Posters

Test of visual Strehl ratio metric to predict visual performance in healthy and cataract eyes

Poster Details

First Author: S. Gholami NETHERLANDS

Co Author(s):    T. van den Berg   N. Reus                 

Abstract Details

Purpose:

We tested the use of ocular visual Strehl ratio (VSR), an image quality metric derived from wavefront aberrations, as means to quantify the severity of age-related cataract in terms of visual acuity (VA). VSR is the ratio of the impact of the (aberrated) retinal Point Spread Function (PSF) at stimulating the neural portion of the vision to the impact of an ideal (unaberrated) PSF. This metric was proposed by L. Thibos and R. Applegate as a tool to predict VA. In this study, we wanted to independently evaluate the VSR as a predictor of VA in healthy and cataract eyes.

Setting:

Rotterdam Ophthalmic Institute, Netherlands

Methods:

In this exploratory observational study, we included 20 eyes of 20 patients with nuclear, cortical, and posterior subcapsular cataract and 20 healthy eyes of 10 healthy subjects. Mean age was 36 ± 11.8 years in the healthy group and 70 ± 8.3 years in the cataract group. We calculated the VSR from aberrations as well as sphere and cylinder errors. Ocular aberrometry (using ORK, Schwind) and measurement of uncorrected distance visual acuity (using standard ETDRS chart) were performed in all subjects.

Results:

VA decreased linearly as a function of ocular VSR in both groups. The slope of the regression line (log(MAR) = a + b x log(VSR)) was 0.32 and 0.25 in the healthy and cataract groups respectively. The difference in regression between two groups was not significant. The correlation between ocular log(VSR) and log(MAR) was significant in both groups (r = -0.89 and r = -0.72 in the healthy and cataract groups respectively, P < 0.05 in both groups). The relation we have found corresponds with that of the original authors.

Conclusions:

We looked at the possibility of using one image quality metric called visual Strehl ratio measured in frequency domain which is derived from wavefront aberrations as means to quantify particularly the severity of age-related cataract in terms of visual acuity. We conclude that visual acuity can be predicted from this metric in both healthy and cataract eyes.

Financial Disclosure:

NONE