Study: Haze a possibility for smokers

Boston-Smoking seems to be an independent risk factor for the development of corneal haze in patients who underwent refractive procedure to treat –5 D or more of myopia, but not for patients with lower levels of myopia and hyperopia, reported J. Richard Townley, MD, of Massachusetts Eye & Ear Infirmary, Boston.

“Haze is often associated with the total diopters of treatment, astigmatic correction, the length of the steroid taper, and exposure to ultraviolet light,” explained Dr. Townley, who, at the time of this study, was the clinical director of ophthalmology services at Lackland Air Force Base, San Antonio, TX. He is a cornea fellow at the Massachusetts Eye & Ear Infirmary. “A literature search identified more than 800 articles about haze and its effects after refractive surgery.

“However, only one prospective study addressed the effect of smoking and the development of haze,” Dr. Townley said. “Because the study included only 100 patients and a small percentage of those developed haze, the study was considerably underpowered.”

Dr. Townley and colleagues conducted a retrospective review of 25,313 patients and matched control patients who underwent a refractive procedure to determine the percentage of patients who developed haze in association with smoking.

Factors that the investigators looked at were: age, race, gender, use of mitomycin C (MMC), refractive correction, length of steroid taper, amount of haze, and number of treatments. Of these patients, 157 developed haze that was graded more than mild. The medical records of these patients were reviewed for tobacco use.

Among the 157 patients, most were Caucasian, most women were taking oral contraceptives, and MMC had been used in only one patient. Postoperative steroid use after refractive surgery ranged from 2 months to 4 months. Most of the patients had undergone PRK (n = 127), LASEK (n = 32), and one LASIK. The amount of the refractive treatment varied from +3.9 D of hyperopia to –8 D of myopia (mean, –4.7 D).

Interestingly, the haze was evenly distributed between smokers and nonsmokers, and the patients who developed haze had undergone a small amount of refractive treatment.

“When the smokers were included, we found a significant difference between patients who received more refractive treatment and those who received smaller treatment, with those patients with more haze among the smokers who received more refractive treatment,” Dr. Townley said.

The study found that smoking was indeed a risk factor for the development of haze in treatments for more than –5.0 D of myopia. 

“Patients should still be encouraged to stop smoking,” Dr. Townley said. “Surgeons could also consider a longer steroid taper with application of prophylactic MMC.”

He pointed out the retrospective nature of the study as a limitation and that it was underpowered because the rate of haze development was so low. A large multicenter prospective study would be required to reach definitive conclusions.

Dr. Townley has no financial interest in the topic of this report. The views expressed in this report do not reflect those of the U.S. Air Force or the U.S. Government.