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Clemente Paz, Roberto Sanchez, Elisa Colombo, Luis Issolio; Contrast threshold measurement system in N and PSC cataract. Journal of Vision 2013;13(15):P15. doi: 10.1167/13.15.50.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To analyze the performance of a computerized system for threshold contrast measurement in the quantification of intraocular scattering in cataract eyes using a clinically validated straylightmeter as reference.
Materials and Methods: In a first stage the ophthalmologist separated two cataract groups regarding the cataract type: 21 eyes with nuclear cataract and 22 with posterior subcapsular cataract. The selection procedure considered a wide cataract development range, from early to mature cataract. An exclusionary condition was set and it consisted in BCVA higher than 0.6. In a second stage performed at the Visual Optic Laboratory straylight and contrast threshold measurement were performed with psychophysics systems C-Quant and FVC100 respectively. C-Quant uses the compensation comparison method to obtain a straylight measurement and FVC100 uses sinusoidal gratings of different spatial frequencies to find the contrast threshold. In this study, only one spatial frequency (2c.p.d.) measurements were performed and the representative value of each eye was the average of five replications. Then correlation between these two variables was analyzed through statistic software.
Results: Different regression models were applied and it was found that the best data fitting in both cataract types was exponential. In nuclear cataract case the R2 correlation coefficient resulted 0.69 while in posterior subcapsularcase it was 0.67.
Discussion: Our results suggest that contrast threshold measurement from FVC100 is a useful tool to be performed as clinical test considering both nuclear and posterior subcapsular cataract quantification.
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