Abstract
PurposeWe investigated the effects of retinal ischemia, neurodegeneration, and subclinical edema on best-corrected visual acuity (BCVA) in the early stages of diabetic retinopathy (DR).MethodsIschemia was evaluated by the microvascular parameters measured by optical coherence tomography angiography. Neurodegeneration and subclinical edema were identified by the intraretinal layer thickness obtained by optical coherence tomography. Eyes with nonproliferative diabetic retinopathy (n = 132) from 89 patients were analyzed. Eyes were classified as having normal BCVA (n = 88 [66.7%], Snellen equivalent ≥ 20/20) or decreased BCVA (n = 44 [33.3%], Snellen equivalent < 20/20). The prevalence of ischemia, neurodegeneration, and subclinical edema was explored in patients with and without decreased BCVA, and correlations between BCVA and these pathological pathways were determined.ResultsVessel density in the deep retinal capillary plexus (DRCP) and thickness of ganglion cell layer plus inner plexiform layer (GCL-IPL) were significantly lower in eyes with decreased BCVA compared with eyes with normal BCVA (both P < 0.05). In the final multiple regression predictive model, age, DRCP vessel density, and GCL-IPL thickness (all P ≤ 0.044) were predictors of BCVA. DRCP vessel density and GCL-IPL thickness have an interactive effect on visual acuity. The proportions of ischemia and neurodegeneration were significantly higher in eyes with decreased BCVA than in eyes with normal BCVA (P = 0.001 and P = 0.004, respectively).ConclusionDuring the natural course of the early stages of DR, ischemia and neurodegeneration were the main disease pathways associated with visual acuity, and the mechanisms varied among patients.
Highlights
Diabetic retinopathy (DR) is a leading cause of vision impairment and blindness among working adults worldwide [1]
This is because commonly measured parameters, such as the size of the foveal avascular zone (FAZ) assessed by fluorescein angiography and whole retinal thickness assessed by optical coherence tomography (OCT) are of limited use for characterizing ischemia, neurodegeneration, and edema present in the early stages of DR
Based on multiple regression models that affected the best-corrected visual acuity (BCVA) outcome, we explored the interactions between the ganglion cell layer plus inner plexiform layer (GCL-inner plexiform layer (IPL)) thickness and deep retinal capillary plexus (DRCP) vessel density with BCVA as the outcome (Table 5), and the interaction was observed to be significant (P < 0.001)
Summary
Diabetic retinopathy (DR) is a leading cause of vision impairment and blindness among working adults worldwide [1]. DR is conventionally described as a microvasculopathy; the gold standard of severity classification is based on this concept [7], and greater levels of DR severity usually correspond to worse vision loss This correlation is very weak in nonproliferative diabetic retinopathy (NPDR) [8, 9]. There is no information regarding any potential interaction of these phenotypes that can affect visual acuity in the early stage of DR in patients who have no apparent macular complications This is because commonly measured parameters, such as the size of the foveal avascular zone (FAZ) assessed by fluorescein angiography and whole retinal thickness assessed by optical coherence tomography (OCT) are of limited use for characterizing ischemia, neurodegeneration, and edema present in the early stages of DR
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