Richard F. Dennis

Topical Mitomycin-C for subepithelial fibrosis after refractive corneal surgery

OBJECTIVE To determine the effectiveness of mitomycin-C (MMC), 0.02%, in preventing recurrence of corneal subepithelial fibrosis after debridement and/or keratectomy in patients who have undergone refractive corneal surgery. DESIGN Noncomparative case series. PARTICIPANTS Eight eyes of five patients with corneal subepithelial fibrosis who had previously undergone radial keratotomy (n = 4) or photorefractive keratectomy (n = 4). INTERVENTION All eyes underwent epithelial debridement followed by a single intraoperative application of MMC (0.02%) for 2 minutes followed by saline irrigation. The eyes were then patched, or a bandage contact lens placed until epithelial healing was complete. MAIN OUTCOME MEASURES Corneal clarity and best-corrected visual acuity (BCVA). RESULTS In all cases, the cornea remained clear with no recurrence throughout the follow-up period (6-25 mos., mean, 13.8 mos). No adverse reactions were reported. BCVA improved in all cases. CONCLUSIONS Subepithelial fibrosis can be a visually disabling condition after refractive corneal surgery. Topical application of MMC (0.02%) may be a successful method of preventing recurrence of subepithelial fibrosis after debridement.

Absence of Normal Keratan Sulfate in the Blood of Patients With Macular Corneal Dystrophy

We measured levels of sulfated keratan sulfate in serum using a monoclonal antibody in an enzyme-linked immunosorbent assay. Sulfated keratan sulfate was not detected in the serum of 16 patients with macular corneal dystrophy, but was present at normal levels in 66 patients with other corneal diseases. There were no differences with respect to age, sex, and other ocular findings. This monoclonal antibody recognizes a sulfated carbohydrate epitope present in both corneal and skeletal keratan sulfate. Since most serum keratan sulfate is derived from the cartilages, the defect in keratan sulfate synthesis in macular corneal dystrophy may not be restricted to corneal cells. This assay should prove useful in the diagnosis of macular corneal dystrophy, particularly in children at risk before the appearance of opacification.

Effect of Mitomycin C on the Corneal Endothelium When Used for Corneal Subepithelial Haze Prophylaxis Following Photorefractive Keratectomy

PURPOSE To evaluate the potential effect of topical mitomycin C (MMC) on the corneal endothelium of myopic patients undergoing photorefractive keratectomy (PRK). METHODS Sixteen eyes with a planned ablation depth >75 microm underwent PRK followed by 0.02% MMC applied for 12 seconds using a methylcellulose sponge. Endothelial specular microscopy was performed with the Keeler-Konan specular photomicroscope in 16 eyes before and at least 1 year after surgery. Mean follow-up was 18 months (range: 12 to 24 months). Mean cell density, coefficient of variation of mean cell area, and percentage of hexagonal cells were measured and calculated using computerized morphometric analysis. RESULTS Mean endothelial cell densities before and after surgery were 2882 +/- 783 cells/mm2 (range: 1511 to 4022 cells/mm2) and 2867 +/- 588 cells/mm2 (range: 1638 to 3881 cells/mm2), respectively (P > .05). Mean coefficient of variation before and after surgery was 0.30 +/- 0.07 (range: 0.23 to 0.49) and 0.26 +/- 0.04 (range: 0.22 to 0.33), respectively (P=.06). Mean percentage of hexagonal cells before and after surgery was 61% +/- 6.8% (range: 47% to 70%) and 66% +/- 6.7% (range: 54% to 75%), respectively. CONCLUSIONS Administration of MMC for haze prophylaxis following PRK did not have a significant effect on quantitative endothelial cell density or qualitative morphometric parameters in this study.

Transepithelial phototherapeutic keratectomy/photorefractive keratectomy with adjunctive mitomycin-C for complicated LASIK flaps

Purpose: To evaluate the efficacy of transepithelial phototherapeutic keratectomy/photorefractive keratectomy (PTK/PRK) with prophylactic mitomycin‐C for the treatment of refractive errors and maintenance of corneal clarity following flap complications in laser in situ keratomileusis (LASIK). Setting: Outpatient tertiary care center, Chicago, Illinois, USA. Methods: Ten eyes of 10 patients with LASIK flap complications had transepithelial PTK/PRK for correction of ametropia. Mitomycin‐C 0.02% was applied to the stroma for 2 minutes following laser ablation. Postoperative uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA), refractions, and slitlamp examinations were obtained. Results: Preoperatively, the mean UCVA was 20/400 (range 20/40 to counting fingers), the mean BSCVA was 20/28.5, and the spherical equivalent refractive errors ranged from +4.00 to −10.75 diopters (D). After the procedure, the mean UCVA was 20/28, the mean BSCVA was 20/21, and the spherical equivalent refractive errors ranged from +0.37 to −1.00 D. The mean follow‐up ranged from 8 to 28 months. No patient experienced delayed reepithelialization, haze, or other signs of toxicity. Conclusion: Mitomycin‐C can be a useful adjunctive therapy for the prevention of haze when applying surface excimer laser therapy to a cornea following LASIK flap complications.

Macular corneal dystrophy Lack of keratan sulfate in serum and cornea

An ELISA assay using a monoclonal antibody (ET-4-A-4) that recognizes a sulfated carbohydrate epitope in both keratan sulfate type I (corneal) and type II (skeletal) was employed to quantify keratan sulfate in serum and corneal tissue from patients with macular corneal dystrophy (MCD). This assay disclosed significant quantities of keratan sulfate in the serum in 45 healthy individuals (251 +/- 78 ng/ml), and in 66 patients with various corneal diseases (273 +/- 101 ng/ml). In contrast keratan sulfate was not detected (less than 2 ng/ml) in the serum of 16 patients with histopathologically confirmed MCD. Keratan sulfate was also detected in extracts of normal corneas and corneal tissue with a variety of pathologic conditions, but was virtually absent in corneal tissue from five patients with MCD. In corneas with MCD the chondroitin sulfate/keratan sulfate ratio was considerably higher than that of all normal and pathologic corneas studied. Since keratan sulfate in the serum appears to be derived predominantly from the normal turnover of cartilage these studies strongly suggest that the defect in keratan sulfate synthesis in MCD is not restricted to corneal cells and that MCD is one manifestation of a systemic disorder of keratan sulfate. The cartilage changes, however, do not have clinical significance. Moreover, since keratan sulfate can be detected in the blood of newborns it should be possible to diagnose MCD prior to corneal opacification.

Reduced Application Time for Prophylactic Mitomycin C in Photorefractive Keratectomy

OBJECTIVE To determine whether the duration of mitomycin C (MMC) 0.02% application affects visual outcome or the incidence of subepithelial haze in patients undergoing photorefractive keratectomy (PRK) with prophylactic administration of MMC. DESIGN Retrospective, comparative case series. PARTICIPANTS Two hundred sixty-nine eyes undergoing PRK. METHODS This was a retrospective comparative case series that included 269 eyes that underwent PRK with prophylactic MMC application for 120 seconds (group 1, n = 74), 60 seconds (group 2, n = 36), or 12 seconds (group 3, n = 159). The mean preoperative spherical equivalent was -6.49 diopters (D) in group 1, -6.77 D in group 2, and -7.10 D in group 3. Photorefractive keratectomy was performed using a modified nomogram. All eyes received a single intraoperative application of MMC (0.02%) after laser ablation for the above specified durations. MAIN OUTCOME MEASURES Best-corrected visual acuity and corneal haze score. RESULTS Best-corrected visual acuity was 20/23 in group 1, 20/20 in group 2, and 20/21 in group 3. The mean haze score+/-standard deviation (scale, 0.00-4.00) was 0.11+/-0.31 in group 1, 0.14+/-0.28 in group 2, and 0.07+/-0.20 in group 3 throughout a mean follow-up of 31 months in group 1, 16 months in group 2, and 10 months in group 3. No eyes had a haze score of more than 1.00. CONCLUSIONS There was no statistically significant difference in postoperative best-corrected visual acuity or haze scores among the 3 groups. Administration of prophylactic MMC 0.02% for 12 seconds after PRK seems to be equally efficacious for haze prophylaxis when compared with longer application times of 60 and 120 seconds.