Abstract
Purpose: :
To evaluate effect of nuclear cataracts (NC) upon visual acuities measured in mesopic and glare conditions using the Central Vision Analyzer (CVA) and equivalent ETDRS charts, and to determine the relationship with measures of straylight and visual task impairment.
Methods: :
22 eyes with a nuclear lens opacity (>NO3,NC3 LOCSIII grading) were examined. Visual acuity was tested with the CVA interactive program under 3 mesopic (99%, 50% and 25% MC, against 3cd/m 2 background) and 2 glare environments (98%, 10% and 8% MC against 200 cd/m2background). Acuity was also measured with equivalent MC ETDRS charts in the same dark room and then in sunlight with a 15% MC ETDRS chart. Straylight was evaluated by C-Quant and task impairment assessed using the Activities of Daily Living questionnaire (ADVS). NC results were compared with an age-matched control group of 50 emmetropic eyes without cataract.
Results: :
Compared to control eyes, a significant reduction in VA that exceeded test-retest reliability of 0.15 logMAR was found for NC eyes for the 3 CVA glare modules, averaging 0.2 logMAR worse with 10% MC, 0.27 logMAR with 98% MC, and 0.3 logMAR with 8% MC. Excellent Pearson correlation (r=0.75 to 0.95, p<0.05) and Bland&Altman agreement was found between CVA acuities and acuities obtained with similar contrast ETDRS charts, and between acuities with CVA 10% MC and 8% MC glare modules and acuities obtained with 15% MC ETDRS chart placed with the sun overhead and at 15o off-axis. Significant correlation was observed between C-Quant log(s) and acuities obtained with the 10% and 8% glare CVA modules (r=0.530, p=0.02 and r=0.641, p=0.01), but correlation of neither with LOCS III grading (p>0.05). Subgroup analysis of ADVS for driving tasks provided significant correlation with acuities of both 98% CVA modules and 50% and 25% mesopic modules (Spearman r=0.851 to 0.573, p<0.05) while near tasks correlated with all modules. C-Quant straylight log(s) correlated only with distance tasks (r=0.822, p<0.01).
Conclusions: :
Vision deterioration was found for eyes with nuclear cataract under glare environments when there was no reduction of high or low contrast mesopic acuity. CVA 10% and 8% MC glare module testing, conducted in a darkened room, produced similar acuities as 15% MC ETDRS charts placed in sun-filled environments, validating observations by Vos. C-Quant straylight measurements significantly correlated with the acuities measured with the CVA glare modules, but understanding the relationship with visual task impairment will require further investigation.
Clinical Trial: :
Ehtikkommsion der Stadt Wien Austria, EK 07-110-VK
Keywords: contrast sensitivity • visual acuity • cataract