Purpose
To evaluate the inner retinal surface (IRS) morphology via adaptive optics (AO) retinal imaging during six months follow up after pars plana vitrectomy for idiopathic epiretinal membrane (ERM).
Methods
Six eyes of six patients with ERM were recruited in this study. Of these, two patients had fovea-attached type 1A ERM and four patients had type 1B ERM based on OCT classification. A flood-illumination AO retinal camera was used to obtain images of the IRS before and 1-, 3- and 6-months after surgery; 8°x 3° degree AO montages were created in order to investigate the changes of IRS microstructures across the central retina during follow-up. In addition, SLO/OCT imaging was performed in order to obtain both wide-field and cross-section views of the retina. Visual function was measured by best-corrected visual acuity (BCVA) and MP1 microperimetry.
Results
Before surgery, several structures were identified in AO images of the ERM, which included macrofolds, microfolds and hyper-reflective features. The macrofolds (width: ≥25 μm) correlated with the superficial retinal folds seen with SLO, whereas the microfolds (5-10 μm) could not be detected by wide fundus imaging. The hyper-reflective features showed different shape and dimension and were randomly spread across the ERM. After surgery, the number of both macro- and micro-folds was greatly reduced in all cases; there were still numerous hyper-reflective features spread across the IRS, however showing different shapes than preoperatively. Crater-like features (40-160 μm diameter) were visualized over the IRS postoperatively. Retinal nerve fiber bundles could be well appreciated only after surgery. BCVA improved in all cases. MP1 retinal sensitivity increased from 15.3 ± 2.4 dB to 18.6 ± 1.1 dB from preoperatively to six months postoperatively (P=0.06). Central retinal thickness decreased from 577±101 μm to 447±32 μm (P=0.04) six months after surgery.
Conclusions
Adaptive optics imaging provides new insight into the changes to inner retinal interface following ERM surgery. Monitoring of IRS microstructures could be valuable to understand the relationship between their pathological changes and clinical measures of visual function in patients with idiopathic ERM.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
688 retina