Scleral expansion unreliable for presbyopia, French study says

TOULOUSE, France - Scleral expansion band implantation resulted in inconsistent and unpredictable results with a low level of patient satisfaction, according to a small study here.

François J. Malecaze, MD, and colleagues evaluated the safety and efficacy of surgery using scleral expansion bands (SEBs) in a small prospective, noncomparative case series.

Six patients were enrolled. Four received implants in one eye and two in both eyes. Implantation of the SEBs was performed using the standard technique described by Ronald Schachar, MD. Subjects were observed at six postop examination intervals through 1 year.

The key efficacy measures were distance-corrected near visual acuity and subjective amplitude of accommodation.

The study showed that distance visual acuity was similar before and after surgery. The near visual acuity and the subjective amplitude of accommodation were temporarily improved in three eyes. However, in the other five eyes, no improvement of accommodation or near vision was noted after the SEB surgery.

The authors note that SEBs were developed by Dr. Schachar, who has proposed a controversial theory of presbyopia. His theory holds that presbyopia is caused by the continued growth of the eye's natural lens, reducing the distance between the lens and the ciliary muscle that causes the lens to change shape. This relaxation of the zonules prevents accommodation. By inserting SEBs, the surgeon increases the distance between the muscle and the lens, thus increasing zonular tension and allowing the accommodative system to work again.

The more widely held theory of Helmholtz says that the lens stiffens with age, preventing it from changing shape in accommodation. If that theory is true, scleral implants would have little effect on the eye's ability to accommodate.

This study can be found in the December issue of Ophthalmology.