Abstract
purpose. To study retrospectively the frequency of myopia progression and risk factors for progression in a sample of adult contact lens wearers.
methods. From a database of 815 soft contact lens wearers, patients were identified whose age was between 20 and 40 years, who had at least −0.50 D spherical equivalent of myopia in both eyes, three or more refractions, and ≥5 years of follow-up. Only data from the right eye were used. Progression was defined as an increase of at least −1.00 D over 5 years. Subjects were also asked to complete a questionnaire regarding their ocular history, demographics, family history, and the amount of time spent performing different tasks at home and at work.
results. Two hundred ninety-one subjects met the eligibility criteria with a mean baseline refractive error of −3.29 ± 1.92 D and a mean age of 28.5 ± 5.0 years. Of these, 21.3% progressed by at least −1.00 D over the 5-year period. The 5-year rate of progression decreased with increasing age (χ2 = 12.44, P = 0.006). One hundred ninety-seven subjects (67.6%) completed and returned questionnaires. “Progressors” (N = 41) did not differ from “nonprogressors” (N = 156) in terms of hours per day spent reading and writing, computer use, education level, family history of myopia, age of onset of myopia, and contact lens wear.
conclusions. In this database of soft contact lens wearers, myopia progression was common for subjects in their twenties and less common for those in their thirties.
The majority of myopia develops during the school years and stabilizes in the teenage years.
1 Nonetheless, a number of individuals show myopic changes after entering college. This may manifest as an increase in myopia in a previously myopic subject (adult myopia progression) or as the onset of myopia in a previously emmetropic or hyperopic individual (adult onset myopia). The National Research Council Committee on Vision Working Group on Myopia Prevalence and Progression reviewed more than 500 articles on myopia, the majority of which were published since 1950.
2 They concluded that “myopia can start or progress after [age] 16, although it is less severe and limited to a smaller proportion of individuals.” They also noted that myopic shifts are apparently small enough to go undetected in cross-sectional, population-based studies. On the basis of the studies reviewed, the report concluded that up to 40% of low hyperopes and emmetropes entering college and military academies are likely to become myopic by the age of 25. Conversely, in populations where college graduates are excluded, <10% of hyperopic or emmetropic individuals become myopic before the onset of presbyopia. Eye care practitioners are now describing adult myopia progression in 30- to 40-year-old patients, anecdotally associated with professional or graduate school and/or increasing computer use.
We retrospectively studied a group of adults between 20 and 40 years of age using a contact lens research clinic database to determine the proportion of subjects that undergo significant myopia progression and the risk factors associated with myopia progression.
A retrospective study was conducted using a database of 815 soft contact lens wearers from a contact lens industry research clinic (CIBA Vision, Duluth, GA). Patients attended this research clinic for routine contact lens care and involvement in new clinical studies, primarily studies evaluating different soft contact lenses and contact lens care systems. To remain in the clinic database, patients had to receive a full eye examination at least once every 2 years from an optometrist or ophthalmologist and had to provide the clinic with a copy of their spectacle prescription. Most likely, this examination did not include a cycloplegic refraction. Presumably, the patients’ motivation for remaining in the database was to receive free contact lenses and solutions rather than because their myopia was increasing and their visual acuity was decreasing. The database included patient information from between 1977 and 1996. Patient age ranged from 10 to 70 years, with up to 17 years of follow-up. Information on strabismus and visual acuity was not available. The tenets of the Declaration of Helsinki were followed, and informed consent was obtained from subjects.
Patients were identified whose ages were between 20 and 40 years and who had at least −0.50 D spherical equivalent of myopia in both eyes at baseline, three or more refraction visits, and ≥5 years of follow-up. Patients were not excluded on the basis of high myopia, anisometropia, or astigmatism. Myopia progression was defined as an increase in myopia of at least −1.00 D spherical equivalent over a 5-year period, although we also present progression data for a criterion of −0.75 D spherical equivalent. Progression was defined by the first visit when a given criterion was reached. The proportion of subjects that progressed over a 5-year period was then calculated. Only data from the right eye were included.
Subjects who met the above entry criteria were mailed a questionnaire asking about their ocular history, demographics, family history of myopia, and the amount of time spent performing different near vision tasks at work and at home. Because the subjects’ refractive data were retrospective, subjects were asked the following question: “Over the past 10 years, how much of your time (in hours per day) during work has been spent doing each of the following activities: driving, reading and writing, in meetings, using a computer/VDT?” Subjects were asked a similarly worded question regarding their home activities. Subjects were not required to provide any refractive data. Completed questionnaires were returned in an enclosed business reply envelope. They received $10 reimbursement for returning a completed questionnaire.
Subjects were categorized as progressors or nonprogressors on the basis of the previously described −1.00 D criterion for myopia progression, and data were compared between the two groups. Descriptive statistics (means, standard deviations, medians) were generated. Univariate and multivariate analyses, controlling for covariates, were performed using logistic regression and odds ratios with 95% confidence intervals (CI) reported.
One hundred ninety-seven subjects (67.6%) completed and returned the questionnaires. Of the remaining 94 subjects, 29 questionnaires were returned as undeliverable. If these subjects are excluded, the response rate increases to 75.1%. The mean refractive error (−3.30 ± 1.85 D), mean age (28.7 ± 4.9 years), and frequency of progression (20.8%) for the responders were not significantly different from those for the nonresponders (−3.26 ± 2.05 D, 28.1 ± 5.0 years, and 22.3%). Of the 197 subjects who completed questionnaires, 41 were categorized as progressors (at least −1.00 D over the 5-year period) and 156 as nonprogressors.
Questionnaire results are summarized in
Tables 2 and 3 . The sample is predominantly female, white, and well educated. Subjects began wearing spectacles at a mean age of 14.3 ± 5.9 years and contact lenses at a mean age of 21.8 ± 6.4 years. More than 80% had at least one parent or sibling who was myopic. Ninety percent were currently wearing soft contact lenses.
The only statistically significant difference between the two groups was that progressors began wearing spectacles at an older age than nonprogressors (16.5 ± 6.3 years vs. 13.7 ± 5.6 years, odds ratio by univariate logistic regression = 1.08, 95% CI = 1.02 to 1.14,
P = 0.009). The groups did not differ in terms of the age that they began wearing contact lenses (progressors mean, 22.1 ± 5.9 years and non progressors mean, 21.7 ± 6.5 years) or their current lens wear schedule
(Table 2) .
The odds ratios presented in
Table 3 are controlled for age at baseline and age at which subjects began wearing spectacles. Progressors did not differ from nonprogressors in terms of hours per day spent reading and writing, computer use, education level, or current mode of refractive correction. Given that multiple comparisons are presented, it is appropriate to use more conservative alpha values by applying the Bonferroni correction
(Table 3) . Adopting different criteria for myopia progression, e.g., −0.75 D, did not substantially alter the study findings presented in
Tables 2 and 3 , nor did restricting the age range to <35 years. Controlling for other potential confounding variables, i.e., gender, age, education, race, and age when contact lens wear began, also did not alter the findings.
Our data demonstrate that significant myopia progression (at least −1.00 D over 5 years) occurred in roughly 20% of this population of young myopic adults wearing soft contact lenses, although caution should be exercised in generalizing the results from our database to populations with different occupations or modes of refractive correction. Progression was more common in subjects in their twenties but still occurred in >10% of adults in their thirties. Using different criteria for progression revealed that ∼36% of subjects progressed by at least −0.75 D. These estimates may be unstable because refractions were performed by a large number of clinicians, and it is not known what proportion of refractions was performed under cycloplegia. In spite of these potential sources of variability, only one subject regressed by at least +1.00 D compared with 62 who progressed by at least −1.00 D.
There have been a number of recent reports of myopia progression in adulthood, and a selection are summarized in
Table 4 .
3 4 5 6 7 8 9 10 It is difficult to make direct comparisons between our results and the studies listed in
Table 4 because of the different periods of follow-up, methodology, populations studied, and the various criteria for progression. Nonetheless, some comment is appropriate. McBrien and Adams
9 reported that 108 of 223 myopic eyes (48.4%) in their sample of microscopists (mean age, 29.7 years) progressed by at least −0.37 D over 2 years. Studies of students and military recruits in their twenties suggest that between 26% and 47% of myopes progress by at least −0.50 D over a period of up to 3 years.
3 4 6 Data on older subjects are scarce, but Ellingsen et al.
8 found a mean shift of −0.39 D per decade in myopes in their thirties and Waring et al.
7 reported a mean myopic shift of −0.65 D across 10 years in the fellow eye of 47 Prospective Evaluation of Radial Keratotomy (PERK) Study patients who had elected not to undergo radial keratotomy on their second eye. Our results provide further evidence that myopia progression is common in adults.
We found that the frequency of myopia progression was similar in subjects with at least −3.00 D of myopia at baseline (16.9%) and those with less than −3.00 D (23.7%). Previous studies are contradictory on this issue. In a retrospective study of military recruits, O’Neal and Connon
4 found that myopes over −3.00 D progressed at a faster rate than lower myopes, but they do not give the upper range of myopia in their sample. More recently, Ellingsen et al.
8 reported that subjects with less than −1.00 D of myopia progress at a faster rate during adulthood than those with between −1.00 and −6.00 D of myopia, in a retrospective practice-based study.
Our sample is different from those used in previous studies. Although we studied a clinic-based sample, the patients’ likely motivation for remaining in this clinic database was most probably to receive free contact lenses and solutions. Presumably, their frequency of attendance was not motivated by changes in their refractive error, their visual acuity, or both. In contrast, Zadnik and Mutti
3 and Ellingsen et al.
8 retrospectively studied practice records, raising the possibility of higher rates of progression because patients whose myopia is progressing may be more likely to return more often for eye care.
Unlike some previous reports of adult myopia progression, our study was conducted on subjects from a broad range of occupations rather than a single professional group, e.g., optometry students,
6 military recruits,
4 or microscopists.
5 9 Nonetheless, our sample was somewhat homogenous in a number of other ways. As a group, subjects were well educated
(Table 2) and, on average, spent most of their workday engaged in near work activities
(Table 3) . Ninety percent were also soft contact lens wearers. There are some reports that myopia progression is more common in soft contact lens wearers than spectacle lens wearers. A recent randomized clinical trial of adolescent subjects, however, suggests that the effect is small, at least in teenagers.
11 An alternative hypothesis is that progressing myopes may need to wear their contact lenses more, and hence any association between contact lens wear and myopia may not be a cause-effect relationship.
Few of the recent studies listed in
Table 4 evaluated near work as a potential risk factor. Adams and McBrien
5 found no association between the number of hours per week spent performing microscopy and myopia progression, although 60% of myopic microscopists who progressed during their 2-year study reported no change in refractive error before entering the profession.
9 Kinge et al.
12 reported a significant association between myopic changes and time spent reading scientific literature, on practical near work, and at lectures in a 3-year longitudinal study of 192 engineering students. No relationship was found between refractive change and time spent on the computer or watching television.
The only factor associated with myopia progression in our sample was the age at which the subject began wearing spectacles. On average, progressors were nearly 3 years older than nonprogressors when they began wearing spectacles. This suggests that myopia that develops at a younger age, stabilizes sooner.
We were unable to find an association between adult myopia progression and near work, but the limitations of our assessment of near work activities makes the findings difficult to interpret. This was a retrospective study, and subjects were asked to estimate the average number of hours per day spent doing various activities over the past 10 years. This period may not coincide with the period during which refractive error data were available, and the subjects’ ability to recall their activities may be suspect. Subjects’ work and home activities were unlikely to have been consistent over such a lengthy period. Furthermore, the validity and reliability of our questionnaire were not evaluated before its use. Much of the literature on near work and myopia relies on similar methodology
5 10 or surrogate measures such as occupation, education, or intelligence.
2 We have recently begun a prospective study of risk factors associated with myopia progression using novel methodology for the assessment of daily activities.
12
The high proportion of subjects showing myopia progression as adults has ramifications for refractive surgery. The long-term patient satisfaction with refractive procedures, such as LASIK, and their cost-effectiveness may be adversely affected by myopic changes subsequent to the procedure.
In summary, myopia progression is common in this adult sample, but we failed to find any association of myopia progression with near work, education, family history, or mode of refractive correction. Progressors began wearing spectacles at an older age than nonprogressors. Prospective investigations are warranted to overcome the limitations of this retrospective study.
Supported by Grants R03-EY11798 and R21-EY12273 from the National Eye Institute, National Institutes of Health, Bethesda, Maryland.
Submitted for publication June 17, 1999; revised February 19, 2002; accepted March 11, 2002.
Commercial relationships policy: N.
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked “
advertisement” in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Corresponding author: Mark A. Bullimore, The Ohio State University, College of Optometry, 338 West 10th Avenue, Columbus, OH 43210-1240;
[email protected].
Table 1. The Rate of Myopia Progression in Different Age Groups (at Baseline) and the Sample as a Whole
Table 1. The Rate of Myopia Progression in Different Age Groups (at Baseline) and the Sample as a Whole
Baseline Age (y) | Frequency of Progression of At Least −0.75 D (%) | Frequency of Progression of At Least −1.00 D (%) |
20–25 | 48.2 (40/83) | 34.9 (29/83) |
25–30 | 35.3 (36/102) | 19.6 (20/102) |
30–35 | 27.3 (18/66) | 13.6 (9/66) |
35–40 | 25.0 (10/40) | 10.0 (4/40) |
Total | 35.7 (104/291) | 21.3 (62/291) |
Table 2. Summary of Subjects’ Responses to Questionnaire
Table 2. Summary of Subjects’ Responses to Questionnaire
Variables | Total (N = 197)* | Nonprogressors (N = 156) | Progressors (N = 41) | Odds Ratio | 95% CI | P value |
Gender | | | | 1.02 | 0.48–2.18 | 0.96, † |
Female | 140 (71.1) | 111 (71.1) | 29 (70.7) | | | |
Male | 57 (28.9) | 45 (28.9) | 12 (29.3) | | | |
Ethnicity | | | | — | | 0.09, ‡ |
African-American | 28 (14.4) | 22 (14.2) | 6 (15.0) | | | |
Caucasian | 154 (79.0) | 125 (80.7) | 29 (72.5) | | | |
Other | 13 (6.6) | 8 (5.2) | 5 (12.5) | | | |
Education | | | | | | 0.24, † |
<High school | 2 (1.0) | 2 (1.3) | 0 (0) | | | |
High school | 31 (15.7) | 23 (14.7) | 8 (19.5) | 1.00 | | |
Some college | 60 (30.5) | 53 (34.0) | 7 (17.1) | 0.40 | 0.13–1.22 | |
College degree | 61 (31.0) | 46 (29.5) | 15 (36.6) | 0.91 | 0.34–2.48 | |
Some graduate Education | 43 (21.8) | 32 (20.5) | 11 (26.8) | 1.03 | 0.36–2.96 | |
Type of contact lenses | | | | — | | 0.47, ‡ |
RGP | 7 (3.6) | 7 (4.5) | 0 (0) | | | |
Soft | 178 (90.4) | 139 (89.1) | 39 (95.1) | | | |
Not wearing | 12 (6.1) | 10 (6.4) | 2 (4.9) | | | |
Family history | | | | | | |
Mother myopic | 74 (37.6) | 54 (34.6) | 20 (48.8) | 1.80 | 0.90–3.61 | 0.01, † |
Father myopic | 58 (29.4) | 43 (27.6) | 15 (36.6) | 1.52 | 0.73–3.13 | 0.26, † |
Siblings myopic | 137 (69.5) | 110 (70.5) | 27 (65.9) | 0.81 | 0.39–1.68 | 0.56, † |
Any family members myopic | 167 (84.8) | 132 (84.6) | 35 (85.4) | 1.06 | 0.40–2.79 | 0.90, † |
Table 3. Summary of Subjects’ Responses to Questionnaire
Table 3. Summary of Subjects’ Responses to Questionnaire
Variable | Total (N = 197)* | Nonprogressors (N = 156) | Progressors (N = 41) | Odds Ratio | 95% CI | P value |
Time spent (hours per day) during work: | | | | | | |
Driving | 1.58 ± 1.44 | 1.65 ± 1.51 | 1.30 ± 1.05 | 0.85 | 0.60–1.20 | 0.36, † |
Reading and writing | 3.45 ± 2.27 | 3.46 ± 2.36 | 3.42 ± 1.95 | 0.97 | 0.82–1.15 | 0.72, † |
Meetings | 1.41 ± 1.05 | 1.40 ± 1.01 | 1.46 ± 1.20 | 1.09 | 0.74–1.59 | 0.66, † |
Computer/VDT | 3.79 ± 2.40 | 3.84 ± 2.47 | 3.59 ± 2.15 | 0.94 | 0.80–1.11 | 0.49, † |
Time spent (hours per day) outside of work: | | | | | | |
Driving | 1.78 ± 1.23 | 1.81 ± 1.30 | 1.68 ± 0.90 | 0.89 | 0.60–1.32 | 0.57, ‡ |
Sports | 1.16 ± 1.28 | 1.21 ± 1.37 | 0.98 ± 0.81 | 0.92 | 0.63–1.36 | 0.68, ‡ |
Reading | 1.91 ± 1.20 | 1.91 ± 1.15 | 1.89 ± 1.37 | 1.04 | 0.75–1.43 | 0.84, ‡ |
Computer | 1.16 ± 1.38 | 1.17 ± 1.35 | 1.13 ± 1.51 | 0.92 | 0.67–1.27 | 0.62, ‡ |
TV | 2.37 ± 1.39 | 2.47 ± 1.48 | 1.99 ± 0.95 | 0.72 | 0.52–0.99 | 0.04, ‡ |
Video games | 0.22 ± 0.62 | 0.26 ± 0.68 | 0.06 ± 0.22 | 0.25 | 0.04–1.51 | 0.13, ‡ |
Crafts | 1.18 ± 1.34 | 1.25 ± 1.42 | 0.88 ± 0.95 | 0.75 | 0.48–1.20 | 0.23, ‡ |
Table 4. Recent Studies of Adult Myopia Progression
Table 4. Recent Studies of Adult Myopia Progression
Study | Sample | Age (y) | Design | Key Finding | Limitations |
Zadnik and Mutti 3 | 87 law students | Early 20s | Retrospective, variable follow-up | 47% progressed by at least−0.50 D | Clinic-based sample, with presentation bias |
O’Neal and Connon 4 | 497 military recruits | 17 to 21 at entry mean = 18.5 | Retrospective, 2.5 years | 37% progressed by at least−0.50 D (55% of myopes) | Limited age range, limited follow-up, males only |
Adams and McBrien 5 | 251 microscopists | 21 to 63 at time of studymean = 29.7 | Retrospective, variable time | 49% reported adult progression | Self-reported data, poorly defined progression |
Grosvenor and Scott 6 | 79 students | 18 to 34 at entry mean = 21.5 | Prospective, 3 years | 26% progressed by at least−0.50 D (27% of myopes) | 33% loss to follow-up |
Waring et al. 7 | 47 radial keratotomy patients | 21 to 58 at entry mean = 33.5 | Prospective, 10 years | Mean myopic shift =−0.65 D | Potential bias in group who declined 2nd eye surgery |
Ellingsen et al. 8 | 413 practice patients | Grouped by decade | Retrospective, 10 years | Subjects increased by−0.39 D during their 30s | Retrospective, potential bias |
McBrien and Adams 9 | 166 microscopists | 21 to 63 at entry mean = 29.3 | Prospective, 2 years | 48% progressed by at least−0.37 D | Only one professional group |
Kinge et al. 10 | 192 students | 20.6 at entry | Prospective, 3 years | Mean myopic shift =−0.51 D | Limited age range, only one professional group |
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