It has been largely supplanted by newer, more accurate operations, such as photorefractive keratectomy, LASIK, Epi-LASIK and the phakic intraocular lens.

The incisions relax the steep central cornea in patients with myopia in order to achieve a decreased need for correction.

As the cells migrate from the depth of the plug up to the surface, some die before reaching it, forming breaches in the otherwise healthy epithelial layer.

[7][8][9] The risk is estimated to be between 0.25%[6] and 0.7%[10] Healing of the RK incisions is very slow and unpredictable, often incomplete even years after surgery.

Their vision can still be restored with Epi-LASIK, photorefractive keratectomy, LASIK or phakic lens extraction, or cataract surgery.

[19] Beginning in 1936, Japanese ophthalmologist Tsutomu Sato conducted research in anterior and posterior keratotomy, an early form of refractive surgery that attempted to treat keratoconus, myopia and astigmatism by making incisions in the cornea.

At first successful, Sato's technique resulted in bullous keratopathy in up to 70% of patients related to endothelial damage.

After the glass was removed by this method and the cornea healed, Fyodorov found that the boy's visual acuity had improved significantly.