A number of studies have been conducted in recent years highlighting the potential advantages of contact lenses for minors (defined here as those aged <18 years old).1–4 Using a pediatric quality-of-life survey tool known as the Pediatric Refractive Error Profile, Walline et al.1 and Rah et al.2 have demonstrated that contact lens wear dramatically improves how children (which they defined as those aged 8 to 12 years) and teenagers (aged 13 to 17 years) feel about their appearance and participation in activities, leading to greater satisfaction with their refractive error correction. Children can achieve long wearing times3 and also benefit from contact lenses through an enhancement of a variety of self-perceptions such as physical appearance, athletic competence, and social acceptance.4
These quality-of-life and self-perception benefits, along with the known improvements that contact lenses have compared with spectacles for the correction of myopia—such as increased magnification (which can enhance visual acuity), unobstructed field of view and the absence of prismatic peripheral field distortion—serve as a sound rationale for clinicians to offer contact lenses to minors as a viable treatment for refractive error.
An important consideration in prescribing any medication or medical device for minors is that the prescribed medication or appliance is safe. Concerns in this regard have recently been raised by Wang et al.,5 who reported that contact lenses accounted for most medical device-associated adverse events (23%) in the pediatric population (defined as birth to 21 years) in emergency hospital department visits in the United States from January 1, 2004, through December 21, 2005. However, most of these events were described as contusions/abrasions, conjunctivitis, and hemorrhage, which were generally superficial and self-limiting and did not require hospitalization. As well, many of these events, such as conjunctivitis which has a high incidence in minors, may have occurred coincidentally with contact lens wear.
Contrary to these concerns expressed by Wang et al.,5 studies conducted in the United States6 and Singapore7 have demonstrated no difference between children and teenagers in respect of adverse ocular signs observed with the slitlamp biomicroscope. The authors of both studies concluded that contact lenses provide no additional health risk to children.
Notwithstanding the report of Wang et al.,5 the positive outcomes of the above studies in respect of the benefits of fitting children and teenagers with contact lenses suggest that practitioners can adopt a positive approach to fitting these age groups. However, little is known of the extent to which contact lenses are fitted to minors around the world, and whether there is a difference between adults and minors in respect of factors such as lens materials, designs, replacement frequencies, wearing modalities, and care systems used. To answer these questions, we conducted an audit of prescribing data collected in 38 countries over a 5-year period (2005 to 2009).
General Conduct of the Annual Survey
Between January and March of each year from 2005 to 2009, a survey was undertaken in 38 countries using the following procedure. In each country, a paper or electronic (e-mail) survey form was sent to up to 1000 randomly selected contact lens practitioners (opticians, optometrists, and/or ophthalmologists, depending on the market). In some countries, such as Australia, survey forms were sent to virtually every practitioner. In other countries, such as the United Kingdom, survey forms were sent to a random selection of practitioners. In large countries with dispersed populations, such as China and Russia, survey forms were sent to practitioners in a select number of major urban cities. The survey forms were sent along with a request that they be completed within 3 months of receipt. Although there is no clear evidence for seasonal variation in the types of contact lenses prescribed, the survey was conducted at approximately the same time of year to minimize any possible seasonal effects.
The same survey format was used each year, and by way of example, the 2009 survey form used in Australia is shown in the Appendix (http://links.lww.com/OPX/A52). This survey was a one-sided form, on which practitioners were requested to enter a number of background details and to supply generic information about the first 10 contact lens fits performed after receipt of the survey form. Practitioners were asked to return the form irrespective of the number of patients seen (if fewer than 10). The information gathered about lenses and care systems is detailed in Table 1. The returned forms were logged and data from each form were manually entered into an Excel (Microsoft Corporation, Redmond, WA) spreadsheet to facilitate data analysis.
As this analysis is concerned with the prescribing of contact lenses to minors, data relating to individual lens wearers were stratified into groups that were considered to represent different stages of maturity, in respect of a combination of factors such as the prevalence of myopia,8,9 communication skills, lens handling capabilities, and level of financial and contact lens-related decision-making independence. The age ranges and defining characteristics of these groups are given in Table 2. Data relating to the adult group are also presented in this table for comparison purposes.
Differences among practitioners in relation to the amount of contact lens fitting performed were taken into account by assigning an appropriate weighting to each recorded contact lens fit. This was achieved by estimating the number of contact lens fits performed each year by each respondent (based on the date information provided on the survey form) and using this as a weighting factor. For example, the data generated by a practitioner completing all 10 fits in 1 week were given twice the weighting of a colleague who fitted 10 patients in 2 weeks.
Data were mined with the aid of the Excel Pivot Table function. Statistical analysis of differences was conducted using logistic regression models (JMP, SAS Institute Inc., Cary, NC) for soft lens fits. Separate analyses were undertaken to evaluate differences in lens material type (rigid, hydrogel, silicone hydrogel) between the age categories and for the distribution of rigid lens designs prescribed. The 95% confidence limits were determined using Wilson method.10
During the 5-year survey period, data were collected in relation to 105,734 contact lens fits, with a mean country response rate of 2,804 fits (100 to 23,205 fits). A detailed breakdown of this data, stratified for age group and sex, is given in Table 3. There was a significant difference in male:female sex balance between age groups (χ2 = 26.3, p < 0.0001).
There was considerable variance among the 38 countries surveyed with respect to the proportion of fits to minors, ranging from >20% of all lens fits in Iceland, Colombia, and Spain, and <5% in the United Arab Emirates, Qatar, and China (Fig. 1).
The proportion of lenses fabricated from the three primary contact lens material types—rigid, hydrogel, and silicone hydrogel—was significantly different among the four age groups (χ2 = 330.0, p < 0.0001; Fig. 2). The proportion of rigid lenses fitted to infants and children was greater than that for teenagers and adults. Orthokeratology fits represented 2, 47, 23, and 5% of rigid lenses dispensed to infants, children, teenagers, and adults, respectively. This difference was statistically significant (χ2 = 527.4, p < 0.0001). Overall, 28% of rigid lens fits to minors were orthokeratology lenses. Scleral lenses were fitted to 0.7, 0.1, 0.2, and 0.2% of infants, children, teenagers, and adults, respectively (χ2 = 3.0, p = 0.4).
In the survey, the issue of lens design was addressed by asking respondents to indicate the primary purpose of fitting the lenses in relation to the various descriptors within the “Lens Design” category (Table 1). Fig. 3 represents the proportion of fits into spherical, toric, and tinted soft lenses, excluding bifocal/multifocal and monovision fits, for each of the age categories. These proportions were significantly different between groups (χ2 = 133.9, p < 0.0001). A higher proportion of toric lenses were fitted to infants and children vs. teenagers and adults. Infants were not fitted with tinted lenses. Two percent of children and 1% of infants were fitted with bifocal lenses.
As can be seen in Fig. 4, there were substantial differences between age categories with respect to soft lens replacement frequency (χ2 = 357.6, p < 0.0001). A much higher proportion of fits to infants were in the “other” category compared with the other groups; in this context, “other” refers to less frequent lens replacement, such as three monthly, six monthly, annual, or unplanned replacement. The highest proportion of daily disposable lenses was to children, followed by teenagers, adults, and infants. Fewer infants were fitted with two weekly replacement lenses than the other three age categories.
We arbitrarily define “part-time” and “full-time” as wearing lenses one-to-three times per week and four-to-seven times per week, respectively. Considering soft lenses, there were significant differences between age categories in this regard (χ2 = 10.6, p = 0.014), with the highest proportion of part-time fits to children (15%) and the lowest to infants (5%; Fig. 5).
Significant differences were apparent in the proportions of extended wear vs. daily wear soft lens fits, which are shown in Fig. 6 stratified by material type (hydrogel vs. silicone hydrogel; χ2 = 134.2, p < 0.0001). The highest proportion of extended wear lenses fits was to infants (13%), followed by adults (10%), children (7%), and teenagers (5%).
Fifty-five per cent of all lens fits to infants were new fits. Putting infants aside, the proportion of new fits decreased with age (Fig. 7; (χ2 = 3009.0, p < 0.0001). No significant differences were apparent between age groups with respect of the type of soft lens care solutions used (χ2 = 12.3, p = 0.2). The predominant form of lens care was multipurpose solutions, representing 91% of the care systems used by all age categories combined.
Given that this survey is essentially a large-scale random sample of lens wearers, it can be assumed that the total number of fits in the various age categories accurately reflects the proportion of contact lenses fitted. Certainly, the very small proportion of contact lenses fitted to infants is not unexpected given the low prevalence of myopia in this age group and the limited, albeit vital, application of contact lenses for the management of complex refractive errors and binocular vision anomalies and for therapeutic and prosthetic purposes. In general, the increase in the proportion of contact lens fits is commensurate with the increasing prevalence of myopia with age,9 and the need for a presbyopic correction in the adult group.
There are many possible reasons for the difference between nations with respect to the extent of contact lens fitting to minors. Differing age demographics may play a minor role.11 More importantly, there are key differences between nations in the training, attitudes, and collective confidence of the predominant practitioner groupsa—opticians, optometrists, and ophthalmologists—in relation to pediatric lens fitting. Differences in the extent of commercial and professional promotion of contact lenses to younger age groups may also influence the extent of contact lens prescribing in different regions.
There will also be variations in contact lens prescribing to minors in different regions of the world, and even within some large countries, relating to socioeconomic factors and levels of public awareness in eye care. For example, in China, the provision of contact lenses and associated eye care for minors in large urban centers, with ready access to large hospitals and other forms of sophisticated urban infrastructure, is likely to be very different from that in remote, rural areas. In some parts of East Asia, standards of contact lens care possibly lag behind those in the western world. For example, orthokeratology is a procedure that has a high prevalence among minors (discussed further below). Watt and Swarbrick12 have attributed the high incidence of microbial keratitis associated with this procedure in East Asia—particularly in China and Taiwan—over the past decade, to poor levels of hygiene, the uninformed use of tap water, and unregulated lens supply in these counties.
Previous reports of contact lens prescribing demographics in an adult population have demonstrated a greater proportion of contact lens fits to females vs. males.13,14 The findings in this study of a sex imbalance in adult and teenager lens wearers in favor of females are consistent with those observations. This sex imbalance is likely attributed to a greater desire among females for the cosmetic advantages of contact lenses.
Although the sex imbalance observed in this study was significantly less pronounced for infants and children, there were still more fittings to females in these age groups. This latter finding is unexpected, because contact lens fitting to infants and children would be expected to be based solely on medical or refractive indications and unrelated to cosmetic considerations. The mean sex balance at all age groups in the 38 countries surveyed is close to unity,11 and we have been unable to find any evidence in the literature of a sex bias in refractive defects or ophthalmic abnormalities among infants and children that could account for the higher rate of contact lens fitting to females. This bias may in part emanate from gender-based societal or cultural mores of parents, who may be more inclined to superimpose their own beliefs of the cosmetic benefits of contact lenses on their daughters rather than their sons. Girls typically appear much more mature than boys at the same age, so eye care practitioners may be more likely to fit them at a younger age than boys, which could explain the higher prevalence of contact lens fitting among female children.
The high proportion of rigid lenses fitted to infants reflects the benefits of this lens type for the very young.15–17 Rigid lenses have the advantage over soft lenses of being easier to insert and remove in small eyes, and correcting aphakia,15 high myopia, and irregular astigmatism. Also, given the difficulties that are often encountered when conducting an accurate subjective refraction in infants, rigid lenses have the benefit of ensuring that any astigmatism will be corrected even if the subjective refraction yields inconclusive results. The low incidence of microbial keratitis with rigid lenses18 may be another motivation for fitting this lens type to infants.
Seventeen percent of all contact lenses fitted to children were rigid lenses. According to Jones-Jordan et al.,16 children adapt less well to rigid lenses than soft lenses,16 necessitating a careful evaluation of the advantages and disadvantages of prescribing rigid vs. soft lenses for children.
That 28% of all fits to minors were for orthokeratology attests to the popularity of this mode of correction for younger age groups around the world,19,20 notwithstanding concerns about increased levels of microbial keratitis associated with orthokeratology, as discussed above.12 The mean extent of myopic reduction with orthokeratology is about 2.00 diopter (D)13 [with correction up to 4.00 D possible20], making this form of contact lens correction especially suited to younger age groups in which refractive errors are lower during the early years of myopic development.21 The high proportion (47%) of rigid lens fits to children that were for orthokeratology, as noted in this study, is consistent with the finding of the survey of Chan et al.22 that the age range of orthokeratology fits to children in Hong Kong was 6 to 15 years. According to these authors, myopia control was the primary motivation for parents choosing orthokeratology for their children, despite inconclusive evidence of the efficacy of orthokeratology for this purpose.20
Visser et al.23 have reported that the primary indications for scleral lens fitting today are keratoconus (50%) followed by postpenetrating keratoplasty (20%), with lesser indications being irregular astigmatism, keratitis sicca, corneal dystrophy, and multiple diagnoses. In this survey, only 0.2% of minors and 0.2% of adults were fitted with scleral lenses, highlighting the highly specialized but vital role that such lenses have in the clinical management of rare ocular abnormalities in minors as well as adults.
High and/or irregular astigmatism is an important indication for optical correction in pediatric ophthalmic practice.24 The higher proportion of toric soft lenses prescribed to infants and children, compared with teenagers and adults, found in this survey suggests that correction of astigmatism constitutes a significant proportion of the indications for fitting contact lenses to these age groups. This statistic also reflects the imperative of providing a full optical correction to optimize vision during the critical early years of ocular development.
Tinted disposable contact lenses are not fitted to infants because this lens type is generally only prescribed for self-perceived cosmetic enhancement. The small amount of bifocal lens fitting to children may be attributed to (a) the potential—albeit controversial— for these designs to arrest the progression of myopia25,26 or (b) correction of accommodative esotropia or convergence excess.
Daily disposable lenses are available in limited spherical and toric power ranges compared with two weekly and monthly replacement lenses and custom-designed lenses.27 The low level of prescribing infants with daily disposable lenses, and lenses for part-time wear, probably relates to the need to provide a full sphero-cylindrical refraction, to be worn all the time, to this age category, for the reasons outlined above. That children are prescribed the highest proportion of daily disposable lenses—followed by teenagers and adults—is consistent with the view of Walline et al.28 that this replacement modality is especially suited to children and teenagers. This is because the simplicity of daily replacement systems, without the need for lens maintenance, is likely to enhance compliance. The higher rate of fitting infants with lenses that are replaced less frequently (i.e., 3 monthly, 6 monthly, annual, or unplanned replacement) is probably attributed to the need to prescribe custom design lenses for high ametropia and/or astigmatism, and possibly special designs for smaller eyes.29 These lenses are generally far more expensive than mass-manufactured disposable lenses, making regular lens replacement economically unfeasible.
Extended wear contact lenses are frequently prescribed for infants to ensure maximum effect of the refractive correction during all the waking hours, which of course may be irregular in the very young. As well, fitting infants with extended wear lenses offers more convenience for their adult carers,30 avoiding the requirement for constant lens insertion and removal and lens maintenance that would otherwise be required in the course of irregular sleep/wake cycles. The significantly higher rate of extended wear fitting in infants compared with the other three age groups reflects the above considerations. Our survey data indicate that the vast majority of extended wear lenses fitted to infants are made from silicone hydrogel materials. Presumably, this is because of the superior oxygen performance of this lens type,31 especially with higher prescriptions—which are often required by infants—and the consequent thicker lens profiles.
The high proportion of refits among infants is likely to relate to the difficulty in prescribing the optimal lens type and the consequent necessity of undertaking a number of fitting trials before the best lens type is found. Also, the rapid rate of refractive change and eye growth during the very early years may require constant lens refitting. Aside from infants, the increasing proportion of refits with increasing age is a consequence of both an increased probability of a lens being refitted the longer lenses have been worn and increasing myopia with age.
Notwithstanding expected differences between groups with respect to the extent of usage of lens care solutions (this being inversely proportional to the extent of daily disposable lens fits), the high percentage usage of multipurpose solution in all age groups reflects the general dominance and clinical versatility that this form of care system has in the contact lens field.
The findings of this survey provide valuable new information about current patterns of fitting contact lenses to minors. Contact lens prescribing to this age group is different in many aspects to that of adults, and the overall extent of prescribing for minors varies considerably among nations. Compared with other age groups, infants tend to be prescribed a higher proportion of rigid, soft toric and extended wear lenses, predominantly as refits for full-time wear, and less daily disposable lenses. Children are fitted with the highest proportion of daily disposable lenses and have the highest rate of fits for part-time wear. Teenagers have a similar lens fitting profile to adults, with the main distinguishing characteristic being a higher proportion of new fits. Orthokeratology is a popular form of optical correction for children. We anticipate a substantial increase in contact lens prescribing for minors as recently developed “anti-myopia” soft contact lenses begin to enter the market over the next few years.32 Clinicians can use the data presented here to compare their own patterns of contact lens prescribing to minors.
Members of the International Contact Lens Prescribing Survey Consortium:
Nathan Efron, Australia; Philip B. Morgan, United Kingdom; 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, Colombia; José Manuel González-Méijome, Portugal; Hans-Jürgen Grein, Germany; Christina N. Grupcheva, Bulgaria; Magne Helland, Norway; Hreinn Ingi Hreinsson, Iceland; John Hsiao, Taiwan; Lee Kai Hung, Singapore; Motozumi Itoi, Japan; Deborah Jones, Canada; Razmig Knajian, Middle East; 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.
School of Optometry
Queensland University of Technology
Kelvin Grove, Queensland 4059
The survey form used in Australia in 2009 is available as appendix on online at http://links.lww.com/OPX/A52.
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a Unregistered merchants are regrettably also involved in contact lens fitting in certain unregulated parts of the world, but this category of lens supplier was not surveyed in this work.