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Best protection against pterygium is avoiding exposure
Use of topical steroids following surgery reduces recurrence.
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TORONTO – The most effective form of prevention against the development of pterygium is regularly wearing sunglasses and hats with a brim when in the sun, said a professor in the department of ophthalmology and vision sciences at the University of Toronto.
![William Dixon, MD [photo]](/images\OSN\200602b\dixon.jpg) William Dixon |
“Some studies are now coming out saying that the crucial period is under the age of 10 in terms of exposure to the sun,” said William Dixon, MD. “Maybe this means that we have to put our kids in sunglasses as well as hats.”
A study published in the American Journal of Pathology investigated possible mechanisms of action of ultraviolet irradiation, in particular UV-B exposure, in the development of pterygium. While research is ongoing into how UV exposure leads to pterygium development, speculation is that it breaks down the limbic barrier.
“Why treat it? For some people, it’s just cosmetic,” Dr. Dixon said. “A lot of people don’t like the pink bump. Additionally, it can induce astigmatism and irregularity to the cornea. If you remove that, the patient’s vision may improve.”
Surgical tips
Speaking at an ophthalmology update organized by the University of Toronto here, Dr. Dixon offered ophthalmologists surgical tips and other information in treating pterygium.
He said if the pterygium surface looks irregular, a biopsy should be done to rule out malignancy.
When conducting the excision of the pterygium, Dr. Dixon said that it is important to clean the limbus and to make as smooth a junction as possible between the sclera and the cornea.
Intraoperatively, mitomycin-C 0.02% can be used as an adjunct, but he cautioned that its use can lead to postoperative complications, so clinicians need to be careful about the duration of use.
“It’s used anywhere from 12 seconds to 5 minutes,” he said.
Reducing recurrence
One study published in the British Journal of Ophthalmology in 2004 found a statistically significant difference in the rate of recurrence between patients who underwent excision with mitomycin-C and those who received limbal conjunctival autograft. Those who underwent the autograft experienced much less recurrence, he said.
 | Pterygium. Characterized by elastotic degeneration of the ground substance of the conjunctiva with irregular hyperplasia of the epithelium, numerous horizontal blood vessels, and invasion of the superficial layers of the cornea. Image: The Atlas of Ophthalmology Photo CD, SLACK Incorporated |
Postoperatively, the application of topical steroids decreases recurrence and should be used routinely following surgery to remove pterygium, according to Dr. Dixon.
“If you use topical steroids four times a day for at least 2 months postoperatively, recurrence can be reduced from 15% to 4%, so it makes sense to apply them,” he said.
Dr. Dixon referred to a retrospective study published in the Journal of the Medical Association of Thailand,which found 21 recurrences in 137 patients (142 eyes) with primary pterygium who underwent excision with conjunctival autograft. The recurrence rate was 14.8% for all eyes, but 4% when patients who did not receive adequate corticosteroid therapy were excluded.
There are associations between the development of pterygium and age and gender.
Dr. Dixon cited an epidemiological study of pterygium published in September of 2005 and conducted in the Riau Archipelago in Indonesia. Investigators found that rates of the condition advanced with age: the mean age was 42.9 among subjects who had the condition, compared to 18.7 among subjects who did not have the condition. The risk of disease was three times greater in men.
Outdoor workers also face an increased risk of pterygium, Dr. Dixon noted.
For Your Information:
- William Dixon, MD, Ophthalmologist-in-chief, Sunnybrook and Womens College Health Sciences Center, can be reached at 2075 Bayview Ave., Suite M1-302, North York, Ontario, M4N 3M5; 416-487-9100; fax: 416-480-4481; e-mail: william.dixon@sw.ca.
- Louise Gagnon is an OSN Correspondent based in the Toronto area.