Standard 6-mm Compared with Widefield 16.5-mm OCT for Staging of Posterior Vitreous Detachment

Abstract

To assess whether 6-mm OCT scans, which image the macula, can distinguish complete from partial posterior vitreous detachment (PVD) in comparison with 16.5-mm OCT scans, which image the macula, optic nerve, and mid periphery. Retrospective cross-sectional study. We compared 6-mm and 16.5-mm scans in 157 eyes of 157 retina clinic patients (mean age, 50 years; range, 10-64 years) with diabetic retinopathy (36%), no retinal disease (19%), and various retinal conditions (45%). We also analyzed 16.5-mm scans in 35 healthy eyes (asymptomatic fellow eyes of patients with unilateral retinal conditions; mean age, 46 years; range, 9-63 years). Each participant underwent Heidelberg Spectralis imaging with the standard lens (6-mm scan) and/or the 55° lens (16.5-mm scan). On 6-mm scans, we classified eyes as stage 3 partial PVD when the posterior vitreous cortex was visualized without visible attachment. On 16.5-mm scans, we classified eyes as stage 3 when the vitreous was attached at the optic nerve and separated from the macula. On both scan types, we classified eyes as stage 4 when neither the premacular bursa nor the posterior vitreous cortex were visualized. We assessed the accuracy of this system for detecting complete PVD on 6-mm scans by calculating test characteristics using 16.5-mm scans as a reference standard. Posterior vitreous detachment stage (0-4). Posterior vitreous detachment stage was identical in 6-mm and 16.5-mm scans in 88% of eyes. Compared with 16.5-mm scans, 6-mm scans detected complete PVD (vs. earlier stages 0-3) with 91% sensitivity and 99% specificity. Seven eyes were classified as no PVD on 6-mm scans and were classified as partial PVD on 16.5-mm scans because vitreoretinal separation was localized to the mid periphery. All 16.5-mm scans showed some degree of PVD, including scans from 9 participants between 9 and 20 years of age. Six-millimeter scans distinguished complete from partial PVD with good sensitivity and specificity but missed the earliest stages of PVD, which occur in the mid periphery. Posterior vitreous detachment may begin as early as the second decade of life.