Abstract
Purpose :
Contrast sensitivity loss in early retinal and optic nerve diseases is often spatial frequency selective. Here we determine the sensitivity of a new spatial contrast sensitivity (SCS) vision chart [Adhikari, Carter, Feigl & Zele, 2022, 2023] for detecting photopic and mesopic visual abnormalities compared to high contrast visual acuity.
Methods :
We recruited 99 people, including 54 patients with eye conditions (9 people with diabetes without diabetic retinopathy, 10 with early age-related macular degeneration (AMD), 24 glaucoma suspects, 11 high myopes (> -6 D), and 45 age-matched healthy controls (age range: 20 - 88 years). SCS was measured in the central retina using a printed version of the chart with 10 radial axes each at a fixed contrast (0.28 - 100% Weber), and with a different spatial frequency in each row of the rings (3 - 60 c/°). In glaucoma suspects and controls, SCS was also measured at a fixed frequency of 1.5 c/° at 12 peripheral retinal locations (5°, 10°, and 15° eccentricities; each at 45°, 135°, 225°, and 345° meridians). Measurements were performed in photopic (~123 cd.m-2) and mesopic (~1 cd.m-2) lighting.
Results :
All participants with eye conditions had a 6/6 visual acuity in photopic lighting at ~18% contrast, but did not reach 6/6 at 100% contrast in mesopic lighting. Compared to healthy controls, SCS was significantly lower in AMD at 3, 6, 8, and 12 c/° with greater reductions in mesopic lighting. In patients with diabetes, SCS was significantly reduced at 6 and 8 c/°, and in high myopia at all tested frequencies (3 - 60 c/°). Glaucoma suspects had normal central SCS but exhibited reduced peripheral SCS, with greater reductions in mesopic lighting. In healthy controls, the SCS function was low pass, with a generalised downward shift in mesopic lighting described by a linear function where Mesopic SCS = 1.25*Photopic SCS-1.38 (log units).
Conclusions :
The spatial contrast vision chart detects frequency-selective contrast deficits in the early stages of central and peripheral retinal and optic nerve abnormalities in patients with normal high contrast visual acuity. The pattern of spatial vision loss is disease dependent. Additionally, we provide a simple model for predicting mesopic SCS from photopic SCS, relevant in diseases where mesopic vision offers increased sensitivity to the presence of subtle vision deficits.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.