Facedown Positioning Following Surgery for Large Full-Thickness Macular Hole: Summary of a Randomized Clinical Trial and Invited Commentary
June 2020
Pasu S, Bell L, Zenasni Z, et al; The Positioning in Macular Hole Surgery (PIMS) Study Group. Facedown positioning following surgery for large full-thickness macular hole: a multicenter randomized clinical trial. JAMA Ophthalmol. Published online May 7, 2020. doi:10.1001/jamaophthalmol. 2020.0987
Smiddy WE, Flynn HW Jr, Vanner EA. Facedown Postoperative Positioning for Large Macular Holes. JAMA Ophthalmol. doi:10.1001/jamaophthalmol.2020.0987 Published online May 7, 2020.
Full thickness macular hole (MH) is often treated with vitrectomy, internal limiting membrane peel, and gas tamponade. A period of postoperative facedown positioning may be advised to promote contact of the gas bubble with the macula to facilitate hole closure. This can be a challenging and uncomfortable task for patients, especially those with other health conditions that limit their ability to position appropriately. One systemic review found that for smaller macular holes (< 400 micrometers in minimum diameter), there was no significant association between facedown positioning and hole closure. For MH greater than 400 micrometer diameter, several studies have suggested that face-down positioning may improve hole closure rate, though these studies are heterogenous with use of varying tamponade agents, which makes it difficult to let these results guide practice.
The study by Pasu et al was a prospective multicenter trial that sought to determine if facedown positioning improves rate of closure for MH with > 400 micrometer diameter and duration of <12 months. 185 patients were treated with PPV/ILM peel/14% C3F8 followed for at least 3 months. Patients were randomized 1:1 to either perform facedown or face forward positioning for 8 hours per day for 5 days. The baseline characteristics of both groups were similar, though the facedown positioning group had a slightly smaller median macular hole diameter (480 vs 517 micrometers).
The primary outcome was closure of the MH determined 3 months following surgery. Secondary outcome measures at 3 months were visual acuity, participant-reported experience of positioning, and quality of life measured by the National Eye Institute Visual Function Questionnaire 25 (NEI VFQ-25).
Macular hole closure was observed in 77/90 (85.6%) of those who were advised to position face forward and 84/88 (95.5%) of those advised to position facedown (P = .08). The mean (SD) improvement in best-corrected visual acuity at 3 months was 0.34 (0.69) logMAR (equivalent to 1 Snellen line) in the face-forward group and 0.57 (0.42) logMAR (equivalent to 3 Snellen lines) in the facedown group (P = .01). The median NEI VFQ- 25 score was 89 in the facedown group and 87 in the face-forward group (P=0.41).
The authors concluded that MH closure in those advised to position facing down was not shown to be superior to MH closure in those facing forward. However, secondary visual acuity outcomes appeared to be superior in the facedown group. A possible benefit to visual acuity is unclear, although facedown positioning might protect phakic eyes against gas induced cataract.
In a related commentary about the above article, Smiddy and colleagues point out that while the study did not find a statistically significant difference in MH closure rate, the significant difference in visual acuity (20/80 in facedown group vs 20/120 in face forward) should actually be considered the most important outcome metric to guide clinical decision making. They also highlight that the study did not include a non-inferiority evaluation. In a superiority evaluation such as this one, the lack of a statistically significant outcome should not lead to a conclusion that the groups’ anatomic results are the same.
Smiddy et al also note that the consensus among many surgeons is to approximate facedown positioning for 24 hours per day. Thus, the differences between the treatment groups are expected to be less, because of the lower “dosage” of facedown positioning in this study (8 hours rather than 24 hours). He concludes that while these results do not encourage abandonment of facedown positioning, they are sufficient to encourage the surgeon to attempt surgery on a patient who will not be able to maintain a facedown position stringently.
