GP Practice Management

GP lenses, virtually limitless in design and optical correction, afford wearers uncompromising physiology and visual acuity.

GP Practice Management

GP lenses, virtually limitless in design and optical correction, afford wearers uncompromising physiology and visual acuity.

By Susan Resnick, OD, FAAO

Eyecare practitioners who regularly prescribe and fit GP lenses gain long-term patient loyalty as well as the opportunity for practice differentiation and growth. Yet, according to "International Contact Lens Prescribing in 2005" (January 2006) by Morgan et al, GP lenses represented only 10 percent of new fits and 11 percent of refits worldwide. And, as reported in "Contact Lenses 2005" (January 2006) by Joseph Barr, OD, MS, FAAO, of the estimated 36 million contact lens wearers in the United States, only about 10 percent to 13 percent wear GP lenses.  

The underutilization of such a valuable and versatile modality seems rooted, for the most part, in practitioner apprehension, according to "Use of Presbyopic Contact Lens Corrections in Optometric Practice" (April 2005) by Harris et al. Complexity of design, increased chair time, and probability of patient rejection are some of the most typical misperceptions about GP lens fitting.

While the prospect of fitting GP lenses may foster real feelings of anxiety, you can easily overcome them. You can readily navigate the learning curve to developing proficiency in evaluating and prescribing GPs with proper patient management combined with a proactive, yet systematic clinical approach. With today's advanced designs, materials and sophisticated manufacturing techniques, even your first few GP lens patients are likely to adapt in an exemplary fashion.


GP Candidates by Patient Population
Children and teens Conventional or corneal reshaping
Moderate to high astigmats, any age Spherical, front- or back-surface or bitorics
Marginal dry eyes Any design
Prevent possible ocular health compromise  Any design
Occupational/long wearing time  Moderate to high-Dk daily or extended  wear or reverse geometry/corneal reshaping
Maintain binocular vision throughout presbyopia Bountiful multifocal options

Your Target Population is Likely Already in Your Exam Chair

Whether your goal is introducing GP lenses to your practice or expanding your existing range of specialization and expertise, your target population consists of both prospective new fits or refits .

Consider GP lenses as an excellent option for children and teens who will benefit from their ease of handling, reduced chance of allergic or infectious complications and lower frequency and severity of prescription changes. Overnight corneal reshaping lenses are an increasingly attractive option for this population. Successfully implementing this technology often serves as a valuable practice builder.

Moderately to highly astigmatic patients of any age invariably achieve better visual results with GP lenses. Consider spherical GP lenses for your moderately astigmatic patients who are new to lens wear or for those current soft lens wearers who aren't completely satisfied. Toric design lenses present an even better option for patients who have greater than 2.50D of corneal astigmatism or for those manifesting visually significant residual astigmatism.

GP lenses may be a better initial choice for patients who have marginally dry eyes and, in particular, for soft lens patients who experience reduced wearing time or are on the verge of dropping out of lens wear. The excellent surface wettability and oxygen transmission, combined with the fact that GP lenses do not undergo bulk dehydration and tightening on the eye, are features which can reduce contact lens-induced dry eye symptoms.

Even with the increasing options in silicone hydrogel lenses for occasional overnight or extended wear, GP lenses still prove the safer option for patients of all ages desiring this wearing schedule. GPs result in fewer incidences of inflammatory and sight-threatening conditions. Whether in conventional spherical design for around-the-clock wear or in reverse geometry design for overnight corneal reshaping, consider the convenience and freedom this option might afford to patients who have occupational requirements to wear their correction for long periods (such as police and emergency personnel and healthcare workers).

Perhaps the largest untapped segment of the current target population is new and existing lens wearers who have reached presbyopic age. Today's improved GP multifocal designs allow you to offer current lens wearers these more sophisticated and generally more visually and cosmetically acceptable alternatives to monovision or reading glasses. In particular, consider multifocal aspheric GP lenses for patients of all ages who spend a significant portion of their day at the computer.

Table 1 summarizes how best to match prospective GP candidates with an appropriate GP design.

Educating Your Staff and GP Candidates


Identifying GP Lens Candidates


   Patients who express dislike of full- or part-time spectacle wear.
   Young patients at risk for progressive myopia.
   Astigmats who previously failed with soft lenses.
   Patients who have irregular corneas.
   Patients who have high visual demand or sensitivity.


   Patients who have contraindicative pre-existing ocular or systemic medical conditions.
   Patients who use medications that significantly reduce tear volume.
   Patients who exhibit greater than normal resistance to having their eyes touched.
   Patients who report higher than average sunlight sensitivity.
   Patients who report dust or particle sensitivity.
   Patients who have pre-existing prejudices against GP lenses.
   Patients who show little positive expression during your discussions.

To be sure, as you gain experience in fitting the various designs and modalities of GP lenses, your level of confidence will increase accordingly. Over time, mere clinical proficiency develops into true expertise. But this evolution is not an absolute guarantee of the personal success and professional rewards to which you undoubtedly aspire. As with any aspect of your professional endeavors, achieving success at what you do is largely a function of how you go about doing it. Consider these key steps for developing and managing a successful GP lens practice.

Implement Your Front Desk and Technical Staff into Your GP Treatment Plan As important as proper patient communication is to implementing a treatment plan for any form of vision correction or for managing ocular disease, it's perhaps even more so when introducing and fitting GP lenses.

Educate your front desk personnel as to the types of lenses you fit and the diversity of refractive errors they correct. Be sure they understand it's their role to convey to a telephone caller that the consultation and examination visit is the first step in determining whether GP lenses are an option for that caller. The terminology your staff uses, combined with positive intonation and reassuring body language, will go a long way in conveying the positives and setting your patients at ease.

Finally, explain to your staff that the majority of patients who do proceed with fitting will successfully adapt and become excellent referral sources.

For patients who do not successfully adapt to GP contact lenses, make sure your administrator is familiar with details and positive verbiage to communicate any limited risk or refund policy that you incorporate into your fee structure.

Identify GP Candidates I discussed earlier that certain patient populations are rich in prospective candidates for GP lenses. But not every patient from those groups will succeed. You need to identify which patients would do well with GP lens wear. Table 2 outlines the different characteristics of ideal — and not so ideal — candidates.

Patient/Practitioner Communication When presenting GP lenses, it's important to present all contact lens options neutrally. This allows patients to ask questions and participate in the decision making process. While they are ultimately looking to you for a professional recommendation, patients are more accepting and compliant with a treatment plan when they feel they have a role in their care. Your discussion about various lens options should include GP features and benefits applicable to vision, health, comfort and the patient's lifestyle requirements.

Again, be aware of nonverbal communication (body language and facial expression) when explaining lens options to patients, who often tune in more to your tone and demeanor than to your words.

First Steps You've identified your prospective GP wearer and the patient is on board with trying GP lenses. Now you need to properly evaluate the patient to initiate the fitting process. The sidebar on page 35 offers six GP clinical tips.

Tips for Successful GP Fitting

You're now ready to begin the fitting process. The following tips will help you succeed in this endeavor.

Contact Lens Technician's Vital Role in GP Success It's most helpful to have a well-trained contact lens technician involved from the onset of the fitting process. Delegating tasks such as application and removal of diagnostic lenses and patient training on lens application, removal and care not only significantly reduces chair time, but permits efficient patient flow. It also provides the patient with greater support, motivation and security.

Your technicians should be well versed in patient-friendly GP terminology. For example, they should replace words such as discomfort, irritation and pain with initial sensation, edge awareness and itchy sensation. Tell patients before transferring them to your assistant that they will feel a slight lid sensation. Once again, your technician must echo your words and mirror your enthusiasm.

It's common practice among experienced GP lens fitters to use a topical anesthetic during initial GP application with new wearers. This allows you to more accurately perform your over-refraction and fit evaluation.

Your technician should say: "This cushioning solution reduces initial sensitivity and reflex tearing. The effect wears off after a few minutes. By then, much of your initial adaptation will have occurred."

Recommended GP Diagnostic Fitting Sets While you may need to fit GP lenses empirically from time to time, diagnostic lens fitting offers several important advantages. Patients experience and overcome the initial psychological hurdle of experiencing lenses on their eyes. At the same time, you can most accurately judge fitting characteristics and perform a careful over-refraction, which increases the chance of achieving a dispensable pair on the first lens order.

Diagnostic fitting allows you to confirm that you can achieve an acceptable fit and that the patient has a reasonably good probability of adaptation. We are accustomed to having a large inventory of prescriptions on hand, and with today's "on demand" mentality, patient satisfaction is greatly enhanced with same day dispensing. Increasingly, experienced and busy GP fitters are adopting the same approach for their workhorse GP lens designs.

If you're just starting out or slowly building expertise in specialty designs such as toric, multifocal or keratoconus, a minimum number of diagnostic sets will suffice. Even if you elect to use topographically derived trial lens designs, don't underestimate the value of actually evaluating a lens in a given material as it interacts with the patient's lid and tear film.

Fitting Myopia and Hyperopia Spherical Designs Keep on hand powers of –3.00D and –6.00D and standard overall diameter (OAD) of 9.4mm in a low or moderate (25 to 50) Dk material. Your Contact Lens Manufacturers Association (CLMA) member laboratory consultant will recommend peripheral curves for a tri-curve design, or alternatively you may choose an aspheric design. For hyperopia, stock powers of +3.00D manufactured from a high (51 to 100) Dk material ranging in base curve from 40.50D to 45.25D in 0.25D steps.

Aim for a Korb upper-lid-attached fit and order a final OAD large enough to allow an optical zone diameter larger than the pupil size in dim illumination.

Tools for Meeting the Toric Challenge Use a base curve toric, spherical front surface design when a patient has 1.50D or more of corneal cylinder and you obtain a residual cylinder of more than 0.75D upon over-refraction with a spherical GP. The residual cylinder should be at the same axis as the corneal toricity and approximately one-half the amount.

Use a prism-ballasted, front-surface toric when a patient has 0.75D or more of internal cylinder and the cornea is spherical or minimally toric. Choose a bitoric design for higher degrees of corneal astigmatism. These are typically greater than 2.00D to correct for the cylinder induced by a back-surface toric and to provide better corneal alignment.

Diagnostic fitting with bitoric contact lenses is virtually as simple as fitting spherical GP lenses. Many CLMA member laboratories have bitoric fitting sets for loan or purchase. Spherical power effect bitoric lenses are available in 10-lens sets with 2.00D, 3.00D or 4.00D of cylinder. I recommend the 3.00D bitoric fitting set for most fits with 3.00D to 5.00D of corneal cylinder to effectively cover a range of corneal toricity.

Select the indicated lens, usually 0.12D to 0.50D flatter than K. Then, perform a spherical over-refraction and add this value to both diagnostic lens powers. Order the final design in a lens material equivalent to what you'd choose for the corresponding power spherical lens.

Achieving Aspheric and Progressive Multifocal Success Follow CLMA member laboratories' fitting guidelines for your initial lens selection. While I prefer diagnostic fitting, many practitioners do equally well fitting empirically by providing the laboratory with all necessary information. This is certainly an excellent way to begin the process of trying different designs on your first few fits to determine your designs of choice. A minimum of two types of aspheric designs will generally cover most needs.

Both presbyopic patients new to lens wear and current single-vision GP wearers are potentially excellent candidates for aspheric multifocals. Although many sources report a relatively high success rate with monovision, why abandon your goal of providing clear, comfortable, binocular vision when managing GP wearers? Today's improved GP multifocal designs and sophisticated manufacturing capabilities provide enhanced visual functioning that can lead to greater patient satisfaction and higher success rates.

Aspheric multifocals are available in a variety of designs in all varieties of GP materials, which offer superior wetting capabilities and a range of oxygen transmissibility (Dk/t). Today's more advanced designs incorporate low back-surface eccentricity or spherical back surface with front-surface eccentricity. These newer design platforms offer easier conversion of fit from the patient's current spherical lens parameters and reduced corneal molding, which often occurs secondary to progressive GP lens wear.

Some aspheric designs now boast add powers in a range of +2.50D to +3.50D. Manufacturers offer flexibility in available optical zone sizes and/or incorporate greater adds through front surface modification. Some CLMA member laboratories also provide aberration control to offer even better visual quality through distance and intermediate transition zones.

When selecting patients for progressive aspheric GP lenses, look for appropriate levels of motivation and high visual sensitivity. Consider these designs for early presbyopes who don't have a highly critical distance demand and for patients who spend much of their time at a computer. Athletes often prefer them as well because they move less with the blink.

Anatomical considerations should include pupil size of 5mm or less in normal room illumination and a well-centered corneal apex with low or flaccid lower lids. These patients are not good candidates for a translating (alternating or segmented) design.

The key to success with GP multifocals is to have a positive and optimistic, but realistic approach. Set appropriate patient expectations by:

• Advising patients that multifocal lenses will adequately address 75 percent to 85 percent of their visual requirements.

• Suggesting auxiliary spectacles may be necessary for tasks such as night driving or reading fine print.

• Reminding patients that optimum lighting is necessary for maximum visual comfort. Tell them, "This is no different from what you experience with your progressive spectacles."

Six GP Clinical Tips

1. For the preliminary exam to an actual diagnostic lens evaluation, use the same procedures as you would for standard manifest refractive testing and anterior segment work-up.

2. Measure pupil diameter, horizontal visible iris diameter, palpebral aperture size, blink rate and lid tension.

3. Corneal topography is highly recommended but not absolutely essential. Diagnostic mapping can help identify pre-existing corneal irregularities, determine the location of the corneal apex and aid empirical fitting with software analysis.

4. Use a biomicroscope to examine lids, cornea, conjunctiva and meibomian glands and to perform tear film evaluation for volume and break-up time data.

5. Provide pre-fitting therapeutic intervention for any pre-existing conditions such as papillary hypertrophy, blepharitis, mild lid margin disease or mild tear film deficiency.

6. When warranted, outline ongoing treatment concomitant with lens wear in advance to the patient. This might include lid hygiene or use of topical steroids, cyclosporine, artificial tears and/or mast cell stabilizers.

Follow-up Care and Problem Solving Pearls

Perform progress evaluations typically after one week, one month and three months of lens wear, with semi-annual exams thereafter.

Evaluating New GP Wearers After dispensing, it's good practice for technicians to conduct a follow-up call two to three days later so they can immediately address any minor problems and review proper lens care and handling. They can schedule a more immediate re-evaluation if any patient-reported adaptation problems seem urgent.

For All Wearers:

• Use sodium fluorescein, which is essential to evaluate the lens-to-cornea relationship.

• Use a Wratten filter in combination with your slit lamp's cobalt blue filter to achieve better visibility of the fluorescein pattern.

• Use larger diameter lenses (OAD/OZD= 9.8mm/9.4mm) especially for younger, more active patients and athletes to minimize lens decentration.

• Check edge shape and design, which are the most important parameters in initial lens comfort. A smooth and well-rounded edge apex minimizes lens awareness during the blink. GP lenses are now of consistently higher quality, but it's still important to inspect the lens edge before dispensing to be sure it is free of defects.

• Check for foreign body tracks and peripheral corneal drying (3 o'clock and 9 o'clock staining). These are less common because of the new low-edge clearance designs (minimal, but adequate, distance from the edge of the lens to the cornea). In the rare case you encounter these problems, consult with your laboratory on modification of peripheral curve radii and width or specify aspheric peripheral curves.

• To manage poor surface wettability, first try to determine the cause and then differentiate between poor compliance in cleaning and handling or physiologic causes such as tear deficiency, lid margin disease, inherent material defect or poor blink pattern. Consider a change in lens material if you appropriately address compliance and physiological factors but the problem persists.

Another excellent remedy or preventive measure is to use the newly available plasma coating. Surface plasma treatment to increase the wettability of GP lenses is analogous to methods employed for this purpose in the manufacture of silicone hydrogels and may improve overall lens comfort and wearing time.

The Bottom Line

Over time, your success and confidence with GP lenses will increase exponentially. To help ensure your success, a variety of professional resources are available. The most valuable are trained consultants at your CLMA laboratory. You can also use Web resources offered by the GP Lens Institute at

Dr. Resnick acknowledges Barbara Anan Kogan, OD, for her help with this article.

Dr. Resnick is a principal in the New York City based specialty contact lens practice of Drs. Farkas, Kassalow, Resnick and Associates, PC. She is a Diplomate of the Cornea and Contact Lens Section of the American Academy of Optometry and an advisory panel member of the GP Lens Institute.