Abstract
Eyes with long axial lengths exhibit thinning of the inner retinal layers, which is associated with increased multi-focal ERG latencies. The goal was to determine if central and peripheral retinal thinning is associated with temporal contrast sensitivity (TCS) deficits. Measurements were made on 21 subjects with refractions from 0.25 D to −9.25 D and axial lengths from 22.65 to 27.51 mm. TCS for sinusoidal flicker was measured from 2 to 40 Hz at the fovea, and at 7° eccentricity in the superior and inferior retina. The stimulus was a 1° s.d. Gabor patch on a uniform white field. Retinal thickness in the fovea (central 1 mm) and perifovea (3–6 mm ring) was measured with a spectral domain OCT. Full retinal thickness is the thickness from the retinal pigment epithelium (RPE) to the inner limiting membrane (ILM); inner retinal thickness is the thickness from the inner plexiform layer (IPL) to the ILM. Foveal TCS at 5 to 40 Hz was significantly lower in subjects with central 1 mm full retinal thickness below 246 microns (p< 0.05 in t-tests) but was not significantly related to axial length. TCS at 30 Hz in the superior and inferior retina was significantly lower in eyes with smaller inner retinal layer thickness in the perifoveal ring (p< 0.05 in regressions); superior retina TCS was similarly correlated with superior hemifield and superior quadrant inner thickness (p< 0.05). Subjects with axial lengths longer than the mean of 24.29 mm exhibited significantly decreased TCS at 30 Hz (p=0.025) and 40 Hz (p=0.03) in the inferior retina and at 40 Hz (p=0.016) in the superior retina. Thinning of the fovea and inner perifoveal retina is associated with decreased temporal contrast sensitivity in the corresponding visual field region, which may indicate reduced function of retinal neurons where the retina is thinned.
Acknowledgement: MCPHS University