Contact Lens Care and Supplemental Procedures

CLIFFORD SCOTT, O.D., M.P.H. & PAUL WHITE, O.D.
NOV. 1996

When contact lens practitioners master these supplemental procedures, they are better able to meet specific patient needs.

Periodically, we all encounter patients who present with an unusual problem. By adapting proven concepts to new uses, we may be able to devise innovative solutions. The following information about punctum plugs, opaque prosthetic contact lenses, ocular photography and foreign body removal illustrates how practitioners can use fundamental and supplemental procedures to meet specific patient needs.

PRE-OCULAR TEAR FILM

The pre-ocular tear film is the host environment for contact lenses in vivo. Some important functions of the pre-ocular tear film are to:

• produce optically smooth and clean anterior corneal and contact lens surfaces;
• provide a rinsing system to remove debris from the cornea and between the cornea and contact lens;
• create a reservoir and passageway for gases, such as oxygen and carbon dioxide;
• maintain proper osmotic equilibrium and pH;
• combat infection by its bacteriostatic and bacteriocidal agents;
• wet the eye and the contact lens; and
• to create a surface tension and capillarity to hold lenses in place.

An inappropriate pre-ocular fluid quantity or quality can interfere with successful contact lens wear, and contact lens wear can disrupt the quantity or quality of pre-ocular tear fluid. The pre-ocular fluid/lens interaction alters both the surface contour and the optics of hydrogel lenses. In vivo, dehydration of hydrogel lenses is very common. When a soft lens stored in solution at room temperature (about 70^o F) is placed on the cornea (about 95^o F), the temperature gradient dehydrates the lens, more so with higher water content lenses. This is the principal reason for the so-called equilibration period. There's also a constant state of cyclic dehydration: tear film breakage and evaporation at the anterior surface and fluid withdrawal from the lens itself due to an osmotic pressure gradient.

Cyclic dehydration, which is exacerbated by environmental factors such as low humidity or high temperatures, can change lens dimensions and fitting relationships. Coatings on hydrogel lenses can also change lens dimensions, fitting relationships and lens dehydration. Various soft lens manufacturers claim that their materials dehydrate or coat less than others. These claims are substantiated for some patients.

DRY EYE: CAUSES AND TREATMENTS

Total average volume of pre-ocular fluid is about 1/5 of a drop. It is secreted at the rate of about 1/30 of a drop per minute. These small volumes have to fulfill all of the functions described, an often impossible task for contact lens wearers, especially 'dry-eyed' patients. Dry eye is a disorder of the pre-ocular tear film due to decreased aqueous quantity or increased evaporation from lipid deficiency which damages the ocular surface and causes discomfort. Aging is one of many causes of dry eye. It is estimated that more than a third of people over 40 years old have clinically significant dry eyes. Females are more affected than males.

Dry eyes may relate to deficiencies of the aqueous, lipid or mucin layers of the pre-ocular tear film, as well as to blinking abnormalities and corneal epithelial abnormalities.

Aqueous deficiencies include keratoconjunctivitis sicca (KCS), Sjögren's syndrome, trauma to the lacrimal glands, chemical burns and use of medications that decrease aqueous production. Anti-anxiety agents, anticholinergics, antihistamines, phenothiazines and oral contraceptives may all decrease aqueous production. Sjögren's syndrome (SS-KCS) is immunologically mediated, causes corneal staining and may be associated with manifestations of immune ocular surface disease such as corneal ulcers, rheumatoid nodules and scleritis.

Mucin deficiencies result from impairment of conjunctival goblet cells and can be related to hypovitaminosis A, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, chemical burns and trachoma. Specific artificial tear preparations that stimulate conjunctival mucin may be used, but efficacy varies.

Lipid deficiencies may be linked to meibomitis and blepharitis which can decrease tear film evaporation time. Treatment relates to the efficacy of the conventional treatments for meibomitis or blepharitis.

Treatment for dry eye may include artificial tear preparations, methyl cellulose sustained-release inserts placed in the inferior cul-de-sac and punctal occlusion.

Artificial Tears

The most common treatment for run-of-the-mill dry eye problems is the use of artificial tears, although it's difficult to know which tear substitute is most efficacious based solely on its biophysical properties or chemical composition. Trial-and-error often determines the best tear substitute and its frequency of application. Unfortunately, the retention, duration and overall efficacy of any artificial tear product is lower than required by many patients. Retention is better with ophthalmic lubricating ointments applied at bedtime.

Rewetting or reconditioning drops for contact lens wearers are similar to artificial tears, but are often less viscous. Since the products used with a contact lens in situ must be compatible with the lens material, the overall efficacy of contact lens rewetting drops, as well as of artificial tears, is somewhat limited.

Some evidence suggests that age-related aqueous decrease is related to changes in circulating hormone levels, as estrogens probably up-regulate and androgens down-regulate immune activity. Increased evaporation is caused by an abnormal lipid level due to meibomian gland dysfunction (MGD), which is more common after age 40. MGD is characterized by plugged openings in the meibomian glands and a change in the appearance and consistency of the meibomian secretion.

Punctal Occlusion

Punctal occlusion can be temporary, semi-permanent or permanent. Temporary occlusion is accomplished with collagen plugs, which soften and dissolve five to 10 days after insertion. They are used as an efficacy test to determine if more permanent punctal occlusion is advisable. Instill one or two drops of topical proparacaine or tetracaine. Insert the plugs (usually without prior punctal dilation) until they are not visible in the upper and lower puncta of one or both eyelids. After insertion, the plugs swell.

Semi-permanent occlusion is done with non-dissolvable silicone plugs. Lacrimedics (Herrick) plugs are designed to be inserted into the horizontal canaliculus. Removal requires naso-lacrimal irrigation. The silicone punctum plugs manufactured by Eagle Vision (also distributed by CIBA Vision Ophthalmics) and those manufactured by Oasis and FCI have a flange that remains on the top of the punctum after insertion to facilitate removal. Insertion requires topical anesthesia either as one or two drops instilled in the eye, or by use of a cotton swab soaked in anesthetic and held as a pledget against the punctum for about 30 seconds. Some plugs come pre-loaded on a stylus to simplify handling. Usually, the punctum requires pre-dilation with an appropriate instrument to facilitate insertion and to assure that the plug will be held in place by the tension of the punctal ring. Because the top of the plug remains visible, both practitioner and patient easily can verify that it remains in place (Figs. 1 & 2).

FIG. 1: INSERTING A DIAGNOSTIC COLLAGEN ROD INTO AN UNDILATED PUNCTUM

FIG. 2: INSERTING A SILICONE PLUG INTO A DILATED PUNCTUM.

For permanent punctal occlusion, electric cautery or laser punctoplasty scars the punctum closed.

Moisture Shields

Moisture chamber goggles may offer some relief for patients with recalcitrant dry eye. When cosmesis is not an issue, such as with a non-responsive, hospitalized patient with severe corneal exposure, swimming goggles are an inexpensive, practical method to increase the ambient humidity. They are also easily removed for maintenance of hygiene or instillation of ocular medications. For more active individuals, Eagle Vision offers a moisture shield kit made of flexible vinyl that can easily be wedged into the eyewire of the patient's spectacles. The posterior border is trimmed to conform to the shape of the eye (Figs. 3, 4 & 5).

FIG. 3: SWIM GOGGLES MAY RELIEVE SEVERE KERATO-CONJUNCTIVITIS FIG. 4: CUSTOM MOISTURE SHIELD INTEGRATED INTO THE PATIENT'S EYEGLASS FRAME (TOP VIEW).

FIG. 5: CUSTOM MOISTURE SHIELD CRAFTED FROM EAGLE VISION KIT (SIDE VIEW).

OPAQUE PROSTHETIC CONTACT LENSES

Opaque tinted corneal and scleral contact lenses have been available for six decades. Opaque tinted hydrogels have been used for more than 20 years cosmetically on normal seeing eyes and as prosthetics for disfigured, poorly seeing or non-seeing eyes. Hydrogel prosthetic lenses improve abnormal appearance or improper visual function and may be used for:

• corneal abnormalities: band keratopathy; gerontotoxon; posttraumatic irregularities;
• iris or pupil abnormalities: aniridia; albinism; heterochromia; iridectomy; iridotomy; coloboma;
• crystalline lens abnormalities: aphakia; pseudophakia; subluxated lens; inoperable cataract; retrolental mass;
• vitreo-retinal abnormalities: maculopathy; retinopathy;
• extraocular muscle abnormalities: monocular or binocular diplopia; strabismus;
• sensory abnormalities: amblyopia and other forms of occlusion therapy; and
• globe abnormalities: buphthalmos; phthisis bulbi.

One study indicated that about three-quarters of prosthetic hydrogel lenses were fitted to essentially non-seeing eyes. Of these, about 34 percent were for corneal scars, 11 percent for inoperable cataracts and 24 percent for diplopia caused by vitreo-retinal problems. Translucent cosmetic enhancement hydrogel lenses may effectively mask fainter corneal scars. Inoperable dense cataracts may be masked with prosthetic hydrogel lenses that have no iris tinting, but have a black opaque pupillary zone whose diameter corresponds to the pupil size of the patient's other eye.

Opaque tinted lenses for prosthetic uses have similar overall parameters and are fitted in a manner similar to those used for cosmetic enhancement on normal eyes. Relative lens stability will reduce lens decentration and the associated malpositioning of the tinted portion onto the sclera and the pupillary portion away from the pupil.

Some companies have preset materials, parameters, iris colors and artificial pupil diameters. Others offer custom services whereby practitioners use clear hydrogel lenses to obtain the desired fit, then send the lenses to the company to add the iris and pupil characteristics. The practitioner measures the visible horizontal iris diameter and then orders the artificial iris diameter about 0.5mm to 1.0mm smaller to avoid scleral overlap. Then the practitioner selects the desired iris color to approximate the color of the patient's other iris. Color-balanced (flash) photographs may also help the lab to match the color more precisely. Because it's virtually impossible to match the nuances of the normal iris color under varied ambient lighting conditions, practitioners often order a matching lens for the other eye. Lenses with a clear pupillary area must center, otherwise decentration will cause visual disturbances and impair the visual field of a seeing eye (Figs. 6 & 7).

 

FIG. 6: OPAQUE PERIPHERY CONTACT LENSES; LEFT PUPIL CLEAR, RIGHT PUPIL OPAQUE.

FIG. 7: PATIENT WEARING OPAQUE PERIPHERY SOFT LENSES WITH OCCLUDER LENS IN LEFT EYE. NOTE THE EXO-DEVIATION MANIFESTED WHEN FUSION IS LOST.

Patients can use many of the standard lens care procedures and solutions, but should be aware that some solutions may adversely affect the color retention of the lenses. Manufacturers routinely supply maintenance information with the lenses, and they should be consulted if there are questions about the appropriateness of a technique or a solution for their lenses.

Opaques For Seizures

A 52-year-old woman had a history of seizures since age 13 and was diagnosed with temporal lobe epilepsy at age 45. She had determined that the seizures were triggered by flickering fluorescent lights, and that wearing a patch over either eye could prevent onset of the seizures. Since she is a practicing attorney, that solution was cosmetically unacceptable. Although she is emmetropic, we fit her with a matching pair of opaque periphery lenses with a clear pupil in one lens and an opaque pupil in the other. Imprinted opaque lenses are not totally light opaque, but they offer a wide range of colors for cosmesis.

We used diagnostic opaque hazel lenses from Wesley-Jessen to obtain a satisfactory fit and sent them to Adventures in Color to be back surface coated with opaque black. One lens was made with a 5.0mm opaque pupil, while the other had a clear 5.0mm pupil. On her eyes, it was difficult to detect the difference between them. She adapted quickly and has been wearing the lenses as needed for the past two years without any seizures.

Opaques For Photophobia

A 38-year-old female developed an Adie's pupil. She had been a facultative hyperope, although she had not worn eyeglasses until the onset of the condition, when she lost all accommodative ability in the affected eye. She had tried a number of remedies to relieve her unilateral photophobia, including various forms of pilocarpine (pilocarpine drops, Pilopine gel and Ocuserts). Frustrated by the fluctuations in her vision resulting from the accommodative response to these medications, she decided to try opaque periphery contact lenses. She obtained a satisfactory fit and refractive correction with Wesley-Jessen diagnostic prosthetic opaque lenses with clear pupils, which have a black or gray matrix underprint and are overprinted with the colored iris pattern. She obtained a pair of lenses with the appropriate distance powers and was satisfied using only her unaffected eye for near vision.

A NEW EXTERNAL CAMERA

Ocular photography has become a vital component of contemporary eye care. Photos are useful to document visible changes and to demonstrate various conditions, especially when referring patients to other health care providers. Slit lamp and fundus photography require sophisticated equipment and good technical skills. Hand-held, external, ophthalmic cameras are usually modified 35mm, single-lens reflex cameras capable of taking high quality, close-up, flash pictures, but must be readjusted when changing the field of view or when moving the camera to a different distance.

Polaroid Corporation recently introduced a specialized medical camera, designed for use by health care providers, including eyecare practitioners. The Macro-5 SLR camera uses Spectra-type color film to produce high resolution 3"x 4" 'instant' photos. Selecting a view (single eye, eye and adnexa, both eyes, full face or head and shoulders) sets the focus. At each magnification, a pair of aiming lights, which converge at the lens focal point, is projected toward the subject. The camera automatically adjusts the power output of the flash system for each distance (Figs. 8, 9 & 10).

FIG. 8: POLAROID MACRO-5 SLR EXTERNAL EYE CAMERA.

FIG. 9: MAGNIFICATION SELECTION TURRET.

FIG. 10: CONTROL PANEL.

To take a picture, select an appropriate magnification, partially depress the shutter button to activate the focusing system, center the aiming lights on the subject area and move the camera in or out until the two dots of light are superimposed. There is no need to focus through the viewfinder. Fully depressing the button takes the photo and the camera ejects the exposed print from its base. The image appears in 60 seconds, with full color saturation in about five minutes.

An override is available to compensate for very light or very dark skin tones which 'fool' the auto-exposure meter. While the default setting using two flash tubes minimizes harsh shadows, each flash produces a separate corneal reflection which looks unnatural in eye photography. Either flash can be shut off by the push of a button. The remaining flash produces twice the light output to maintain proper exposure. For fluorescein photography, a clip-on exciter/barrier filter assembly is available. The camera compensates for the reduced light transmission by appropriately increasing the output of the flash system.

FOREIGN BODY REMOVAL

Every contact lens on an eye is inherently a foreign body, but most eyes can accept this intrusion when the contact lens material, design and fit are within acceptable limits. However, physical alterations of the lens by coatings, scratches, rips or chemical buildup may lead to mechanical, chemical, or auto-immune negative responses of abrasion, staining, hyperemia, vascularization, GPC, infiltration and ulceration. Proper lens care and appropriate lens replacement can help prevent or resolve these responses and limit the foreign body sensation.

Just as with non-contact lens wearers, external mechanical or chemical foreign elements can impinge upon the ocular surface of the cornea, bulbar conjunctiva or palpebral conjunctiva of contact lens wearers. Sometimes, the lens acts as a barrier to protect the ocular tissue, while other times, the contact lens entraps the foreign elements against the ocular tissue. When the former occurs, often the lens must be replaced. When the latter occurs, the foreign elements must be neutralized or removed.

Emergency room staff is often not prepared to offer more than first aid to individuals seeking treatment for corneal foreign bodies. Superficial treatment provides relief from pain, prevents secondary complications, and is a skill that should be mastered by all eyecare providers.

Although no procedure should be performed on an eye until visual acuity has been ascertained, instilling a drop of anesthetic permits a more accurate measurement of vision and a more thorough examination. Evert the lids to assure that there are no other particles there and assess the location and depth of all materials using a slit lamp with an optic section. Fluorescein flows in the meniscus that surrounds any foreign body and highlights transparent materials, such as glass or plastic, that would otherwise be difficult to observe in white light. It also delineates the surface tracks made by a foreign body trapped under the upper lid. A penetrating foreign body may produce Seidel's sign, aqueous percolating through the cornea and diluting or washing away the fluorescein in the area. Penetrating objects are best removed by someone capable of dealing with potential intraocular complications.

Copious irrigation with sterile solution can remove many surface particles. Aerosol saline is convenient for one-handed operation while holding the lids, but use a squeeze bottle to generate a more forceful stream. Do this procedure away from the slit lamp to avoid splashing. Two forceful bursts of five seconds or so are usually sufficient. On slit lamp re-examination, if the particle is still present on the surface, swabbing with two sterile cotton swabs may remove it. A dry swab, slightly fluffed up, is the ideal implement to snag the edge of a rough, flat piece of rust impressed against the cornea. A wet swab, lubricated with saline or contact lens cushioning solution, minimizes abrasions during attempts to dislodge a surface particle. The nylon loop at the opposite end of the corneal magnet's handle is used in a similar fashion.

Remove ferro-magnetic corneal foreign bodies (nickel, steel and iron) with either a weak bar magnet or a stronger electromagnet. Because of its high magnetic field, an electromagnet may also attract foreign bodies below the surface of the cornea. Obtain diagnostic images of the internal eye, x-ray, CT-scan or b-scan ultrasound to preclude the possibility of displacing an intraocular foreign body. Avoid using MRI because of its very strong magnetic field (Fig. 12).

FIG. 12: COMPARISON OF MAGNETIC FLUX BETWEEN OCULAR ELECTROMAGNET AND HAND-HELD FOREIGN BODY MAGNET.

For deep foreign bodies, use penetrating instruments. Spuds are available in blunt and sharp designs. A blunt spud is used to dislodge particles, while a sharp spud, which looks like a lance, is used to carve into overlying corneal tissue and to tease the particle back along its entry path. Hold all instruments parallel to the cornea in case the patient unexpectedly moves forward.

Sterile, single-use, disposable needles are often used because of their sterility and versatility. Small particles are best removed with a small bore needle, such as a 25-gauge, while larger particles come out more easily with a larger diameter needle, such as an 18-gauge. Mounting the base of the needle onto a wet cotton swab provides a handle that can be held like a pencil for fine control. Use the point of the needle to get under and remove the particle while creating minimal disruption to the cornea, similar to the way a splinter would be removed from a tender area of the skin.

Iron foreign bodies that have been in place for a day or longer will often have a prominent rust ring, ferrous material that has dissolved into the adjacent water soluble stroma. This rusty-colored tissue is often softer that the healthy cornea surrounding it and can be bluntly dissected with a needle. Use a special low-rpm, low-torque rust ring remover, such as an Alger brush, in a polishing motion to produce a smooth excavation base.

After removing the foreign body, instill a topical antibiotic to prevent infection. The squeegee action of the upper lid passing over the margin of the corneal excavation may enlarge the area and cause more pain. Use professional judgment to determine the appropriate follow-up procedures. Shallow excavations that appear as though they will heal spontaneously do not require patching. A ribbon of antibiotic ointment squeezed onto the eye may provide sufficient lubrication.

If the excavation is deep enough or large enough to cause concern about healing, tape the lid shut. A pressure patch is not necessary. A short piece of one-inch wide tape pressed over the closed lid will suffice. In most cases, the patient will be unable to blink. This technique is simple enough that the patient can instill medication and retape the lid.

Corneal injuries can trigger an anterior chamber reaction. Some experts recommend that any corneal insult sufficient to require patching should also be treated with a drop of cycloplegic, such as cyclopentalate or scopolomine, to minimize iris inflammation. Educate patients about the pupillary and accommodative effects of these medications.

Gradual Extraction

A 45-year-old male was referred for evaluation of a foreign body sensation in both eyes. He was undergoing rehabilitation after being severely injured in a bomb blast two months earlier. Metallic dust apparently had been blown at him forcefully, as he had many small, dark particles imbedded in the skin of his face. His eyes had been open, as there were no foreign bodies on the skin of the upper lid. His vision was correctable to 20/20 in each eye. Slit lamp examination revealed dozens of tiny foreign bodies, both on the surface and at various depths in the anterior cornea and on the bulbar conjunctiva. He reported that, at an earlier eye exam to rule out intraocular damage, an ophthalmologist had removed many particles from both eyes.

After thorough irrigation, we passed a magnet over the surface of his corneas, attracting a number of superficial particles to it. The remaining particles were below the surface. Because of the large number of foreign bodies, an invasive removal process would have been too painful and debilitating. Over the next five months, he stopped in whenever he had symptoms (about twice a week) to have particles that had migrated to the surface removed with a small foreign body magnet. By the time he was discharged, we had removed about half of the initial particles from the cornea. Very few, if any, from the bulbar conjunctiva had come to the surface. CLS

Dr. Scott is a professor at the New England College of Optometry and a staff optometrist at the West Roxbury VA Medical Center. Dr. White is also a professor at NEWENCO where he is the chief of the contact lens service.

Neither Dr. Scott nor Dr. White has a financial interest in any of the companies or the products discussed.

References are available from Dr. White,The New England College of Optometry, 424 Beacon St., Boston, MA 02115.

SPECTRUM NOV. 1996

 

QUESTIONS

1. Among the more important functions of the pre-ocular tear film are to:

a. provide a rinsing system

b. create a reservoir and

passageway for gases

c. maintain proper osmotic

equilibrium and pH

d. all of the above

2. Cyclic dehydration of a soft contact lens in situ is affected by:

a. osmotic pressure gradient

b. humidity

c. temperature

d. all of the above

3. Total average volume of pre-ocular tear film is about:

a. 1/15 of a drop

b. 1/10 of a drop

c. 1/5 of a drop

d. none of the above

4. Mucin deficiencies result from:

a. impairment of conjunctival goblet cells

b. anti-anxiety agents

c. keratoconjunctivitis sicca

d. meibomitis and blepharitis

5. Meibomian gland dysfunction (MGD) is most common:

a. after the age of 40

b. for 30-year-olds

c. for 20-year-olds

d. for 10-year-olds

6. Temporary punctal occlusion is done with:

a. silicone plugs

b. collagen plugs

c. electric cautery

d. laser punctoplasty

7. Which of the following silicone punctum plugs does not have a flange that remains on the punctum's top:

a. Lacrimedics

b. Eagle Vision

c. Oasis

d. FCI

8. Which of the following punctum plugs is removed by naso-lacrimal irrigation:

a. Lacrimedics

b. Eagle Vision

c. Oasis

d. FCI

9. An opaque prosthetic soft lens with a black pupil may be used for:

a. inoperable dense cataract

b. amblyopia

c. diplopia

d. all of the above

10. Iris/pupil abnormalities for which opaque prosthetic lenses may be used include:

a. aniridia

b. heterochromia

c. coloboma

d. all of the above

11. In the study mentioned, prosthetic hydrogel lenses were used most often for:

a. vitreo-retinal problems

b. inoperable cataracts

c. corneal scars

d. strabismus

12. A prosthetic opaque hydrogel lens should be fitted with:

a. stable position

b. no tinted portion onto

the sclera

c. pupillary centration

d. all of the above

13. The Macro-5 SLR camera:

a. uses Spectra-type color film

b. produces 3" x 4" instant

photos

c. focuses automatically

d. all of the above

14. Full color saturation of the picture takes about:

a. 1 minute

b. 5 minutes

c. 10 minutes

d. 15 minutes

15. The foreign body characteristics of a contact lens can lead to which of the following types of responses:

a. mechanical

b.chemical

c. auto-immunological

d. all of the above

16. With foreign body elevation, fluorescein:

a. highlights transparent

materials

b.delineates surface tracks of eyelid-trapped foreign bodies

c. both "a" and "b"

d. neither "a" nor "b"

17. Seidel's sign involves:

a. a penetrating foreign body

b. aqueous percolating through

cornea

c. dilution of fluorescein

d. all of the above

18. Surface particles may be removed by:

a. forceful irrigation

b. sterile cotton swabs

c. both "a" and "b"

d. neither "a" nor "b"

19. Ferro-magnetic foreign bodies include:

a. nickel

b. steel

c. iron

d. all of the above

20. To preclude the possibility of displacing an intraocular foreign body, which of the following should NOT be used:

a. x-ray

b. MRI

c. CT-scan

d. b-scan ultrasound