The Medical Model: Contact Lens Evaluation

The medical model contact lens evaluation is a comprehensive assessment that you should perform on all current and potential contact lens patients.

By Jack Schaeffer, O.D.

Goal Statement:

The medical model contact lens evaluation thoroughly encompasses patient history, patient evaluation, contact lens/disinfection solution selection and patient education. The medical model delivers a higher level of care because it provides a better understanding of not only the patient's ocular status, but also his or her systemic health, which may affect the entire contact lens experience.

Faculty/Editorial Board:

Jack Schaeffer, O.D.

Credit Statement:

COPE approval for 2 hours of CE credit is pending for this course. Check with your local state licensing board to see if this counts toward your CE requirement for relicensure.

Joint-Sponsorship Statement:

This continuing education course is joint-sponsored by the Pennsylvania College of Optometry.

Disclosure Statement:

Dr. Schaeffer has no relationships to disclose.

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Today, the contact lens is recognized as a medical vision correction device. When developing a medical model contact lens evaluation, it is important to look at "the big picture." The big picture encompasses your entire practice philosophy and patient-care delivery system. If you have established your practice as a primary-care medical model-based system, your contact lens division should also be based on a medical model. In today's competitive, fast-paced economy, organizing your practice as a comprehensive contact lens eye-care facility is imperative for success in the medical model.

The medical model contact lens evaluation thoroughly encompasses patient history, patient evaluation, contact lens/disinfection solution selection and patient education.

The medical model delivers a higher level of care because it provides a better understanding of not only the patient's ocular status, but also his or her systemic health, which may affect the entire contact lens experience.

Patient History

Every contact lens evaluation must begin with a comprehensive patient history. This includes the patient's social history, ocular history, systemic history, family history, contact lens history, contact lens compliance history, contact lens solution history and pharmaceutical use history. As you examine your patients, you will begin to see the critical relevance of history in the medical model.

• Social history. A social history includes occupation, preferred sports/activities and personal/special needs. This information gives us insight as to whether the patient requires extended-wear contact lenses, daily disposable lenses, or bifocal/multifocal lenses vs. mono-vision. It will also help you to determine the most ideal replacement schedule—daily, weekly, monthly or bimonthly.

• Ocular history. While this seems self-explanatory, ocular history is a fundamental part of your comprehensive evaluation. For example, if a patient has a history of infiltrative keratitis, you may decide to see him or her more frequently (every two to three months) than your patients who have no history of complications. Also, this patient likely will require a particular lens material and solution that you might not consider prescribing to a patient with no significant ocular history.

• Medical history. A patient who presents with preexisting systemic conditions often will require specialized contact lenses as well as a personally tailored follow-up regimen. A patient with a medical history of rosacea, for example, warrants a dry eye evaluation before any contact lens prescription is determined. Because of a previous medical diagnosis, either a higher level of suspicion or a lower level of tolerance will be accepted with corneal staining results and/or patient symptoms. Several medical conditions, such as rheumatoid arthritis, will directly affect your patient's safety and the overall outcome in a medical model contact lens evaluation.¹ So, you must take the time to determine if your patient has any preexisting systemic conditions, and if so, how they could negatively impact contact lens health and safety performance.

• Family history. To fully know and understand your patient, you must be familiar with his or her genetic background. If the patient has a strong family history of macular degeneration and you discover some early drusen in his or her maculae, consider prescribing sunglasses and/or UV-protective contact lenses along with vitamin therapy.^2-4 A comprehensive medical model contact lens evaluation should include a dilated retinal exam because it is very important to make certain that all ocular structures are healthy and prepared for contact lens wear.

• Contact lens history. Contact lens history is arguably one of most important areas of your entire evaluation. For example, imagine that a patient presents with a small scar from a sterile or infectious corneal ulcer. Should this patient select extended-wear contact lenses? Possibly, but probably not. Clearly, patients with a history of corneal ulcer are more likely to develop new ulcers in the future. In this case, it is best to suggest daily wear only, or accept/extend the current regimen with strict follow-up every two to three months. But, if you allow this patient to use an extended wear contact lens, he or she will be at a higher level of risk for complications than other wearers.^5,6
  
  
• In a patient who is at slightly higher risk, you should consider prescribing a 30-day contact lens with instructions to discard every two weeks or a two-week extended lens with instruction to discard on a weekly basis. Be sure to schedule a high-risk patient for follow-up every three months, vs. every six months for a normal continuous wear patient.

  Or, consider a patient who has experienced a previous ocular infection because he or she over-wore the lenses beyond his or her doctor's recommendation. This patient not only needs a comprehensive contact lens evaluation, but also a medical examination along with a possible dry eye evaluation before you prescribe any contact lenses. Instruct this patient to avoid contact lens wear for at least one to two months before returning for a complete contact lens evaluation.

  As part of the contact lens medical history, ask the patient if he or she has an up-to-date pair of glasses to wear if and when the patient experiences a complication related to contact lens wear. Many eye infections are worsened when the patient continues to wear his or her contact lenses because he or she does not have a pair of glasses. Clearly, an advanced state of ocular infection dramatically reduces the patient's chances for a good outcome and makes corneal scarring almost inevitable.^7,8

• Contact lens compliance history. It is likely that more than 50% of your patients are not compliant with their replacement schedules, solution usage and/or cleaning regimens.⁷ It is up to you to make sure that your patients become more compliant. The only way that you are able to influence patients' rates of compliance is through patient education.

  Your patients must understand the importance of compliance—and they must be part of this compliance team. Put all contact lens and solution dispensing protocols in writing so that your patients have concrete instructions on proper care regimens. In addition to verbal and written education, it is important to use video instruction in your office to visually reinforce everything that your patients need to know and understand.

  Be certain to communicate the possible repercussions of poor compliance to your patients. For example, a frank discussion on corneal ulceration, corneal infection and loss of vision should promote improved compliance with the lens care regimen.

  If you follow up with a new contact lens patient within six months, take the time to review compliance protocols and address any questions he or she may have. When working with children, this step is particularly crucial.

• Contact lens solution history. Part of the compliance protocol includes prescribing solutions. Many patients may change and exchange their lens solutions between office visits.

  This action can inadvertently promote contact lens-related problems, such as severe infection. Some solutions will likely cause problems for certain patients, but not others. The only way to determine which solution is best for your patient is to examine him or her at follow-up and stain the eye.

• Pharmaceutical history. Many medications on the market today can cause a wide variety of ocular side effects. (See "Identify the Ocular Side Effects of Systemic Medications," January 2008.)

Determine appropriate contact lens options, solutions and follow-up schedules based upon the medications your patient takes.

Ocular Evaluation

Following the patient history, you must conduct an extensive ocular examination, including a dry eye screening. Your two primary goals in the medical model are disease prevention and a comfortable contact lens-wearing experience. An organized and systematic approach is always best in the medical model. Begin your evaluation with the most external structures and move in toward the cornea.

• The adnexa. Begin your evaluation by inspecting the skin for any type of problems or systemic issues, such as contact dermatitis, herpes simplex virus (HSV) scars and basal cell carcinoma, which may compromise the safety of both contact lens wear and the patient's overall health.

• The eyelids. It is critical to examine your patient's eyelids during the evaluation. Diagnosing and treating blepharitis, lid wiper epitheliopathy (LWE), meibomian gland disease (MGD) and trichiasis can make all the difference in a truly healthy, comfortable contact lens experience. Staining with two or more stains and meibomian gland expression will help in the diagnosis of LWE and MGD.⁹

  If you diagnose either condition, reschedule the patient to assess severity and initiate treatment. Do not further analyze or treat any disease presentations that are found during the your examination. Remember, consider the medical model contact lens examination as solely a screening device for existing medical or ocular conditions.

• The palpebral conjunctiva. The upper lid is one of most important areas to examine for either the presence or absence of giant papillary conjunctivitis (GPC). Use of the proper lens, lens edge system and solution helps to prevent GPC.

• The bulbar conjunctiva. The bulbar conjunctiva must be documented as part of the medical model. Employing both corneal staining and conjunctival injection, be sure to check for pinguecula, lymphectasia and conjunctival chalasis. You may also note a presentation of dry eye or allergy.

• The limbus. Use of multiple stains will reveal the presence of eye infections, inflammations and allergies at the limbus. Here, you should also look for corneal neovascularization, corneal infiltrates and/or limbitis.¹⁰

• The cornea. A thorough examination of the cornea is the most important part of the medical model evaluation for contact lenses. Starting with the limbal-corneal junction, look for the presence or absence of infiltrates, neovascularization, staining and dellen (thinning). Moving toward the central cornea, look for staining, scarring, epithelial basement membrane dystrophy (EBMD), recurrent corneal erosion (RCE), dry eye and signs of previous infection.

Again, if you diagnose any condition, be certain to reschedule the patient to assess the severity and applicable treatment regimen at a later date.

Specialized Testing

A medical model contact lens evaluation also will include specialized testing, as necessary. Corneal topography, pachymetry, endothelial cell counts, anterior segment photography and Schirmer's test are but a few options.

Perform topography and document the patient's anterior segment if you note any corneal abnormalities, record pachymetry readings on all continuous-wear patients to determine corneal thickness, and note endothelial cell counts to determine any changes caused by any previous contact lens wear.

Contact Lens Selection

Now that you have completed your patient's comprehensive history and have documented his or her ocular status, you must determine which contact lens and contact lens solution is best suited for this individual. If you are working with a patient who is at risk for a potential complication, you need to reconsider your usual lens and solution choices. And, remember to adjust an at-risk patient's follow-up schedule as necessary.

For example, if a patient presents with slight early changes in the superior palpebral conjunctiva that indicate GPC, make sure to prescribe a lens that will not rub or invade Kessing's space (the space between the columnar cells and the ocular surface) and does not bind protein and lipids.

The lens type will differ per patient, and only a follow-up visit with lens surface inspection can determine if it is an appropriate option. Also, because this patient has sensitive eyes, consider prescribing a peroxide system.

Most importantly, you should recommend a daily disposable lens, although in a very early case of upper lid inflammation, discarding a lens on a weekly, bimonthly or monthly basis is acceptable, proper care.^11,12

Ask the patient to return for follow-up in one or two months to check for any possible changes to the upper lid. At this follow-up appointment, be sure to look for protein or lipid buildup on the lens, and examine the lens on the patient's eye to determine clarity of the anterior surface.

Or, if a patient presents with early changes at the limbal-corneal junction that are indicative of early neovascularization, suggest a silicone hydrogel lens, because it may offer the best permeability in the periphery.¹³

In a patient who wears silicone hydrogel lenses, look for conjunctival flaps or staining at all follow-up visits. Also, be sure to check for small GPC patches in the center of the lid.

Finally, if a patient presents with early signs of anterior basement membrane dystrophy (ABMD), EBMD and/or mild dry eye, schedule him or her to return for a medical dry eye work-up. The work-up will help you determine if and how the patient's ocular surface disease must be treated before prescribing contact lenses.

Be sure to conduct this patient's dry eye work-up and contact lens evaluation at separate visits to ensure the best care possible. The comprehensive dry eye workup is a true medical visit that requires the dedicated time necessary to determine a complete diagnosis and treatment regimen.

Specialty Contact Lens Options

• Lenses for advanced astigmatism
• Custom toric lenses
• Scleral and mini-scleral lenses
• Hybrid lenses
• Reverse-geometry lenses
• Corneal reshaping lenses
• Gas-permeable lenses
• Keratoconic lenses
• Multifocal lenses
• Lenses for low astigmatism
• Wavefront lenses
• Post-refractive lenses

Specialty Contact Lenses

The medical model practice should offer all of the contact lens modalities that are available on the market today. Most specialty contact lens practices offer more than 50 different brands of lenses. If you use the same lens brand on every patient, you are not running a medical model practice. In the medical model, you must seek the perfect lens for every patient.

For example, a lens that does not center well should not be prescribed, even if there is full corneal coverage. The same goes for either excessive or limited lens movement. Both coverage and movement issues can be eliminated through selection of the most appropriate lens. Always keep several alternative contact lens choices and specialty lenses on hand (see "Specialty Contact Lens Options," left).

Disinfection Solutions

There are many excellent contact lens disinfection solutions on the market today. That said, you must be knowledgeable about the chemical composition of various solutions and how well each of them work with different lens types.

When a solution and a contact lens are combined, a new contact lens entity is created: the "contact lens-solution complex." Every patient's contact lens-solution complex is unique.

The only way to determine each patient's optimum contact lens-solution complex is to write a prescription for both a specific solution and contact lens, and ask the patient to return for follow-up in two to three weeks. Be sure to instruct the patient to wear his or her lenses for at least two to four hours before the appointment.

At the follow-up, evaluate the lens on the patient's eye. Then, remove the lens and stain the eye with fluorescein. Following staining, evaluate the conjunctiva, eyelids and corneas for staining or any changes from normal.

If a change in lenses or solutions is warranted, a second follow-up visit will be necessary to determine the efficacy of the new contact lens-solution complex.

Lens case hygiene is just as critical to comfortable contact lens wear as a prescribed disinfection solution. Many ocular infections, such as microbial keratitis, may result from improper cleaning of the lens case.¹⁴ Instruct your patients to replace their cases on a monthly basis, or every three months if they demonstrate effective lens case cleaning habits.

Patient Education

Contact Lens Options

• Daily wear vs. continuous wear
• Multifocal vs. monovision
• Daily, weekly or monthly replacement
• Multipurpose solution vs. peroxide
• Astigmatic vs. spherical
• Gas-permeable vs. soft
• Gas-permeable vs. hybrid

Patient education is one of the most overlooked aspects of the comprehensive medical model contact lens evaluation. Ultimately, it is your responsibility to inform your patients about contact lens regimen choices (see "Contact Lens Options," right) and disease processes related to contact lenses, as well as proper contact lens care, solution compliance and follow-up protocol. Here are a few items and suggestions to consider in regard to proper patient education:

• Continuous-wear contact lenses. Patients who use continuous-wear contact lenses are approximately four to five times more likely to develop corneal infection than those who use daily-wear lenses.^5,6 So, you must inform all patients who opt for continuous-wear lenses about the fundamental importance of lens hygiene and the recommended discard schedule.
  
  
• Also, instruct continuous-wear patients to return for a follow-up evaluation in six months after the initial fitting, or at any time if they experience such complications as redness, blur or pain. If they do experience any associated complications, instruct them to remove the lens and make an appointment at your office immediately.

Is prescribing continuous-wear lenses dangerous and/or careless on your behalf? Absolutely not. For many doctors and patients, continuous-wear lenses are not only an ideal, but also a comfortable modality. Just remember, when considering continuous-wear lenses, you are not simply selling contacts—you are selling a process that needs continuous care.

• Monovision contact lenses. Patients often have difficulty driving at night when first wearing monovision lenses.¹⁵ For both the patient's safety and the safety of other motorists, be sure to prescribe appropriate distance eyewear that can be worn in conjunction with the contact lenses.

  The distance lenses will require another refraction over the mono-vision lens.

• Education supplementation and reinforcement. Because there is so much material to discuss during a medical model contact lens evaluation, your patients will likely feel overwhelmed. Consider the use of supplemental educational materials or consultations to reinforce the most essential aspects of proper contact lens care.

  In our office, we ask each patient to watch a video that covers specific contact lenses and disinfection solutions. Then, we have a contact lens technician sit one-on-one with each patient and discuss an organized written checklist of all the information covered during the initial evaluation.

  We prefer that each patient meet with a technician—even if he or she has been wearing contact lenses for several years. Finally, we provide the patient with a written contact lens instruction sheet to take home and review.

• Progress visits. After patients are comfortable with the lenses, schedule them for a six-month follow-up progress visit. Ask them to bring their lenses, solutions and contact lens cases to this visit, so that you may judge their compliance level.

  Patients with poor compliance, for example, may switch disinfectant solutions without first consulting you or may not clean their lens cases adequately. Take this opportunity to further educate the patient about his or her lenses, address any compliance issues and answer any related questions.

This article has demonstrated and explained the importance of a medical model contact lens evaluation. As doctors who prescribe contact lenses as medical devices, we have three primary goals: to diagnose any eye disease that will affect contact lens wear or the patient's health; to prevent any medical complications from the contact lenses and solutions; and to ensure healthy, safe, comfortable contact lens wear. So, if you follow all aspects of the medical model, specifically patient history, patient evaluation, contact lens/disinfection solution selection and patient education, you can provide the best available care for your contact lens patients.

Dr. Schaeffer is the president and CEO of Schaeffer Eye Center in Birmingham, Ala., a 13-location practice that offers laser vision correction, comprehensive contact lens services, high fashion eyewear and sunglasses.

References

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2. Bialek-Szymaska A, Misiuk-Hojlo M, Witkowska K. Risk factors evaluation in age-related macular degeneration. Klin Oczna 2007; 109(4-6):127-30.
3. O'Connell ED, Nolan JM, Stack J, et al. Diet and risk factors for age-related maculopathy. Am J Clin Nutr 2008 Mar;87(3):712-22.
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5. Spoor TC, Hartel WC, Wynn P, Spoor DK. Complications of continuous-wear soft contact lenses in a nonreferral population. Arch Ophthalmol 1984 Sep;102(9):1312-3.
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9. Korb DR, Greiner JV, Herman JP, et al. Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers. CLAO J 2002 Oct;28 (4):211-6.
10. Lee SW, Lee SC, Jin KH. Conjunctival inclusion cysts in longstanding chronic vernal keratoconjunctivitis. Korean J Ophthalmol 2007 Dec;21(4):251-4.
11. Bielory L. Ocular Allergy Treatment. Immunol Allergy Clin North Am 2008 Feb;28(1):189-224, vii.
12. Stapleton F, Keay L, Jalbert I, Cole N. The epidemiology of contact lens related infiltrates. Optom Vis Sci 2007 Apr;84(4):257-72.
13. Long B, McNally J. The clinical performance of a silicone hydro-gel lens for daily wear in an Asian population. Eye Contact Lens 2006 Mar;32(2):65-71.
14. Stapleton F, Keay L, Edwards K, et al. The incidence of contact lens-related microbial keratitis in Australia. Ophthalmology 2008 Oct;115(10):1655-62.
15. Evans BJ. Monovision: a review. Ophthalmic Physiol Opt 2007 Sep;27(5):417-39.