PRK plus mitomycin-C useful approach after PKP

November 15, 2005

Long-term follow-up and a controlled trial of PRK with adjunctive mitomycin-C after PKP compared with LASIK after PKP for keratoconus are needed.

Approximately 40,000 corneal transplant procedures are performed annually, but visual rehabilitation in these patients can be difficult because of surgically induced astigmatism and anisometropia. Contact lenses have traditionally been employed for visual rehabilitation in these individuals. Many patients, however, are not candidates for contact lenses because of poor manual dexterity, functional impairment, lack of motivation, or environmental factors.

LASIK a concern

Performing PRK in these patients diminishes the concern relating to ectasia, but corneal haze is commonly seen in post-PKP eyes following PRK.

At the World Cornea Congress in Washington, DC, earlier this year, data were presented that demonstrated that intraoperative MMC may be safely and effectively used as an adjunct with PRK in visually rehabilitation after PKP. This presentation was awarded first prize at the meeting.

All subjects had undergone PKP for keratoconus, were contact lens-intolerant, and had had their sutures removed at least 3 months prior to study enrollment. The study included eight eyes of seven patients with a mean age of 36 years. Seven of the eyes were myopic, and one was hyperopic.

Before undergoing PRK, the uncorrected visual acuities (UCVA) were 20/200 in one eye, 20/400 in two eyes, and count fingers in five eyes. The preoperative best spectacle-corrected visual acuities (BSCVAs) were 20/20 in one eye, 20/25 in five eyes, 20/30 in one eye, and 20/40 in one eye. The mean preoperative spherical equivalent of the seven myopic eyes was –5.96 ± 3.02 D and mean preoperative cylinder was 3.86 ± 2.11 D. Regarding the single hyperopic eye, the manifest refraction was +7 –4.75 × 125 = 20/25, and the spherical equivalent was +4.63 D preoperatively.

All surgical procedures were performed using either the STAR S4 (AMO/VISX) or the Technolas (Bausch & Lomb) excimer laser. All cases were performed by one surgeon (Eric D. Donnenfeld, MD).

Postoperative care

After PRK photoablation, 0.02% MMC was applied to the corneal stromal bed for 2 minutes with a Merocel sponge (Medtronic Ophthalmics). All subjects wore bandage contact lenses until their epithelia closed. Patients were prescribed ofloxacin 0.3% (Ocuflox, Allergan) four times daily for 5 days; prednisolone acetate 1.0% on a tapering regimen: four times daily for 2 weeks, three times daily for the next 2 weeks, then twice daily for 2 weeks, followed by once daily for 2 weeks.

Also, ketorolac tromethamine ophthal-mic solution 0.5% (Acular, Allergan) was prescribed twice daily for 2 days. Patients were followed daily until their epithelia closed and at 1 week, 1 month, 3 months, and 6 months postoperatively.

All patients had a postoperative BSCVA of between 20/20 and 20/30. The mean refraction of seven myopic eyes at 6 months was –1 ± 0.72 D (spherical equivalent) and 0.60 ± 0.52 D (cylinder) at 6 months. Regarding the single hyperopic eye, the manifest refraction was +0.25 –0.75 × 165 = 20/25, and the spherical equivalent was –0.13 D at 3 months postoperatively.

All patients maintained corneal clarity, lost no lines of BSCVA, and no one developed corneal haze. There were no adverse reactions to the corneal button, scarring, or healing abnormalities.