Key messages
1. Pars plana vitrectomy with internal limiting membrane flap technique compared to pars plana vitrectomy with internal limiting membrane peeling for treating macular holes may result in better vision after three or more months.
2. Pars plana vitrectomy with internal limiting membrane flap technique compared to pars plana vitrectomy with internal limiting membrane peeling for treating macular holes probably results in a higher likelihood of macular hole closure
3. There is a need for high-quality research in this area to confirm these results and measure other effects of the different surgeries.
What is macular hole?
The macula is a small area in the center of the retina (the light-sensitive layer of cells lining the back of the eye). A macular hole is a gap that opens in the macula. Macular holes vary in size, and can be idiopathic (occurring spontaneously without a specific underlying disease), traumatic (caused by an injury), and myopic (associated with near-sightedness).
What is pars plana vitrectomy?
Vitrectomy is removal of the vitreous humor (the gel that naturally fills the eye). It is a crucial step to be able to access the retina. The pars plana is part of the eye that does not touch critical internal eye structures such as the retina. In pars plana vitrectomy (PPV), the eye surgeon inserts the surgical instruments through the pars plana to avoid damaging the retina or adjacent eye structures.
What is internal limiting membrane peeling and internal limiting membrane flap?
The internal limiting membrane (ILM) is the innermost layer of the retina. ILM peeling and the ILM flap technique are used to treat macular holes. Peeling refers to complete removal of the ILM from the retina surrounding the macular hole. The ILM flap technique involves separating a portion of the ILM from the retina and inverting it to cover the macular hole.
What did we want to find out?
We wanted to examine whether PPV with the ILM flap technique was better than PPV with ILM peeling for treating large macular holes.
What did we do?
We searched for studies that evaluated PPV with ILM flap versus PPV with ILM peeling for treatment of large macular holes. We compared and summarized the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We found four studies that had treated 285 eyes of 275 people diagnosed with large macular holes. The average age of the people taking part was 59.4 years to 66 years. Two studies were conducted in India, one in Poland, and one in Mexico. No studies reported conflicts of interest or financial support.
PPV with ILM flap compared to PPV with ILM peeling may result in better vision and probably increases the likelihood of macular hole closure.
What are the limitations of the evidence?
In three of the four studies, the people measuring the results of the surgery may have known which treatment each study participant had received, and this knowledge may have influenced their assessments. The studies reported the results at different time points after surgery, which may have affected the assessment of vision. There were some differences in the surgeries across the studies; for example, in two studies, all people had cataract surgery combined with PPV.
How up to date is this evidence?
The evidence is current to December 2022.
We found low-certainty evidence from four small RCTs that PPV with the inverted ILM flap technique is superior to PPV with ILM peeling with respect to BCVA gains at three or more months after surgery. We also found moderate-certainty evidence that the inverted ILM flap technique achieves more overall and type 1 MH closures. There is a need for high-quality multicenter RCTs to ascertain whether the inverted ILM flap technique is superior to ILM peeling with regard to anatomical and functional outcomes. Investigators should use the standard logMAR charts when measuring BCVA to facilitate comparison across trials.
Macular hole (MH) is a full-thickness defect in the central portion of the retina that causes loss of central vision. According to the usual definition, a large MH has a diameter greater than 400 µm at the narrowest point. For closure of MH, there is evidence that pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling achieves better anatomical outcomes than standard PPV. PPV with ILM peeling is currently the standard of care for MH management; however, the failure rate of this technique is higher for large MHs than for smaller MHs. Some studies have shown that the inverted ILM flap technique is superior to conventional ILM peeling for the management of large MHs.
To evaluate the clinical effectiveness and safety of pars plana vitrectomy with the inverted internal limiting membrane flap technique versus pars plana vitrectomy with conventional internal limiting membrane peeling for treating large macular holes, including idiopathic, traumatic, and myopic macular holes.
The Cochrane Eyes and Vision Information Specialist searched CENTRAL, MEDLINE, Embase, two other databases, and two trials registries on 12 December 2022.
We included randomized controlled trials (RCTs) that evaluated PPV with ILM peeling versus PPV with inverted ILM flap for treatment of large MHs (with a basal diameter greater than 400 µm at the narrowest point measured by optical coherence tomography) of any type (idiopathic, traumatic, or myopic).
We used standard methodological procedures expected by Cochrane and assessed the certainty of the body of evidence using GRADE.
We included four RCTs (285 eyes of 275 participants; range per study 24 to 91 eyes). Most participants were women (63%), and of older age (range of means 59.4 to 66 years). Three RCTs were single-center trials, and the same surgeon performed all surgeries in two RCTs (the third single-center RCT did not report the number of surgeons). One RCT was a multicenter trial (three sites), and four surgeons performed all surgeries. Two RCTs took place in India, one in Poland, and one in Mexico. Maximum follow-up ranged from three months (2 RCTs) to 12 months (1 RCT). No RCTs reported conflicts of interest or disclosed financial support. All four RCTs enrolled people with large idiopathic MHs and compared conventional PPV with ILM peeling versus PPV with inverted ILM flap techniques. Variations in technique across the four RCTs were minimal. There was some heterogeneity in interventions: in two RCTs, all participants underwent combined cataract-PPV surgery, whereas in one RCT, some participants underwent cataract surgery after PPV (the fourth RCT did not mention cataract surgery). The critical outcomes for this review were mean best-corrected visual acuity (BCVA) and MH closure rates. All four RCTs provided data for meta-analyses of both critical outcomes. We assessed the risk of bias for both outcomes using the Cochrane risk of bias tool (RoB 2); there were some concerns for risk of bias associated with lack of masking of outcome assessors and selective reporting of outcomes in all RCTs.
All RCTs reported postoperative BCVA values; only one RCT reported the change in BCVA from baseline. Based on evidence from the four RCTs, it is unclear if the inverted ILM flap technique compared with ILM peeling reduces (improves) postoperative BCVA measured on a logarithm of the minimum angle of resolution (logMAR) chart at one month (mean difference [MD] −0.08 logMAR, 95% confidence interval [CI] −0.20 to 0.05; P = 0.23, I2 = 65%; 4 studies, 254 eyes; very low-certainty evidence), but it may improve BCVA at three months or more (MD −0.17 logMAR, 95% CI −0.23 to −0.10; P < 0.001, I2 = 0%; 4 studies, 276 eyes; low-certainty evidence). PPV with an inverted ILM flap compared to PPV with ILM peeling probably increases the proportion of eyes achieving MH closure (risk ratio [RR] 1.10, 95% CI 1.02 to 1.18; P = 0.01, I2 = 0%; 4 studies, 276 eyes; moderate-certainty evidence) and type 1 MH closure (RR 1.31, 95% CI 1.03 to 1.66; P = 0.03, I² = 69%; 4 studies, 276 eyes; moderate-certainty evidence). One study reported that none of the 38 participants experienced postoperative retinal detachment.