6533b872fe1ef96bd12d3969

RESEARCH PRODUCT

Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes

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Color perimetry has interesting clinical application for the diagnosis and detection of certain eye conditions, due to the variations that certain diseases can cause in chromatic thresholds, both in the red-green (RG) and the blue-yellow (BY) pathways.[1,2,3,4] The separate study of the visual function of both the chromatic and achromatic mechanisms could be more efficient in detecting sensitivity variations, and such variations would not be obscured by the intrusion of other mechanisms. Currently, the supply of conventional perimeters that are capable of performing a chromatic perimetry test is very limited and with reduced options regarding the possibility of choosing the physical characteristics of the stimulus (see Monhart[5] for a review of the available techniques). For the study that we have carried out, we have used a multichannel perimetric technique, which provides the user with the choice of a wide range of characteristics of the stimulus, such as chromaticity, spatial and temporal frequency, size, duration or border smoothing.[6,7] It allows measurements of contrast sensitivity in different directions of the color space and with stimuli with different space-time features with a dual objective: to determine in which pathway the losses are greater and to maximize the probability of detecting these losses by modifying the detectability of the stimuli by means of their spatiotemporal frequency content. This procedure has the additional advantage of yielding results that can readily be compared between stimuli, since the task performed by the observer is always the same. With this technique, we hope to detect early functional losses, before clinical signs are observable or in the asymptomatic stages, which with conventional perimetry testing could still go unnoticed. The interpretation of the results would be much easier if we could ensure that in each stimuli used we are isolating a particular visual mechanism. Unfortunately, although selected stimuli particularly favor a single mechanism, we cannot be sure of silencing the rest. Mechanism isolation would improve the ability to detect loss of functionality of the visual system, according to previous results[8,9,10,11] and this is the motivation behind different lines of research based in the multichannel perimetry technique used in this paper. Focusing in this type of the perimetric test, our aim is to illustrate how different perimetric techniques contribute to gain a clearer picture of the functional losses experienced by a given patient. To this end, we show four illustrative cases of two pathologies affecting the visual system (glaucoma and diabetes), at two stages of the evolution of the disease (patients with and without obvious clinical signs).