GP Lens Case Grand Rounds Troubleshooting Guide

Optimizing Initial Comfort and Achieving Successful Adaptation to Corneal GP Lenses: Edward S. Bennett, OD, MSEd, FAAO, FSLS

Background

The most important factor in obtaining success with a new corneal GP wearer is optimizing the initial experience they have with GP lenses. With the many benefits and applications of GP lenses including excellent quality of vision, astigmatic correction, correction of presbyopia, impact on the progression of myopia in young people, and the visual benefits for the irregular cornea patient, GP lenses should be an integral part of EVERY practice which provides contact lens care to patients. However, there is often a fear by new contact lens wearers about having a foreign body on the eye and, in some cases, they have been told that corneal gas permeable (GP) lenses are uncomfortable. Likewise, many practitioners are hesitant to fit corneal GP lenses for fear of how the patient will react to lens wear, possible perceived complexities in lens design and fitting and perhaps increased chair time. These concerns may be managed, and adaptation optimized, via the following four-step plan: 1) Communicating GPs to the patient, 2) Use of a topical anesthetic, 3) Optimize initial vision, and 4) Comfortable lens design.

Four Step Initial Comfort Program

1. Communicating Corneal GP Lenses to Your Patient

It is important to first note that patients depend upon the prescribing practitioner to assist them in deciding which contact lens would be best for them. If the practitioner is not interested in this as a viable option to patients – either via their nonverbal behavior or their verbal comments – patients are very likely to detect this and be dissuaded from GP lenses. Conversely, if the practitioner feels that a GP is the best option for the patient, the patient will likely agree.

This philosophy was confirmed in a study conducted at the University of Missouri-St. Louis and Pacific University Colleges of Optometry. New corneal GP wearing subjects were divided into three groups for their GP fitting experience. At the diagnostic fitting visit one group observed a video of a practitioner communicating corneal GP lenses to a patient using such terms as “discomfort”, “pain”, and “feels like something is always on the eye”. In addition, it was evident in his nonverbal behavior that he was not a GP advocate. The second group observed a doctor who used neutral terms such as “lens awareness” and “lid sensation” while emphasizing that the long-term comfort of corneal GP lenses is typically very good. However, his nonverbal communication was not positive (i.e., unenthusiastic). The third group of subjects observed a practitioner who discussed adaptation using the same terminology as the previous practitioner but was enthusiastic about GPs as a viable contact lens correction option. The results of this one month study showed that 6 of 19 subjects in Group One dropped out; 2 of 17 in Group Two dropped out and 0 of 13 subjects in Group Three dropped out. In addition, the subjects in Group Three were much more compliant in submitting their daily questionnaires.

It is evident that avoiding strong terminology and offering GPs as a viable option is important. I always assume that my patients may have heard that GPs are uncomfortable and, using the aforementioned terminology, emphasize that today’s designs exhibit better initial comfort than their predecessors while providing excellent vision and good long-term comfort.

2. Use of a Topical Anesthetic at the Fitting Visit

The use of a topical anesthetic immediately prior to the initial application of corneal GP lenses will increase the initial comfort and reduce apprehension. This is especially beneficial for first-time GP contact lens wearers as well as soft lens wearers who are being refitted into corneal GP lenses. In fact, with the latter group it is not uncommon to hear comments that the lens awareness with GP lenses is not as much as they would have predicted while the vision is excellent.

Several studies have found that the use of a topical anesthetic prior to lens insertion results in a more positive perception of adaptation and a higher success rate. In a one month 80 subject study, 38 of 40 subjects who had an anesthetic at the fitting visit successfully completed the study; 32 of 40 subjects who did not have an anesthetic completed the study. In addition, there has been no evidence to indicate that anesthetic use prior to corneal GP fitting increases corneal staining. In addition, although topical anesthetic application is typically limited to the initial application of GPs only, patients rarely complain of excessive awareness after subsequent applications of GP lenses. The most important time period in the mind of the apprehensive first-time GP lens wearer is the first few minutes after lens application. If the comfort is optimized via the use of a topical anesthetic, this can be a powerful tool in creating a satisfied and successful GP wearer. It is important, however, for the anesthetic effect to wear off while the patient is wearing the lenses such that they can gradually experience awareness and achieve a realistic lid-edge sensation.

3. Good Initial Vision

If the first pair of lenses a corneal GP wearing patient applies is in their prescription and, therefore, they experience the most powerful benefit of GP lenses – good vision – it is certainly possible that their perception of initial awareness will be less. Therefore, although diagnostic fitting has the benefits of practitioner confidence about the final lens parameters, whenever possible, ordering lenses empirically or fitting out of a GP inventory provides patients with this benefit. In fact, it can result in a “Wow factor” which is especially important with patients being refit from soft lenses as a result of poor vision. Empirical fitting is increasingly successful as a result of continuing advances in manufacturing technology resulting in more consistent edges, ultra-thin profiles and aspheric or pseudo-aspheric peripheries.

Obviously, there are patients in which diagnostic fitting is necessary including segmented translating presbyopic lenses, irregular cornea fitting and patients interested in corneal reshaping. Likewise, initially fitting several patients into spherical designs will give the fitting practitioner confidence in GP design, fitting and evaluation, making the later empirical fitting easier and more successful.

4. Comfortable Corneal GP Lens Design

Several factors are important in a GP lens design that will be comfortable initially. These include the following:

Ultra-Thin Design. All CLMA member laboratories have ultra-thin designs which are approximately .03 – .05mm thinner than standard designs. This results in a lens that has 30 – 40% less mass and more likely to exhibit a lid attachment fitting relationship. The exceptions to ultra-thin use would be patients with moderate-to-high corneal astigmatism (i.e., ≥ 1.50D) in which flexure can be problematic.
Alignment Fitting Relationship. Evaluating the lens-to-cornea fitting relationship with fluorescein and striving for an alignment fit is important. In high corneal astigmatism (often ≥ 2.50D), the use of a bitoric design is typically indicated for this reason.
Large Overall Diameter. The continuing introduction of large diameter (typically 10 – 12mm) designs which result in lid attachment, good centration and reduced movement with the blink as compared to more conventional smaller designs.
Avoid Excessive Edge Clearance. With fluorescein there should be slightly greater edge clearance than centrally. If excessive pooling is present peripherally several problems may result including corneal desiccation via funneling the peripheral tear film under the lens edge, decentration via increased lid interaction with the lens edge and reduced initial comfort.
Consistent Edge Design. A rolled tapered smooth edge is very important for initial comfort. Fortunately with current manufacturing methods, defective edges are a rare problem.
Use of Lenticulation When Indicated. The use of a plus lenticular on all high minus power (often ≥ -5D) and a minus lenticular on all low minus power (≤ -1,50D) and all plus power designs is important to optimize centration and, therefore, initial comfort.

Avoid terms such as “discomfort” and “pain.” Substitute terms such as “lens awareness” and “lid sensation” when describing corneal GP lenses.

Use a topical anesthetic prior to the initial application of corneal GP lenses on all new GP wearing patients.

Whenever possible, the first lenses that are fit to new GP wearing patients are – via empirical or inventory fitting which provides optimal vision and comfort.

The use of an ultra-thin design will often optimize comfort; a larger overall diameter, low-medium edge clearance and a lenticular (when indicated) may also optimize initial comfort.