RGP insights

Pinguecula and Pterygium: To Fit or Not To Fit

BY TIMOTHY B. EDRINGTON, OD, MS
DECEMBER 1998

The diplomates in the Cornea and Contact Lens Section of the American Academy of Optometry were surveyed about their contact lens management of patients presenting with pinguecula and pterygium, and Drs. James P. Prediger and Linda L. Edmondson published the results

pterygium, and Drs. James P. Prediger and Linda L. Edmondson published the results in Optometry and Vision Science (1993). Ninety-six percent of the respondents said they fit contact lenses on patients with pingueculae. Fifty-one percent of them stated no preference for prescribing rigid or soft contact lenses, 29 percent preferred fitting soft lenses, and 19 percent preferred rigid lenses. Sixty-four percent of the respondents reported fitting contact lenses on patients with pterygia, with 48 percent of them preferring soft contact lenses.

Pingueculae: Choosing a Camp

There are two primary camps when it comes to fitting contact lenses on patients with pingueculae -- fit 'em large or fit 'em small. The rationale for fitting large overall diameter soft contact lenses is to cover part or all of the pinguecula so that the lens edge doesn't bump into and irritate it. Small overall diameter soft lenses are prescribed to prevent the lens edge from coming into contact with the pinguecula. Also, small diameter lenses might drape the cornea better, assuring good optics. Try either philosophy. Corneal staining and bulbar conjunctival injection at follow-up visits will guide management. If unacceptable positive slit lamp findings occur, immediately join the other camp and refit.

The large and small diameter camps also exist when you prescribe RGPs. Three-nine staining, and its tendency to enhance engorgement of the nasal and temporal bulbar conjunctival vessels, is the driving force behind this decision, since physical contact with the pinguecula should not be an issue. Advocates of a large overall diameter count on the ability of the lens to swab fresh tears over the nasal and temporal corneal surfaces during and between blinks. Proponents of small diameters try to minimize lens thickness, especially edge thickness, to minimize lid gap. So, the eyelids recontact the peripheral cornea before being lifted away by the pinguecula. Ocular lubricants may be a useful adjunctive therapy.

Besides overall diameter, base (and peripheral) curve-to-cornea fitting relationships and their effect on lens position and movement are important lens design variables to consider. Edge thickness and edge profile have direct effects on lid gap. Patient variables such as lid tonicity and tear film stability are also important.

Pterygia: Proceed With Caution

Pterygia can be a contraindication to contact lens wear. The more the leading edge of the pterygium has encroached onto the cornea, the more likely I am to advise the patient to not pursue contact lenses. Prior to fitting a patient with a pterygium, I inform him that frequent follow-up care is essential. Documenting the encroachment of the leading edge with baseline photographs or detailed drawings prior to fitting is advisable. Corneal staining patterns at follow-up visits dictate lens design changes, modifications to wearing schedules or discontinuance of lens wear.

Help is On the Way

I currently serve as faculty advisor for a research project on the effect of rigid lens overall diameter on incidence and severity of corneal staining and bulbar conjunctival injection in patients with pinguecula, conducted by fourth-year SCCO students Cindy Pung and Leena Gayakwad. The study is a cross-over design, with patients wearing 9.8 (large) and 8.8 (small) mm overall diameter rigid lenses. We look forward to sharing our findings with you.

Dr. Edrington is a professor and chief of contact lens services at the Southern California College of Optometry.