International Contact Lens Prescribing

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
January 2002

Survey results from six countries provide a snapshot of contact lens prescribing around the world.

Gaining access to statistical information about contact lens markets is difficult. Around the world, manufacturers often hold such data, but it can be commercially sensitive, and it is usually not made publicly available. On the other hand, when such data do exist, they are generally sales values which are not readily converted into wearer numbers. For practitioners, a helpful approach is to understand prescribing trends from colleagues at a national and international level. This allows for individual prescribing habits to be benchmarked against a peer group.

For a number of years, we have been tracking prescribing patterns in the United Kingdom (UK) contact lens market and, more recently, we have followed contact lens fitting habits in other countries. In 2001, we surveyed six countries: Australia, Canada, Greece, Netherlands, Norway and the UK. To allow for sound inter-market comparison, the same protocol was carried out in each country. At the start of January, 1,000 survey forms were mailed to randomly-selected practitioners in each country, with the exception of Norway where there are less than this number of contact lens practitioners in the country. Here 502 practitioners were selected, representing 90 percent of those licensed to fit lenses.

The survey forms were identical, allowing for language considerations. Each form requested some basic background information about the practitioner completing the questionnaire and then solicited generic (unbranded) information about the first 10 patients fitted with contact lenses after receipt of survey. 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 nature of lens prescribing. This weighting was based on the contact lens activity of the respondents, as determined from the dates provided on the questionnaire. Thus, 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.

Figure 1. Most countries showed higher rates of refits than new fits.

Demographics and Background Information

Response rates ranged from 4 percent in Greece to 30 percent in Norway with an overall response rate of 15 percent. Information was gathered about 7,515 contact lens fits across the six countries. The mean age for the group was 31.9 years, with national averages varying from 28.2 in Greece to 33.3 in the UK and the Netherlands. Females accounted for 64 percent of all fits internationally, ranging from 59 percent in Norway to 67 percent in Canada. Most countries reported fewer new fits than refits (Figure 1). The global figure for new fits was 46 percent with extremes of 38 percent for Canada and 51 percent for Norway. These values may represent an indirect measure of the health of the contact lens market ­ countries attracting more people into lenses for the first time would have a higher new fit proportion.

	Figure 2. The Netherlands showed a much higher level of new rigid lens fitting than other countries.

Soft vs. Rigid Lenses

Perhaps the most commonly-asked question about the mode of contact lens practice within a country is the proportion of rigid contact lenses used (Figure 2). In this survey we found that 14 percent of all fits were rigid lenses, although significant differences existed between countries and when new fits were compared to refits (Figure 3). In particular, the level of rigid lens fitting was much greater in the Netherlands compared with other countries, and more rigid lenses were prescribed as refits than as new fits. For example, in the UK, 7 percent of new fits were with rigid lenses compared to 21 percent of refits.

Soft lenses Across all countries, mid-water content lenses (40 percent to 60 percent water) accounted for about 60 percent of fits. Low-water content lenses accounted for no new fits in Norway, but for 24 percent of new fits in Greece. High-water content lenses accounted for one quarter of all fits. Silicone hydrogel materials were used for 7 percent of all fits, accounting for 24 percent of soft lens refits in Australia and none of the soft new fits in the Netherlands. Silicone hydrogels were not always used for extended wear. In the UK and in Norway, 94 percent and 99 percent of silicone hydrogel fits, respectively, were for extended wear. These values were 26 percent for Canada and 22 percent for the Netherlands.

Figure 3. Once again, The Netherlands takes the lead in rigid fitting, this time with refits.

In all countries, most soft lenses were spherical (Figure 4). Torics accounted for 21 percent of all fits, ranging from 12 percent for new fits in Greece to 31 percent of new fits in Norway. Tinted lenses which were used in 15 percent of all new fits in Greece compared with no refits in the Netherlands. There was also considerable variation for soft lens multifocals which accounted for 7 percent of all soft lens fits, peaking at 16 percent for new fits in Canada.

An area with considerable international variation is soft lens replacement frequency. In all countries except Greece, over 90 percent of soft lenses were prescribed on a planned replacement basis. Daily replacement lenses were popular in Norway (36 percent of new fits) and the UK (22 percent). For lenses replaced every one or two weeks, Australia was the major market (44 percent of new fits) with these lenses rarely fitted in the Norway or the UK (3 percent and 1 percent of new fits, respectively). Lenses replaced on a monthly basis were the most commonly prescribed option in all countries, representing 55 percent of all lenses fitted.

Figure 4. Most new patients received spherical lenses, while torics and tinted and multifocals also made the list.	Figure 5. Most patients wearing extended wear are existing patients, not new fits.

Overall, most lenses were fit on a daily wear basis: 94 percent of all fits. Extended wear was usually prescribed as a refit; in other words, practitioners seemed more content fitting an existing wearer with an extended wear modality than a neophyte (Figure 5). For example, in the UK, 1 percent of new fits were extended wear, compared with 12 percent of refits. In Australia, these values were 7 percent and 18 percent, respectively. In Australia, Norway and the UK, over 95 percent of extended wear fits were with silicone hydrogel lenses compared with 19 percent for Canada and 18 percent for the Netherlands (Figure 6).

Figure 6. Australia, Norway and The Netherlands showed a very high percentage of silicone hydrogel fits.	Figure 7. Australia and Canada fit higher numbers of toric and multifocal rigid lenses.

For patients requiring lens care, multi-purpose care systems were prescribed in more than three-quarters of fits in all countries and in 95 percent of cases in Australia. One-step peroxide systems were more popular than their two-step equivalents, although this was not the case for Canada and the Netherlands. Other options such as heat and chlorine disinfection were also minimally reported.

	Figure 8.Most soft lenses were prescribed on a planned-replacement basis.

Rigid lenses Mid-Dk materials (40 to 90 Dk) were the most commonly prescribed materials, accounting for 63 percent of all fits. Interestingly, the country using the most rigid lenses, the Netherlands, fitted a high proportion of low-Dk lenses (30 percent) compared with the country fitting the least rigid lenses, Norway (8 percent). Most RGPs were spherical; however, there were significant numbers of toric and multifocal lenses fitted in some countries, Australia and Canada in particular (Figure 7).

Most rigid lenses were not replaced on a planned basis, although about half of the RGPs fit in Norway were prescribed on an annual replacement basis. Most rigid lenses were fitted on a daily wear basis, with the exceptions of Australia (9 percent of refits) and Norway (22 percent of all rigid lens fits).

Summary

This analysis clearly indicates that the contact lens markets surveyed retain highly individual characteristics. However, we see a number of general trends. For example, soft lenses account for 86 percent of lenses fitted. Typically, these lenses are non-spherical, manufactured from low-water content hydrogel material and prescribed on a planned replacement basis (Figure 8). Rigid lenses are frequently fitted in more complex situations, such as presbyopia or astigmatism. The differences among countries highlight the influence of optometric and optical training institutions and local clinical education initiatives.

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 Research Director 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.