Contact Lens Prescribing Trends at a University Clinic

MICHAEL G. HARRIS, O.D., J.D., M.S., JAMES HERZMAN, O.D., ROD MURRAY, O.D., AND SALVADOR VALLARTA, O.D.

This study investigates whether the contact lens prescribing experience at one university clinic is analogous to what students will encouter as practitioners.

The University of California, Berkeley School of Optometry (UCBSO) is responsible for training its students in the most up-to-date contact lens treatment options available for correcting refractive error while ensuring patient satisfaction and ocular health. To determine how the UCBSO Clinic is meeting this challenge, we evaluated the contact lens prescribing trends during a six-month period and compared them to national prescribing trends reported in marketing research studies by Johnson & Johnson, Bausch & Lomb and Contact Lens Spectrum.

APPLICATIONS FOR OUR DATA

Practitioners are most comfortable prescribing lenses with which they have experience, so it would seem that the percentage of contact lenses prescribed in a university clinic is a good indication of future trends in contact lens prescribing. Knowing which modalities or lens types are prescribed by practitioners would allow academic institutions to gear instruction towards the most commonly prescribed lenses and to improve student familiarity with lenses that are not commonly prescribed.

METHODS

We analyzed and categorized all contact lens orders from the UCBSO Clinic from March 1, l996, to August 31, 1996, a total of 2409 orders. Contact lens orders at UCBSO are generated from eye exams and contact lens fittings performed at the school. Patients may refill their contact lens prescription if it has been less than a year since their last comprehensive eye exam or if there is less than a year until their next planned contact lens follow-up visit. Thus, contact lens orders are an accurate reflection of the prescribing trends at the UCBSO Clinic.

Most orders were for a specific contact lens type prescribed for both eyes and we counted them as one order. When two different contact lenses were prescribed for one patient, we considered each lens type an individual contact lens order. We also counted one lens order only when the patient lost a lens or when parameter changes were made for one eye only. Contact lens orders indicate the usual quantities of lenses for the particular contact lens modality being prescribed, and we counted each order as one regardless of the number of boxes of lenses ordered. We didn't analyze the number of lenses prescribed within each order.

The time period involved included three months of the regular spring semester and three months of summer session. While the number of patients and the quantity of lens orders diminished during the summer session, we believe the numbers obtained are an accurate reflection of UCBSO Clinic's prescribing trends.

The RGP orders were categorized by RGP trade names. Soft lens orders were categorized by the listing in "Tyler's Quarterly Soft Contact Lens Parameter Guide." To find the relative frequencies of lens orders for a particular product, we tallied the total number of orders for a specific product, divided that number by the total number of lens orders and multiplied by 100. For example, out of the total number of 550 RGP orders, there were 192 orders for Oxyflow F-30. Hence, the relative percentile of Oxyflow F-30 to all RGP orders was: 192/550 x 100 = 34.9 percent.

FREQUENCY OF SOFT LENSES VS. RGPs PRESCRIBED

Soft contact lenses accounted for 77.2 percent of all contact lens orders, compared to 22.8 percent for RGPs. Data obtained from Bausch and Lomb's "Trends in Lens Care" report indicates that nationally, RGPs constituted 7 percent of new fits in 1996. The January 1997 Contact Lens Spectrum article, "Contact Lenses and Vision, The Annual Report," listed the number of RGP new fits and refits for 1996 as 10 percent (Fig. 1).

Our data indicates a significantly higher percentage of RGP contact lenses prescribed at the UCBSO Clinic than reported national trends. This difference could be attributed to several factors. It's possible that more challenging patients requiring more sophisticated lenses are referred to a university clinic, so more time may be spent with each patient. Also, an academic institution must teach RGP fitting and may encourage more lens changes to be made when a "clinically acceptable" but somewhat less-than-ideal fit is achieved. In addition, we can't rule out the fact that students have less experience then practicing optometrists.

TRACKING LENS BRANDS & CATEGORIES

Our results showed that 93.6 percent of RGPs ordered were spheres, 4.9 percent were bitorics, 0.9 percent were bifocals and 0.5 percent were torics (Fig. 2). RGP brands ordered included Oxyflow F-30 (34.9%), Polycon II (31.3%), Plia Flex 02 (11.3%), and Fluorocon (6.4%). The remaining 16.1 percent incorporated various other brands (Fig. 3).

Regarding soft contact lenses, 81 percent prescribed were spheres, 18.5 percent were torics, 2.7 percent were extended/flex wear spheres, 1.9 percent were extended/flex wear torics and 0.5 percent were multifocals (Fig. 4). Of the conventional wear lenses prescribed, Cibasoft lenses accounted for 41.7 percent, CSI Clarity DW Clear for 34.9 percent, Cibasoft Standard for 6.7 percent, Aquaflex Superthins Minus for 2.7 percent, and other brands comprised the remaining 14 percent (Fig. 5). For disposable lenses, two-week replacement Acuvue accounted for 40.4 percent, Seequence for 28.7 percent, New Vues for 12.3 percent, 1-Day Acuvue for 6.1 percent and all others for 5 percent (Fig. 6).

We found that 44 percent of soft lenses prescribed were disposable, 33 percent were daily wear and 23 percent were planned replacement. Reported national trends indicate that 44.8 percent of new fits in 1996 were disposable, 38.2 percent were daily wear and 17 percent were planned replacement (Fig. 7).

According to our results, 5.1 percent of the prescribed soft lenses were FDA approved for extended wear, although they were not necessarily prescribed to be worn on an extended wear basis. National trends, however, reported that extended wear lenses account for 16.6 percent of lenses prescribed. This difference is most likely attributed to the conservative philosophy of an academic faculty towards currently available soft lenses worn on an extended wear basis.

CONCLUSION

Based on our data, we concluded that the prescribing trends at the UCBSO Clinic were similar to reported national trends with two major differences: a significantly higher percentage of RGP lenses and a significantly lower percentage of extended wear lenses were prescribed at UCBSO. CLS

Dr. Harris is a clinical professor, an associate dean and the chief of the Contact Lens Clinic at the University of California, Berkeley School of Optometry. Drs. Herzman, Murray and Vallarta are all recent graduates of UCBSO.

We thank the Morton D. Sarver Laboratory for Contact Lens and Corneal Research, Johnson & Johnson Vistakon, Bausch & Lomb, Dr. George Mertz and Diane Lowe for their help with the study.

References are available upon request to the editors at Contact Lens Spectrum. To receive references via fax, call (800) 239-4684 and request document#31. (Be sure to have a fax number ready.)