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.
Release Date: April 2009
Expiration Date: April 30, 2012
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.
Jack Schaeffer, O.D.
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.
This continuing education course is joint-sponsored by the Pennsylvania College of Optometry.
Dr. Schaeffer has no relationships to disclose.
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
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
- 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
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
- 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
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
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
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.
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
- 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
- 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
Again, if you diagnose any condition, be certain to reschedule the
patient to assess the severity and
applicable treatment regimen at a
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
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
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
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
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
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,"
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.
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
- 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.
- 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
- 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
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
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
- Villani E, Galimberti D, Viola F, et al. Corneal involvement in rheumatoid arthritis: an in vivo confocal study. Invest Ophthalmol Vis Sci 2008 Feb;49(2):560-4.
- Bialek-Szymaska A, Misiuk-Hojlo M, Witkowska K. Risk factors evaluation in age-related macular degeneration. Klin Oczna 2007; 109(4-6):127-30.
- 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.
- SanGiovanni JP, Chew EY, Clemons TE, et al. The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22. Arch Ophthalmol 2007 Sep;125(9):1225-32.
- 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.
- Keay L, Edwards K, Stapleton F. An early assessment of silicone hydrogel safety: pearls and pitfalls, and current status. Eye Contact Lens 2007 Nov;33(6 Pt 2):358-61; discussion 362-3.
- Lindsay RG, Watters G, Johnson R, et al. Acanthamoeba keratitis and contact lens wear. Clin Exp Optom 2007 Sep;90(5):351-60.
- Wilcox MD. Pseudomonas aeruginosa infection and inflammation during contact lens wear: a review. Optom Vis Sci 2007 Apr;84(4): 273-8.
- 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.
- Lee SW, Lee SC, Jin KH. Conjunctival inclusion cysts in longstanding chronic vernal keratoconjunctivitis. Korean J Ophthalmol 2007 Dec;21(4):251-4.
- Bielory L. Ocular Allergy Treatment. Immunol Allergy Clin North Am 2008 Feb;28(1):189-224, vii.
- Stapleton F, Keay L, Jalbert I, Cole N. The epidemiology of contact lens related infiltrates. Optom Vis Sci 2007 Apr;84(4):257-72.
- 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.
- 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.
- Evans BJ. Monovision: a review. Ophthalmic Physiol Opt 2007 Sep;27(5):417-39.