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Mitomycin C for the Retreatment of Corneal Haze after PRK Versus Prophylactic Use
Originally posted on the OPHTHALMIC HYPERGUIDE August 14, 2008
A 40-year-old woman with no significant medical or ocular history presents with corneal haze and residual myopia after PRK without the prophylactic use of mitomycin-C.
Presentation prior to PRK: Preoperative manifest refraction was -8.00 -2.50 D x 89 in the right eye and -8.75 -1.75 D x 91 in the left eye, with best spectacle-corrected visual acuity (BSCVA) of 20/20 in both eyes. Cycloplegic refraction was -7.50 -2.50 D x 92 in the right eye and -8.25 -2.00 D x 90 in the left eye. Keratometry was 43.25 x 45.12 @ 004 in the right eye and 43.00 x 44.75 @ 180 in the left eye. Central corneal thickness was 545 µm in the right eye and 551 µm in the left eye. Computerized topography was normal in both eyes. Slitlamp examination showed anterior basement membrane dystrophy in both eyes.
PRK procedure: The PRK correction was performed in the left eye with the LADARVision 4000 (Alcon Laboratories Inc., Fort Worth, Texas). The stromal photoablation depth was 96 µm using a 6.0-mm optical zone. A bandage contact lens (Soflens 66; Bausch & Lomb, Rochester, NY) was applied and prednisolone acetate 1% (Predforte; Allergan, Irvine, Calif.), ketorolac tromethamine 0.5% (Acular; Allergan), and ciprofloxacin 0.3% (Ciloxan; Alcon Laboratories Inc.) were prescribed four times a day for 1 week. Prednisolone acetate 1% was tapered over the next 3 weeks.
Post-PRK presentation: Two weeks after surgery, the uncorrected visual acuity (UCVA) was 20/30; with a residual refractive correction of -0.50 -0.25 D x 165, visual acuity was 20/20.
Four weeks after surgery, significant subepithelial central corneal haze (3+/4+)1 was observed, and the patient’s vision decreased to a BSCVA of 20/30 with a residual error of -1.25 -0.50 D x 175 (Slide 1).
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Slide 1. Patient presenting with corneal haze after PRK. |
Clinical course of action: Five months postoperatively, the patient’s left eye was surgically enhanced with PRK and adjunctive MMC 0.02% application for 2 minutes, followed by copious irrigation with balanced salt solution (Slide 2). Three months after the PRK enhancement with MMC, UCVA and BSCVA improved to 20/25, with a refraction of -0.50 -0.50 D x 155; a corneal opacity (2+) remained.
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Slide 2. MMC applied after PRK. |
Because of the increased risk of haze, PRK was performed in the right eye with application of MMC 0.02% for 2 minutes. At 3 months postoperatively, the patient presented with a clear cornea in the right eye upon slitlamp examination and UCVA of 20/20 with a residual refractive error of -0.50 -0.50 D x 085.
Comments
The antimitotic properties of MMC inhibit keratocyte replication and differentiation into myofibroblasts, the cells responsible for corneal haze formation. Furthermore, MMC induces myofibroblast apoptosis and necrosis.
This case indicates that in the presence of previously existing corneal haze, MMC may not entirely remove the corneal opacity. However, MMC was effective in preventing corneal haze in the contralateral eye. The primary use of MMC was more effective in preventing haze formation in highly myopic eyes undergoing PRK than when MMC is used during PRK retreatment.2
References
- Fantes FE, Hanna KD, Waring GO 3rd, et al. Wound healing after excimer laser keratomileusis (photorefractive keratectomy) in monkeys. Arch Ophthalmol. 1990; 108:665-675.
- Netto MV, Chalita MR, Krueger RR. Corneal haze following PRK with mitomycin C as a retreatment versus prophylactic use in the contralateral eye. J Refract Surg. 2007; 23:96-98.