Abstract
Purpose :
Visual acuity assessed using standard charts is not as effective for evaluation of vision in patients with acuity worse than 20/200 nor does hand motion or finger counting assessments provide the accuracy required in the drug development process. Moreover, Inherited retinal disease patient subpopulations are often pediatric and lack communication skills. The availability of an objective method of assessment for this population group is thus a clear need. The objective of the present study is the development of such a method using the well-known concept of optokinetic response (OKN).
Methods :
A succession of striped stimuli viewed at 40cm were presented on a tablet computer to a group of four normally sighted subjects. Successive Luminit light shaping diffusive media were used to reduce visual acuity to approximate 1.8, 2.4 and 2.6 logMAR levels. Saccadic OKN eye movements were identified using an automated eye tracker. Stripe widths of the stimuli were presented from logMAR 1.0 (20/200) to 3.4. The width of the stripe was varied to determine a threshold. Three thresholds were determined at each level.
Results :
Thresholds were obtained quickly and repeatably for the test subject group for both the 1.8, 2.4 and 2.6 LogMAR reference levels. Mean assessed visual acuity for all subjects was 1.84 ± 0.019, 2.31 ± 0.039 and 2.56 ± 0.032logMAR. Thresholds showed good agreement with computer displayed optotypes sized for 1.8 and 2.4 logMAR.
Conclusions :
An objective visual testing method based on OKN may prove useful in tracking effect of treatment in retinal and optic nerve disease subjects with very low vision. This test is currently being evaluated in a trial for low vision pediatric patients.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.