia during the first month of treatment. Methods. Twenty-nine healthy volunteers (age: 22.34 ± 8.08 years) with mean spherical equivalent refractive error −2.10 ± 0.93D were evaluated at baseline and days 1, 7, 15, and 30 of OK treatment. Light distortion was determined using an experimental prototype. Corneal aberrations were derived from corneal topography for different pupil sizes. Contrast sensitivity function (CSF) was analyzed for frequencies of 1.50, 2.12, 3.00, 4.24, 6.00, 8.49, 12.00, 16.97, and 24.00 cpd under photopic conditions. Results. Average monocular values of all light di…

Clinical use of the ocular point spread function for retinal image quality assessment

The purpose of this study is to demonstrate the clinical use of the point spread function (PSF) as metric for the assessment of retinal image quality in eyes with different ocular conditions. The PSF was computed from the wavefront aberrations obtained in seven eyes with different ocular conditions: emmetropia, myopia, hyperopia, post-myopic laser in situ keratomileusis (LASIK), post-hyperopic LASIK, keratoconus, Intacs ® in keratoconus, radial keratotomy (RK), LASIK after RK, cataract, phacoemulsification after cataract surgery, and LASIK after astigmatic keratotomy. The Strehl intensity ratio was calculated for all the PSFs computed. The PSF was correlated with the change in the optical e…

Intraocular lens centration and stability: efficacy of current technique and technology

Purpose of review The manuscript presents a review of recently published studies analyzing different methodologies to assess centration and stability of intraocular lenses after implantation. Recent findings Considering that there is no current gold standard for centration and stability of intraocular lenses after implantation, we have summarized the different techniques used clinically for intraocular lenses centration and stability estimation. We have described the use of Scheimpflug imaging, the anterior segment optical coherence tomography and photography analysis used for lens position estimation. Techniques used to assess lens rotation are based on image analysis on digital retroillum…

A 12-month Prospective Study of Tear Osmolarity in Contact Lens Wearers Refitted with Daily Disposable Soft Contact Lenses

SIGNIFICANCE Tear osmolarity has been reported as one of the best diagnostic tests for dry eye disease and its management. Contact lens wear is thought to influence tear homeostasis. Understanding how regular wear of contact lenses and their type affect tear osmolarity is important. PURPOSE The purpose of this study was to assess changes in tear osmolarity and ocular symptoms over a period of 12 months following refitting contact lens wearers with daily disposable contact lenses. METHODS Fifty subjects aged (mean ± SD) 26 ± 4 years were refitted with either silicone-hydrogel (delefilcon A, SiHy, n = 34) or hydrogel (omafilcon A, Hy, n = 16) daily disposable soft contact lenses. Study includ…

The tear film and the optical quality of the eye

The stability of the tear film plays an important role in the optical quality of the eye. Various methods have been developed to quantify the contribution of the tear film to optical quality, including the double-pass optical method, Hartmann-Shack wavefront sensing, videokeratoscopy, retroillumination analysis, and interferometry. In addition to assessing the effect of tear film irregularities, these methods can aid in the diagnosis of dry-eye related conditions and the monitoring of therapy. This review describes the methodologies used to assess the relationship between the tear film and optical quality of the eye and summarizes the most important findings obtained with these methods with…

Evaluation of Physiological Parameters on Discomfort Glare Thresholds Using LUMIZ 100 Tool

Purpose To assess the links between discomfort glare sensitivity and physiological factors such as eye biometry, refraction, skin phototype, age, and gender among a large sample of healthy human subjects. Methods A total of 489 participants who were 20 to 70 years old (241 men, 248 women) underwent discomfort glare threshold measurements via the LUMIZ 100. Eye biometry and optical quality were measured using a Zeiss IOLMaster 700 biometer and i.Profiler aberrometer. Iris color, skin tone, age, gender, eyeglasses use, chronotype, fatigue level, self-evaluation of light sensitivity, and time spent outdoors were determined. Statistical analysis was carried out using nonparametric Mann–Whitney …

Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens

Purpose To compare the optical and visual performance of a dual-focus (DF) contact lens used for myopia control with a single-vision (SV) contact lens of the same material. Methods A randomised, double-masked crossover study. Twenty-eight healthy, myopic volunteers between 18 and 32 years of age (23.49 +/- 4.07 years) participated in this study. The sensory dominant eye for distance vision was determined. Refraction, best-corrected visual acuity (VA) and aberrations for 3 mm and 5 mm pupil diameters were quantified without a contact lens in situ. Subjects were fitted with two contact lens designs: DF and SV, both made of omafilcon A material. The Quality of Vision (QoV) questionnaire, over-…

Medium-term visual, refractive, and intraocular stability after implantation of a posterior chamber phakic intraocular lens to correct moderate to high myopia.

To evaluate the medium-term refractive and visual outcomes and the complications after implantation of a silicone posterior chamber phakic intraocular lens (PC pIOL) for moderate to high myopia.Oftalmar, Medimar International Hospital, Alicante, Spain.Retrospective case series.Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, and intraocular pressure were evaluated during a medium-term follow-up. Postoperative complications were also studied.The study enrolled 35 eyes (mean preoperative spherical equivalent [SE] -10.25 diopters [D] ± 3.19 [SD]) of 20 patients with a mean age of 31.83 ± 8.87 years and a mean follow-up of 57.34 ± 9.24 months. The mean UDVA improved…

Effect of sport-tinted contact lenses for contrast enhancement on retinal straylight measurements

PURPOSE: To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method. METHODS: Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred. RESULTS: The subjects' mean straylight values were 0.90 +/- 0.09 at baseline and 0.95 +/- …

VisuMax®femtosecond laser for corneal refractive surgery

Femtosecond lasers are increasingly present in ophthalmologic surgical theaters for a variety of reasons. These include faster and better visual outcomes, increased accuracy and predictability for corneal flap thickness in laser in situ keratomileusis procedures. Recent applications of modern femtosecond lasers have broadened the range of uses: keratoplasty, intrastromal segment insertion and even glaucoma and presbyopia surgery. This device profile provides an overview of the advantages of femtosecond lasers in ophthalmic surgery, paying special attention to the new VisuMax® femtosecond laser from Zeiss/Meditec.

Corneal thickness differences between sexes after oxybuprocaine eye drops.

PURPOSE We aimed to analyze the corneal thickness (CT) values of female and male subjects before and after instillation of oxybuprocaine 0.4% anesthetic eye drops. METHODS The CT of 30 female subjects and 28 male subjects was measured using scanning-slit corneal topography (Orbscan Topography System II, Orbscan, Inc, Salt Lake City, UT). Measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 0.4% eye drops. RESULTS The difference between the baseline values and those obtained after anesthesia ranged as follows: male subjects: central, -26 to +24 μm; superior, -24 to +23 μm; inferior, -19 to +20 μm; nasal, -25 to +30 μm; and temporal, -21 to +20 μm; female…

Performance of the compensation comparison method for retinal straylight measurement: effect of patient's age on repeatability

Aim: The assessment of repeatability and reproducibility of retinal straylight measurements with the C-Quant straylight meter (Oculus AG, Germany) and the effect of patient’s age on the instrument performance are tested with a series of experiments. Methods: First, 20 eyes from 20 subjects (mean age 26.9 (SD 2.7) years, mean refractive error −1.34 (2.72) D) were examined with the C-Quant straylightmeter, taking 10 consecutive readings. Five subjects were also examined on five consecutive days to assess reproducibility. Additionally, repeated measures of straylight from 84 subjects of ages ranging from 19 to 86 years (mean (SD): 42.4 (24.0) years) were retrospectively analysed to assess the …

The Effect of Anesthetic Eye Drop Instillation on the Distribution of Corneal Thickness

PURPOSE To address the effect of topical instillation of oxybuprocaine on the relative distribution of corneal thickness (CT) in young healthy subjects. METHODS Prospective study involving 30 eyes of 30 emmetropic subjects (24 ± 3 years). Corneal thickness measurements were carried out before and 3 minutes after the instillation of oxybuprocaine 4% using slit-scanning corneal topography (Orbscan topography system II). No acoustic correction factor was applied. The mean of 5 consecutive Orbscan measurements was obtained at the center and 3 mm from the visual axis in the temporal, superior, nasal, and inferior hemimeridians. RESULTS No significant mean differences were found at any corneal lo…

Tear film stability over a myopia control contact lens compared to a monofocal design

Background: To compare the short-term effect of two contact lenses on pre-lens tear film stability and comfort: dual-focus contact lens (MiSight) and a monofocal contact lens (Proclear 1-day).Methods: This randomised, double-masked, crossover study was performed in twenty-eight healthy, myopic volunteers aged between 18 and 32 years (23.5 +/- 4.1 years). Only one randomly chosen eye was assessed. Distance vision and refraction were evaluated at baseline. Each contact lens type (monofocal and dual-focus) was randomly fitted, always in both eyes. A visual analogue scale between 0 and 10 was used to assess general comfort, physical comfort, and visual comfort. Tear Film Surface Quality (TFSQ) …

OCT applications in contact lens fitting

Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essenti…

Ocular autofluorescence in diabetes mellitus. A review

Diabetes mellitus is a metabolic disease with a considerable impact on healthcare owing to its increased prevalence and high mortality rate. Structural, morphological, and physiological changes in each of the ocular components have been described in detail. Autofluorescence has been described as a good indicator of metabolic activity. The aim of the present review is to provide an overview of ocular endogenous fluorophores in the cornea, the crystalline lens, and the retinal pigment epithelium, the effects of diabetes mellitus and therefore the potential of autofluorescence assessment for screening and monitoring changes in diabetic patients.

Neural Adaptation to Optical Quality Defects

From an optical perspective the eye is far from perfect. This is a fact that is extensively supported by literature; for instance, Prof. Navarro recently provided us with a fantastic critical review on the various theories behind the different eye models and their flaws.1 The human eye has considerable amounts of higher-order aberrations even when it is emmetropic,2 with great inter-individual variability. Besides, higher-order aberrations are still postulated to have a role in the development of the refractive error, although it is not clear the extent to which this may be (see Charman WN for a review).3 The known optical limitations of the normal human eye raised the question as to what t…

Intrasubject repeatability of corneal power, thickness, and wavefront aberrations with a new version of a dual rotating Scheimpflug–Placido system

Purpose To determine the intrasubject repeatability of a recently introduced dual-camera rotating Scheimpflug–Placido imaging system (Galilei G4) in determining corneal thickness, power, and wavefront aberrations in young healthy subjects. Setting University of Valencia, Valencia, Spain. Design Prospective evaluation of diagnostic technology. Methods The study comprised right eyes of 25 subjects aged 20 to 40 years with a spherical equivalent ranging from −4.25 to +1.00 diopters. The central corneal thickness, thinnest point value and location, anterior and posterior surface curvatures, total corneal power, and corneal wavefront aberrations were measured for distance vision using the dual S…

Corrigendum to “Short-term changes in light distortion in orthokeratology subjects"

Artigo completo publicado na revista "BioMed Research International, (2015), 1-7" e disponível no RepositóriUM em: http://hdl.handle.net/1822/33375

Optical quality after instillation of eyedrops in dry-eye syndrome

Purpose To study the effect of eyedrop instillation on the optical quality of the air–tear film interface at the anterior cornea in cases of dry eye. Setting University of Valencia, Valencia, Spain. Methods Corneal aberrations (total, spherical-like, and coma-like) were determined from corneal elevation maps and purpose-designed software in cases of dry eye before, immediately after, and 10 minutes after lubricating eyedrop instillation (Blink Intensive Tears). All data were decomposed using Zernike polynomials to yield the root-mean-square wavefront deviations for pupil diameters of 3.0 mm and 5.5 mm. Outcome measures included comparison with clinical tear breakup time (TBUT). Results Wave…

Determination of corneal volume from anterior topography and topographic pachymetry: application to healthy and keratoconic eyes

Purpose: To describe a method to measure corneal volume from topography and pachymetry, and test its clinical use on a sample of healthy human subjects and a case of circumscribed posterior keratoconus. Methods: Corneal curvature (PCT 200® corneal topography system; Optopol Technology SA, Zawiercie, Poland) and ultrasonic topographic pachometry on 25 points (Ophthasonic ® A-Scan/Pachometer III; Teknar Inc., St Louis, MO, USA) were measured on each of 12 young healthy corneas and one cornea suffering from circumscribed posterior keratoconus. Topography and pachymetry data were used to calculate the coordinates for the corresponding points on the posterior surface of the cornea. TableCurve 3D…

Analysis of the possible benefits of aspheric intraocular lenses: review of the literature.

We reviewed recently published studies that analyzed the visual and optical quality in eyes with different spherical and aspheric intraocular lenses (IOLs). Recent studies focused on visual quality metrics, such as visual acuity and contrast sensitivity, under photopic and mesopic lighting conditions and optical metrics, such as wavefront aberrations, especially spherical aberration. The results in this review were used in an attempt to understand whether there is a visual and/or optical benefit of implanting aspheric IOLs over implanting spherical IOLs.

Prevalence of corneal astigmatism before cataract surgery.

To analyze the prevalence and presentation patterns of corneal astigmatism in cataract surgery candidates.University of Valencia, Valencia, Spain.Refractive and keratometric values were measured before surgery in patients having cataract extraction. Descriptive statistics of refractive and keratometric cylinder data were analyzed and correlated by age ranges.Refractive and keratometric data from 4,540 eyes of 2,415 patients (mean age 60.59 years +/- 9.87 [SD]; range 32 to 87 years) differed significantly when the patients were divided into 10-year subsets. There was a trend toward less negative corneal astigmatism values, except the steepest corneal radius and the J(45) vector component, in…

Online Vs In-person Education: Evaluating the Potential Influence of Teaching Modality on Dry Eye Symptoms and Risk Factors During the COVID-19 Pandemic.

OBJECTIVES: To assess the potential effects of switching to online lecture format on dry eye symptoms and dry eye disease (DED) risk factors. METHODS: An anonymous cross-sectional online survey was conducted in 812 university students (mean age, 21.5±4.0 years). Participants were classified according to the number of hours the participants took online lectures into online students or in-person students. Respondents completed a total of three DED questionnaires (Ocular Surface Disease Index [OSDI]; 5-item Dry Eye Questionnaire; 8-item Contact Lens Dry Eye Questionnaire) and were surveyed on dry eye risk factors contemplated by the Tear Film and Ocular Surface Society Dry Eye Workshop II in a…

A pilot study on the differences in wavefront aberrations between two ethnic groups of young generally myopic subjects

A comparative population-based cross-sectional study design was used to examine the prevalence of wavefront patterns in two different ethnic groups, and the relationship of these patterns with ocular biometrics and gender. The Shin–Nippon SRW5000 open field autorefractor, the Wavefront Analysis Supported Customized Ablation (WASCA) wavefront analyser and the IOLMaster were used to determine wavefront aberrations, mean spherical equivalent (SE) refractive error and axial length (AL). Seventy-four eyes from 74 young healthy subjects (44 British Asians, 30 Caucasians; 36 men, 38 women; mean age 22.51 ± 3.89 years) with mean SE averaging )1.90 ± 2.76 D (range )10.88 to +2.19 D) were examined. R…

Quantitative corneal anatomy: evaluation of the effect of diabetes duration on the endothelial cell density and corneal thickness.

Purpose To evaluate the differences in endothelial cell density (ECD) and central corneal thickness (CCT) between type II diabetic patients and age-matched healthy controls, and determine the impact of time from diagnosis. Methods This is a comparative study of 77 eyes of type II diabetic patients (33 males, 44 females) and 80 eyes of healthy subjects (42 males, and 38 females) whose ages ranged from 38 to 56 years. CCT, ECD, HbA1c levels, and Goldmann tonometry were measured. Results The CCT was significantly higher and the ECD significantly lower in long-term diabetic patients (10 years + since diagnosis) when compared with short-term diabetic patients (<1 year since diagnosis) and contro…

Preliminary in vivo positional analysis of a posterior chamber phakic intraocular lens by optical coherence tomography and its correlation with clinical outcomes

Purpose: To analyze by spectral-domain optical coherence tomography the anatomical relationship of a specific type of posterior chamber phakic intraocular lens (pIOL) implanted in cases of high to moderate myopia with the adjacent intraocular structures and to correlate it with clinical outcomes. Methods: Prospective observational case series including 18 eyes with high to moderate myopia (spherical equivalent between −5.88 and −15.75 D) of 9 patients (age range, 29–49 years) undergoing bilateral Phakic Refractive Lens (PRL, Zeiss) implantation. Postoperative visual acuity, refraction, contrast sensitivity (CS), and ocular higher order aberrations (HOA) were evaluated. Furthermore, the in v…

Effect of contact lens surface properties on comfort, tear stability and ocular physiology.

Aim: Retrospective analysis of different contact lens wearing groups suggests lens surface lubricity is the main factor influencing contact lens comfort. However, the examined commercially available contact lenses differ in material and design as well as surface properties. Hence this study isolates the contribution of lens surface properties using an ultra-thin coating technology. Methods: Nineteen habitual contact lens wearers (21.6. ±. 1.7years) wore formofilcon B soft monthly disposable contact lenses with and without coating technology modified surface properties for a month each in a randomised double-masked cross-over study. Objective non-invasive: breakup time (NIKBUT), NIKBUT avera…

Short-Term Impact of FS-LASIK and SMILE on Dry Eye Metrics and Corneal Nerve Morphology

PURPOSE To analyze the short-term (up to 1 month) clinical outcomes in patients undergoing corneal laser refractive surgery and the impact on dry eye disease (DED) metrics and corneal nerves using in vivo confocal microscopy (IVCM). METHODS The unaided distance visual acuity, corrected distance visual acuity, and spherical equivalent refraction (SEQ) were determined in 16 and 13 patients undergoing FS-LASIK and SMILE, respectively. DED metrics assessed were Ocular Surface Disease Index, Dry Eye Questionnaire 5-items (DEQ-5), tear film osmolarity, tear meniscus height, noninvasive keratograph breakup time (NIKBUT), ocular staining, and meibomian gland atrophy. An automated analysis of cornea…

Subjective Satisfaction in Long-term Orthokeratology Patients

Purpose: To AU3 evaluate the subjective satisfaction in visual stability, night vision complains, and light distortion phenomena, and also the number of hours and days per week of lens wear, in patients with myopia undergoing orthokeratology (OK) treatment for at least 1 year. Methods: A visual analog scale (VAS) questionnaire containing 18 items was administered to 44 patients, 29 women and 15 men (mean age, 24.39 6 9.11 years), with a baseline spherical equivalent refractive error of 22.40 6 0.94 diopters and astigmatism up to 20.5 diopters. Average treatment period by the time of data collection was 19 6 7 months. Patients rated their satisfaction with the correction, with complaints of …

Reliability of manual segmentation of cornea, contact lens and tear film using a high-resolution OCT

In this study, we aimed to evaluate the intra/inter-session and intra/inter-observer variability of manual segmentation of thickness of the pre-lens tear film, contact lens (CL), post-lens tear film, epithelium, bowman’s layer, stroma and the whole cornea and CLs with a flat and a steep fit, using a commercial high-resolution spectral domain optical coherence tomographer (OCT). Two different observers obtained three repeated measures in two separate sessions. A high correlation was found between the values obtained by the two different observers, except for the thinner layers, epithelium, and Bowman’s layer. Inter-observer analysis showed a high consistency in the measurements obtained by b…

Optical quality of the diabetic eye: a review

Diabetes mellitus is a metabolic disorder characterized by the presence of chronic hyperglycaemia. Several structural, morphological, and physiological changes in each of ocular component have been described in detail during the past decades. Due to these abnormalities, the diabetic patient undergoes a degradation of the retinal image by an increase of higher ocular aberrations and ocular scattering coming from mainly tear film, cornea, and crystalline lens. This review aims to provide an overview of current knowledge about the effects of diabetes mellitus in these optical phenomena and its consequence on the visual quality of the diabetic patient.

Systemic, environmental and lifestyle risk factors for dry eye disease in a mediterranean caucasian population

Objectives: To assess systemic, environmental and lifestyle risk factors for dry eye disease (DED) in a Mediterranean Caucasian population. Methods: A cross-sectional study was performed on 120 Caucasian participants aged between 18 and 89 years (47.0 ± 22.8 years). Medical history, information regarding environmental conditions and lifestyle, Ocular Surface Disease Index, Dry Eye Questionnaire-5, non-Invasive (Oculus Keratograph 5 M) breakup time, tear film osmolarity and ocular surface staining parameters were assessed in a single clinical session to allow DED diagnosis based on the guidelines of the Tear Film and Ocular Surface Society Dry Eye Workshop II Diagnostic Methodology Report. A…

Comparison of two artificial tear formulations for dry eye through high‐resolution optical coherence tomography

Purpose:  The aim was to determine the efficacy of two artificial eye-drop formulations by analysing the lower tear film meniscus volume through a commercial high-resolution spectral-domain optical coherence tomographer. Methods:  Twenty dry eye patients (12 men, eight women, aged 57.5 ± 8.4 years) with refractive errors from -2.50 to +0.75 D (mean -1.34 ± 1.02 D) and cylinders lower than 1.00 D were examined. Tear meniscus volume was measured before, immediately after and 10, 30 and 60 minutes after instillation using the Copernicus high-resolution spectral-domain optical coherence tomographer (Optopol Tech SA, Zawiercie, Poland). Volume was calculated from the local area obtained from tom…

Visual and optical performance with hybrid multifocal intraocular lenses

During the past years, the wish to become independent of spectacles has been growing among cataract and presbyopic patients due to many factors, such as the increase in near visual demands, the aesthetic need for a spectacle-free image and ageing of refractive surgery patients, among others. This review assesses recently published studies that analyse visual and optical performance through different metrics of eyes implanted with multifocal intraocular lenses (IOLs), particularly hybrid IOL designs. The published evidence suggests that hybrid multifocal IOLs provide very good outcomes in a number of visual and optical performance parameters. Patients implanted with this type of IOL obtain a…

“In situ” corneal and contact lens thickness changes with high resolution OCT

Purpose: To show the utility of high resolution spectral domain optical coherence tomography (HR SOCT) for the in situ evaluation of epithelial, stromal and contact lens (CL) thickness changes under closed-eye conditions without lens removal. Settings: Clinical and Experimental Optometry Research Lab, University of Minho, Portugal. Methods: Eight young healthy patients wore a thick soft CL during 90 minutes under closed-eye conditions and measures of epithelial and stromal corneal thickness were obtained at regular intervals using a HR SOCT (Copernicus HR, Optopol Tech. SA, Poland). Results: Minimal changes in epithelial thickness were detected with a transient statistically significant inc…

Retroespalhamento luminoso das córneas de pacientes com diabete melito dependente e não dependente de insulina: estudo piloto

ABSTRACT Purpose: To compare central corneal backscatter obtained from Scheimpflug images between patients with insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM and NIDDM, respectively) and healthy controls. Methods: Seven patients with IDDM (7 eyes), eleven patients with NIDDM (11 eyes), and sixteen healthy subjects (16 eyes) were included in this pilot study. Scheimpflug imaging system (Pentacam, Oculus Inc., Germany) was used to obtain optical sections of the cornea. Seven meridians were analyzed for each eye, oriented from 70° to 110°. Optical density values for the central 3-mm and 5-mm zones of the cornea were obtained by image analysis using external software. Resu…

Response of the aging eye to first day of modern material contact lens wear

Objectives: To investigate the ocular surface of an aged population wearing a daily disposable contact lens over their first day of wear. Methods: Forty eyes from forty presbyopic subjects were fitted a daily CL (Delefilcon A). Tear osmolarity, tear meniscus area (TMA) and ocular surface aberrations (total higher order root means square (RMS)) were assessed at baseline (t0), at 20 minutes (t1) and after 8 hours (t2) of wear. Fluorescein corneal and conjunctival staining and tear break up time (TBUT) were performed at t0 and t2. Results: No statistically significant changes were found between t0, t1 and t2 for TMA, and between t0 and t2 for fluorescein corneal and conjunctival staining. TBUT…

Stereoacuity After Refractive Lens Exchange With AcrySof ReSTOR Intraocular Lens Implantation

Purpose: To evaluate stereoacuity before and after refractive lens exchange (RLE) with AcrySof ReSTOR intraocular lens (IOL) implantation. Methods: Stereoacuity was measured using the Titmus stereotest at 40 cm under photopic conditions (85 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR Natural (SN60D3 model) implantation in 30 hyperopic eyes of presbyopes with low astigmatism (⩽1.00 diopter [D]). Stereoacuity measurements after implantation were compared with those found before surgery. Results: Stereoacuity was unchanged after RLE with pseudoaccommodative IOL implantation. In this population of non-cataractous hyperopes with excellent preoperative stereoacuity (46.42±1.36 se…

Comparison of Macular Thickness in Patients with Keratoconus and Control Subjects Using the Cirrus HD-OCT

Purpose.The aim of the present study was to compare macular thickness in patients with keratoconus (KC) with macular thickness in healthy subjects.Subjects and Methods.Twenty-six patients with KC and 52 control subjects were included. The macular structure was evaluated using a Zeiss Cirrus HD-OCT. The scan pattern used was 512 × 128, which covers an area of approximately 6 × 6 mm of the retina. The cube volume was assessed as well as macular thickness in each of the 9 sectors defined by the software.Results.The mean signal strength was significantly lower in the KC group (mean 8.4, range 6–10) compared with the control group (mean 9.7, range 7–10),P&lt;0.0001(unpairedt-test). There were no…

Use of digital displays and ocular surface alterations: A review.

Digital display use has been accepted to be implicated as a contributing factor for dry eye disease (DED). Abnormal blinking during computer operation, including a reduced blink rate and an incomplete eyelid closure, increased palpebral fissure as consequence of high visualization angles, and meibomian gland dysfunction associated to long-term display use, are behind the increased prevalence of dry eye signs and symptoms found in digital display users. Previous research reveals significant reductions in tear volume and stability, alterations in tear film composition, including increased osmolarity, inflammatory cytokines, oxidative stress markers and reduced mucin secretion, eyelid abnormal…

Retinal Straylight Before and After Penetrating Keratoplasty in an Eye with a Post-Herpetic Corneal Scar

Objetivo: Estudio in vivo de la luz dispersa que alcanza la retina en un paciente antes y despues de someterse a una queratoplastia penetrante (o sus siglas en ingles, PKP). Metodos: En un paciente varon de 65 anos con una ulcera corneal herpetica se midio la proporcion de luz dispersa que alcanza la retina tanto antes como despues de una PKP, utilizando para ello un metodo psicometrico denominado "de comparacion por compensacion" («Compensation comparison method», C-Quant straylightmeter, Oculus GmbH, Alemania). Resultados: La cantidad de luz dispersa que alcanza la retina medida antes de la cirugia fue elevada en comparacion con los valores obtenidos en estudios previos en sujetos normale…

Confocal scanning laser ophthalmoscopy versus modified conventional fundus camera for fundus autofluorescence.

Fundus autofluorescence (FAF) is a noninvasive imaging method to detect fundus endogenous fluorophores, mainly lipofuscin located in the retinal pigment epithelium (RPE). The FAF provides information about lipofuscin distribution and RPE health, and consequently an increased accumulation of lipofuscin has been correlated with ageing and development of certain retinal conditions. Areas covered: An exhaustive literature search in MEDLINE (via OVID) and PUBMED for articles related to ocular FAF in retinal diseases and different devices used for acquiring FAF imaging was conducted. Expert commentary: This review aims to show an overview about autofluorescence in the RPE and the main devices use…

Contrast sensitivity after LASIK flap creation with a femtosecond laser and a mechanical microkeratome

ABSTRACT PURPOSE: To compare the effects on contrast sensitivity of the IntraLase femtosecond laser for flap creation (IntraLASIK) and standard LASIK for myopia. METHODS: Two hundred eyes of 100 consecutive patients underwent LASIK treatment using the VISX S2 laser system. The femtosecond laser (15 kHz IntraLase) was used for flap creation in 100 eyes (50 patients) and a mechanical microkeratome (Carriazo-Barraquer) was used in 100 eyes (50 patients). Best spectacle-corrected contrast sensitivity was measured before and 6 months postoperatively in the IntraLASIK and mechanical LASIK groups. The IntraLASIK and mechanical LASIKinduced changes in contrast sensitivity were compared under photop…

Visual performance with simultaneous vision multifocal contact lenses.

Purpose:  The aim was to assess visual performance after PureVision high addition multifocal contact lens (PM) fitting through contrast sensitivity measured under different illumination levels for both distance and near. Methods:  In a cross-over study, 20 presbyopic patients were randomly assigned to PM or spectacles. Near contrast sensitivity was measured with the Vistech VCTS 6500 system. Distance contrast sensitivity and distance visual acuity (VA) were measured with the Functional Vision Analyser under photopic (85 cd/m2) and mesopic (3.0 cd/m2) conditions, the latter also under two levels of induced glare: 1.0 lux and 28 lux. Near VA was measured by logMAR charts under approximately 8…

Objective measurement of intraocular forward light scatter using Hartmann-Shack spot patterns from clinical aberrometers. Model-eye and human-eye study.

Purpose To apply software-based image-analysis tools to objectively determine intraocular scatter determined from clinically derived Hartmann-Shack patterns. Setting Aston Academy of Life Sciences, Aston University, Birmingham, United Kingdom, and Department of Optics, University of Valencia, Valencia, Spain. Methods Purpose-designed image-analysis software was used to quantify scatter from centroid patterns obtained using a clinical Hartmann-Shack analyzer (WASCA, Zeiss/Meditec). Three scatter values, as the maximum standard deviation within a lenslet for all lenslets in the pattern, were obtained in 6 model eyes and 10 human eyes. In the model-eye sample, patterns were obtained in 4 sessi…

Optical quality of the eye after lens replacement with a pseudoaccommodating intraocular lens

To examine the optical quality of healthy presbyopic eyes before and after implantation of the pseudoaccommodating AcrySof ReSTOR Natural intraocular lens (IOL) (Alcon Laboratories) by measuring visual acuity and wavefront aberrations.University of Valencia, Fernández-Vega Ophthalmological Institute, Valencia, Spain.Monocular refraction and photopic distance (6 m) and near (0.33 m) visual acuities were determined before and after clear lens extraction with bilateral AcrySof ReSTOR Natural IOL implantation in 30 hyperopic eyes (+0.50 to +4.00 diopters [D]) of presbyopic patients with low astigmatism (or = 1.00 D). Postsurgical binocular visual acuity was measured over a range of effective di…

An Emerging Method to Assess Tear Film Spread and Dynamics as Possible Tear Film Homeostasis Markers

This study aims to assess the performance of an analysis method to measure in vivo the movement speed of tear film particles post-blink as a measure of tear film spreading. Ocular surface parameter...

Reliability results of straylight measurements using the C-Quant

Purpose Assessment of repeatability and reproducibility of straylight measures with the C-Quant straylightmeter (Oculus AG, Germany), effect of age on reliability measures and correlation of measures determined with new methods of scatter determination. Methods Results from different studies will be presented. For repeatability assessment, 20 eyes (age 26.9±2.7 years) were examined with the C-Quant, taking 10 consecutive readings. 5 subjects were also examined on 5 consecutive days to assess reproducibility. Repeated measures from 84 subjects, age range 19-86 years, were analysed to assess the effect of patient’s age. Software was developed to quantify scatter from centroid patterns obtaine…

Corneal Thickness Response after Anesthetic Eye Drops: Our Own Results and Meta-Analysis.

We aimed to test if there are different patterns in the central corneal thickness (CCT) response after instilling oxybuprocaine anesthetic eye drops and also to determine whether there is a significant change in the CCT. CCT was measured in 60 eyes of 60 healthy subjects before and during the hour after oxybuprocaine 0.4% eye drops were instilled. In addition, a systematic review and meta-analysis were carried out in order to answer the following PICO (patient, intervention, comparison, and outcome) question: What effect do anesthetic eye drops have on CCT values? We found no significant changes in the mean CCT values during the hour’s observation (ANOVA, p=0.209), and the meta-analysis rev…

Retinal straylight in patients with monofocal and multifocal intraocular lenses

Purpose To determine the differences in retinal straylight perceived by patients with monofocal intraocular lenses (IOLs) and patients with multifocal IOLs. Setting Vissum-Instituto de Oftalmologico de Alicante, Alicante, Spain. Methods In this prospective study, contrast sensitivity and retinal straylight were measured prospectively 6 months postoperatively in 67 eyes of 40 patients with a monofocal or multifocal IOL. In the monofocal group, a ThinOptX IOL (ThinOptX, Inc.) was implanted in 12 eyes and an Acri.Smart 48 S IOL (Acri.Tec) in 20 eyes. In the multifocal IOL group, a ReZoom IOL (Advanced Medical Optics) was implanted in 13 eyes and a ReSTOR IOL (Alcon Laboratories) in 22 eyes. Re…

Evaluation of the anterior chamber angle in keratoconus and normal subjects.

To evaluate the anterior chamber angle in keratoconus eyes by use of the Visante™ OCT and Orbscan™ II.Anterior chamber angle was measured with the Visante™ OCT and Orbscan™ II in 52 subjects, 26 KC subjects and 26 age and control subjects.When comparing the nasal and temporal angles obtained with the two techniques no correlation was found (R(2) always below 0.01) in either the control subjects or in the KC subjects. Despite this, there was an overall statistically significant difference in mean anterior chamber angles (p0.001) between Visante™ OCT and Orbscan™ II. There was no statistical difference (p0.05) between nasal and temporal anterior chamber angles when comparing controls and KC s…

Systemic, environmental and lifestyle risk factors for dry eye disease in a mediterranean caucasian population

Abstract Objectives To assess systemic, environmental and lifestyle risk factors for dry eye disease (DED) in a Mediterranean Caucasian population. Methods A cross-sectional study was performed on 120 Caucasian participants aged between 18 and 89 years (47.0 ± 22.8 years). Medical history, information regarding environmental conditions and lifestyle, Ocular Surface Disease Index, Dry Eye Questionnaire-5, non-Invasive (Oculus Keratograph 5 M) breakup time, tear film osmolarity and ocular surface staining parameters were assessed in a single clinical session to allow DED diagnosis based on the guidelines of the Tear Film and Ocular Surface Society Dry Eye Workshop II Diagnostic Methodology Re…

Contrast sensitivity after refractive lens exchange with diffractive multifocal intraocular lens implantation in hyperopic eyes

Contrast Test chart at distance and near under 3 luminance levels (85.0 cd/m 2 , 5.0 cd/m 2 , and 2.5 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR IOL implantation in 30 hyperopic eyes with presbyopia and low astigmatism (%1.0 diopter). Results after surgery were compared with those before surgery. RESULTS: Six months postoperatively, the mean residual spherical equivalent refractive error was 0.21 diopter G 0.19 (SD). The best corrected distance and near visual acuities were comparable to those before surgery. For distance vision, the safety index was 1.02 and the efficacy index was 0.91. For near vision, the values were 1.04 and 1.02, respectively. There were no statistical…

Evaluation of the MGDRx eyebag treatment in young and older subjects with dry eye symptoms

Summary Objectives This study aims to evaluate the relationship between application of the MGDRx thermal eyebag and dry eye signs and symptoms in young and older subjects and to compare the results between the two groups. Methods Thirty young, healthily volunteers between 18 and 31 years of age (23.95 ± 3.94 years) and thirty older subjects between 61 and 90 years of age (77.97 ± 8.11 years) participated in this study. Ocular surface parameters were assessed using the Oculus Keratograph 5 M, following the guidelines of the Tear Film and Ocular Surface Dry Eye Workshop II Diagnostic Methodology report. Only subjects with a positive score on at least one questionnaire and an initial Non-Invas…

Spotlight on fundus autofluorescence.

Fundus autofluorescence (FAF) imaging is based on the fluorescence from ocular endogenous fluorophores located in the retinal pigment epithelium and choroid, mainly lipofuscin and melanin. It is a noninvasive technique that provides information about the spatial distribution of lipofuscin/melanin and retinal pigment epithelium health status. An overview about the fluorophores responsible for FAF imaging and the usefulness of FAF imaging in the noninvasive assessment and monitoring of retinal diseases, such as age-related macular degeneration, diabetic retinopathy, diabetic macular edema, central serous chorioretinopthy, retinitis pigmentosa and retinal dystrophies, are discussed in this rev…

OCT for Assessing Artificial Tears Effectiveness in Contact Lens Wearers

PURPOSE: To apply a commercially available high-resolution spectral domain optical coherence tomographer (SOCT) to assess the change in tear volume after application of a new artificial tears formulation specifically developed for contact lens (CL) users. METHODS: Twenty OD from young healthy CL wearers (mean age, 24.7 ± 3.5 years) with refractive errors ranging from -0.75 to -2.50 D (mean, -1.56 ± 0.69 D) were examined. All subjects were fitted with Focus Dailies CL (Ciba Vision), and two drops of Blink Contacts (AMO), lubricating formulation specifically developed for CL wearers, were instilled after baseline measures. Tear meniscus volume (TMV) was measured immediately after and 1 min, 1…

Book Review

Performance of a new device for the clinical determination of light discomfort

PURPOSE To assess the performance of a new device for the clinical determination of light discomfort on a large sample of healthy human subjects. METHODS A total of 489 subjects ranging from 20 to 70 years old (241 men, 248 women) were evaluated with the LUMIZ™ 100 to determine light discomfort. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Repeated measures ANOVA, Kruskal-Wallis, and correlation analysis were applied to test for differences between repeated measures, and effect of age on reliability. RESULTS Discomfort thresholds obtained are well distributed across the light intensity…

Visual and optical performance with the ReZoom multifocal intraocular lens

Purpose This study evaluated visual acuity, contrast sensitivity, and wavefront aberrations after refractive multifocal intraocular lens (IOL) implantation. Methods A prospective study comprising 174 eyes of 87 patients who had bilateral implantation of a multifocal IOL was carried out. A control group of 100 eyes of 50 age-matched patients with a monofocal IOL was used for comparison. Uncorrected and corrected distance and near visual acuity, contrast sensitivity (CS), and wavefront analysis (Hartmann-Shack) was performed 6 months after surgery. Contrast sensitivity was tested for distance and near under mesopic (2 cd/m2) and photopic conditions (90 cd/m2). Results Distance photopic CS was…

Corneal Aberrations, Contrast Sensitivity, and Light Distortion in Orthokeratology Patients: 1-Year Results.

Purpose. To evaluate the corneal higher-order aberrations (HOA), contrast sensitivity function (CSF), and light distortion (LD) in patients undergoing orthokeratology (OK). Methods. Twenty healthy subjects (mean age: 21.40 ± 8 years) with mean spherical equivalent refractive error M = −2.19 ± 0.97 D were evaluated at 1 day, 1 month, and 1 year after starting OK treatment. Monocular LD, photopic monocular CSF, and corneal HOA for 6 mm pupil size were measured. Results. LD showed an increase after the first night (𝑝 0.05). Spherical-like, coma-like, and secondary astigmatism HOA RMS increased significantly (𝑝 ≤ 0.022) from baseline to 1-month visit, remaining unchanged over the follow-up. C…

The posterior chamber phakic refractive lens (PRL): a review

Implantation of phakic intraocular lenses (pIOLs) is a reversible refractive procedure, preserving the patient’s accommodative function with minimal induction of higher order aberrations compared with corneal photoablative procedures. Despite this, as an intraocular procedure, it has potential risks such as cataracts, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis. Currently, only two models of posterior chamber pIOLs are commercially available, the implantable collammer lens (STAAR Surgical Co.) and the phakic refractive lens (PRL; Zeiss Meditec). The number of published reports on…

Light distortion of soft multifocal contact lenses with different pupil size and shape

Purpose: To study the light distortion effects of soft multifocal contact lenses and the influence of different pupil size and shape.Methods: A total of 14 eyes of 7 healthy contact lens users (mean age 28.6 +/- 8.5 years) were recruited. The "Light Disturbance Analyser" device was employed for light characterization. The selected lenses were the monthly disposable "Biofinity multifocal" (CooperVision, CA, USA), both centre-distance and centre-near designs (addition power + 2.50 D). Two circular pupils of 3 mm and 5 mm of diameter, and an elliptical shape (3 horizontal and 5 vertical mm) were used. Metrics such as the light distortion index (LDI), best-fit circle radius and its irregularity…

Diagnostic Capability of a New Objective Method to Assess Meibomian Gland Visibility

SIGNIFICANCE The diagnosis of dry eye disease and meibomian gland dysfunction (MGD) is challenging. Measuring meibomian gland visibility may provide an additional objective method to diagnose MGD. PURPOSE This study aimed to evaluate the ability of new metrics to better diagnose MGD, based on measuring meibomian gland visibility. METHODS One hundred twelve healthy volunteers (age, 48.3 ± 27.5 years) were enrolled in this study. Ocular surface parameters were measured using the Oculus Keratograph 5M (Oculus GmbH, Wetzlar). Subjects were classified according to the presence or absence of MGD. New metrics based on the visibility of the meibomian glands were calculated and later compared betwee…

Clinical Impact of a Spontaneous Decentration of a Phakic Refractive Lens

PURPOSE To evaluate the clinical impact and possible causes of a spontaneous decentration of a phakic refractive lens (PRL) implanted in a highly myopic eye, and analyzing the visual, refractive, and aberrometric outcome as well as the possible causes for this phenomenon. METHODS The description of a case of bilateral high myopia corrected by implantation with the phakic intraocular lens (pIOL) PRL (Carl Zeiss Meditec, Germany) is presented and documented. Both eyes had similar anatomical configuration, and therefore, a pIOL (Model 101) with the same size was implanted without any associated intraoperative complication. Clinical outcomes were evaluated during a 3-month follow-up. RESULTS Im…

A comparison of the Canon TX-20P™ non-contact tonometer and pachymeter in healthy eyes

Background: The aim of this study was to compare the intraocular pressure (IOP) and the central corneal thickness (CCT) measurements obtained with the Canon TX-20P™ with IOP measured with Goldmann applanation tonometer (GAT) and the CCT measured with ultrasound (US) pachymetry in healthy eyes. Methods: Thirty one healthy voluntary subjects participated in the study, age ranging from 16 to 81 years (mean age 50.9 years). In total 58 eyes were selected for analysis. All measurements were performed by the same examiner. The measurements were taken in the same order in all subjects: Canon IOP and CCT, Goldmann IOP and US CCT. Results: A strong correlation was found between IOP for both CCT comp…

Comparison of partial coherence interferometry and ultrasound for anterior segment biometry.

To assess the performance of a partial coherence interferometry (PCI)-based device for the determination of anterior segment biometry.Clinica Centrofama, Cartagena, Murcia, Spain.Central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) were measured with the ACMaster PCI anterior segment biometer and an Echoscan US-1800 ultrasound (US) biometer/pachymeter with and without cycloplegia. To determine the precision of the instruments, the same examiner took 30 consecutive CCT, ACD, and LT measurements in a single subject under the same conditions and with and without cycloplegia. The same measurements were performed in additional subjects.Twenty-one eyes (16 subjec…

Pilot Study on Visual Function and Fundus Autofluorescence Assessment in Diabetic Patients.

Purpose. Evaluate optimized fundus autofluorescence (FAF) imaging in early stages of diabetic retinopathy (DR) and relate findings with conventional colour fundus imaging and visual function in diabetic patients and control subjects.Materials and Methods. FAF and colour images were obtained using the CR-2 Plus digital nonmydriatic retinal camera in seven diabetic patients and thirteen control subjects. Visual-Functioning Questionnaire-25 (VFQ-25) and Diabetes Self-Management Questionnaire (DSMQ) were used to assess the quality of life and diabetes self-care. Contrast sensitivity function (CSF) was evaluated with the Vistech 6500 chart.Results. FAF and optimized-FAF imaging showed more retin…

Comparison of higher order aberrations measured by NIDEK OPD-Scan dynamic skiascopy and Zeiss WASCA Hartmann-Shack aberrometers.

&lt;h4&gt;PURPOSE&lt;/h4&gt;&lt;p&gt;To compare the measurement of wavefront aberrations in non-cyclopleged human eyes with Hartmann-Shack and dynamic skiascopy wavefront analyzers.&lt;/p&gt; &lt;h4&gt;METHODS&lt;/h4&gt;&lt;p&gt;Eighty eyes of 40 healthy young adults (19 men, 21 women; mean age 20.8±2.5 years) with refractive errors ranging from +1.50 to –9.75 diopters (D) sphere and up to 1.75 D cylinder (mean spherical equivalent refraction –2.12±2.69 D) were examined with the Zeiss/Meditec WASCA and NIDEK OPD-Scan wavefront analyzers and with the Nippon SRW5000 binocular, open-field autorefractor without the instillation of antimuscarinic agents. Three measurements were taken with each s…

Effects of Ageing on the Anterior Segment of the Eye Structure and Function

[Excerpt] The world will soon have more aged people than children and more people at extreme old age than ever before [1]. Improving quality of life as well as reducing severe disability due to age-related problems has become key for the health systems worldwide. The ageing of the world population has both structural and functional consequences for the human visual system; changes due to ageing occur in all the structures of the eye causing a variety of effects. Over the last few years, great advances in ophthalmic instrumentation allow the determination of ocular parameters to a level of detail without precedent. Such advances allowresearcherstodevelopspecificdevicesforvisualcorrection and r…

Corrigendum to “Short-Term Changes in Light Distortion in Orthokeratology Subjects”