Children require contact lenses for a variety of reasons. They may require contact lens wear because of aphakia,1-8 ocular trauma,9,10 amblyopia therapy,10-12 or refractive error. Contact lenses for aphakia, trauma, and amblyopia therapy may be medically necessary, but contact lenses for refractive error are generally elective; so eye care practitioners, parents, and children must decide together whether a child should be fitted for contact lens wear.
Many children require vision correction at an early age because myopic refractive error typically develops at about 8 years of age.13,14 There is less consensus about the timing of a correction of moderate hyperopic or astigmatic refractive errors, and these errors may not be identified until children begin to perform concentrated near work activities, typically around the age of 6 or 7 years. Contact lenses may therefore be used to correct refractive error beginning early in life.
Anecdotally, many eye care practitioners fit teens with contact lenses, but they will not fit children with contact lenses until they are at least 12 to 13 years old. It has been proven that children as young as 8 years are capable of wearing soft,15-19 gas permeable,16,20-24 and corneal reshaping contact lenses,25-27 but a comparison of fitting children and fitting teens with contact lenses has never been performed.
The reasons that eye care practitioners do not routinely fit children younger than 12 or 13 years old may vary. They may perceive that younger children will take longer to fit with contact lenses and therefore cost the practice valuable chair time; that younger children will experience greater adverse effects; that younger children will not benefit from contact lens wear as much as teenagers; or that younger children may not be mature enough to be responsible for contact lens care.
Several studies have shown that children as young as 8 years old are mature enough to care for their contact lenses independent of parental intervention, and that children experience few adverse side effects of contact lens wear.16,17,26,28 However, no investigations of chair time associated with contact lens fitting have been conducted for children.
The purpose of this investigation was to compare the chair time associated with soft contact lens fittings (fitting, insertion and removal training, and three follow-up visits) and the ocular side effects of contact lens wear between 8- to 12-year-old children and 13- to 17-year-old teens.
METHODS
This research was approved by the Institutional Review Boards at each clinical site (Ohio State University College of Optometry, New England College of Optometry, and University of Houston College of Optometry), in accordance with the Declaration of Helsinki. Following explanation of the nature and possible consequences of the study, a legal guardian provided informed consent, and the children provided informed assent. Each clinical center recruited a similar number of children and teens to the study. To ensure that all examiners used similar procedures, a Manual of Procedures explained specifically how to conduct all measures, and examiners met before study initiation to discuss procedures. The examiners were certified via written tests on how to perform visual acuity, autorefraction, biomicroscopy, contact lens fitting, and insertion and removal training.
All subjects were between the ages of 8 and 17 years and required vision correction to see optimally. Their ocular health was not contraindicated for contact lens wear, they had 20/25 or better best-corrected visual acuity in each eye, and no previous contact lens wear experience. All spherical refractive errors were between +5.00 D and -9.00 D, and astigmatism was less than -2.25 D, measured by noncycloplegic subjective refraction.
At the baseline visit, all subjects underwent retinoscopy; a manifest refraction; autorefraction and autokeratometry; high-contrast, best-corrected, distance logMAR visual acuity according to a standardized protocol; biomicroscopic examination; contact lens fitting; and lens insertion and removal training. At this visit, parents provided demographic information about their children, and both the parent and subject completed surveys about spectacle wear. If the children were not able to insert and remove their contact lenses during the baseline visit, they attended additional visits until they could perform the task adequately. Insertion and removal training consisted of talking about contact lens care as well as inserting and removing a contact lens three times.
Subjects returned for follow-up visits at 1 week, 1 month, and 3 months after the last contact lens insertion and removal training visit to perform high-contrast distance logMAR visual acuity with contact lenses, undergo contact lens fit assessment and biomicroscopic evaluation, and to complete surveys. If a dilated fundus examination had not been performed within the previous 12 months, one was performed at a follow-up visit.
Visual acuity was performed while the child stood 4 m from a high-contrast logMAR visual acuity chart illuminated between 75 and 120 cd/m2. The subject wore the results of the refraction in a trial frame at baseline, and his or her habitual contact lenses at all follow-up visits. Beginning at the 20/50 line, subjects read the first letter of every line until one letter was missed. They then read all five letters in the line two lines above the letter they missed. If one letter was missed, the subject read all five letters on the line above and this continued until all five letters were read correctly. The subject then continued to read all five letters on every line down the chart until three or more letters were missed on a given line, and the number of letters read correctly was recorded.
Noncycloplegic autorefraction was performed using the Grand Seiko WR-5100K (Grand Seiko Co., Hiroshima, Japan) while the child viewed 20/50 letters that were presented beyond the subject's far point on a Badal track. Ten readings were recorded and averaged according to the methods proposed by Thibos.29 Autokeratometry readings were recorded from the autorefraction printout.
A biomicroscopic examination was performed and recorded on all subjects. Corneal staining, conjunctival staining, bulbar redness, and limbal redness were graded from 0 to 4 according to CCLRU photographic standards.30 Infiltrates were graded as present or absent. Microcysts were counted and given a grade as follows: 1 = <10, 2 = 11 to 24, 3 = 25 to 49, and 4 = 50 or more. Neovascularization was recorded as the maximum distance from the limbus that any vessel protruded into each cornea. Upper and lower tarsal abnormalities were graded 1 to 4 as follows: 1 = slight injection without texture, 2 = mild papillae/follicles <1 mm in diameter, 3 = significant papillae/follicles <1 mm in diameter and/or marked injection, 4 = localized or generalized papillae/follicles greater than or equal to1 mm in diameter with or without marked injection. Corneal edema was categorized as; 1 = barely discernible localized corneal cloudiness; 2 = faint but definite localized or generalized corneal cloudiness; 3 = significant localized or generalized corneal cloudiness; or 4 = definite widespread corneal cloudiness.
Subjects were fitted with either ACUVUE ADVANCE with HYDRACLEAR or ACUVUE ADVANCE for Astigmatism soft contact lenses (Johnson & Johnson Vision Care, Jacksonville, FL). All subjects with <0.75 D of astigmatism were fitted with ACUVUE ADVANCE with HYDRACLEAR. The 8.3 base curve was placed on the right eye, and the 8.7 base curve was placed on the left eye when fitting spherical contact lenses and the base curve of the lens with the best fit was ordered for both eyes. If both contact lenses provided similar fits, then the flattest base curve was dispensed for both eyes. If only one spherical lens was fitted, then the 8.3 base curve was attempted first if the flattest corneal curvature was >45.00 D. If visual acuity was not correctable to 20/20 because of uncorrected astigmatism or the subject had 1.00 D or more astigmatism, the subject was fitted with ACUVUE ADVANCE for Astigmatism contact lenses. All contact lenses had to settle for 15 min before assessing the fit. If ACUVUE ADVANCE contact lenses did not fit properly, examiners were allowed to fit any brand they thought was necessary. The subjects were all dispensed OPTI-FREE RepleniSH with TearGlyde (Alcon, Ft. Worth, TX) multipurpose disinfecting solution, but they were given AQuify Multi-Purpose Solution (CIBA Vision, Duluth, GA) if they developed symptoms that were attributed to an allergy to the original solution.
Movement and centration of the contact lenses were assessed either 15 min after the fitting or during routine biomicroscopy examination when the subject reported for follow-up visits. Movement of the lens was clinically assessed in 0.25-mm increments up to 1 mm in primary gaze and up gaze. Centration of the lens was recorded as covers the cornea, covers the cornea but decenters to limbus, or incomplete corneal coverage. Toric contact lenses rotation was assessed fifteen minutes after insertion at the baseline visit and at every follow-up visit, by lining the orientation of the slit lamp beam with the marking on the lens and recording the direction (nasal or temporal) and magnitude in degrees.
To determine whether practitioners may predict patients who are more likely to be successful contact lens wearers, examiners were asked to assess how easy they think the subject will be to fit and teach insertion and removal before beginning the examination (based on initial impressions only). They were to mark one of four choices: extremely easy, easy, difficult, extremely difficult.
The procedures conducted for standardized protocols of fitting, insertion and removal training, and follow-up visits are included in Table 1. The time of each procedure was measured with a stopwatch. If the insertion and removal training required more than one visit, the time for each subsequent visit was added to get a total time for the insertion and removal training. The total time was the sum of all of the timed sessions. All times were rounded to the nearest half minute.
Serious adverse events were characterized as any unexpected event that occurred during the study and resulted in a loss of two or more lines of best-corrected visual acuity. A nonserious adverse event was considered as anything that led to discontinuation of contact lens wear for a period of time but completely resolved.
The subjects received free contact lenses, solutions, and eye care throughout the 3-month study. Each subject also received a $10 gift card at each follow-up visit, and a $50 gift card or savings bond at the final visit.
Basic descriptive statistics were calculated using mean ± standard deviation (SD) for continuous variables and frequency tables for categorical variables. Differences were tested with a t-test analysis for the continuous variables and the χ2 or Fisher's exact test for the categorical variables. To assess which variables were associated with amount of time required to fit children and teenagers with contact lenses, univariate regression models were fit using potential covariates. Final multiple regression models were built using significant variables from the univariate models first, and testing the remaining variables once again.
RESULTS
We screened 176 children to enroll 169 subjects in the CLIP Study between February 14, 2006 and July 12, 2006 at three clinical centers. The reasons for exclusion were excessive cylinder (n = 3), emmetropia (n = 3), and sphere out of the allowable range (n = 1). Subjects were grouped according to their age at the baseline examination: children included 8 to 12 year olds, and teens included 13 to 17 year olds. Seven subjects were fitted with contact lenses other than ACUVUE ADVANCE with HYDRACLEAR or ACUVUE ADVANCE for Astigmatism because of poor fit (n = 6) or poor comfort (n = 1) with the original lens. Of the 338 eyes, 58 (17.2%) were initially fitted with ACUVUE ADVANCE for astigmatism; 13 (22.4%) of the eyes that required toric contact lenses were children's eyes. Twelve subjects did not complete the study, but there was not a significant difference in the proportion of children (8%) or teens (6%) who were not captured at the last study visit. Data from the subjects who wore different lenses and from subjects who did not report for the last visit were included in the analyses.
The groups were similar with respect to gender, ethnicity, and parent and sibling spectacle wear (Table 2). On average, the children reported receiving their glasses at an age of about 8 months younger than the teens. Fewer than half of the subjects were white and approximately one-fourth of each group was Hispanic. The two groups had similar average refractive errors, with more than 2.00 D myopia and very little astigmatism, and their corneal curvatures were similar (Table 3). Although the teens had statistically better binocular visual acuity, the mean difference was not clinically relevant.
There were no differences in the proportion of children and teens exhibiting the biomicroscopy signs in Table 4 or the contact lens fitting characteristics in Table 5, so all biomicroscopy and contact lens fitting results will be described for the entire sample. At baseline, 3% of the subjects showed any grade of corneal staining, and this did not differ significantly across time (χ2, p = 0.03). Approximately 7% of subjects showed any grade of conjunctival staining at baseline. The proportion of conjunctival staining differed throughout the study (χ2, p = 0.0006) and was significantly greater at all follow-up visits than baseline.
Bulbar and limbal conjunctival injection were rare at baseline and did not differ significantly over the study period (χ2, p = 0.40 and 0.14, respectively). Upper and lower tarsal abnormalities were prevalent in this group of subjects, but did not differ significantly over 3 months (χ2, p = 0.40 and 0.76, respectively). Little corneal edema or neovascularization were noted over the course of the study and did not differ significantly throughout the study (Fisher's exact test, p = 0.56 and 0.34, respectively). No microcysts or infiltrates were noted throughout the study.
Contact lens fitting characteristics are shown in Table 5. In primary gaze, the vast majority of subjects exhibited <0.5 mm movement of the contact lenses throughout the study. Most subjects also exhibited complete corneal coverage with the contact lenses. On average, the initial contact lens power was very close to the power predicted from the spherical equivalent from the manifest refraction, and <10% of the subjects exhibited an over-refraction of more than ±0.50 D at the baseline visit. After the baseline visit, fewer than 5% of the subjects exhibited an over-refraction of more than ±0.50 D. When they were fitted with a toric lens at the baseline visit, approximately half of them showed no rotation. The rest of the subjects were split between nasal and temporal rotation. Typically, the rotation of the toric contact lens was between 5 and 10 degrees.
Table 6 shows the mean (±standard deviation) time needed to fit subjects, teach insertion and removal, and conduct follow-up examinations. The fitting and all follow-up visit times were similar for children and teens. The only statistically significant differences between children and teens were the insertion and removal training times and the overall times. The total time was approximately 15 min greater for children than teens, and the primary reason for this difference was the extra 10 minutes it took children to learn insertion and removal of contact lenses. There were 16 extra visits required for 15 subjects (seven children and eight teens). On average, the extra time required at the extra visits was 56.7 ± 37.9 min for children and 22.5 ± 17.4 min for teens (Student's t-test, p < 0.0001).
To determine factors that may lead to or may predict the total time required for a young contact lens patient, we used univariate regression models. Factors considered were gender, age (both continuous and by group), spherical refractive error component, examiner assessment of how easy a subject would be to fit before the fitting, number of years of spectacle wear, whether a parent wore contact lenses, and whether a sibling wore contact lenses. There were not enough toric lens wearers to determine whether fitting a toric lens correlated with increased total time. In the univariate analyses, age (both continuous and dichotomous) and ease of fitting assessment by the eye care practitioner were statistically significant, but none of the others were. In a multivariate model, these factors remained statistically significant. Age treated continuously with ease of fit yielded a slightly higher r2 value than child versus teenager. Based on the final model, adjusted for age, the least square mean for the examiners' assessment of extremely easy to fit subjects was 84.3 min, for easy to fit subjects it was 98.4 min, for difficult to fit subjects it was 109.8 min, and for subjects assessed as extremely difficult to fit the least squares mean was 170.0 min.
DISCUSSION
Although several studies have proven that children are capable of wearing a variety of contact lens modalities,16-19,23-27 parents who enroll their children in pediatric contact lens studies often report that their eye care practitioner would not fit a child younger than 12 or 13 years with contact lenses. Eye care practitioners who fit teens often refuse to fit children with contact lenses even though there are no investigations reported in the literature that indicate that children benefit less from contact lens wear than teens or that they require more chair time.
If children require much more chair time than teens, experience more adverse effects than teens, do not adapt to contact lens wear as easily as teens, or do not benefit from contact lens wear as much as teens, then doctors may be justified in waiting to fit patients until they are older than 12 years.
In the current study, the total chair time required for contact lens management was estimated to be on average 15 min greater for children than teens. However, the greatest difference in time occurred during the insertion and removal training. Many eye care practitioners have staff members teaching contact lens insertion and removal to patients. Under these circumstances, the extra time required for fitting the child would not likely decrease the potential productivity of the doctor because optometric instruments are not required for teaching insertion and removal of contact lenses and because the doctor is available to examine other patients while a child is learning to insert and remove contact lenses.
The absolute time reported for each activity in this paper should not be translated into chair time in a practice because a standardized protocol was followed in this study that requires more time than would be necessary in practice. For example, children underwent a standardized visual acuity assessment with the right eye, left eye, and both eyes that was in addition to Snellen visual acuity checks. Furthermore, all contact lenses settled on the eye for 15 min before assessment, and this is rarely done in practice. The times that are reported in this investigation are useful for comparing times between children and teens, but they may overestimate the actual time required to fit a typical young person with contact lenses in practice.
Anatomically and physiologically, children's and teens' eyes are very similar. We would not expect any group differences in how eyes respond to contact lens wear unless they were associated with differences in how the groups care for their contact lenses. No serious adverse events were reported during the 3-month study, and there were no obvious differences between the biomicroscopic findings for children and teens. Five nonserious adverse events were reported during the study: three cases of viral keratitis (two teens and one child) and two cases of suspected contact lens overwear (one teen and one child). All cases resolved completely and the subjects were able to resume contact lens wear. Overall, both groups seemed to adequately care for their contact lenses, but the potential for noncompliance may be further reduced by teaching parents how to properly care for the contact lenses and encouraging parental support.
Biomicroscopic signs, such as corneal and conjunctival staining, increased from baseline to the 1-week and 1-month visits. The prevalence typically decreased to or below baseline prevalence by the 3-month visit. This indicates that there is an adaptation period for contact lens wear, and initial corneal changes should not signify a need to change contact lens material, solutions, or modality.
The fact that age as a continuous variable was more predictive of total chair time than categorizing age as child vs. teen shows that people may tend to gradually improve dexterity or become less afraid of touching the eye with age rather than experiencing a sudden shift in attitude or ability in adolescence. The regression analyses also showed that eye care practitioners were able to determine whether it would take longer to work with a particular subject based on their initial impression of the subject, therefore eye care practitioners may use their judgment to help determine whether or not a child should be fitted with contact lenses. Anecdotally, doctors in the study said that they assessed the motivation, anxiety, maturity, hygiene, and aperture size of the child as well as parental enthusiasm to determine whether or not a child may be easy to fit with contact lenses.
During the 3-month study, few differences between children and teens were observed in terms of required chair time or adverse effects of contact lens wear. However, the children and teens were participating in a study and received free eye care and materials, which may result in improved compliance for both groups. When comparing the results of the two groups though, we can conclude that eye care practitioners should not use specific criteria based on age alone to determine whether or not a young person can be fitted with contact lenses because children and teens physiologically adjust to contact lens wear similarly and both are capable of providing adequate care for contact lenses. Thus, eye care practitioners should consider fitting children younger than 12 or 13 years with contact lenses.
ACKNOWLEDGEMENTS
Supported by the Vision Care Instituteâ„¢, LLC
CLIP Study Group: Ohio State University College of Optometry, Columbus, OH: Jeffrey J. Walline, OD, PhD (Principal Investigator); Monica Chitkara, OD (Study Optometrist); David A. Berntsen OD, MS (Study Optometrist); Stacy Long, BS (Study Coordinator).
University of Houston College of Optometry, Houston, TX: Ruth Manny, OD, PhD (Principal Investigator); Amber Gaume, OD (Co-Investigator and Study Optometrist); S. Ailene Kim OD (Study Optometrist); Giselle M. Garza, BS (Study Coordinator).
New England College of Optometry, Boston, MA: Marjorie J. Rah, OD, PhD (Principal Investigator); Ronald K. Watanabe, OD (Study Optometrist); Nicole B. Quinn, OD (Study Optometrist); Jason R. Chin, OD (Study Optometrist); Kimberley W. Chan, OD (Study Optometrist); Paulette Tattersall, Dip Pharm, MSc (Study Coordinator).
Optometry Coordinating Center, Columbus, OH: Lisa A. Jones, PhD (Director); Loraine T. Sinnott, PhD (Senior Statistician); Linda Barrett (Data Entry Technician).
Jeffrey J. Walline
The Ohio State University
College of Optometry
338 West Tenth Avenue
Columbus, OH 43210-1240
e-mail: walline.1@osu.edu
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