0000000000329606
AUTHOR
César Albarrán Diego
Validation of a set of compact and low-cost Stokes lenses aimed at refractive astigmatism measurement for optometric practice
We describe the construction and characterization of three Stokes lenses that can be used in optometric practice to measure different ranges of refractive astigmatism using subjective routines. The proposed set of Stokes lenses is assembled from Risley prism mounts coming from a Nidek phoropter in which the optical prisms are replaced by three different sets of cylindrical lenses ( ± 0.75, ± 1.25, and ± 1.75 D) coming from a trial lens case to cover a different astigmatism range (1.5, 2.5, and 3.5 D in modulus, respectively). We present the experimental characterization of the three Stokes lenses with the power vector notation and use an automatic lensmeter (Topcon CL-300) for dioptric powe…
Lentes intraoculares multifocales refractivas de nuevo diseño segmentado
La presbicia y las cataratas son dos condiciones oculares relacionadas con el envejecimiento del cristalino, que presentan una elevada incidencia conjunta por encima de los 60 años. Dada la tendencia, claramente visible en los estudios de pirámides poblacionales, al envejecimiento en la población mundial por la mayor esperanza de vida, ambas condiciones van a tener una enorme incidencia en el futuro. Ambas comparten una opción terapéutica común: la sustitución del cristalino por una lente intraocular multifocal (LIOMTF), que permite a los pacientes restaurar su visión y además obtener un amplio rango de distancias con visión funcional sin necesidad de ayudas ópticas. En la actualidad existe…
Binocular vision alterations after refractive and cataract surgery: a review.
To review binocular and accommodative disorders documented after corneal or intraocular refractive surgery, in normal healthy prepresbyopic patients. A bibliographic revision was performed; it included works published before 1st July 2017 where accommodation and/or binocularity was assessed following any type of refractive surgical procedure. The search in Pubmed yielded 1273 papers, 95 of which fulfilled the inclusion criteria. Few publications reporting binocular vision and/or accommodative changes after refractive surgery in normal subjects were found. The reduction in fusional vergence is the most frequently reported alteration. Anisometropia is an important risk factor for postoperativ…
An alternative clinical routine for subjective refraction based on power vectors with trial frames.
PURPOSE Subjective refraction determines the final point of refractive error assessment in most clinical environments and its foundations have remained unchanged for decades. The purpose of this paper is to compare the results obtained when monocular subjective refraction is assessed in trial frames by a new clinical procedure based on a pure power vector interpretation with conventional clinical refraction procedures. METHODS An alternative clinical routine is described that uses power vector interpretation with implementation in trial frames. Refractive error is determined in terms of: (i) the spherical equivalent (M component), and (ii) a pair of Jackson Crossed Cylinder lenses oriented …