Coating the inner and outer surfaces of the artificial eye is a tear film. People normally blink the eyelids about every six seconds to replenish this tear film. Tears have four main functions on the artificial eye:
- wetting the conjunctival lining of the socket, preventing damage due to dryness,
- creating a smooth optical surface on the front of the microscopically irregular acrylic surface,
- providing lubrication and acting as a vehicle to remove debris from the prosthetic surface, and
- containing an enzyme called “lysozyme” which destroys bacteria.
The tear film resting on the prosthetic surface has three layers:
- Lipid layer,
- Aqueous Layer, and
- Mucin Layer.
The top layer of the tear film is the lipid or oily layer. This layer prevents the aqueous layer beneath it from evaporating, as well as preventing the tears from flowing over the edge of the lower eyelid.
Below the lipid layer is located the aqueous layer of the tear film. This middle layer is the thickest of the three tear layers. The aqueous fluid contains salts, proteins and lysozyme.
The bottom layer is the mucin layer. This layer adheres to the “hydrophobic” (water-repelling) acrylic surface of the prosthesis. Therefore, for a tear layer to be able to remain on the prosthetic surface without rolling off, the “hydrophilic” (water-attracting) mucin layer is necessary.
A deficiency of any of the three layers of the tear film can lead to a “dry eye” condition, causing anything from mild eye irritation to severe pain. Interestingly, in some cases, excessive tearing or watering of the eyes can be a symptom of a dry eye condition. This is because when, for whatever reason, there is an inadequate normal tear layer on the eye, irritation results; the latter causes an overproduction of the lacrimal gland and a flooding of lacrimal fluid into the eye.
Besides excessive tearing, symptoms associated with dry eyes can include the following:
- eye irritation, scratchiness, grittiness, or pain,
- redness of the conjunctival tissue,
- a burning sensation in the eye,
- a feeling of something in the eye,
- eyes that feel “glued shut” after sleeping,
- excess mucosal drainage, and
- discomfort wearing the prosthesis.
There can be multiple causes of a dry eye condition for a prosthetic eye wearer:
- lid or blinking problems,
- reading or working at a computer screen for long periods of time,
- medications like antihistamines, oral contraceptives, beta blockers, diuretics, tranquilizers, pain relievers, or antidepressants,
- a dry climate (including heating and air conditioning in a home, airplane, or hotel room), wind, UV radiation, tobacco smoke, and dust,
- diseases such as rheumatoid arthritis, Sjogren’s syndrome, keratoconjunctivitis sicca, xerophthalmia, lupus erythematosus, Grave’s disease, diabetes, or scleroderma
- hormonal changes accompanying menopause,
- chemical, radiation, or thermal burns to the eye,
- vitamin A deficiency,
- aging, since the tear glands produce fewer tears as we age,
- protein adhesion to prosthetic surface,
- scratches on the prosthetic surface, or
- ill-fitting prosthesis.
A dry eye problem often can be relieved with the use of lubricating eyedrops, which are instilled daily or as needed onto the prostheic surface. These types of drops can soothe the socket, moisturize dry spots, supplement tears, and protect conjunctival tissue from further irritation. They provide comfort and a nice shiny, even tear layer over the prosthesis. They have a higher viscosity than natural tears, so they need to be insilled less frequently, often just once or twice per day. The lubrication allows for easier blinking, less drainage from the socket, and a very natural appearance.
Soothing eye drops are also available. These drops have the same viscosity as natural tears, which means they will not be as long lasting as the lubricants, but they do have soothing properties to control allergies, discomfort, itchiness, inflammation and excess mucosal drainage.
Some patients chose to try “artificial tears” type eyedrops to alleviate the sypmtoms of dry eye. These are not very successful because they do not last very long. Most “artificial tear” drops only contain saline, which evaporates very quickly. Some eyedrops contain “vasoconstrictors” (chemicals such as tetrahydrozaline or naphazoline), which constrict the conjunctival blood vessels, thereby reducing the amount of redness on the surface of the eyes. We do not recommend these drops for prosthetic eye wearers as they damage the tissue lining the anophthalmic socket.
Should you have any difficulty with your current regimine, we recommend working with your Ophthalmologist, Optometrist and your Ocularist to determine the root of your symptoms and come up with an appropriate solution. With a healthy fit of your prosthesis, frequent polishing and proper lubrication, your prosthesis should be able to fit and function well. Our goal is to provide our patients with excellent comfort and cosmesis for the most natural, realistic result possible.