Radial Keratotomy Correction

Excerpt

Refractive surgery is a laser procedure performed to alter the eye’s refractive power and reduce dependence on spectacles and contact lenses. Radial keratotomy was among the first and most widely performed refractive surgical procedures of the 20th century. Approximately 10% of practicing ophthalmologists in the United States (US) have performed several hundred thousand radial keratotomy procedures. Lans demonstrated in the late 19th century that deep radial incisions in the anterior cornea caused central corneal flattening with peripheral steepening. Sato later performed posterior radial keratotomy in 8 patients with keratoconus in the 1930s. Enhanced flattening resulted from longer and deeper incisions. Although initially effective, the Sato technique ultimately produced bullous keratopathy in up to 70% of patients due to endothelial damage.

Improvements to the radial keratotomy procedure, restricting incisions solely to the anterior corneal surface, were undertaken in the 1970s in Russia. The use of multifactorial formulae and nomograms, incorporating both patient and surgical variables, improved predictive performance. Radial keratotomy correction was introduced to the US in 1978 by Bores et al, Myers, and Cowden, with multiple surgeons performing procedures and publishing anecdotal results. Early publications were optimistic, and reported complications were few. These observations prompted the National Institutes of Health to fund the Prospective Evaluation of Radial Keratotomy (PERK) study, which assessed the safety, efficacy, stability, and predictability of the technique.

The PERK study involved 12 surgeons practicing at 9 clinical centers, who performed radial keratotomy on 793 eyes of 435 patients with myopia ranging from 2 to 8 diopters. Technique refinements and improvements continued following the PERK study. Younger individuals exhibit greater rates and extent of wound healing, requiring more extensive surgery to achieve equivalent outcomes compared with older individuals. Advances in surgical equipment, including diamond blades and ultrasonic pachymeter calibration, further improved procedural predictability. With the introduction of more accurate and stable laser refractive surgery, ie, photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and intraocular lens (IOL) surgery, the popularity of radial keratotomy correction has decreased considerably. However, given the large number of patients who have undergone this procedure, knowledge of radial keratotomy and its variants remains essential for managing cases requiring subsequent visual rehabilitation.