Face-down positioning may help close large macular holes

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James Bainbridge

Postoperative face-down positioning may improve closure of macular holes larger than 400 µm, according to a study.

“The pros and cons of face-down positioning have been widely discussed in recent years. On one hand, it might enhance the effects of the gas tamponade by ensuring that the macula is consistently in contact with the surface of the gas bubble. On the other hand, face-down positioning is uncomfortable and in some cases unfeasible even with specially designed supports. It is in fact a significant deterrent for some people considering surgery,” James Bainbridge, PhD, FRCOphth, said at the Euretina meeting in Paris.

The first reports on vitrectomy surgery for macular hole date back to 1982, with six cases treated by Gonvers and Machmer, and 1991, with 52 eyes treated by Kelly and Wendel. In the latter study, the closure rate was 58%, and vision improved by two lines in 42% of eyes.

“Since then, we have seen in randomized controlled trials that surgery for stage 2, 3 and 4 macular hole offers a better long-term outcome than the natural history. Reports of anatomical closure rate are on the order of 82% to 100%,” Dr. Bainbridge said.

Most of these reports describe positioning, but how critical positioning is in determining the final results is still being considered, he said. The extent to which gas tamponade impacts the final outcome must be established.

“Gas may prevent recruitment of fluid to the subretinal space, possibly by more than one mechanism, including surface tension and buoyancy. In addition, the bubble meniscus may provide a surface template that allows glial cells to migrate across the hole,” Dr. Bainbridge said.

Benefits

Face-down positioning might help by increasing both the surface tension and buoyancy effects of the gas bubble or by ensuring consistency of contact of the bubble meniscus with the hole, thus improving anatomic closure.

But how strong is the evidence in favor of face-down positioning? There are case series published in the last decades showing that good anatomical and visual results can be obtained with short-term face-down positioning or none at all.

Various authors have emphasized how the difficulty and discomfort of face-down positioning can lead to poor compliance or even deter surgery. Other studies have investigated potential complications, such as ulnar nerve injury, risk of thromboembolism and faster progression of cataract.

Pilot trial

In a controlled pilot trial at Moorfields Eye Hospital in London, 30 patients with idiopathic, full-thickness macular holes of stage 2, 3 or 4 were randomized to receive macular hole surgery with or without face-down positioning. Age, gender and duration of macular hole were similar.

The researchers performed 20-gauge three-port vitrectomy with induction of posterior vitreous detachment, trypan blue-assisted internal limiting membrane peeling and fluid-air exchange using C3F8 14%. After surgery, subjects were randomized to one of two study arms. In the posturing arm, patients were positioned face-down for 50 minutes per hour for 10 days. In the second arm, patients were asked to avoid only face-up position.

The primary endpoint was macular hole closure on biomicroscopy and optical coherence tomography 6 weeks after surgery. Adherence was not estimated.

“Of those allocated to face-down posturing only, one of 15 holes did not close, compared to six out of 15 in the non-posturing group. This had a significance level of 8%,” Dr. Bainbridge said.

Subgroup analysis was performed to assess hole closure according to size. Smaller holes of less than 400 µm, four and five in the two groups respectively, had a closure rate of 100% in both groups. A significant difference was found for larger holes of more than 400 µm; in the posturing group, only one in 11 holes did not close, while in the non-posturing group, six out of 10 did not close.

“Our study was only small, but it suggests that posturing might improve outcome of surgery, particularly for large holes,” Dr. Bainbridge said. – by Michela Cimberle

References:

• Gonvers M, Machemer R. A new approach to treating retinal detachment with macular hole. Am J Ophthalmol. 1982;94(4):468-472.
• Kelly NE, Wendel RT. Vitreous surgery for idiopathic macular holes. Results of a pilot study. Arch Ophthalmol. 1991;109(5):654-659.
• Verma D, Jalabi MW, Watts WG, Naylor G. Evaluation of posturing in macular hole surgery. Eye (Lond). 2002;16(6):701-704.

• James Bainbridge, PhD, FRCOphth, is an honorary consultant ophthalmologist at the Moorfields Eye Hospital in London, U.K. He can be reached at Institute of Ophthalmology, 11-43 Bath Street, London EC1V9EL; +44-20-76086889; fax: +44-20-76086963; email: j.bainbridge@ucl.ac.uk.
• Disclosure: No products or companies are mentioned that would require financial disclosure.