Scleral reinforcement surgery

History

Posterior staphyloma in high myopia was first described by Scarpa in the 1800s. Speculation about reinforcement began in the 19th century; Rubin noted that sclera reinforcement 'is probably the only one of all the surgical techniques [for myopia] which attempts to correct a cause, rather than an effect'. Early procedures resected a ring of sclera from the equator to shorten the eyeball. Later procedures placed grafts over the posterior part of the eye to modify axial length.

Shevelev proposed transplantation of fascia lata in 1930. Curtin promoted donor-sclera grafting. Momose introduced Lyodura in 1976. Snyder and Thompson had positive outcomes with modifications; Curtin and Whitmore expressed dissatisfaction with negative conclusions.

High myopia

Myopia is one of the leading causes of blindness worldwide, resulting from both genetic and environmental factors such as mechanical stretching, excessive eye work and accommodation, and elevated intraocular pressure. It affects children and adults; in many cases myopia stabilizes after growth completes, but severe chronic cases can lead to vision loss. Degenerative myopia, also called malignant, pathological, or progressive myopia, involves posterior sclera elongation and thinning (at least 25.5 mm to 26.5 mm) with high refractive errors of at least -5 to -7.5 diopters that increase yearly.

Fundus changes include posterior staphyloma, caused by the eye growing posteriorly and losing its spherical shape. As the staphyloma enlarges, choroidal tissue thins and Bruch's membrane breaks, creating lacquer cracks. Neovascularization may occur, with blood vessels protruding through cracks and leaking beneath the photoreceptor layer, leading to hemorrhaging, scarring, and macular degeneration. Untreated high myopia can cause retinal detachment, glaucoma, and a higher risk of cataracts.

Procedure

The surgery begins with an incision through the conjunctiva and Tenon's capsule, positioned roughly 6 millimeters from the corneal limbus. Using a strabismus hook, the lateral, superior, and inferior recti muscles are isolated. Connective tissue is detached from the posterior pole and the inferior oblique muscle.

A material strip is guided beneath the separated muscles and advanced deep toward the posterior pole. Its two ends are then crossed over the medial rectus muscle and stitched to the sclera on the medial side of both the superior and inferior recti muscles. Finally, the conjunctiva and Tenon's capsule are sutured closed.

Controversy

Scleral reinforcement surgery is rarely performed in the United States, and there are few published studies on it. Obtaining and storing donor sclera is challenging, while synthetic alternatives remain under development.

The operation is far more common in places like Japan and the former Soviet Union. Surgeons disagree on the best time to perform it: some push for early intervention in children to stop myopia from worsening, while others reserve it for cases of high myopia already causing macular damage. Additionally, each surgeon sets their own specific requirements for patient eligibility.

Did You Know?

• Three basic techniques exist: X-shaped, Y-shaped, and single strip support; single strip support is often preferred as it provides the widest area of support and reduces risk of optic nerve interference.
• Human sclera and Lyodura are thought to offer the best support; artificial materials such as nylon or silicone are not suggested.
• Sclera from cadaver or animal tendons runs the risk of being rejected.