Purpose
To compare stereoscopic and monoscopic optic nerve images from diabetic (DM) subjects in an ocular telemedicine program for glaucomatous features using nonmydriatic, 200 degree ultrawide field imaging (UWFI) and mydriatic, 35 mm color slide photos (ETDRS field 1) and to assess UWFI stereographic projection on optic nerve analysis.
Methods
96 eyes of 48 DM subjects underwent UWFI and ETDRS photos at the same visit. Two independent, masked glaucoma specialists (BJS/LRP) graded structural optic nerve head and peripapillary features indicative of glaucoma. Disparities were adjudicated by consensus. Stereo- vs. monoscopic agreement was calculated using the weighted kappa (κ) statistic for cup/disc ratio (CDR) and unweighted κ for binary and categorical variables. Agreement was defined as poor (< 0.20), fair (0.21-0.40), moderate (0.41-0.60) or good (0.61-0.80). A subset of 18 stereographically projected, monoscopic, UWFI were compared to unprojected, stereoscopic UWFI.
Results
Mean age was 56±16 years; 56% male, 42% type 1 DM and mean DM duration 20±11 (3-49) years. Based on ETDRS photos (N=96 eyes), diabetic retinopathy (DR) was absent in 24%, mild nonproliferative DR (NPDR) in 32%, moderate NPDR in 38%, and severe/very severe NPDR in 6%. Mono- and stereoscopic optic nerve agreement for both modalities are shown in Table 1. Key features of each imaging modality are summarized in Table 2. Monoscopic evaluation for both modalities identified fewer glaucoma-suspicious optic nerves (-4.2% for UWFI and -8.4% for ETDRS photos) but these differences were not statistically significant (P>0.5).
Conclusions
These data suggest that UWFI can be utilized in telemedicine for disc evaluation of DM patients. In this cohort, there was good agreement between mono- and stereoscopic UWFI and monoscopic projected UWFI and stereoscopic ETDRS photos for CDR and suspicion of glaucoma. Stereographic projection of monoscopic UWFI did not appear to have a significant impact on optic nerve evaluation when compared to stereo ETDRS field 1. The potential effect and clinical relevance of UWFI optical distortion and projected correction on glaucoma evaluation requires further evaluation.