Evaluating Retinal Sensitivity Losses on Microperimetry in Diabetic Macular Ischemia – One Year Result

Abstract

Purpose : To report microperimetry changes over one year in diabetic macular ischemia (DMI), defined as optical coherence tomography-angiography (OCT-A) confirmed foveal avascular zone (FAZ) ≥0.5 mm² or parafoveal capillary dropout ≥1 quadrant.

Methods : This one-year prospective observational study was conducted at two tertiary centers. Eighty-eight stable-treated proliferative diabetic retinopathy patients (97 eyes) with evidence of DMI and best-corrected visual acuity ≥54 Early Treatment Diabetic Retinopathy Study letters (Snellen equivalent 20/80) were recruited. Microperimetry was done to assess the mean change in overall retinal sensitivity (oRS) and point-wise sensitivity (PWS) at baseline and twelve months within the 3x3 millimeter (mm) macula. Decreased retinal sensitivity (RS) was defined as <25 decibels (dB). Severe and mild RS losses were defined as 7 and 2 dB losses in PWS, respectively. The areas most vulnerable to RS loss were explored.

Results : There was no statistically significant change from baseline in mean oRS at one year. Only 1% had severe oRS loss of ≥7 dB, and 4% lost ≥7 dB in ≥5 loci, while 10% showed mild oRS of ≥2 dB, and 73% lost ≥2 dB in ≥5 loci. The locations most vulnerable to severe RS loss were the foveola and temporal parafovea (Figure 1). Eyes with baseline oRS ≥25 dB were more likely to experience oRS loss in the 3x3 mm macular region (55% vs 32%, P = .01) and superior parafovea (53% vs 28%, P = .01) (Table 1).

Conclusions : Severe oRS loss of ≥7 dB over one year in eyes with DMI is relatively uncommon compared to mild oRS loss of ≥2 dB. Severe PWS losses were mainly observed in the foveola and temporal parafoveal areas.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Figure 1. A Heat Map of the Most Vulnerable Loci at Risks of Severe and Mild Retinal Sensitivity Loss at One Year. The most vulnerable regions to severe retinal sensitivity loss are the foveola and temporal parafovea (highlighted in red on the loss ≥7 dB map).

 

Table 1. A Comparison of Retinal Sensitivity Loss at One Year Between Eyes with Good and Impaired Retinal Sensitivity at Baseline Using 25 dB as the Cutoff. Eyes with oRS ≥25 dB were more likely to have RS loss of any degree in the 3x3 macular region and superior parafovea than their counterparts.