RetFluidMapping – an OCT-Leakage based tool for abnormal retinal fluid mapping of pre cystoid macular edema

Abstract

Purpose : To map abnormal retinal fluid accumulation in pre cystoid macular edema in the initial stages of diabetic retinopathy using optical coherence tomography leakage (OCT-Leakage) algorithm during a 3-year follow-up.

Methods : Seventy-four eyes from type 2 diabetic individuals, one eye per patient, were followed in a 3-year longitudinal study with 1-year intervals using OCT-Leakage. OCT-Leakage is an image analysis algorithm that analyzes the reflectivity intensity of the OCT structural raw data to quantify and assess the location of abnormal accumulation of fluid in the retina. Using a intensity threshold calculated from a normative database, the OCT-Leakage algorithm projects the below threshold optical reflectivity voxels to a perpendicular plane to the depth direction, showing the abnormal accumulation of retinal fluid as two dimensional binary maps. Low optical reflectivity ratios (LOR) were calculated for each retinal layer. The RetFluidMapping software prototype is a 3D data visualization and custom reporting tool based on the OCT-Leakage algorithm, that allows to map the accumulation of retinal fluid distribution, amount, extent, and depth location in each retinal layers. Central retinal thickness for each participant was collected at each visit to check for the development of center involved macular edema (CIME). Best corrected visual acuity (BCVA) was recorded to document the presence of any visual loss.

Results : At baseline, eyes with CIME were distributed similarly in the 3 ETDRS stages, 9% (n=2/23) in ETDRS 10-20, 10% (n=3/31) in ETDRS 35 and 15% (n=3/20) in ETDRS 43-47, remaining stable throughout the follow-up period. At the end of the follow-up, all eyes with CIME showed increased LOR ratios independent of EDTRS level, while for subclinical CIME 60% of eyes showed increased LOR ratios. In eyes with subclinical CIME and CIME, LOR values showed marked fluctuations between visits which are associated with vision loss (p=0.047).

Conclusions : The prevalence of subclinical CIME and CIME in non-proliferative diabetic retinopathy occurs independently of the severity of the retinopathy. The accumulation of extracellular fluid can be monitored using the OCT-Leakage algorithm. The RetFluidMapping is a useful software tool for the interpretation of the OCT-Leakage results.

This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.

 

LOR fluctuations and BCVA variations during the follow-up period of subclinical CIME and CIME eyes