contact lens
materials
Therapeutic
Uses of Silicone Hydrogel Lenses
BY
JEFF SCHAFER, OD, MS
When fitting
contact lenses primarily to protect the cornea or promote healing, they're known
as therapeutic or bandage contact lenses. Fitting a bandage lens is a billable procedure
using the CPT
code 92070, which is described as the "fitting of a contact lens for the treatment
of disease, including the supply of the lens."
Bandage Lens Applications
A contact lens can act as a protective barrier to the cornea in
conditions with eyelid loss and/or dysfunction that could result in exposure keratitis.
With trichiasis or entropian, a contact lens can protect the cornea from inward-facing
lashes. In cicatrizing conjunctival diseases such as ocular pemphigoid, Stevens-Johnson
syndrome, chemical or thermal burns, or trachoma, a contact lens can offer protection
from exposure and prevent symblepharon.
A bandage lens may act as a splint to support weak areas in cases
of corneal perforation or descemetocele. Bandage lenses can also enhance the rate
of corneal wound healing by preventing the disruption of migrating epithelial cells
that aren't completely adhered to the basement membrane. A bandage lens can be an
alternative to debridement or phototherapeutic keratectomy in recurrent corneal
erosion cases.
An additional useful benefit of a bandage lens, but perhaps most
important to patients, is symptom relief. The presence of a contact lens greatly
reduces severe pain associated with exposed nerve endings resulting from a compromised
epithelium.
Lens Characteristics and Fitting
An ideal therapeutic lens will minimize hypoxia, tear film disruption
and mechanical trauma while promoting recovery of the condition being treated. Oxygen
transmissibility should be maximized, particularly when a patient will wear the
lens continuously.
Additionally, the overall diameter should offer complete limbal
coverage and you should choose a proper base curve. Adequate movement of approximately
0.5mm is necessary, but avoid excessive movement to prevent further tissue compromise.
In the recent past, the off-label use of traditional disposable
hydrogels became popular as bandage lenses because of their low cost and availability
as diagnostic lenses. However, silicone hydrogel materials offer a better alternative
with superior Dk/t values and a range of base curves to choose from. Both PureVision
(balafilcon A, Bausch & Lomb) and Night & Day (lotrafilcon A, CIBA Vision)
have received FDA approval for therapeutic use, and a great deal of literature reports
on the safety and efficacy of silicone hydrogel materials used for therapeutic purposes.
Patient Management
Although silicone hydrogels offer a greatly reduced risk of hypoxia,
you should monitor bandage lens wearers with frequent follow-up visits. Minor complications
include redness, irritation and vascularization. Hypoxia from a tight-fitting lens
or from low Dk/t can lead to corneal edema, which may worsen the condition being
treated.
Monitor the lens for deposits and replace it frequently if necessary,
and watch for GPC. Evaluate the cornea for any signs of corneal infiltrates or worse
— microbial keratitis. Initiate concurrent topical antibiotic therapy in conditions
that involve epithelial compromise.
More Choices, Better Care
Silicone hydrogel lens materials have revolutionized the way I
manage patients. The outstanding oxygen transmissibility and higher modulus of silicone
hydrogel materials make these contact lenses ideal for therapeutic use.
Dr. Schafer is a clinical
assistant professor and chief of the contact lens service at The Ohio State University
College of Optometry.
Contact Lens Spectrum, Issue: May 2006