Spectral Domain Optical Coherence Tomography Parameters Associated with Visual Acuity in Patients with Resolved Center-Involved Diabetic Macular Edema

Abstract

Purpose: : Visual acuity (VA) is only modestly correlated with optical coherence tomography (OCT) measured macular center subfield thickness (CST). Thus, we studied additional retinal parameters on Spectral Domain OCT (SD OCT) that may better correlate with VA.

Methods: : Patients with current (N=6 eyes) or resolved ciDME (N=7 eyes) had ETDRS VA testing before peripapillary and macular imaging using Spectralis SD OCT (Heidelberg Engineering, Heidelberg, Germany). Retinal layers were segmented by customized Matlab software and manually corrected using a high resolution interactive digital tablet: nerve fiber (NFL), ganglion cell & inner plexiform (GCL-IPL), inner nuclear & outer plexiform (INL-OPL), outer nuclear (ONL), and photoreceptor & RPE (Ph-RPE). Masked graders evaluated the presence and location of structural disorganization, intraretinal cysts, subretinal fluid, epiretinal membranes, hard exudates, and photoreceptor disruption using standardized data collection forms.

Results: : Thirteen eyes of 9 subjects had active ciDME/good VA (CST=>310 µm, VA>=20/25, N=6), resolved ciDME/good VA (CST<310 µm, VA >=20/25, N=3), or resolved ciDME/poor VA (CST<310 µm, VA<20/32, N=4). All ciDME/poor VA group had been treated with anti-VEGF therapy and 3 eyes had a history of macular laser. Of the 3 resolved ciDME/good VA eyes, 2 eyes had been treated with focal laser and 1 eye had received anti-VEGF therapy. There was no statistical relationship between VA and CST; however, poor VA outcome was strongly associated with the presence of any disruption of the photoreceptor layer (p= 0.006, 0% of active ciDME/good VA, 33.3% resolved ciDME/good VA eyes, 100% resolved ciDME/poor VA eyes). Photoreceptor disruption in the central macula was more highly correlated with visual loss than disruption in the more peripheral macula (p= 0.006 vs. p= 0.01). Temporal peripapillary retinal NFL thickness, previous treatment modality, and the presence of intraretinal cystic changes, subretinal fluid or epiretinal membranes were not significantly associated with VA among the three groups.

Conclusions: : SD OCT identified disruption of the photoreceptor layer is highly associated with poor VA outcome in patients with resolved ciDME. This finding might eventually be used to predict functional treatment response and provide future insights into mechanisms of VA loss.

Keywords: edema • imaging/image analysis: clinical • diabetic retinopathy