Retinal Displacement after Scleral Buckle versus Combined Buckle and Vitrectomy for Rhegmatogenous Retinal Detachment
Shivani V. Reddy, MD
Talley Eye Institute
Bansal A, Naidu SC, Marafon SB, et al. Retinal Displacement after Scleral Buckle versus Combined Buckle and Vitrectomy for Rhegmatogenous Retinal Detachment: ALIGN Scleral Buckle versus Pars Plana Vitrectomy with Scleral Buckle. Ophthalmol Retina. 2023;7(9):788-793. doi:10.1016/j.oret.2023.05.012
Low integrity retinal attachment (LIRA), a term used to measure postoperative retinal displacement, has recently gained traction as an outcome measure of successful rhegmatogenous retinal detachment (RRD) repair. The advent of multimodal imaging, particularly fundus autofluorescence (FAF), has facilitated the diagnosis of retinal displacement after various RRD repair modalities. Particularly following pars plana vitrectomy (PPV), LIRA has been theorized to occur secondary to displacement of residual subretinal fluid under thin, elastic retinal tissue from the buoyant force of a gas tamponade, leading to retinal stretching prior to reattachment. LIRA has been implicated as a main cause of postoperative aniseikonia in RRD patients. RPE pump-based procedures such as pneumatic retinopexy or scleral buckling (without drainage) are expected to have a lower rate of LIRA based on its mechanism.
In this prospective, multicenter, non-randomized clinical trial, the authors aimed to compare the retinal displacement risk in patients with fovea-involving RRDs who underwent scleral buckle (SB) vs combined PPV with scleral buckle procedure (PPV-SB). The primary outcome measure was the proportion of eyes with LIRA on FAF imaging 3 months postoperatively. Functional outcomes associated with LIRA by treatment group and impact of external drainage on LIRA in the SB group were also measured. Patients under age 18, eyes with significant media opacities, grade B PVR or worse or other structural retinal pathologies were excluded. SB patients underwent cryotherapy followed by placement of segmental buckles with or without encircling buckles, with drainage and tamponade per surgeon discretion. PPV-SB patients underwent encircling buckling, 360 depressed shaving, subretinal drainage performed preferentially through the breaks (drainage retinotomy per surgeon’s discretion) and injection of isoexpansile SF6 or C3F8 gas, with PFO and silicone oil use being allowed. Postoperative Snellen BCVA, metamorphopsia and aniseikonia were assessed via testing by technicians masked to the procedure. Spectralis or Optos widefield FAF images were taken 3 months postoperatively, with qualifying images assessed for LIRA by 2 masked graders.
Of 123 enrolled patients, 91 had successful primary reattachment and gradable FAF images at 3 months postoperatively. The proportion of eyes with retinal displacement or LIRA was 16.7% (7 of 42) in the SB group and 38.8% (19/49) in the PPV-SB group (P=0.02). As expected, SB group had younger, phakic pts with better baseline BCVA and less extensive RRD. The difference in LIRA between procedures remained significant (P= 0.01) after multivariable logistic regression adjusting for the extent of retinal detachment, baseline logarithm of the minimum angle of resolution visual acuity, lens status, and sex. A subgroup analysis of SB group eyes undergoing external drainage found 22.5% (6 of 27) of patients who underwent drainage had LIRA compared to 6.7% (1 of 15) in the non-drainage group( P=0.19).
Differences in mean BCVA (p=0.41), mean horizontal metamorphopsia (MH) scores (p=0.33), mean vertical metamorphopsia (VM) (p=0.14) and mean aniseikonia scores (p=0.82) in SB vs. PPV-SB groups were not statistically significant. A comparison between groups with and without LIRA revealed no statistically significant difference in mean MH (0.067), mean VM (p = 0.20) and mean aniseikonia scores (p=0.45). Strengths of the study are the prospective nature and use of confocal scanning imaging to improve the accuracy of FAF imaging through media opacities. The limitations of the study include the inherent baseline differences in characteristics of SB vs PPV-SB groups, and reduced sensitivity of current FAF imaging. The authors also concluded that the study was inadequately powered to detect a significant difference in LIRA with external drainage in the SB group.
In conclusion, this study demonstrated that patients undergoing PPV-SB have a significantly higher rate of retinal displacement compared to SB patients. The study also demonstrated a trend towards increased LIRA after external drainage in SB patients, as well as a trend towards increased mean MH in patients with LIRA, although these factors did not approach statistical significance in this study. The findings support the theory of retinal displacement being caused by retinal stretching due to iatrogenic movement of subretinal fluid caused by fluid drainage with or without gas tamponade followed by fixation of this stretched tissue to the underlying RPE. Further investigations with higher powered studies will be needed to draw more definitive conclusions.