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Hilde Røgeberg Pedersen, Lene Aarvelta Hagen, Erlend Sommer Landsend, Jon V. B. Gjelle, Øygunn Aass Utheim, Stuart J. Gilson, Tor Paaske Utheim, Rigmor C Baraas; Color vision, dark adaptation and retinal structure in Aniridia. Invest. Ophthalmol. Vis. Sci. 2016;57(12):623. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate color vision, dark adaptation and retinal structure in individuals with aniridia
Twenty-seven males and females, aged 11–67 yrs, with aniridia were included in the study. Color vision was examined with HRR pseudo-isochromatic plates (4th ed., 2002) and the Color Assessment and Diagnosis (CAD) test. Observers viewed the CAD stimulus binocularly with optimal optical correction from a 1.4 m distance. Stimuli size was 2.2 deg with increased luminance noise and slower speed to mask rod intrusion. Color-vision deficiency (CVD) was defined if CAD thresholds in standard normal units (SNU) > 2.5. Rod and cone mediated dark adaptation (DA) were measured with the Roland Consult DarkAdaptometer after a 5 min photobleach (7000 cd/m2) with fixation target at 20 deg temporal eccentricity. Speed of DA was characterized by the time to the rod-cone break (TRCB). Visual acuity (VA), corneal and lens opacities were assessed. Retinal straylight was measured with the Oculus C-Quant using the compensation comparison method. The central 30 deg of both eyes were imaged with the Heidelberg Spectralis OCT. Foveal, para- and perifoveal retinal layers and severity of foveal hypoplasia (FH) were analyzed by calculating longitudinal reflectivity profiles (LRP) after correction of scaling for individual axial length.
VA ranged from logMAR 0.00–1.76. Two subjects were classified with tritan and three with red-green (RG) CVD on the HRR. Five males and 13 females were classified to have a RG CVD on the CAD (RG threshold 2.6–16.6 [SNU]). Three of these were also classified with tritan CVD (YB threshold 4.5–11.6 [SNU]), including the two HRR-classified tritans. The three with RG CVD on the HRR had CAD RG of 3.1, 4.9 and 8.4. TRCB was normal compared with age-matched controls. Measurements of retinal thickness, relative lengthening of the photoreceptor layer and outer nuclear layer, showed a considerable variation in FH grade. A significant positive correlation was found between FH severity, logMAR VA (p<0.001) and RG threshold (p=0.02). LogMAR VA, RG and YB thresholds increased with keratopathy severity (all p<0.05). No significant correlations were found between RG threshold and age, lens opacities or retinal straylight.
The results suggest that the observed red-green deficiencies may be secondary to foveal hypoplasia as a consequence of a central structural organization that is similar to that in normal perifovea.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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