PROSTHETIC CONTACT LENSES

Prosthetic Lens Patient Management

Learning to fit prosthetic contact lenses can add a rewarding new dimension to your practice.

By Sunny M. Sanders, OD, FAAO

Dr. Sanders serves as the assistant dean for Clinical Affairs of the Eye Care Center at the Southern California College of Optometry as well as coordinator for the Ocular Prosthetic Services and the Practice Management Curriculum. Her primary teaching responsibilities include contact lenses, ocular prosthetics and practice management. Dr. Sanders lectures in the areas of contact lenses, ocular prosthetics and practice acquisition and management.

Eyecare practices have routinely offered tinted and colored contact lenses to provide cosmetic changes to patients' eye color and overall appearance. Beyond this cosmetic application of tinted and colored contact lenses, other therapeutic uses also exist. Aside from the practice building aspect of adding this unique use of colored contact lenses to the services you offer, the life-changing results are rewarding beyond explanation.

Efforts to enhance the appearance of disfigured eyes or unusual ocular cosmetic situations have always presented special challenges. Tinted and colored contact lenses can be used as prosthetic devices, but this use is not commonly associated with general eyecare practice. We are uniquely positioned to use our knowledge and training in contact lenses to design and create these special cosmetic and therapeutic effect lenses.

Applications

A hydrophilic prosthetic lens is essentially a hydrophilic (soft) contact lens that is optimally fit on the existing eye tissues and then tinted or pigmented to mask the disfigurement or undesirable condition and/or to handle visual or vision performance issues.

Common prosthetic contact lens uses can include ocular masking of either sighted or non-sighted eyes that require a prosthetic lens for cosmetic management of conditions such as colobomas, cataracts, corneal leukomas, diplopia, amblyopia, aniridia, albinism, injuries and other disfigurements or abnormalities. The ideal outcome is to match or recreate the patient's natural appearance. Duplication of the natural pupil, iris and scleral appearance is the goal as well as any possible visual enhancement.

Patients today can choose from a variety of colored contact lenses to enhance their natural eye color or to feel more comfortable with their cosmetic appearance. Patients may request subtle color enhancements, very dramatic color changes or even correction of anomalies. To create these various effects, the contact lens colors range from opaque to transparent.

Opaque Prosthetic Lenses

Several companies manufacture "stock" prosthetic soft lenses, which have some set parameters and iris color choices (Figure 1). The opaque stock prosthetic contact lenses are usually designed to be replaced annually. The available colors are applied to the front surface of the contact lens as an opaque color "paint" and generally are successful for many patients. In addition to specifying the iris color, other variables to determine include pupil size, base curve radius and power.

Figure 1. 1a (top) shows an eye prior to application of an opaque stock prosthetic lens. 1b (bottom) shows the cosmetic result of prosthetic lens application.

Fit these designs diagnostically using the colored fitting sets available from the manufacturers. It's prudent to diagnostically fit either a lens from the colored fitting set or a clear lens of the same material and power prior to ordering the final prosthetic colored lens for the patient. This step assures wearing success. Patients should treat the diagnostic lens as they would any other lens design. Instruct patients on proper care and handling of the lens, then provide the appropriate care system and instruct them to gradually build their wearing time to the accepted level. All prosthetic contact lens follow-up visits should encompass the accepted standards of care associated with routine care of contact lens patients.

If the available stock colors are not acceptable to a patient, then custom hand-painted colored prosthetic lenses are an option (Figures 2 and 3). Custom hand-painted prosthetic soft contact lenses may be preferred when trying to match light or unusual iris colors. More precise iris color tones and even scleral colors with appropriate veining can be created with this technology. During this process, a technician hand-paints special pigments on the front surface of the soft contact lens. The pigments bind to the front surface. Because such lenses are custom painted to order, you can specify the iris and pupil position and even decenter them on the lens to correct for any misalignment of the eye. This technique can cosmetically correct an eye-turn on a non-seeing eye.

Figure 2. Examples of hand-painted custom prosthetic contact lenses.

Figure 3. 3a (top) shows a patient prior to application of a hand-painted prosthetic contact lens. 3b (bottom) shows the improved cosmetic appearance after lens application.

When fitting hand-painted lenses for therapeutic or cosmetic application, it's important to precisely measure, document and specify the following parameters as seen on the natural eye that you want to duplicate on the hand-painted contact lens:

• Iris diameter in the horizontal and vertical dimensions.

• Iris detail such as flecks, spokes, etc.

• Pupil sizes in dim, bright and normal room illuminations.

• Limbal ring detail: thick or thin, and color.

• Other anatomical traits to match.

The final specifications should match the natural eye as closely as possible.

If you are fitting a misaligned eye and wish to mask (hide) the misdirected eye, then I suggest using a prism-ballasted, large-diameter scleral soft lens.

Hand-painted contact lenses generally require the use of methafilcon (53 percent water) or ocufilcon (55 percent water) lens materials. These materials are best for adherence of the pigments used for hand-painting. Another advantage to the custom hand-painted lens option is the availability of common prescription power ranges as well as most extended power ranges both for spherical and cylindrical components. This allows for correction of most refractive errors in this custom therapeutic device.

As with opaque prosthetic stock lens designs, you should diagnostically fit a clear contact lens of the chosen material and correct power prior to color being added. This step helps ensure that you don't obtain a custom, non-returnable prosthetic lens that the patient is unable to wear.

Once you successfully fit the clear design, you need to determine the color detail. Close-up photos of the patient's natural eye provide the most accurate color matching or detail documentation. Digital photographs are preferred. A digital SLR (single-lens reflex) camera is very accurate in capturing the detail and exact colors of the natural eye. A digital point-and-shoot camera, which can take a clear close-up photo of the patient's face/eye within about 12 inches of the facial plane, will be able to take a very acceptable photo.

Another way to provide a record of the patient's natural eye color is to send the painting laboratory diagnostic colored contact lenses, prosthetic eyes, or prosthetic eye color chips. It's important to color match using a variety of lighting types. Viewing the color chips next to the natural eye in natural, fluorescent and incandescent light sources will provide the most accurate match.

Many hand-painted lenses require an oxidizing care system, but make sure to obtain exact care instructions from the laboratory providing the hand-painting. Hand-painted lenses are to be worn on a daily wear basis and generally are replaced annually.

Tinted Enhancer Lenses

Enhancer lenses are tinted with transparent natural-eye-color enhancing tints. The dyes used for this process actually penetrate the contact lens material. Because the colored dyes do not coat the surface of the contact lens like a "paint" pigment can, the colored dye usually remains transparent. The most common colors are aqua, blue and green. There are custom enhancer and therapeutic tinted lenses that are available in brown, brown-black, magenta, purple/violet, pink, orange, green and yellow. These colors are used for more dramatic appearance changes and for vision performance enhancement.

Ready-made tinted contact lenses are available from a few different contact lens manufacturing companies, but they're limited to a few replacement and wear schedule modalities. There may also be limitations on available power ranges. An alternative option for obtaining this type of tint effect is to create the tints using a soft contact lens tinting system in your practice. The system we use in the Eye Care Center of the Southern California College of Optometry is the Softchrome In-Office Tinting System (Softchrome, Inc., Figure 4). This simple-to-use system allows you to tint almost any hydrogel material (limited silicone hydrogel capability) with transparent and opaque colors either to enhance an iris color or modify it (Figure 5). The tinting system kit includes a choice of patterned templates to create pupil and iris combinations, the dyes, tinting equipment and instructions. Additional benefits to tinting contact lenses "in house" include cost savings, faster delivery time, color modification options and the ability to apply a tint for cosmetic or therapeutic use to lenses of any available power combination and preferred replacement schedule suitable to the individual circumstances and patient.

Figure 4. The Softchrome In-Office Tinting System.

Figure 5. Examples of in-office tinted lenses.

To create a prosthetic effect, you can intensify the tints to mask many ocular conditions (Figure 6). Additionally, by using black dye, which is more opaque than other colors used in the tinting system, you can tint the contact lens to create opaque areas on the lens. This technique allows you to create prosthetic contact lenses with a normal pupil appearance when using the black dye to create a pupil effect. Opaque pupil contact lenses can also be used outside the prosthetic arena for amblyopia occlusion therapy.

Figure 6. 6a (top) shows a patient prior to application of a tinted prosthetic contact lens. 6b (bottom) shows the improved cosmetic appearance after lens application.

You can create a clear pupil area by tinting a solid iris mask pattern, and, when using black dye, you can create a light-blocking iris mask for treating conditions such as aniridia. The opaque iris mask and pinhole pupil effect can dramatically help in such cases. Depending on the needs of the patient, you can create and diagnostically fit an opaque black mask the size of an iris with a variety of pupil aperture openings.

One advantage of tinting lenses yourself is the capability to tint almost any contact lens polymer and thus to choose a lens with a more frequent replacement schedule.

You can also easily produce therapeutic tinted lenses that help patients who have color deficiencies discern color. The result is commonly an enhanced reading ability, reduced glare, increased contrast sensitivity and improved color discrimination. Sports enhancements are also an option — green tints may help tennis players, yellow tints are used in baseball and hunting, and blue and violet tints may be beneficial for snow sports.

As with the other therapeutic and prosthetic contact lens types discussed, tinted designs should be worn on a daily wear schedule using the manufacturer's recommended care system. Recommend rewetting drops as appropriate for any of the lens polymers used. Schedule professional evaluations for every six months and lens replacement for every twelve months unless you prescribe planned-replacement lenses.

Rewarding for Your Practice

Eye care includes vision correction, vision protection, functional aspects of vision, health evaluation, and disease diagnosis and treatment as well as psychological wellness. It's essential that we use our knowledge and skills to help all patients meet these needs. Devising special cosmetic or prosthetic solutions to unique situations using the techniques discussed in this article is one such niche. It's obvious that prosthetic and therapeutic contact lenses significantly impact the lives of those we treat. Be a source for custom solutions. Table 1 provides available prosthetic lens and tinting sources. Ocular prosthetic and therapeutic contact lens aspects of patient care can provide endless examples of both patient and practitioner satisfaction; you should consider adding it to your practice if you're interested in outside-the-box creativity and a standard of patient care beyond the norm. CLS