Comparison of Portable Retinal Thickness Analyzer and Spectral Domain Optical Coherence Tomography Retinal Thickness Measurements in Diabetic Eyes

Abstract

Purpose : The portable Retinal Thickness Module (RTM, Kubota Vision) is a novel home-based patient- administered optical coherence tomography (OCT) device to measure retinal thickness and identify macular edema. This prospective instrument validation study evaluated accuracy of patient self-administered RTM device imaging in comparison to a standard clinical spectral domain (SD-OCT) device for measuring retinal thickness in diabetic eyes.

Methods : Patients had nonmydriatic imaging with the RTM device followed by SD-OCT scans (Macular cube, Spectralis, Heidelberg) during a single office visit. Retinal thickness was quantified using manufacturer provided cloud-based AI algorithms. The primary outcome measure was retinal central subfield thickness (CST) on RTM compared with that derived from Spectralis.

Results : A total of 48 eyes from 24 diabetic patients [16.7% no DR, 20.8% mild nonproliferative DR, 14.6% moderate, 12.5% severe and 35.4% proliferative DR; 37.5% with center involved diabetic macular edema] were enrolled. Mean age was 59.5±14.1 (30-81) and diabetes duration 26.2±14.2 (36-63) years, 54.2% type 2 diabetes, 50% female, 68.8% phakic (non-visually significant cataract 54.2%). Mean BCVA was 20/32 (20/16-20/400). RTM was ungradable in 29.2%. Mean CST was 345.4±122.0μm (Spectralis) and 310.2±83.5μm (RTM). Mean difference in CST was 35.2±102.7μm with moderate correlation (r=0.56, p=0.0007) between RTM and Spectralis measures. RTM sensitivity/specificity for detecting CST ≥310μm on Spectralis was 1.00/0.75 and positive/negative predictive value 0.62/1.00. For CST≥ 400μm, these values were 0.67/0.87 and 0.33/0.96.

Conclusions : This study suggests that the portable RTM device may eventually become a feasible home-based tool for OCT determination of retinal thickness and macular edema in diabetic eyes. There was high sensitivity (1.00) and moderate specificity (0.75) in identifying eyes with CST ≥ 310, suggesting potential utility in DR screening. Without mydriasis, gradable images exceeded 70%. However, further refinement of the device will be essential to optimize its agreement with SD-OCT measurements, reduce the ungradable rate and validate its effectiveness in larger cohorts for remote home DR monitoring.

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

 

Scatter plot of the CST measurements on the RTM and Spectralis devices