Abstract
Purpose :
Glaucoma can cause dramatic reduction in visual field prior to any loss of high contrast visual acuity (VA). However, spatial and temporal contrast sensitivity (CS) and color vision can be impaired early in glaucoma. Our purpose was to quantify novel measures of CS and VA with and without glare in a heterogenous cohort of glaucoma patients to develop new metrics for detection and monitoring.
Methods :
30 subjects (mean age 54 ± 12, 23 females) with diagnosed or suspected open or narrow angle glaucoma, scheduled to undergo laser peripheral iridotomy, participated in our IRB approved protocol after written informed consent. Measures included high contrast VA with and without glare (BAT; Brightness Acuity Tester, Marco Ophthalmic), CS across four spatial frequencies (3, 6, 12, 18 CPD) with and without glare (Vector Vision/Guardion: VVG CS), and Pelli-Robson CS. Repeated measures ANOVA, t-tests and sensitivity analyses were used to evaluate CS metrics.
Results :
Mean VA (n=60 eyes) without glare was 0.053 log MAR and slightly decreased (.084) with glare (P < .03). However, two-way ANOVA of VVG CS across spatial frequency and glare showed a significant effect of spatial frequency (F=71.4, P <.0001) but no significant effect of glare (F = 2.53, P = 0.1). The VVG CS test did reveal decreased CS in 54% to 79% of eyes across four spatial frequencies with the greatest decrease at 12 CPD (20/50 equivalent). Moreover, the sum of VVG log CS values computed to approximate area under the CS curve showed that 74% of eyes were below age comparable norms, with Pelli-Robson log CS (mean 1.47) below age norms in 68% of eyes (Elliot et al., 1990).
Conclusions :
Glare disability did not prove to be a strong index of glaucomatous dysfunction, but CS is often decreased in various types and degrees of glaucoma including suspects. Pelli-Robson large letter (20/700) CS proved sensitive, as did VVG higher spatial frequency CS (20/50) also measurable with small letter CS testing, a potential new metric for glaucoma. Finally, the VVG test can be used to sum log CS across spatial frequencies as a sensitive, expedient metric of overall CS which may prove useful to monitor vision in advanced disease.
This is a 2021 ARVO Annual Meeting abstract.