CONTACT LENSES WORLDWIDE
International Contact Lens Prescribing 2002
Survey results from eight countries provide a snapshot of contact lens prescribing around the world.
Philip B. Morgan, PhD, MCOptom, FAAO; Nathan Efron, DSc, MCOptom, FAAO; Craig A. Woods, PhD, MCOptom, DipCLP, FAAO; Deborah Jones, BSc, FCOptom, DipCLP, FAAO; Yiannis Tranoudis, PhD; Eef van der Worp, BSc, FAAO; Magne Helland, BSc, MScOptom; Anna Yeo Chee Hong, BOptom (Hons) MApp Sc; Joseph T. Barr, OD, MS, FAAO; and Gretchyn M. Bailey, NCLC, FAAO
This paper presents our second annual survey of international contact lens prescribing trends. From January to March 2002, we analyzed contact lens prescribing habits in eight countries: Australia, Canada, Greece, the Netherlands, Norway, Singapore, the United Kingdom and the United States. With the exception of Norway and Singapore (545 and 390 surveys, respectively), 1,000 questionnaires were randomly sent out to a cross section of contact lens practitioners.
The exact nature of the practitioner recipients varied due to local conditions. For example, in the United Kingdom, 1,000 names were selected at random from the national register of those able to fit contact lenses (the General Optical Council register); in the United States, 1,000 random names from the subscriber list of Contact Lens Spectrum was used.
As in 2001, each questionnaire requested some basic background information about the practitioner and then solicited generic (unbranded) information about the first 10 patients fitted with contact lenses after receiving the questionnaire. Data about each lens fit fell into the following categories: date, age and sex of patient, new fit or refit, lens material, lens design, lens replacement frequency, number of anticipated uses per week, wearing modality and care system prescribed. When analyzed, a system of weighting was employed to better reflect the contact lens activity of the respondent such that a practitioner completing all 10 fits in one day was afforded a higher activity weighting than a colleague taking eight weeks to complete 10 fits. Importantly, therefore, this was a prospective analysis of contact lens prescribing habits.
Demographics and Background
The response rate ranged from 4 percent in Greece to 28 percent in Norway. Overall, information was provided about 9,073 contact lens fits. Females accounted for 59 percent of fits in Norway and 72 percent in Singapore. The country with the youngest average contact lens fit age was Singapore (26.3 years), and the oldest was the United Kingdom (33.3 years). The proportion of new fits (lenses prescribed to patients with no previous experience) ranged from 32 percent in the United States to 53 percent in the United Kingdom. This parameter is an indirect measure of the health of the contact lens market, with higher levels of new fits suggestive of an expanding wearer base. There was considerable variation among countries in the number of patients for whom part-time contact lens wear (defined as using lenses three times per week or less) was prescribed. This modality accounted for 4 percent of contact lens wearers in the Netherlands and 24 percent of patients in the United Kingdom (Table 1).
Soft vs. GP Lenses
An important benchmark about the style of contact lens practice within a nation is the proportion of gas permeable (GP) lenses which are prescribed. For new fits, this parameter was highest in the Netherlands (25 percent of fits) and lowest in Norway (1 percent of fits) (Figure 1). For refits (lenses prescribed to existing wearers), the values were generally greater. For example, in the United Kingdom, 20 percent of refits wore GP lenses compared with 8 percent of new fits. Overall, 12 percent of all contact lenses prescribed in this survey were gas permeable.
|Figure 1. The relative proportion of soft and rigid lenses prescribed for new fits for Australia (AU), Canada (CA), Greece (GR), the Netherlands (NL), Norway (NO), Singapore (SG), the United Kingdom (UK) and the United States (US).||Figure 2. Soft lens materials for new fits.|
Mid water (40 percent to 60 percent) lenses were the most popular soft lens material, accounting for 80 percent of new soft lenses prescribed in Canada (Figure 2). Low water (less than 40 percent water) contact lenses accounted for only 1 percent of lenses in Norway, but remain common in Singapore (31 percent) and Greece (28 percent). Silicone hydrogel materials were more commonly used for refits, representing 18 percent of lenses in Norway and 15 percent in Australia.
Figure 3. Soft lens designs for new fits.
|Figure 4. Soft lens replacements for new fits.|
For soft lens designs, most lenses were spherical, except in the United States where 51 percent of lenses were non-spherical including 35 percent torics, 10 percent multifocals and 5 percent cosmetic tints (Figure 3). Soft torics were highest in the Netherlands with 39 percent of soft lens fits. This value was lowest in the United Kingdom at 18 percent of new fits.
Daily disposable lenses were popular for new fits in Norway (32 percent), the United Kingdom (28 percent), Singapore (18 percent) and Greece (18 percent) (Figure 4). They accounted for less than one in 10 new fits in Canada (9 percent), the Netherlands (6 percent) and the United States (5 percent). Monthly-replaced lenses were the most commonly prescribed new fit replacement frequency, although one- to two-week replacement lenses were also popular in the United States (46 percent) and Australia (36 percent). Conventional (unplanned) replacements represented 11 percent of new fits in Greece, and less than 0.5 percent of fits in Canada, Norway and the United States.
Extended wear accounted for 9 percent of all soft lens fits (Figure 5). The popularity of this modality was similar among all countries, although it was generally higher for refits than for new fits. This latter observation reflects the increased confidence of practitioners supplying extended wear lenses to existing contact lens wearers rather than to someone with no previous lens experience. The greatest degree of extended wear fitting was in Norway (18 percent of refits) and the United States (16 percent of refits). In Australia, Canada, Norway and the United Kingdom, silicone hydrogels accounted for more than 75 percent of extended wear lenses prescribed (Figure 6). This value was much lower in the Netherlands (29 percent) and Singapore (19 percent).
Some 89 percent of soft lens care systems were described as multi-purpose, with great similarity among all countries in this regard. The remaining care products were mainly peroxide, with a greater proportion of one-step peroxides than two-step peroxides (7 percent and 3 percent, respectively). Chlorine-based care systems accounted for 2 percent of all care products prescribed in Norway.
Figure 5. Soft lenses prescribed for extended wear.
Figure 6. Lens materials used for soft lens extended wear.
Mid Dk materials (40 to 90 Dk) were the most commonly prescribed materials accounting for 55 percent of all fits. Low Dk (less than 40) lenses were the most commonly prescribed material in the United States (69 percent of new fits) and Greece (55 percent), whereas this material type accounted for less than 15 percent of new lenses in Australia and the United Kingdom.
Multifocal lenses represented more than 30 percent of new gas permeable fits in the United States and the United Kingdom, and toric lenses accounted for 42 percent of GP lens fits in Canada.
GP lenses were prescribed on a planned replacement basis in 59 percent of fits in Norway, and between 10 percent to 35 percent in all other countries (Figure 7). Some 14 percent of GP fits in Singapore were on an extended wear basis; this value was 4 percent for Australia and the United States, and 1 percent or less for the other countries (Figure 8).
|Figure 7. GP lens replacements for new fits.||
Figure 8. GP lenses prescribed for extended wear.
There are clear differences in contact lens prescribing habits among the eight countries surveyed in 2002. Although all markets are dominated by soft contact lens fitting, there are clear disparities among countries for the contact lens materials used, the replacement frequencies advocated and the contact lens wear modalities prescribed. On the basis that physiological demands are similar for patients worldwide, these differences must be due to local factors such as teaching methods and traditions, legislative factors, product marketing and consumer pressures.
This survey was funded by the sponsors of Eurolens Research: Bausch & Lomb Incorporated, Alcon Laboratories (UK) Limited, Advanced Medical Optics, CIBA Vision (UK) Limited, CooperVision Limited, Johnson & Johnson Vision Care, Menicon Co. Ltd., Ocular Sciences Limited, Optical Express and Sauflon Pharmaceuticals Limited. In Greece, additional funding was also provided by Johnson & Johnson.
Dr. Morgan is Research Manager of Eurolens Research, UMIST, Manchester, UK.
Dr. Efron is Professor of Clinical Optometry and Director of Eurolens Research, UMIST, Manchester, UK.
Dr. Woods is Senior Research Optometrist of the CVRA and Deputy Clinic Director of the Melbourne Optometry Clinic of the Victorian College of Optometry.
Deborah Jones is the Assistant Clinic Director and Head of the Pediatric and Special Needs Clinic at the School of Optometry, University of Waterloo, Ontario, Canada.
Dr. Tranoudis is Director of the Centre for Contact Lens Research and Fitting 10/10, Athens, Greece.
Eef van der Worp is Head of the Contact Lens Department, School of Optometry, Hogeschool van Utrecht, the Netherlands.
Magne Helland is Associate Professor at the Department of Optometry at Buskerud College, Kongsberg, Norway.
Anna Yeo Chwee Hong is a professor at Singapore Polytechnic.
Joseph T. Barr is editor of Contact Lens Spectrum and assistant dean of Clinical Affairs at The Ohio State University College of Optometry.
Gretchyn M. Bailey is managing editor of Contact Lens Spectrum.