Ocular Surface Characteristics of the Asian Eye

Establishing what lenses you have chosen to prescribe should for most practitioners be reasonably straight forward. A review of your practice management system can tell you how many patients you have fit and with what. Comparing that data to other practices and offices is not so easy. Industry does collect such data but rarely is it readily available and when it is, it is not always easily comprehended. However, over the past decade or so data has been published by The International Contact Lens Prescribing Survey Consortium. This is a research group spearheaded by Dr Philip Morgan, Director of Eurolens Research (Manchester, UK). At the last count data was being collected from 28 different countries. (Morgan et al, 2010a)

Looking at the results of the survey published earlier this year (Morgan et al, 2010a), once again it is apparent that there is great diversity between the participating countries with respect to the utilization of contact lenses in general and specifically silicone hydrogel (SiHy) materials. Of the 28 countries there are six where rigid lenses still represent more than 10% of fits, reaching as high as 23% in the Netherlands and Italy, Figure 1.

Figure 1: Rigid lens fits as a percentage of all lens fits in 2009
(Data, Morgan et al, 2010a)

For the majority of countries soft lens materials predominate. The dominance of soft lenses is no surprise but a review of the split between hydrogel, SiHy materials and daily disposable lenses just shows how varied prescribing is, Figure 2. Only five countries (Belgium, Canada, Czech, New Zealand and USA) prescribe the majority of their soft lenses (over 50%) in silicone hydrogel materials. The number of countries with a high use of SiHy lenses would likely be higher but for the high use of the DD modality in some countries; Taiwan, Qatar, Denmark, Kuwait and Hong Kong all with over 40% DDSCL prescribed. With the recent introduction of SiHy materials for daily disposable lenses it would not be unreasonable to speculate that the share of hydrogel lenses in this market will diminish over the next few years, as SiHy DDSCLs become more widely available.

Figure 2: Percentage of fits for soft daily wear lenses (Data, Morgan et al, 2010a)

SiHy is only the majority of fits in four countries when they are compared to all hydrogel use, but if we consider its percentage for lens materials prescribed for DW and exclude daily disposable lenses, then 14 of the countries surveyed have SiHy lenses prescribed for the majority of fits. Also, when soft lens fits are reviewed by the material categories of Low, Medium, High Water Content and SiHys, for the first time since this survey has been conducted, SiHys are now the most widely fit soft lens material ( Figure 3) with 39% of new soft lens fits. The US and Kuwait actually use SiHy lenses for over 70% of fits.

Figure 3: proportion of fits for soft lenses, categorised by lens material
(Data, Morgan et al 2010a)

Originally, SiHy lenses were launched and marketed solely for extended wear, which very quickly was expanded into daily wear as well. The trend to move away from EW continues and in 2009 extended wear represented only 8% of all fits for all countries surveyed, ranging from zero to as high as 29% in Lithuania and 24% in Norway. Of lenses prescribed for extended wear, SiHys were prescribed 84% of the time, with Italy (26%) and Japan (19%) having the lowest use of SiHy lenses in this mode of wear.

This survey has been performed over a number of years using the same reporting forms and data processes and for some countries this time period has covered ten years or more. Morgan et al (2010b) reviewed the data collected from the surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008. Over this period the proportion of silicone hydrogel lenses in the soft lens market increased for all countries (Figure 4). The also found that SiHy lenses were fit 96% of the time for full time daily wear, compared to 85% for hydrogels (p<0.05). This suggests that patients are able to wear silicone hydrogel lenses for longer hours

Figure 4: growth of Si Hy lens market share, (Figure, Morgan et al 2010b)

In summary Morgan et al (2010b) concluded that SiHy lenses had risen to a 36% overall market for all countries surveyed. SiHy lens use will continue to grow and continue to vary between countries and with the introduction of daily disposable lenses fabricated fromSiHy materials, this growth is likely to continue at a higher rate.

References

1. Morgan PB, Woods CA, Tranoudis Y, Helland M, Efron N, Knajian R, Grupcheva CN, Jones D, Tan KO, Pesinova A, Ravn O, Santodomingo J, Vodnyanszky E, Erdinest N, Hreinsson HI, Montani G, Itoi M, Bendoriene J, van der Worp E, Hsiao JC, Phillips G, Gonzalez-Meijome JM, Radu S, Belousov V, and Nichols J (2010a) International Contact Lens Prescribing in 2009. Contact Lens Spectrum 24(2): 30-36.
   
   
2. Morgan PB, Efron N, Helland M, Itoi M Jones D, Nichols JJ, van der Worp E and Woods CA (2010b). Twenty first century trends in silicone hydrogel contact lens fitting: An international perspective. Contact Lens & Anterior Eye 33(4) 196-198.

The International Contact Lens Prescribing Survey Consortium

Philip B Morgan, United Kingdom; Nathan Efron, Australia; Craig A Woods, Canada; Joseph T Barr, United States of America; Vadim Belousov, Russia; Jolanta Bendoriene, Lithuania; Aris Chandrinos, Greece; Nir Erdinest, Israel; Philip Fine, Israel; Martha Y Gonzalez, United States of America; José Manuel González-Méijome, Portugal; Hans-Jürgen Grein, Germany; Christina N Grupcheva, Bulgaria; Magne Helland, Norway; Hreinn Ingi Hreinsson, Iceland; John Hsiao, South Korea; Lee Kai Hung, Singapore; Motozumi Itoi, Japan; Deborah Jones, Canada; Razmig Knajian, Lebanon; Carla J Mack, United States of America; Edoardo Marani, Italy; Sebastian Marx, Germany; Giancarlo Montani, Italy; Jason J. Nichols, United States of America; Alex Ong, Singapore; Alice Pesinova, The Czech Republic; Geraint Phillips, New Zealand; Simona Radu, Romania; Ole Ravn, Denmark; Svend-Erik Runberg, Denmark; Jacinto Santodomingo, Spain; Mirna S Silih, Slovenia; Kah-Ooi Tan, Singapore; Inga-Lill Thunholm-Henriksson, Sweden; Ioannis G Tranoudis, Greece; Eef van der Worp, The Netherlands; and Edit Vodnyanszky, Hungary.