pediatric and teen cl care
Contact Lenses for Amblyopia Treatment
BY JEFFREY J. WALLINE, OD, PHD, & MARJORIE J. RAH, OD, PHD
Ambylopia affects approximately 3 percent of the United States population, and the best time to treat it is during childhood. Young children don't understand consequences, so it's meaningless to tell them that if they don't wear an eye patch now they'll never develop clear vision. Many refuse to wear a patch because it's uncomfortable, they can't see clearly or they don't like how they appear while wearing it.
Other options are available, such as frosting spectacle lenses, atropine eye drops and contact lens wear. You may prescribe an opaque occluder contact lens or intentionally over-plus lenses to encourage the child to fixate with the amblyopic eye.
Occluder contact lenses are available from several companies, but generally cost $50 to $100 more than do lenses to correct refractive errors. Black, opaque pupil sizes can typically be customized, and in this case bigger is usually better. The opaque center should be 5.0mm or larger, but opaque centers with diameters bigger than 8.0mm completely block light and are less likely to allow a child to peak around a decentered lens.
Penalization due to optical blur may also effectively treat amblyopia, and the lenses are more readily available at standard prices. For the optical blur due to over-plus of the prescription to be effective, the lens-induced blur must be greater than the blur experienced by the amblyopic eye. Therefore, fitting a child with lenses that are over-plussed typically is only effective in patients who have low-to-moderate amblyopia. The child must also be hyperopic. Over-plussing a myopic child results in clear vision at near for the sound eye, which eliminates the stimulus necessary to force the child to use the amblyopic eye to improve vision.
While lenses prescribed for optical blur are more commonly available and less expensive, they're an option for only a select group of patients.
Examining Treatment Options
A study by Joslin and colleagues (2002) examined the efficacy of occluder contact lens wear for patients whose amblyopic vision did not improve while they were prescribed adhesive skin patching. They found treatment was successful for approximately one-third of patients, while one-third never improved because the lens was too difficult to apply. The other third initially improved but later failed because the child learned to dislodge the lens. While on treatment, patients required new lenses about every three months due to loss or damage. The authors recommended fitting children with high-plus occluder lenses to improve handling and to decrease damage frequency.
While high-plus lenses may allow less oxygen to reach the eye, studies indicate that just two hours of occlusion per day is as good as six hours of occlusion for moderate amblyopia. For severe amblyopia, six hours per day is as good as full-time patching.
Justifying the Option
Contact lenses to treat amblyopia may be covered by health insurance, but you must strongly justify why contact lenses are necessary by stating that other therapies weren't successful. You must also prove that studies show the success of occluder contact lenses.
While many treatment options are available, you should also consider contact lens wear to treat amblyopia, especially for patients who do not succeed with other therapy options. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #156.
Dr. Walline is an assistant professor at The Ohio State University College of Optometry, where he conducts studies of pediatric contact lens wear. Dr. Rah is an assistant professor at the New England College of Optometry where she works primarily in the Cornea and Contact Lens Service in patient care, teaching and research.