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Trends in US Contact Lens Prescribing 2002 to 2014

Efron, Nathan*; Nichols, Jason J.; Woods, Craig A.; Morgan, Philip B.

Optometry and Vision Science: July 2015 - Volume 92 - Issue 7 - p 758–767
doi: 10.1097/OPX.0000000000000623
Original Articles
Press Release

Purpose To document contact lens prescribing patterns in the United States between 2002 and 2014.

Methods A survey of contact lens prescribing trends was conducted each year between 2002 and 2014, inclusive. Randomly selected contact lens practitioners were asked to provide information relating to 10 consecutive contact lens fits between January and March each year.

Results Over the 13-year survey period, 1650 survey forms were received from US practitioners representing details of 7702 contact lens fits. The mean (±SD) age of lens wearers was 33.6 (±15.2) years, of whom 65.2% were female. Rigid lens new fits decreased from 13.0% in 2002 to 9.4% in 2014. Across this period, silicone hydrogels have replaced mid water contact lens hydrogels as the soft lens material of choice. Toric lenses represented about 25 to 30% of all soft lens fits. Multifocal soft lenses are generally preferred to monovision. Daily disposable lens fits have recently increased, and in 2014, they represented 27.1% of all soft lens fits. Most lenses are prescribed on 1 to 2 weekly or monthly lens replacement regimen. Extended wear remains a minority lens wearing modality. The vast majority of those wearing reusable lenses use multipurpose lens care solutions. Lenses are mostly worn 7 d/wk.

Conclusions This survey has revealed prescribing trends and preferences in the United States over the past 13 years.

*BScOptom, PhD, DSc, FAAO

OD, MPH, PhD, FAAO

BSc(Hons), PhD, FAAO

Institute of Health and Biomedical Innovation, and School of Optometry and Vision Science, Queensland University of Technology, Kelvin Grove, Australia (NE); Office of the Vice President for Research and Economic Development, The University of Alabama at Birmingham, Birmingham, Alabama (JJN); School of Medicine (Optometry), Deakin University, Waurn Ponds, Victoria, Australia (CAW); and Eurolens Research, The University of Manchester, Manchester, UK (PBM).

Nathan Efron Institute of Health and Biomedical Innovation Queensland University of Technology 60 Musk Ave Kelvin Grove, Queensland 4059 Australia e-mail: n.efron@qut.edu.au

The contact lens field is constantly evolving, with new lens and lens care products constantly becoming available. These changes are fueled by the development of new contact lens materials, lens designs, and solution formulations. In addition, advances and efficiencies in manufacturing technology have facilitated the opportunity for lenses to be replaced on a more regular basis. These changes inevitably impact the way in which contact lenses are prescribed. It is useful to track prescribing trends to allow practitioners to evaluate their own prescribing patterns against national (and international) trends and to serve as a guide to the contact lens industry as to which products, wearing modalities, and replacement frequencies are preferred by practitioners and lens wearers.

The United States is generally considered to be the largest single contact lens prescribing country in the world, comprising about 38.5 million lens wearers1; hence, the importance of monitoring contact lens prescribing trends in this country is especially important. It is somewhat surprising, therefore, that only two surveys have been published in peer-reviewed journals of contact lens prescribing in the United States, both of which were written more than 30 years ago. Morrison2 surveyed 1000 consecutive lens wearers in 1972 and Hewett3,4 surveyed 497 soft lens wearers and 335 rigid lens wearers in 1984. Other more limited surveys have been conducted on specific types of contact lenses, such as disposable extended-wear5 and gas permeable toric6 lenses.

The early studies by Morrison2 and Hewett3,4 provide useful historical markers against which current trends can be compared. However, given that it is now more than 30 years since the last general survey of US contact lens prescribing was published, and in view of the substantial developments that have occurred in the contact lens period since then, a prospective survey of contemporary contact lens prescribing is warranted.

The survey has been conducted annually in the United States since 2002. This has yielded a substantial data set that we shall use to explore prescribing trends over the past 13 years (2002 to 2014, inclusive). We shall attempt to explain the various trends observed.

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METHODS

General Conduct of Annual Survey

Between January and March each year from 2002 to 2014, a survey was undertaken using the following procedure. A random selection of 1000 US-based practitioners who subscribe to the magazine Contact Lens Spectrum were sent a questionnaire by mail, with a request that this be completed within 3 months of receipt of the questionnaire. Although there is no clear evidence for seasonal variation in the types of contact lenses prescribed, the survey was conducted at the same time of year to minimize any possible seasonal effects. Those surveyed were almost exclusively optometrists, although a small number of optical dispensers and ophthalmologists may have also completed and returned survey forms.

We used the same format questionnaire each year, although minor changes were made from time to time as new modalities of lens wear or lens care were introduced. This questionnaire (which we have published in this journal previously7) was a one-sided form; practitioners were requested to enter a number of background details, to supply generic information about the first 10 contact lens fits performed after receipt of the questionnaire, and then to return it to us upon completion. Practitioners were asked to return the form irrespective of the number of patients seen (if fewer than 10).

We ask practitioners completing the form to indicate whether each instance of fitting was a new fit or refit. A new fit is defined as the prescribing and supply of lenses to someone with no previous lens wearing experience or who has not worn lenses for a number of years. A refit is defined as the prescribing and supply of lenses to someone who is an existing wearer who is being fitted because the wearing pattern has changed, another lens type is being tried, a lens is being fitted as a problem solver, and so on. Throughout this article, it should be assumed that we are referring to all fits combined unless we specifically refer to new fits or refits.

The questionnaire captured information about the person who completed the form and data about lenses and care systems as detailed in Table 1. The returned forms were logged and data from each form were manually entered into an Excel spreadsheet (Microsoft Corporation, Redmond, WA) to facilitate data analysis.

TABLE 1

TABLE 1

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Statistical Analysis

Differences among practitioners in relation to the amount of contact lens fitting undertaken were accounted for by giving an appropriate weighting to each recorded contact lens fit. This was achieved by estimating the annualized volume of contact lens fits performed each year by each respondent (based on the date information provided on the questionnaire) and determining a weighting factor. For example, the data generated by a practitioner fitting all 10 fits in 1 week was given twice the weighting of a colleague who fitted 10 patients in 2 weeks as the latter practitioner fits half the volume of lenses over time.

Graphs were generated using summary pivot tables and graph-plotting functions in Microsoft Excel. Changes in fitting practices over time were assessed by generating nominal regression models for categorical data and linear regression models for continuous data, using JMP 11.0 (SAS Institute Inc, Cary, NC).

The statistical confidence of our data is best expressed as the 95% confidence limits around each data point relating to the proportion of contact lens fits. These limits will depend on the overall number of fits reported, which varied from year to year, and the number of reported fits in each category of interest. In our analysis, the main difference in confidence limits is that between soft and rigid lenses, with the greater number of the former lens type providing narrower confidence limits. Using Wilson’s method, we estimate that the 95% confidence limits around data reported for subtypes of soft and rigid lenses per year were about ±4 and ±13%, respectively. When subtypes were grouped across the duration of the study, yielding much larger data sets, these values reduced to ±1 and ±4%, respectively. These confidence limits are not shown in the graphs within this article for clarity of presentation.

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RESULTS

Over the 13-year survey period, 1650 survey forms were returned by practitioners, generating data relating to a total of 7702 contact lens fits.

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Demographics and Patient Base

Averaged over all years of the survey, the patients fitted had a mean (±SD) age of 33.6 (±15.2) years, with a range of 5 to 101 years. Male subjects had a mean (±SD) age of 31.5 (±14.7) years (range, 5 to 90 years) and female subjects had a mean (±SD) age of 34.6 (±15.4) years (range, 5 to 101 years). Fig. 1 shows a histogram of the proportion of lens fits according to age of all reported patients. This distribution appears to be bimodal, peaking at the 16- to 20-year and 46- to 50-year age groups. The average age of patients over the course of this survey is shown in Fig. 2. For new fits, there was an increase in age at fitting over time, from 27.6 years in 2002 to 31.8 years in 2014 (F = 7.4, p = 0.007). Similarly, age for refit cases increased with time from 33.8 years in 2002 to 38.5 years in 2014 (F = 28.2, p = 0.0001). Overall, 65.2% of patients fitted were female.

FIGURE 1

FIGURE 1

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Soft versus Rigid Lenses

The number of rigid lens fits as a proportion of all lens fits decreased over time, from 13.0% in 2002 to 9.4% in 2014 (χ 2 = 52.6, p = 0.0001). The proportion of rigid lenses prescribed as new fits has oscillated considerably and there is no statistically significant trend over time (χ 2 = 2.5, p = 0.48) (Fig. 3). A related approach to comparing the prescribing of rigid versus soft lenses is portrayed in Fig. 4. This graph shows the proportion of rigid and soft lenses that are prescribed as new fits. The proportion of soft lenses prescribed as new fits has fallen gradually from about 30% in 2002 to close to 20% in 2014 (χ 2 = 31.0, p = 0.0001).

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Lens Materials

High water content hydrogel materials (>60% water) and low water content hydrogel materials (<40% water) each represented about 8% of all soft lens fits throughout the entire survey period, with low water content lenses declining to less than 4% for 2012 to 2014 (Fig. 5). The prescribing of lenses manufactured from silicone hydrogel materials, which were introduced into the United States in 2001—1 year before this survey commenced—has steadily increased to a peak of 73% of all soft lens fits in 2010 (χ 2 = 1405, p = 0.0001) and has remained approximately at this level up until 2014. The opposite trend was observed for mid water content lenses (40 to 60% water), with the prescribing of these lenses diminishing over time (χ 2 = 1201, p = 0.0001). Mid water lenses represented about 65% of all soft lenses prescribed between 2002 and 2004, before diminishing substantially to 17% in 2007, and remaining relatively constant since then.

Throughout the survey period, rigid lenses fabricated from low (<40), mid (40 to 90), and high (>90) oxygen permeability (Dk) materials represented 18.9, 49.2, and 22.8%, respectively, of rigid lens fits; in addition, polymethyl methacrylate (PMMA) and scleral lenses were used for 1.5 and 7.7% of rigid lens fits, respectively.

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Lens Designs

Toric lens designs represented about 25 to 30% of all soft lens fits over the survey period (Fig. 6). Cosmetic tinted soft lenses, which were prescribed in 5.4% of soft lens fits in 2002, have declined in use (χ 2 = 71.7, p = 0.0001) and between 2006 and 2014 accounted for about 1% or fewer of soft lens fits each year.

During the survey period, multifocal soft lenses were prescribed more frequently (12.3% of soft lens fits) than monovision corrections (5.0% of soft lens fits). On average, throughout the survey period, the proportion of rigid lens fits prescribed according to lens design was as follows: toric, 11.4%; multifocal, 17.4%; monovision, 7.6%; and orthokeratology, 4.5%, with the balance being spherical lens designs.

Antimyopia lenses, which are designed to arrest the progression of myopia, have been prescribed in very small numbers since 2011, when we started surveying the prescribing of this lens type.

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Lens Replacement Frequencies

Daily disposable soft lenses were introduced into the United States in the mid-1990s. By the time this survey commenced in 2002, this category represented 5.3% of all soft lenses prescribed. This level of prescribing has risen steadily since then (χ 2 = 314, p = 0.0001), reaching 27.1% of all soft lens fits in 2014 (Fig. 7).

In 2002, 1 to 2 weekly and monthly replacement lenses represented 43.9 and 39.8% of all soft lenses prescribed. Overall, prescribing of these modalities has declined slightly over the survey period (χ 2 = 36.3, p = 0.0001), with small changes in prescribing of one of these replacement frequency categories being offset by commensurate opposite changes in the other. Soft contact lenses replaced less often than monthly, and nonplanned replacement, were virtually nonexistent throughout the survey period.

Of all rigid lenses fitted, 40.0% were prescribed on a regular replacement basis (i.e., at least every 12 months).

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Lens Wearing Modalities

The proportion of soft lenses prescribed for extended wear has declined across the period of the survey (χ 2 = 17.1, p = 0.0002) (Fig. 8). On average, only 4.6% of rigid lenses were fitted on an extended-wear basis during the survey period.

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Frequency of Wear

Fig. 9 shows the distribution of the number of days per week that daily, 1 to 2 weekly, and monthly replacement soft lenses and rigid lenses were worn. It can be seen that the vast majority of lenses are prescribed for wearing 7 d/wk. Rigid lenses represented the greatest proportion of fits prescribed for wearing 7 d/wk (91.5%), with daily disposable lenses the least (67.0%). Where lenses were worn on a part-time basis (≤4 d/wk), daily disposable lenses were prescribed more frequently.

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Lens Care Systems

Fig. 10 shows the proportion of lens care systems used throughout the survey period. Multipurpose solutions constitute the vast majority of lens care systems prescribed but their use has fallen overall with time from about 93% of all lens care systems prescribed between 2002 and 2005 to 82.8% in 2014 (χ 2 = 314, p = 0.0001). Commensurate with this observation is the relatively low level of use of one-step hydrogen peroxide solutions, which essentially constitute the balance of care systems in use. It can be seen from Fig. 10 that there has been a general increase in prescribing of peroxide systems over time (χ 2 = 91.2, p = 0.0001). Two-step peroxide systems and other forms of lens care (such as chlorine, heat, ultraviolet, or ultrasound systems) are now essentially redundant.

FIGURE 10

FIGURE 10

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FIGURE 9

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DISCUSSION

Demographics and Patient Base

The mean (±SD) age of patients surveyed between 2002 and 2014 in our study (33.6 [±15.2] years) is commensurate with that of patients prescribed lenses in six other mature contact lens countries over a similar period8; however, it is greater than that reported by Hewett for either regular lens wearers (23.4 years) or occasional and former lens wearers (25.6 years). This may be due in part to the greater maturity of US contact lens practice currently and a greater time having elapsed since the wide-scale availability of soft contact lenses in the in 1970s, meaning that patients attending for refitting are likely to have worn lenses longer and also be older. This difference may also be attributed to the higher proportion of patients fitted with presbyopic corrections in recent years; indeed, the peak in fits for the 46- to 50-year group in the age distribution (Fig. 1) is consistent with this observation. The increase in average age of patients receiving new fits and refits over the 13-year survey period further supports the notion of increased presbyopic fits.

Our finding that 65.2% of contact lens wearers were female is lower than the 1972 survey of PMMA lens wearers by Morrison2 (69% female) and the 1982 survey of rigid and soft lens wearers by Hewett3,4 (76%). The apparent shift toward more male subjects wearing contact lenses may be an indication of changing perceptions of the importance of contact lenses as a valuable ophthalmic aid rather than just an ophthalmic tool for cosmetic enhancement. Our finding is also consistent with international trends, which indicate that 66% of lens wearers are female.8 As alluded to above, the higher rate of usage of contact lenses by female subjects may be related to between-sex differences in the attitudes toward cosmesis generally.9

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Soft versus Rigid Lenses

The results of the present survey reveal that, between 2002 and 2014, rigid lens fitting dropped 13.0 to 9.4% of all contact lenses prescribed. This downward trend in rigid lens prescribing is consistent with that observed in other countries.10

The ongoing decline in rigid lens fitting can be explained by a number of factors. This issue has been discussed previously in some detail by Efron,11 who cites the following 10 reasons: initial rigid lens discomfort, intractable rigid lens–induced corneal pathology (3- and 9-o’clock staining) and lid pathology (ptosis), extensive soft lens advertising, superior soft lens fitting logistics, lack of rigid lens training opportunities, decreased reliance on rigid lenses for solving problems that can now be corrected with soft lenses, improved soft toric and bifocal/varifocal lenses, limited uptake of orthokeratology, lack of investment in rigid lenses, and the emergence of aberration control soft lenses obviating the optical neutralization role of rigid lenses.

The increase in the proportion of rigid lenses prescribed as new lens fits since 2010 may be attributed to the renewed interest in orthokeratology and semiscleral lenses in recent times, with practitioners trying new designs (hence new fits) as they become available.

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Lens Materials

The vast majority of hydrogel lenses available in the United States are made from mid water content materials,12 which accounts for the relatively high rate of prescribing of this lens material category compared with lenses made from high or low water content materials. The reduced rate of prescribing of low water content hydrogel contact lenses can also be attributed to adverse physiological responses13 induced by such lenses because of their low oxygen transmissibility.14

The virtually equal but opposite trends observed in relation to the increased prescribing of lenses made from silicone hydrogels and decreased prescribing of lenses fabricated from mid water hydrogels is most likely attributed to practitioners supplanting hydrogel materials with the newer, more oxygen permeable silicone hydrogel alternatives.

The decline in the use of low-Dk rigid lenses materials probably reflects a desire by practitioners to optimize ocular physiology with rigid lenses of increased oxygen performance. The increased levels of corneal oxygenation afforded by lenses made from materials of high oxygen transmissibility15 are also better suited for overnight orthokeratology.

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Lens Designs

Based on the distribution of astigmatism in prospective contact lens wearers, Holden16 determined that if all astigmatism of at least 0.50 diopters (D), 0.75 D, or 1.00 D were corrected, then 62, 45, or 35% of soft lens wearers, respectively, would need toric lenses. In the United States, toric lenses represented between 25 and 30% of all soft lens fits over the survey period. Thus, the prescribing of toric soft lenses is still falling somewhat short of satisfying even the most liberal of the theoretical prescribing targets outlined above of 35% or more of all soft lenses being of toric form.16

The decline in the prescribing of tinted lenses is likely to be attributed to two factors. First, practitioners may be wary of fitting tinted lenses in view of reports of misuse of this lens genre.17 Second, silicone hydrogel lenses—which have been prescribed more extensively over the past decade (see above)—were not available in tinted form throughout the survey period,12 having been introduced into the United States very recently.

The general preference for prescribing soft multifocal lenses versus monovision correction may relate in part to the introduction over the past decade of innovative and effective multifocal designs fabricated from both hydrogel and silicone hydrogel materials12 and the increasing confidence that practitioners have in such products.

Soft lenses designed specifically for arresting the progression of myopia18 had not been available in the United States up until the time of completing this survey. Although bifocal soft lens designs can be used for myopia control, few practitioners have opted for this approach to date, perhaps reflecting a cautious approach in the absence of a large body of longitudinal clinical data validating this modality.

A relatively high proportion of rigid lenses are multifocals (17%), indicating the apparent clinical success of these designs for presbyopes. This may also reflect the prescribing of multifocals to long-term rigid lens wearers who are entering the presbyopic age group. A small number of orthokeratology fits have been reported, suggesting an ongoing but relatively low interest in this form of rigid lens prescribing.

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Lens Replacement Frequencies

The benefits of daily disposable lenses, namely, increased convenience, eliminating the need for care systems, and improved ocular health,19 have fueled the increasing use of this lens type. Furthermore, the contact lens industry has responded to this demand by introducing more daily disposable lens products, including toric, multifocal, and tinted lenses.12 The shifting balance of 1 to 2 weekly versus monthly disposable lenses appears to be related to the varying success of different manufacturers, who tend to position all of their reusable soft lens products according to a preferred replacement frequency. The greater cost of 1 to 2 weekly versus monthly lenses may also be contributing to the observed trends.

Because rigid lenses are durable and cannot be mass-produced like soft lenses, it is not necessary or viable to replace them more frequently than every 6 months. Despite clinical evidence20,21 of the benefits of rigid lens replacement every 6 to 12 months, most rigid lenses were prescribed on an unplanned replacement basis during the survey period.

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Lens Wearing Modalities

The reason for the apparent decline in extended-wear fitting in the mid-2000s is unclear. This failure to maintain a “steady-state” level of prescribing may be attributed to periodic episodes of adverse publicity in the lay press and worrying epidemiological and clinical reports in the professional literature22,23 relating to serious corneal infections with this lens type.

Despite comparable clinical performance of high oxygen transmissibility rigid lenses and soft (silicone hydrogel) lenses for extended wear,24,25 these US survey results reveal that rigid lenses have seldom been prescribed for extended wear.

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Frequency of Wear

The finding of this survey that 91.5% of rigid lenses were primarily used for wearing 7 d/wk may be attributed to three factors: (1) the physiological necessity to wear these lenses in this manner to avoid inconveniences relating to the requirement of having to readapt to rigid lenses if not worn full time; (2) avoidance of visual problems relating to “spectacle blur,” which can occur when using lenses intermittently (although this is less of a problem with modern high oxygen transmissibility rigid lenses); and (3) the requirement of patients with conditions such as keratoconus, lens dystrophies, and posttrauma and postgraft cases to wear lenses constantly to maintain adequate visual acuity.

A study from Japan26 reported that 78% of patients wearing daily disposable soft lenses used their lenses every day, which is broadly consistent with the finding of 64% reported here for the United States. Reusable soft lenses were worn for 7 d/wk by 90% of patients in Japan26 versus about 83% in the United States. Despite this apparent agreement, Morgan et al.8 surveyed contact lens prescribing trends in seven nations between 2000 and 2009 and found that the proportion of part-time wearers (defined as wearing lenses 1 to 4 d/wk) varied from 1% in the Netherlands to 22% for Japan. This observation supports the notion that there are likely to be national/cultural differences in contact lens prescribing habits; however, the precise mechanisms by which such differences can affect contact lens prescribing are unclear.

Efron et al.27 have introduced the concept of “cost-per-wear,” which defines the ongoing cost to a patient who uses contact lenses according to varying wearing schedules. These authors evaluated the cost-per-wear of daily disposable and monthly replacement soft contact lenses in a commercial setting. Their analysis revealed that for part-time wearers, daily disposable soft lenses have lower cost-per-wear than monthly replacement soft lenses, whereas for full-time wearers, monthly replacement soft lenses are a less expensive option. This analysis illustrates the importance of considering the number of days a patient anticipates wearing their lenses per week when giving advice with respect to the most cost-effective contact lens option.

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Lens Care Systems

The simplicity, convenience, low cost, safety, and efficacy of modern-generation multipurpose lens care solutions28 probably explain the high frequency of use of this form of contact lens maintenance in the United States throughout the past 12 years. The risk of developing toxic epitheliopathy through inappropriate use of hydrogen peroxide systems (especially two-step solutions),28 the polymer-degrading effects of heat disinfection,28 and the low efficacy of chlorine and various nonchemical disinfecting systems (ultraviolet, ultrasound, and agitation)28 have resulted in the disuse of such systems.

One-step hydrogen peroxide systems are still prescribed to a small extent; these products have the advantages of good disinfection efficacy and ocular compatibility.29 The increase in usage of hydrogen peroxide disinfection between 2006 and 2009 may relate to a series of product recalls at this time relating to the increased incidence of microbial keratitis with certain multipurpose solution products30 and the desire of patients and practitioners to opt for the perceived increased safety of one-step hydrogen peroxide disinfecting systems in particular. It appears from Fig. 10 that the damaging impact of multipurpose solution product recalls in the mid-2000s has sustained until the present time.

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Study Limitations

Because this survey was sent to subscribers of a journal related specifically to contact lens practice (Contact Lens Spectrum), respondents could be assumed to be those with a particular interest in contact lenses, and thus the findings of the survey may not fully represent the prescribing habits of the broad spectrum of eye care practitioners in the United States, many of whom may only have a passing interest in, and fit very few, contact lenses. We did not run validation studies to determine the level of compliance, accuracy, and diligence of those completing and returning survey forms. The extent to which returns are truly representative of the geographical and demographic distribution of practitioners and lens wearers throughout the United States is unknown.

Notwithstanding the potential limitations as outlined above, our findings are broadly in line with industry estimates and retrospective surveys of practitioner opinions relating to contact lens prescribing in the United States.1

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CONCLUSIONS

In this article, we have described contact lens prescribing trends over the past 13 years in the United States. In general, changes in these prescribing patterns can be characterized as follows: a significant majority of female patients being fitted with contact lenses; the decline in prescribing of rigid lenses and the low rate of prescribing high and low water content hydrogel lenses; an increase in silicone hydrogel lens fitting; the high (but still suboptimal) use of toric soft lenses for correcting astigmatism; the preference of multifocal soft lenses versus monovision for the correction of presbyopia; the growth of daily disposable lens use, especially in recent years; the fluctuating interest in extended-wear fitting; and the extensive use of multipurpose soft lens care systems. Contact lens prescribing in the future is likely to be more skewed toward daily disposable lenses and silicone hydrogel materials.

Nathan Efron

Institute of Health and Biomedical Innovation

Queensland University of Technology

60 Musk Ave

Kelvin Grove, Queensland 4059

Australia

e-mail: n.efron@qut.edu.au

Received February 11, 2015; accepted March 25, 2015.

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Keywords:

contact lens; prescribing trends; US; survey; rigid lens; soft lens; contact lens solutions; wearing modalities

© 2015 American Academy of Optometry