South American Values of the Optical Straylight Function

Purpose: To access retinal straylight in a Brazilian sample and to compare it with European norms. Methods: Absolute Straylight was assessed using C-Quant that uses an adaptive staircase based on a 2-Alternated Forced Choice task. A young (22.2 ± 2.4 yrs, n = 20) and an old group (53.8 ± 7.4 yrs, n = 21) of subjects were tested. All refractive errors were corrected in the C-Quant device, and no subjects had ocular diseases or vision-threatening conditions (e.g., diabetes, unregulated blood pressure, high intraocular pressure, visible cataract). Eighty-five percent of all subjects in each age group had dark-pigmented eyes. Each eye was tested 3 times, yielding 6 straylight values (s). Only data fulfilling C-Quant reliability criteria were included. Results: There were no statistical differences between the three attempts on each eye (ANOVA, F = 0.993, p > 0.936) and between the two groups (ANOVA, F = 0.893, p > 0.725). Straylight values (s) were fit with an empirical equation to compare to European norms. There were no statistical differences between Brazilian straylight values and European norms for either young or old age groups (ANOVA, F = 5.114, p > 0.993). However, there was a tendency for our s values to be higher than the European norms, consistent with young Brazilian eyes having more light-scattering than age-matched European eyes. Conclusions: Consistent with European norms, light-scattering increases with age in the Brazilian 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 Brazilian data to have higher s values than European values, especially at young subjects, is in the opposite direction from that expected from a dark-eyed population. This suggests the hypothesis that latitude-dependent (Sao Paulo, latitude 23° S, European latitudes between 40° N to 55° N) differences in the light environment could be associated with differences in s values.

Comparison of the Retinal Straylight in Pseudophakic Eyes with PMMA, Hydrophobic Acrylic, and Hydrophilic Acrylic Spherical Intraocular Lens

Purpose. To investigate the intraocular straylight value after cataract surgery.Methods. In this study, 76 eyes from 62 patients were subdivided into three groups. A hydrophobic acrylic, a hydrophilic acrylic, and a PMMA IOL were respectively, implanted in 24 eyes, 28 eyes, and 24 eyes. Straylight was measured using C-Quant at 1 week and 1 month postoperatively in natural and dilated pupils.Results. The hydrophilic acrylic IOLs showed significantly lower straylight values than those of the hydrophobic acrylic IOLs in dilated pupils at 1 week and 1 month after surgery (P<0.05). However, the straylight values of the hydrophilic acrylic IOLs were the lowest among the three IOL groups. No significant difference was observed in straylight between 1 week and 1 month postoperatively in each group with natural and dilated pupils (P>0.05). Moreover, no significant difference was found in straylight between natural and dilated pupils in each group at 1 week and 1 month postoperatively (P>0.05).Conclusions. Although the hydrophobic acrylic IOL induced more intraocular straylight, straylight differences among the 3 IOLs were minimal. Pupil size showed no effect on intraocular straylight; the intraocular straylight was stable 1 week after surgery.