Complications of small clear-zone radial keratotomy

To review the postoperative outcome of patients with radial keratotomy who have clear-zone diameters below 2.75 mm.

A retrospective review was performed of all patients with radial keratotomy who have clear-zone diameters less than 2.75 mm presenting for consultation from August 1993-September 1995. Preoperative records and surgical reports were reviewed, and a thorough ophthalmic examination was performed.

A total of 37 eyes had a clear-zone size below 2.25 mm. Six eyes were excluded from subsequent analysis due to keratoconus. The remaining 31 eyes had an average clear-zone size of 1.5 mm (standard deviation, 0.4 mm; range, 0.9-2.2 mm). Postoperative morbidity included severe disabling glare in 31 (100%) of 31 eyes, contact lens intolerance in 19 (100%) of the 19 eyes fitted, Snellen visual acuity loss (> 2 lines) in 25 (81%) of 31 eyes, inability to drive at night in 11 (69%) of 16 patients, moderate to severe diurnal visual fluctuation in 21 (68%) of 31 eyes, refractive undercorrection by greater than 1 diopter in 16 (52%) of 31 eyes, loss of employment in 4 (25%) of 16 patients, polyopia in 5 (16%) of 31 eyes, refractive overcorrection by greater than 1 diopter in 3 (10%) of 31 eyes, and a retinal detachment attributable to pilocarpine use in 1 (3%) of 31 eyes.

Using radial keratotomy clear-zone diameters smaller than 2.25 mm has a high complication rate and is unsafe. Small clear-zone radial keratotomy should be abandoned. Although this study was limited to clear zones less than 2.25 mm, the authors endorse current recommendations that the clear zone should be at least 3.0 mm in diameter.