Twenty-one studies were included in the review. The number of eyes in each study ranged from five to 100. Follow-up ranged from three to 35 months.
Seventeen studies reported change in mean visual acuity for 255 patients from 259 eyes. Mean postoperative visual acuity across all patients was 0.42 ± 0.45 (20/53) from a baseline of 0.67 ± 0.55 (20/94). All studies showed an improvement in the mean logMAR visual acuity after surgery; in five studies with 20 eyes or more, this had borderline statistical significance (p=0.0625).
In the subgroup of patients whose eyes did not undergo peeling of the internal limiting membrane (178 eyes), mean improvement in visual acuity was from 0.72 ± 0.46 (20/105) to 0.44 ± 0.37 (20/55), 0.28 logMAR units or almost 2 Snellen lines. In patients whose eyes did undergo peeling of the internal limiting membrane (56 eyes), visual acuity improvement was from 0.64 ± 0.32 (20/87) to 0.41 ± 0.26 (20/51) or 0.23 logMAR units.
Nineteen studies categorised patients' eyes as having better, worse or same acuity postoperatively (392 eyes) compared with preoperatively. Of these, 9.2% of eyes worsened, 11.7% were unchanged, and 64.3% (217 eyes) improved (incomplete information meant that the totals did not sum to 100%). Of the 64.3% of eyes that showed improvement, 32.9% had an improvement of 2 or more Snellen lines.
Complications were reported by 15 studies. The most frequent intraoperative complications reported were focal, petechial, spontaneously resolving retinal haemorrhage (5.6% of 250 eyes), and peripheral retinal breaks (1.6% of 250 eyes). Most frequent postoperative complications were cataract (34.7% of 304 eyes; this rate almost doubled in eyes known to be phakic (with natural lens). Epiretinal membrane, retinal detachment and recurrence of epimacular membrane were also reported at incidences from 5.7% to 1.4% (348 eyes).