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Jose R Davila, James Clay Bavinger, Grace E. Dunbar, Maxwell S Stem, Vinicius M. de Castro, Gregory R Jackson, Thomas W Gardner; Reduced foveal thickness correlates with depressed foveal visual function in eyes with diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2017;58(8):91.
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© ARVO (1962-2015); The Authors (2016-present)
Clinicians are familiar with macular thickening in patients with diabetic macular edema but thinning of the macula has received little attention despite reports of inner retinal thinning in patients with no to mild retinal vascular lesions. Jackson et al. previously reported reduced frequency doubling perimetry (FDP) foveal sensitivity in patients with mild non-proliferative diabetic retinopathy (NDPR) (BJO, 2012), so this study examined the relationship between foveal thickness and foveal function in diabetic retinopathy (DR).
Twenty-four control eyes, 30 eyes with non-proliferative diabetic retinopathy (NDPR), and 24 eyes with proliferative diabetic retinopathy (PDR) were evaluated with FDP using the Matrix perimeter (Carl Zeiss Meditec, Dublin, CA) and spectral domain OCT (Heidelberg, Franklin, MA). No eyes had macular edema or prior macular photocoagulation. Retinopathy severity was classified by the ETDRS scale by two reviewers who were masked to visual field data. Outcome data is expressed as mean ± standard deviation. Kruskal-Wallis and Mann-Whitney U tests were used to compare outcomes. Multivariate regression modeling was used to investigate the effects of age, sex, HbA1c, and DR stage on visual outcomes.
Best corrected logMAR visual acuity was -0.05 ± 0.1, 0.02 ± 0.1, and 0.04 ± 0.1, in controls, NPDR and PDR subjects, respectively. Mean foveal thickness (MFT) was 283 ± 23 μm in controls, 281 ± 22 μm in eyes with NPDR, and reduced to 262 ± 30 μm in eyes with PDR (p < 0.01). FDP mean deviation (MD) and foveal sensitivity (FS) were reduced in PDR eyes compared with controls or NPDR eyes (p < 0.01 for all). FS was 30 ± 5 dB in controls and 22 ± 7 dB in PDR eyes. MFT correlated significantly with FDP MD (p = 0.04) and FS (p = 0.02) after controlling for age, sex, HbA1c, and DR stage in multivariate regression analysis. DR severity correlated significantly with FS (p = 0.004) but not MD.
Decreased MFT correlates closely with MD and FS, suggesting MFT as a marker for foveal functional impairment in diabetic retinopathy. These findings represent a previously unrecognized feature of DR and additional studies are underway to determine the mechanism of this aspect of visual impairment due to diabetes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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