Abstract
Purpose::
Advances in posterior segment imaging have enabled simultaneous coronal plane and horizontal optical sections of the vitreo-retinal interface (VRI) in vivo. This study used SLO-OCT to quantitatively characterize the VRI of unifocal premacular membranes to determine if location and size of the lesions are related, and if these factors have any significance with respect to the degree of retinal thickening.
Methods::
SLO-OCT (OTI, Inc. Toronto) imaging was performed on 24 patients with unifocal premacular membranes and pucker without confounding retinal disease. Coronal plane images of the VRI were evaluated with image-analysis software to calculate the area of contraction and the distance of the center of contraction from the fovea. Horizontal OCT sections were used to measure retinal thickness at the center of contraction.
Results::
Premacular membranes were central in 14/24 (58.3%) patients (mean distance from fovea = 2.44 + 0.73 mm) and in the peripheral macula (mean distance from fovea = 7.27 + 1.90 mm) in 10/24 patients (41.7%). At the center of retinal contraction, retinal thickness was greater in central membranes compared to peripheral premacular membranes (386.9 + 64.8µm vs. 294.2 + 117.4µm; p = 0.01). Central membranes also had a 3-fold larger area of retinal contraction as compared to peripheral premacular membranes (87.29 + 42.57 mm2 vs. 29.48 + 23.68 mm2; p = 0.0004). When analyzed by membrane size, 13/24 patients (54.2%) had membranes with large areas of contraction (mean area = 95.69 + 36.68 mm2) while 11/24 patients (45.8%) had membranes with small areas of contraction (mean area = 24.81 + 14.18 mm2). Large membranes had more retinal thickening than small membranes (389.0 + 66.9 µm vs. 300.2 + 113.2 µm; p = 0.01).
Conclusions::
Quantitative analysis of coronal plane images and horizontal optical sections obtained by SLO-OCT imaging of premacular membranes reveals that location and size are important aspects of macular pucker. Central lesions are 3-fold larger and induce one-third greater retinal thickening than peripheral premacular membranes. This may relate to the protective effects of Müller cells and their relative absence in the central macula. The finding that larger and central premacular membranes are associated with greater retinal thickening may influence prognosis and hence impact upon surgical decision-making. Thus, quantitative analysis of premacular membranes with pucker can increase our understanding of pathophysiology as well as improve patient management.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea • vitreoretinal surgery