Histopathology of Radial Keratotomy

We present this case as a pictorial of radial keratotomy (RK) with significant subepithelial fibrosis. This type of scarring is a well-known complication of photorefractive keratotomy but is not as well documented as an adverse effect of RK.^1-4 Although such extensive fibrosis is uncommon, it can develop and cause significant visual impairment.²

A 39-year-old man with a history of RK performed elsewhere 8 years prior had complaints of decreased vision in both eyes. The patient’s preoperative refraction was –9.25 OD and –9.50 OS. According to the patient, the initial surgery was uncomplicated, although both eyes required enhancements. Cycloplegic refraction in our office was –3.50 +0.50 × 70 OD and –13.50 +1.00 × 100 OS, giving a best-corrected visual acuity of 20/200 OD and 20/80 OS. Unfortunately, the patient did not have interval examinations, andso the progression of refractive change to the current level is unclear. Keratometry in both eyes showed extremely distorted and nonsuperimposable mires. Slitlamp examination revealed scars corresponding to the RK incisions and extensive central subepithelial fibrosis within the optical zone (Figure 1). The patient underwent penetrating keratoplasty of the left eye.

Figure 1.

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Clinical photograph demonstrating central subepithelial fibrosis and radial keratotomy scars. The incisions do not extend to the limbus, as there is a 1-mm clear peripheral zone. The central clear zone measured approximately 1.75 mL.

The hazy corneal button measured 9 mm in diameter. Sections revealed corneal tissue with a mild decrease in endothelial cell count. The Descemet’s membrane was unremarkable. There was a moderate amount of stromal scarring present. At the periphery of the specimen, the RK incisions spanned 75% of the corneal thickness. Epithelial inclusion cysts were noted at some of the incision sites (Figure 2). Centrally, there was a subepithelial fibrous plaque (Figure 3). Bowman’s layer was seen under the fibrous plaque. Intraepithelial duplication of basement membrane was seen throughout the specimen (Figure 4).

Figure 2.

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Epithelial inclusion cyst at radial keratotomy incision site. Note the defect in Bowman’s layer and downward proliferation of corneal epithelium. The incision scar (arrows) continues posteriorly beyond the cyst (periodic acid–Schiff; original magnification ×100).

Figure 3.

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A subepithelial fibrous plaque (asterisk) is present in the central cornea between the epithelium (A) and Bowman’s layer (B and arrowheads) (periodic acid–Schiff; original magnification ×100).

Figure 4.

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Within the corneal epithelium, numerous areas of abnormal basement membrane reduplication (arrow) were identified. This one is adjacent to a radial keratotomy scar identified by a break in Bowman’s layer (double arrow) (periodic acid–Schiff; original magnification ×100).

Correspondence: Dr Albert, F4/344 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3284 (dalbert@wisc.edu).

Financial Disclosure: None.