Abstract
Purpose: :
Subjects with high myopia exhibit selective thinning of the inner retina (Shao and Coletta, ARVO, 2011; Shao et al., AAO, 2011). Wolsley et al. (Vis. Res., 2008) found that thinning of the inner retina in myopia correlated with increased mfERG latencies. Our goal was to determine if thinning of the perifoveal inner retina is associated with temporal contrast sensitivity deficits at the corresponding visual field position.
Methods: :
Refractive errors of 15 subjects ranged from 0.00 D to -9.00 D and axial lengths ranged from 22.6 to 27.5 mm. An Optovue RTVue spectral domain OCT was used to measure perifoveal retinal thickness in the 3-6 mm diameter ring, covering approximately 4.5° to 9° eccentricity, sub-divided into quadrants. Inner retinal thickness was defined as the thickness from the inner plexiform layer (IPL) to the inner limiting membrane (ILM). Temporal contrast sensitivity was measured at 7° superior and 7° inferior retinal eccentricity. The stimulus was a 1° s.d. Gabor patch on a uniform 60 cd/m² white field. Temporal contrast sensitivity was measured at frequencies 2, 5, 10, 20, 30, and 40 Hz with sinusoidal flicker.
Results: :
Subjects with axial lengths greater than the median of 24.11 mm exhibited significantly decreased temporal contrast sensitivity at high frequencies of 30Hz and 40Hz (p=0.031 and p=0.032, respectively) in the inferior perifoveal quadrant. This effect was also suggested in the superior perifovea but was not significant (p>0.05 at 30 Hz and 40 Hz). Subjects with inner retina thinner than 100 micron in the inferior perifoveal quadrant had significantly decreased temporal contrast sensitivity at 40 Hz (p=0.038) at the corresponding 7° inferior retinal eccentricity.
Conclusions: :
Subjects with long axial lengths exhibit diminished temporal contrast sensitivity at high frequencies in the inferior perifoveal quadrant. Thinning of the 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 inner retina is thinned.
Keywords: myopia • temporal vision • imaging/image analysis: clinical