Managing the Three D's (Part 1)

BY EDWARD S. BENNETT, O.D., M.S. ED.
FEB. 1996

Rigid gas permeable lenses offer quality vision, ocular health, and reduced progression of myopia, as well as patient retention and profitability. In addition, RGP-induced problems are typically benign and easily managed. We can associate most of these problems with the three D's -- discomfort, dryness and decreased vision.

DISCOMFORT

Initial -- Poor initial comfort is often the result of poor edge quality or a highly sensitive patient. Edge inspection is critical yet more than 40 percent of practices do not verify edges. This is an easy way to lose a potentially successful contact lens patient. Careful inspection and use of a reputable laboratory authorized to manufacture your RGP lens materials of choice is critical.

Some patients are highly sensitive to RGP lens wear (or contact lens wear in general). You'll usually identify these individuals during the vision examination as they are not receptive to lid eversion, tonometry or drop instillation. Although some of these patients are better served with soft lenses, others may still be good candidates for RGPs given the aforementioned benefits. If this is the case, follow these guidelines:

1) Don't use threatening terms such as discomfort or pain. Explain that they will experience some lens awareness as their lids adapt to the lenses. Even non-verbal communication is important. If you're not interested in fitting RGPs, patients can discern this by your facial expressions or tone of voice, even when you feel you've provided a balanced presentation.

2) Use a topical anesthetic at the diagnostic fitting and, if desired, at the dispensing visit. This allows patients to overcome the initial psychological hurdle of contact lens wear. This is important not only with sensitive patients but also with children, keratoconus patients and former soft contact lens wearers. Explain that you're using an anesthetic and that lens awareness will occur gradually as the effects wear off. Anesthesia will also allow you to assess the fitting relationship more quickly.

3) To aid in the adaptation process, build up wearing time more slowly than usual.

Acquired -- Acquired symptoms of discomfort are often the result of an acquired edge defect, a corneal abrasion (i.e., foreign body, vascularized limbal keratitis) or a change in the lens-to-cornea fitting relationship. Careful edge inspection and a comprehensive biomicroscopic evaluation with fluorescein will aid your diagnosis.

DRYNESS

Subjective symptoms of dryness and redness are often caused by a deficient tear film and result in clinical signs of poor surface wettability and peripheral corneal desiccation. Comprehensive tear film quality and volume testing is imperative. Evaluate the tear prism and perform tear break-up time (tear B.U.T.) and Zone-Quick tests. Zone-Quick by Menicon is a brief, relatively comfortable test consisting of a yellow cotton thread pre-soaked in phenol red dye. A value of 10mm or less indicates dry eye.

If the tear B.U.T. is less than 10 seconds, there is a problem. Is the patient taking antihistamines or other medications that adversely affect the tear film? Is blepharitis or meibomianitis present? Obviously, if the patient is taking antihistamines and is symptomatic, he may need to reduce wearing time. Manage blepharitis and meibomianitis with good lid hygiene supplemented by an anti-staph antibiotic ointment for the former and heat with vigorous massage for the latter.

If coalesced peripheral corneal desiccation is present, it's important to ensure that you are using a wettable RGP material and that you have achieved good lens centration. (I'll discuss management of decentration and reduced surface wettability in my April column.)

Vascularized limbal keratitis is a more acute peripheral corneal complication. This condition consists of an elevated, opaque, vascularized area, usually in the exposed 3 and 9 o'clock region of the peripheral cornea. Patients complain of dryness, discomfort and reduced wearing time. VLK is typically caused by a silicone/acrylate lens material (more common with extended wear than with daily wear) with very little to no peripheral edge clearance. Discontinue lens wear and treat with a topical steroid. Prescribe a fluorosilicone/acrylate lens material with a wider, flatter peripheral bevel.

The third D, decreased vision, will be the focus of my April column. CLS

Dr. Bennett is an associate professor of optometry at the University of Missouri-St. Louis, and is executive director of the RGP Lens Institute.