Psychophysical Evaluation of Retinal Straylight among Argentinean Subjects

LONGHI, EMILIA; ISSOLIO, LUIS A; COLOMBO, ELISA M.; FIX VENTURA, DORA; FERNANDES DA COSTA, MARCELO

Fort Lauderdale, Florida

Congreso; ARVO 2011 Annual Metting; 2011

ARVO

Purpose: To measure retinal straylight in an Argentinean population and to compare it with European norms. Methods: Straylight was assessed using C-Quant that uses an adaptive staircase method (Compensation Comparison, Franssen et al., IOVS, 47: 768, 2006). 30 subjects were tested (mean age = 41.39±14.19 yrs). Refractive errors were corrected in the C-Quant apparatus, and the subjects could have ocular diseases or vision-threatening conditions (e.g., diabetes, unregulated blood pressure, high intraocular pressure, clinical diagnosis of cataract), but all subjects had 20/20 visual acuity (with correction, if necessary). Only 6 subjects (20%) had lightly-pigmented eyes. Each eye was tested 3 times, yielding 6 straylight values (s) per subject. Only data fulfilling C-Quant reliability criteria were included. Results: There were no statistical differences between Argentinean straylight values and European norms for this sample (t=0.710, p>0.480). However, there was an evident tendency for the Argentinean straylight values to be higher than the European norms, mainly among the young subjects (between 18 and 30 yrs), and to approach the norms when subjects are older. Conclusions: Consistent with European norms, light-scattering increases with age in the Argentinean sample. This increase is thought to be due, in large part, to age-related changes in lens structure and density. Although the differences between the populations are not significant, the tendency for Argentinean data (mainly young subjects) to have higher straylight values than European values is in the opposite direction from that expected from a dark-eyed population, since darker eyes means less straylight. This suggests the hypothesis that environmental light differences, maybe latitude-dependent (San Miguel de Tucumán, ARG, latitude 26.81ºS, European latitudes between 40ºN to 55ºN) differences could be associated with differences in straylight values among young subjects, and a biological factor could rule straylight among older subjects, getting them close to the norms.