GP Lens Case Grand Rounds Troubleshooting Guide – 06

Vascularized Limbal Keratitis (Keratoconus): Neil Pence, OD, FAAO

Background

Mrs. AK, 55-year-old female, has a history of keratoconus OU, and having had penetrating keratoplasty 2-3 years ago in the right eye only. She is wearing GP lenses in each eye. She reports with entering complaints of increasing intolerance of her lenses, decreased wearing time, and increased redness in the left eye especially.

Test Procedures

Visual Acuities with GP Lenses:

OD: 20/20
OS: 20/30

Over-Refraction:

Plano 20/20
+.25 – .75 x 100 20/25

Keratometry:

OS: 48.00 @ 20/55.50 @ 110 (moderated distortion)

Current GP Lenses:

8.8mm overall diameter, 6.62mm base curve radius, -10.50D unknown design and material

Slit Lamp Evaluation (with Lenses):

The left GP lens centered slightly temporal and inferior; moved well vertically with the blink with a reasonably light touch over the cone area is noted in the fluorescein pattern. Some lateral mid-peripheral bearing was noted, with slightly above average edge lift laterally.

Slit Lamp Evaluation (without Lenses):

OS: Marked conjunctival redness temporally in the interpalpebral or exposed area; a raised hazy lesion just inside the temporal limbus (the 3 o’clock position) between the lens edge and the limbus, with vessel engorgement and encroachment from the limbus into this raised lesion (Figure 1). Moderate inferior superficial punctate keratitis (SPK) was present below the lens edge and at 3 & 9. Similar but much milder appearance presented at the nasal limbus as well (9 o’clock), but not raised, only slightly cloudy and injected.


Figure 1: VLK temporally; note the vessel encroachment and the raised hazy nodule.

Patient Consultation and Education

Diagnosis: Vascularized Limbal Keratitis (VLK)

The problem is chronic dryness and irritation from their persistent 3 & 9 staining. When the SPK has been sufficiently severe to cause VLK, treatment must first revolve around stopping the induced inflammatory process. Secondarily, action must be taken to prevent or lessen the dryness in this area.

This patient was placed on Pred Forte, one drop 4-6 times per day in the left eye, and contact lens wear was discontinued. The patient returned four days later with reduced redness temporally and fewer symptoms of irritation (Figure 2), but requesting to resume GP lens wear again. She felt uncomfortable driving in her glasses. In order to allow her the better vision provided by her GP, but to continue to protect the cornea from dryness and exposure, and keep it moist enough to not induce the inflammatory response, a bandage soft contact lens was placed under her left GP lens. She wore the piggyback system for a one month period, with instructions to limit the wearing time to 8-10 hours a day.


Figure 2: Same patient after treatment with topical 1% prednisolone.

Follow-Up Care and Final Outcome

At one month, she was dispensed a new GP lens: a Dyna Intralimbal lens from Lens Dynamics / 10.8 mm diameter / 7.18mm base curve radius / -6.00D power / with a steeper than normal peripheral edge design requested. (Note: the base curve radius change appears to be large, but the base curve radius for this particular design of lens is essentially chosen by how the lens aligns in the mid-periphery.) Mild inferior central bearing, but good movement and tear exchange were noted.

On a follow-up visit, the lens was noted to fit slightly temporally, resulting in the lens edge being much closer to the limbus than with her previous GP lens. This moved the induced drying area (where the lid is held away from making contact with the cornea due to the lens mass) farther out toward the limbus. This resulted in less redness and irritation. The patient was also asked to keep the wearing time down in the new lens.

While the design changes proved successful, one month later the patient asked to try the piggyback system again, as she desired the longest wearing time possible with her lenses. The soft lens under the GP covers the limbal area and prevents the drying and irritation from occurring to the point of triggering the inflammation again.

Discussion / Alternative Management Options

VLK is a frustrating complication, and is especially problematic for persons who benefit significantly from GP lens wear, such as those with irregular corneas. It is often a combination of drier eyes, or activities that promote drying (such as being in the wind or drafts, large amounts of reading or computer use, etc.), and lens designs or fits that prevent adequate lid wiper effect just outside the edge of the lens. While in this case a soft contact lens was used to keep the cornea from drying as much, generally GP lens parameter changes can improve the situation.

In dealing with VLK, first evaluate and address the dry eye. Evaluate the lid for any evidence of meibomian gland dysfunction (MGD) or blepharitis, and if present institute treatment for the lid condition. Assess the tear quality and quantity, and evaluate the inferior tear prism. If applicable, implement such treatment modalities as tear supplements during the day and at bedtime, and systemic supplements to encourage increased tear production.

Next, evaluate the lens fit and design. VLK may be most commonly caused by excessive edge lift, so consider steeper peripheral curves, or possibly aspheric back surface designs to change the edge lift. The edge lift can also be affected by increasing the optic zone diameter. There can also be a problem with lens edge thickness, so be sure the edge mass is not a problem.

Finally, the lens diameter can affect the condition. As a general rule, it is helpful to move to larger diameter lenses. This is certainly not always the case, however, so it is probably more correct to say just make changes to the diameter. For smaller diameter lenses, try larger. If they are experiencing the problem with larger diameter lenses, go smaller. Look for lenses that also have some lateral movement or sliding when the patient looks laterally. These will be better than lenses that seem to stay perfectly centered on lateral gaze, thus never sliding over to help wet the area just outside the lens edge in primary gaze.

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