Article

CLINICAL: Contact Lenses

Low Vision Applications

Aid patients who have low vision, due to congenital etiologies

Although using contact lenses is not a common strategy for the treatment of acquired low vision, they can provide a benefit for those who have congenital etiologies (described below).

The five following etiologies of reduced vision can benefit from contact lenses.

1 OCULAR ALBINISM

Studies reveal distinct benefits of therapeutic-tinted contact lenses in patients who have ocular albinism, a condition in which, due to the lack of pigmentation in the iris and retina, patients have high amounts of photophobia, glare, a limited VA and nystagmus. A clinical study in Investigative Ophthalmology & Visual Science shows an improvement in logMar VA in patients who wore therapeutic-tinted contact lenses. These patients also experienced an improvement in contrast sensitivity testing with and without glare, along with a reduction in nystagmus intensity. The soft, therapeutic contact lenses were tinted to create an artificial iris, thus minimizing photophobia and glare. This effect will often increase VA and decrease nystagmus.

2 OCCLUSION IRIS FOR ANIRIDIA

In aniridia, the absence of the iris causes photophobia and glare. Other potential ocular abnormalities include limbal stem cell deficiency, glaucoma, cataracts, foveal and optic nerve hypoplasia or underdevelopment. Both visual (photophobia, glare) and cosmesis concerns can be addressed using a painted or computer-printed opaque contact lens. The benefit to the patient is two-fold: It gives the appearance of an iris, and it blocks light to decrease glare in a similar fashion as the natural iris.

3 OPTIC HYPOPLASIA AND CONGENITAL RETINOPATHIES

In etiologies, such as optic hypoplasia and congenital retinopathies, where structures and functions of the eye either did not develop properly or at all, a high minus contact lens used in conjunction with a high plus spectacle lens creates approximately two times magnification. In the case of retinitis pigmentosa or when there is VF constriction, a reverse telescope system may be useful for field expansion. In this scenario, a high-plus contact lens is used in conjunction with a high-minus spectacle lens.

4 COLOR DEFICIENCY

Certain technologies can aid in the perception of colors. For example, a deep red-tinted contact lens (X-Chrom lens, Art Optical) can enhance color perception in patients who have a red/green deficit. The lens is worn monocularly in the non-dominant eye.

5 HIGH AMETROPIA OR ANISOMETROPIA

When your patient presents with a high amount of hyperopia, myopia or anisometropia, consider offering contact lenses as a first line treatment. If your patient’s spectacle prescription is above + or – 10.00 D in any meridian or anisometropia is 3.00 D or greater in any meridian, then your patient qualifies for medically/visually necessary contact lenses. The reason: While ophthalmic lenses can improve VA, limitations include reduced fields of view, image size jumps and image distortion. Contact lenses, however, correct vision at the corneal plane, thus, minimizing visual disturbances. In anisometropia, the reduction in distortion and aniseikonia, or unequal retinal sizes, with contact lenses improves visual quality vs. ophthalmic spectacle lenses, reports the Journal of British Contact Lens Association.

FUTURE SOLUTIONS

Research of new applications for contact lenses are being studied. Along with magnification and text reading, wearable technology may have the ability to detect and describe faces or, someday, interface with augmented reality. OM