Dose-response for Mitomycin-C in prevention of haze in

photorefractive keratectomy for high myopia:

Six month preliminary resultsCDR Elizabeth M. Hofmeister, MD*

CDR Frank M. Bishop, MD*CAPT David J. Tanzer, MD**

Sandor Kaupp, MS*CAPT (ret) Steve Schallhorn, MD***

Navy Refractive Surgery Center, San Diego

Financial disclosures: * Dr. Hofmeister, Dr. Bishop, and Mr. Kaupp have no financial disclosures.** Dr. Tanzer is affiliated with TLC Laser Center*** Dr. Schallhorn is a consultant for AMO

Disclaimer

• The views expressed in this presentation are the personal views of the authors and not the official views of the U.S. Navy or the Department of Defense.

Purpose

• To investigate the safety and efficacy of Mitomycin-C (MMC) 0.1 mg/ml in preventing haze after PRK for high myopia at three different dose durations: • one minute• thirty seconds• fifteen seconds

Methods• Randomized, prospective, placebo controlled,

masked trial.• Patient eligibility:

• Patients were recruited from those who selected PRK independently and those who were deemed ineligible for LASIK due to an inadequate estimated residual beds thickness.

• Mean spherical equivalent -4.50 to 8.00 and no more than 1 diopter of anisometropia

• No medical contraindications for refractive surgery• Age > 21.

Methods• Surgical methods:

• Epithelial removal with rotating brush• VISX S4 platform, wavefront guided ablation profiles with iris registration• Following excimer laser ablation, the study eye was treated with Mitomycin-C

(MMC) 0.1 mg/ml soaking a 6 mm circular sponge, the control eye was treated with a 6 mm sponge soaked with balanced salt solution.

• A bandage contact lens was placed in both eyes, followed by topical gatifloxacin, topical ketorolac, and topical fluorometholone.

• Fluorometholone prescribed in a two month tapering dose schedule.• The patient and providers doing post op checks are masked as to which eye

received MMC.• Study data collected:

• Preoperative and postoperative endothelial cell counts by confocal microscopy• Preoperative and postoperative refractive error• Preoperative and postoperative uncorrected and best corrected visual acuity• Postoperative haze scores using a five point scale (0-4)

Methods: Study data

• One year study: Data collected preoperatively and at 1, 3, 6, and 12 months

• Endothelial cell counts: confocal microscopy

• Haze scores: 0, 1, 2, 3, 4• Visual acuity/contrast acuity• Manifest refraction

Results: Preoperative Characteristics

Group A 60 seconds

Group B30 seconds

Group C15 seconds

Number of patients

10 9 9

Mean pre-op sphere (range)

-5.88 D (-5.00 to -7.25)Std dev: 0.70

-6.03D(-4.50 to -7.75)Std dev: 1.00

-6.04 D(-4.25 to -8.50)Std dev: 1.21

Mean cylinder -0.79 D (-0.00 to -1.50)Std dev: 0.49

-1.90 D(-0.50 to -3.50)Std dev: 0.70

-0.74 D(-0.25 to -1.50)Std dev: 0.35

Sex: male female

7 patients 3 patients

7 patients2 patients

6 patients3 patients

Average age (range)

32.8 years (23-53)

32.9 years(25 -43)

33.1 years(25-43)

Results: Haze scoresCurrent ef f ec t: F(4, 56)=.24195, p=.91334(Computed f or c ov ar iates at their means )

V ertic al bars denote 0.95 c onf idenc e interv als

1M Haze 3M Haze 6M haze

M M C e x posure : ye s

Group: A B C-0.5

0.0

0.5

1.0

1.5

2.0

haze

sco

re

M M C e x posure : no

Group: A B C

Cov ariate means :0M MRc : -.8888890M MRSE: -6.38889

A= 60 sec.B= 30 sec.C= 15 sec.

Results: Endothelial Cell Counts

Current ef f ec t: F(2, 37)=.60278, p=.55257(Computed f or c ov aria tes at their means )

V ertic al bars denote 0 .95 c onf idenc e in terv als

R1 ^1M endo c ell c ount (c onf oc al) R1 ^6M endo c ell c ount (c onf oc al)

MMC ex pos ure: y es

Group:A

BC

-500

-400

-300

-200

-100

0

100

200

300

400

chan

ge in

end

othe

lium

cel

l den

sity

(cel

ls/c

m2 )

MMC ex pos ure: no

Group:A

BC

Cov ar iate means :0M MRSE: -6.416670M endo c e ll c ount (c onf oc al) : 2490.667

Change in endothelial cell count

One month counts

Six month counts

A= 60 sec.B= 30 sec.C= 15 sec.

Study Conclusions

• At six months follow-up, there was no difference in haze scores in eyes of high myopes that received mitomycin and those that didn’t.

• Mitomycin-C had no effect on endothelial cell counts.

• Final twelve month evaluations are pending.

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mitomycin-C to inhibit haze formation after photorefractive keratectomy. J Cataract Refract Surg 2002; 28: 2088-2095.

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• Lee DH, Chung HS, Jeon YC, Boo SD, Yoon YD, Kim JG. Photorefractive keratectomy with intraoperative mitomycin-C application. J Cataract Refract Surg 2005; 31: 2293-2298.

• Pfister RR. Permanent corneal edema resulting from the treatment of PTK corneal haze with mitomycin: a case report. Cornea 2004; 23: 744-747.

• Chang SW. Early corneal edema following topical application of mitomycin-C. J Cataract Refract Surg 2004; 30: 1742-1750.

• Raviv T, Majmudar PA, Dennis RF, Epstein RJ. Mytomycin-C for post-PRK corneal haze. J Cataract Refract Surg 2000; 26: 1105-1106.