Abstract
Purpose: :
To evaluate macular morphological changes associated with poor visual acuity in eyes with idiopathic epiretinal membrane (ERM) using optical coherence tomography (OCT) image segmentation.
Methods: :
Twenty-two patients with idiopathic ERM were enrolled in this study. Ten eyes had best corrected visual acuity (BCVA) of 0.5 or worse (group A) and 12 eyes had 1.0 BCVA (group B). Twelve eyes of 12 age-matched healthy subjects served as controls (group C). "Macular thickness map" protocol was obtained by Stratus OCT in each eye, with subsequent segmentation analysis performed using OCTRIMA software. The thickness of the intraretinal layers was calculated for the central ETDRS region, the pericentral and peripheral ETDRS rings. All measured thickness values were compared among the groups using one-way ANOVA with Newman-Keuls post-hoc analysis. The correlation between LogMAR BCVA and the thickness values was assessed using linear correlation.
Results: :
In the central region, the thickness of the outer nuclear layer (ONL) and the entire retina was significantly increased in group A and B compared to group C, and also in group A compared to group B (p<0.01 for all comparisons). The thickness of each intraretinal layer except the pigment epithelium was significantly increased in group A compared to both groups B and C in the peripheral and also in the pericentral rings (p<0.001 for all comparisons). There was also a significant increase in the thickness of the retinal nerve fiber layer, the inner nuclear layer and the total retina in group B compared to group C in both the peripheral and pericentral rings (p<0.01 for all comparisons). The strongest positive correlation was between logMAR BCVA and the thickness of the ONL and the total retina in the central region; and the thickness of the ganglion cell layer and inner nuclear layer complex in the pericentral ring (r=0.84 and p<0.001 for all cases).
Conclusions: :
Up to now, the photoreceptor inner and outer segment (IS/OS) junction abnormalities were supposed to play the main role in the process of vision loss in idiopathic ERM formation; however, our results suggest that the intermediate layers including the second and third neurons also appear to be involved. Further studies are needed to approve this theory.
Keywords: retina • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • image processing