Abstract
Purpose :
To determine the ability of a semi-automated UWF directed OCT imaging algorithm to detect sub-clinical neovascularization elsewhere(NVE) in eyes with severe NPDR on UWF color imaging.
Methods :
Consecutive patients with severe NPDR who presented to a retina clinic were imaged using a novel semi-automated algorithm to detect NVE. The algorithm acquires 7 consecutive 120-line scans(figure 1:central 9x12 mm raster and 6 mid-peripheral 6x6 mm scans (infero and supero-nasal, infero and supero-temporal, inferior and superior). A trained grader(MA) evaluated each individual line scan to determine the presence of NVE. NVE were graded to be present if the lesion clearly demonstrated a breach in the internal limiting membrane (ILM)on at least 2 consecutive line scans. An entire field considered ungradable if 50% of the line scans were absent or of poor quality limiting the ability to determine retinal morphology or identify the ILM.
Results :
A total of 14 eyes of 13 patients were included in this study, 38.5% were female. Mean age was 45.6±12.7 years, 46.2% type 1, mean duration of diabetes was 18.6±8.9 years and mean HbA1c of 8.6±1.7%. In this cohort, 7/14 (50%) were found to have NVE previously undetected by UWF color imaging (a single NVE in 5 eyes and 2 NVEs in 2 eyes). These NVEs were detected on Raster scan(3), inferior scans (2), supero-temporal scans (2), nasal scans(1)and infero-nasal scans(1). When looking at consecutive line scans with detected NVE, the mean number of lines with NVE was 10.8±8.1 scans (range 2-28). For individual scan areas the overall ungradable rate was 14.3% and by field was highest in the inferonasal(8/14, 57%), superonasal field(3/14, 21.4%), inferior field(2/14, 14.3%), and lowest in the superotemporal and superior fields(1/14, 7.1%). The average time for imaging an individual eye was 3.6 minutes(range of 3.1 – 4.2).
Conclusions :
A semi-automated UWF-guided OCT imaging protocol may allow identification of subclinical NVE in eyes with severe NPDR. Greater difficulty imaging the inferonasal retina may lead to under-detection of NVEs in this area. Clinical use may be feasible with improved workflow given an imaging time of less than 4 minutes. However,the clinical relevance of sub-clinical NVE and risk of future progression or vision loss remains to be established.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.