dry eye dx and tx
Resolving Dry Eye in GP Lens Wearers
BY ANN LAURENZI, OD, FAAO
Although the overwhelming majority of contact lens patients wear soft lenses, many patients either by choice or by clinical necessity wear GP lenses. Such patients may include high astigmats, post-refractive surgery patients who have residual ametropia and/or irregular astigmatism, post-penetrating keratoplasty patients and patients who have keratoconus, pellucid marginal degeneration or corneal trauma.
These patients, just like our soft lens patients, may be challenging to manage when they also have dry eye syndrome/ocular surface disease. Dry eye patients may have inadequate tear volume to properly support the lens fit, and complications can occur.
Diagnostic Staining Patterns
One such example is corneal staining in the 3 o'clock and 9 o'clock positions. This type of desiccation occurs in the peripheral corneal areas adjacent to the edge of the GP lens and results when the corneal surface isn't adequately resurfaced with tears after the blink. If the edge of the GP lens holds the lid away from the corneal surface during the blink, proper spreading of the tears does not occur at the 3 o'clock and 9 o'clock positions, exposing surface epithelial cells and causing desiccation. This type of staining may also be related to incomplete blinking secondary to lens wear, which again causes inadequate tear coverage in that area of the cornea.
The epithelial cells will stain positively with fluorescein secondary to dryness, and the adjacent interpalpebral conjunctiva may also become mildly to severely injected. Patient symptoms may include mild to extreme discomfort with reduced wearing time.
You may also see 3 o'clock and 9 o'clock desiccation with vascularized limbal keratitis, which is a mechanical impingement of the contact lens on the cornea with inadequate tear flow.
Adjusting Lens Fit
Once you have detected 3 o'clock & 9 o'clock staining, you should first examine the lens fit as well as the quality of the tear film. An inferiorly positioned lens with excessive edge lift and inadequate lens movement should be refit. The previously mentioned lid-to-cornea gap resulting from thick edges will also lead to epithelial drying. To improve the fit, strive for a superior lens position and try one or more of the following changes:
- Decrease overall diameter.
- Reduce center thickness.
- Utilize ± lenticulars.
- Reduce edge clearance.
- Steepen peripheral curve radius.
- Narrow the peripheral curve width.
- Reduce edge thickness.
The tear meniscus height is typically lower and conjunctival staining more prevalent in GP patients who have 3 o'clock and 9 o'clock staining.
In conjunction with improving lens fit, frequent application of rewetting drops will increase tear volume and provide corneal lubrication. Drops with which I've found success include Blink (Advanced Medical Optics), a hyaluronic acid-based drop to hydrate and protect the eye, and Soothe XP (Bausch & Lomb), an emollient-based drop to reduce tear evaporation.
Other strategies include using a GP material with good wetting characteristics or plasma treating the lens for better wetting. Punctal occlusion may help maintain tear volume in cases where rewetting drops aren't enough.
If these strategies fail to improve the condition, then using a silicone hydrogel lens in a piggy-back system with the GP lens may eradicate the problem. CLS
Dr. Laurenzi practices at the Cole Eye Institute in Cleveland, Ohio where she specializes in refractive surgery co-management, contact lenses and clinical research.