Clinical study of orthokeratology in young myopic adolescents

A protocol for a single center, randomized, controlled trial assessing the effects of spectacles or orthokeratology on dry eye parameters in children and adolescents

Background

The prevalence of myopia among adolescents is increasing precipitously in China, and the popularity of orthokeratology (OK) lenses as an effective treatment for controlling myopia progression is rising. This protocol assessed and compared the clinical dry eye parameters in children and adolescents with myopia treated with spectacles or OK lenses.

Methods and analysis

This single-masked randomized control trial will include 300 participants (aged 8-17 years) with myopia treated with OK lens (study group) or spectacles (control group). We will record the ocular surface disease index, visual analog scale score, noninvasive tear breakup time, tear meniscus height, meibomian gland score, ocular redness score, visual acuity, tear Matrix Metalloproteinase-9 concentration, tear Lymphotoxin alpha levels at baseline, and after 1-, 3-, 6-, and 12-month.

Discussion

This study will be a standardized, scientific, clinical trial designed to evaluate the dry eye parameters in children and adolescents with myopia treated with OK lenses for myopia control.

Ethics and dissemination

This study has been approved by the Ethics Committee of He Eye Specialist Hospital [ethics approval number: IRB(2023)K024.01]. Before participating in the trial, written informed consent will be obtained from all patient's parents or guardians. The findings of this study will be showcased at both local and international conferences and will also be submitted for publication in reputable peer-reviewed journals.

Trial registration number

Clinicaltrials.gov: NCT06023108 {2a, 2b}.

Characteristics of the Ocular Surface in Myopic Child Candidates of Orthokeratology Lens Wear

INTRODUCTION

The purpose of this study was to investigate the characteristics of objective ocular surface parameters using non-invasive objective instruments in children with myopia who are candidates for orthokeratology lens wear.

METHODS

Children with myopia who are candidates for orthokeratology lens wear were retrospectively investigated. The subjects were divided into three age groups. The Keratograph 5M and LipiView interferometry were used to assess non-invasive tear meniscus height (TMH), non-invasive tear film break-up time (NIBUT), conjunctival hyperemia redness score (RS), meibomian gland loss (MGL) score, lipid layer thickness (LLT), and blink pattern analysis, including the number of partial blinks (PB) and total blinks (TB), as well as the partial blink rate (PBR).

RESULTS

A total of 1119 children with myopia (2070 eyes) aged 7-18 years were selected. The mean TMH, NIBUT, and LLT of the subjects was 0.21 mm, 12.45 s, and 65.28 nm, respectively. The mean RS and upper and lower MGL scores were 0.64, 1.00, and 1.06, respectively. The mean PB, TB, and PBR was 5.13, 6.46, and 0.81, respectively. Age was significantly correlated to all ocular surface parameters (p = 0.00), except for PB. NIBUT and LLT did not differ between male participants and female participants (all p > 0.05). TMH, RS, and upper and lower MGL were significantly higher in male participants than in female participants (all p < 0.01). In addition, NIBUT was positively associated with TMH (r = 0.13, p = 0.00) and LLT (r = 0.28, p = 0.00). Both upper and lower MGL were positively correlated with TMH, PB, and TB (all p = 0.00), whereas upper MGL was negatively correlated with NIBUT and LLT (all p < 0.05). TB was negatively correlated with NIBUT and LLT (all p = 0.00). PB had no relation with TMH, NIBUT, and LLT (all p > 0.05). In addition, PBR was positively correlated with NIBUT and LLT (all p = 0.00) but not with TMH, RS, or MGL (all p > 0.05). Overall, 57.00% had a TMH ≤ 0.2 mm, 43.20% had a NIBUT ≤ 10 s, 48.10% had an LLT ≤ 60 nm, and 88.10% had a PBR > 0.4.

CONCLUSIONS

Child orthokeratology candidates have enhanced tear secretion and increased meibomian gland deficiency with aging. In addition, the adult dry eye diagnostic criteria may apply to orthokeratology candidates aged 12-18 years but should be lower for younger candidates. Given the proportion of abnormal risk, it is necessary to assess tear film status and blink pattern by reliable and feasible objective examination before fitting orthokeratology.

Short-term application of diquafosol ophthalmic solution benefits children with dry eye wearing orthokeratology lens

Purpose

This aim of this study was to evaluate the effect of 3% Diquafosol Ophthalmic Solution (DQS) on children with dry eye from wearing overnight orthokeratology (OrthoK) lenses.

Methods

Myopic children aged 8-18 years with dry eye syndrome were enrolled in this prospective observational study, and they were grouped according to their OrthoK treatment history for at least 1 year. All participants received DQS 4 times per day for 1 month. The following indicators were measured at baseline 1 month after treatment: the Dry Eye Questionnaire-5 (DEQ-5), non-invasive tear meniscus height (TMH), non-invasive tear film break-up time (first and average, NIBUT-F and NIBUT-A), meibomian gland score (MG score), conjunctival hyperemia redness score (R-scan), and blink pattern analysis.

Results

A total of 104 participants (189 eyes) including 40 OrthoK wearers (72 eyes) and 64 Orthok candidates (117 eyes) completed the study. Of all, after DQS treatment for 1 month, DEQ-5 scores reduced from 5.54 ± 3.25 to 3.85 ± 2.98 (t = -3.36, p = 0.00). TMH increased from 0.20 ± 0.05 mm to 0.21 ± 0.05 mm (t = 2.59, p = 0.01), NIBUT-F and NIBUT-A were prolonged from 6.67 ± 4.71 s to 10.32 ± 6.19 s and from 8.86 ± 5.25 s to 13.30 ± 6.03 s (all p = 0.00), respectively. R-scan decreased from 0.69 ± 0.28 to 0.50 ± 0.25 (t = -9.01, p = 0.00). Upper MG scores decreased from 1.04 ± 0.32 to 0.97 ± 0.36 (t = -2.14, p = 0.03). Lower MG scores, partial blink rate, partial blinks, and total blinks did not change significantly. Both break-up time (BUT) and R-scan improved significantly after DQS treatment for 1 month (all p = 0.00) in OrthoK candidates and OrthoK wearers. Among the OrthoK wearers, TMH and dry eye symptoms increased significantly (all p = 0.00) but did not increase in OrthoK candidates (p > 0.05). There were no adverse events related to DQS.

Conclusion

Diquafosol Ophthalmic Solution was effective for children wearing overnight orthokeratology in relieving dry eye symptoms and improving ocular surface parameters, which may help improve children's OrthoK wearing tolerance and compliance.

Evaluation of the meibomian glands using the tear interferometer wearing orthokeratology lenses

Background

To investigate the impact of orthokeratology wear on meibomian glands in Korean pediatric population using the tear interferometer.

Methods

Fifty-three orthokeratology wearers and 79 non-lens wearers were evaluated using the LipiView® II ocular surface interferometer which shows incomplete blink rate, average lipid layer thickness, and meiboscores.

Results

No significant differences in the incomplete blink rate and meiboscores for upper eyelids, but the lipid layer thickness and meiboscores for lower eyelids were significantly higher in the Ortho-K group than in the control group (p = 0.024 and 0.007, respectively). Correlation analysis showed no significant correlation between the duration of orthokeratology wear and the parameters measured by LipiView® (p > 0.05 for all). Among subgroups based on average duration of lens wear, the longer duration (≥ 24 months) subgroup showed higher meiboscores of lower eyelids (p = 0.011), but no other significant differences.

Conclusions

Ortho-K wearers showed no significant differences in the incomplete blink rate and meiboscores of upper eyelids, but they were associated with increased LLT and higher meiboscores of lower eyelids. Thorough examination and close monitoring of orthokeratology wearers is necessary. Prospective and observational studies are needed to further elucidate the relationship between Orthokeratology and meibomian glands.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02365-3.

Efficacy in myopia control

There is rapidly expanding interest in interventions to slow myopia progression in children and teenagers, with the intent of reducing risk of myopia-associated complications later in life. Despite many publications dedicated to the topic, little attention has been devoted to understanding 'efficacy' in myopia control and its application. Treatment effect has been expressed in multiple ways, making comparison between therapies and prognosis for an individual patient difficult. Available efficacy data are generally limited to two to three years making long-term treatment effect uncertain. From an evidence-based perspective, efficacy projection should be conservative and not extend beyond that which has been empirically established. Using this principle, review of the literature, data from our own clinical studies, assessment of demonstrated myopia control treatments and allowance for the limitations and context of available data, we arrive at the following important interpretations: (i) axial elongation is the preferred endpoint for assessing myopic progression; (ii) there is insufficient evidence to suggest that faster progressors, or younger myopes, derive greater benefit from treatment; (iii) the initial rate of reduction of axial elongation by myopia control treatments is not sustained; (iv) consequently, using percentage reduction in progression as an index to describe treatment effect can be very misleading and (v) cumulative absolute reduction in axial elongation (CARE) emerges as a preferred efficacy metric; (vi) maximum CARE that has been measured for existing myopia control treatments is 0.44 mm (which equates to about 1 D); (vii) there is no apparent superior method of treatment, although commonly prescribed therapies such as 0.01% atropine and progressive addition spectacles lenses have not consistently provided clinically important effects; (viii) while different treatments have shown divergent efficacy in the first year, they have shown only small differences after this; (ix) rebound should be assumed until proven otherwise; (x) an illusion of inflated efficacy is created by measurement error in refraction, sample bias in only treating 'measured' fast progressors and regression to the mean; (xi) decision to treat should be based on age of onset (or refraction at a given age), not past progression; (xii) the decreased risk of complications later in life provided by even modest reductions in progression suggest treatment is advised for all young myopes and, because of limitations of available interventions, should be aggressive.

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

OBJECTIVE

To present the study design and the baseline data of a prospective cohort study investigating the safety, refractive correction and effectiveness of myopia control in subjects fitted with orthokeratology (ortho-k) lenses of different compression factors.

METHODS AND ANALYSIS

This study is a 2-year longitudinal, double-masked, partially randomised study. Myopic children aged between 6 and 10 years are recruited and they may choose to participate in either the ortho-k or spectacle-wearing group. Subjects in the ortho-k group are randomly assigned to wear ortho-k lenses of either conventional compression factor (CCF, 0.75 D) or increased compression factor (ICF, 1.75 D). For the ortho-k subjects, the time and between-group effects within the first month of lens wear were analysed.

RESULTS

Sixty-nine ortho-k subjects (CCF: 34; ICF: 35) and 30 control subjects were recruited. There were no significant differences in baseline demographic data among the three groups of subjects (p>0.19). At the 1-month visit, the first fit success rates were 97% and 100% in the CCF and ICF ortho-k group, respectively. A higher percentage of ICF subjects could achieve full correction (CCF: 88.2%; ICF: 94.3%). The change in axial length was significantly higher in the ICF group (CCF, 0.003 mm; ICF, -0.031 mm) (p<0.05). No significant between-group differences in daytime vision or in the coverage and depth of corneal staining between the two ortho-k groups (p>0.05) were observed at any visit.

CONCLUSION

ICF did not compromise the corneal integrity and the lens centration within the first month of lens wear. The preliminary performance of ortho-k lenses with ICF of 1.00D shows that it was safe to be used in the longer term for the investigation of myopia control.

TRIAL REGISTRATION NUMBER

NCT02643342.

Reducing treatment zone diameter in orthokeratology and its effect on peripheral ocular refraction

PURPOSE

To determine whether orthokeratology (OK) induced treatment zone (TZ) diameter can be reduced by altering OK lens design, and if so the impact of modifying TZ diameter on relative peripheral refraction (RPR).

METHODS

16 subjects (mean age 23.4 ± 1.5 years; 8 female) completed the study. Standard (Control) OK lens design (PJ, Capricornia, Australia) or a modified version (Test) where the back optic zone diameter was reduced, and back optic zone asphericity and intermediate lens curves were altered, were worn overnight only for 7-nights in a randomised double masked order, with a minimum 1-week wash out (no lens wear) between lens designs. Full correction of refractive error was targeted. Refraction; best corrected visual acuity (BCVA); RPR (Shin-Nippon NVision-k 5001) along the horizontal and vertical meridians; and corneal topography (Medmont E300) were measured before starting lens wear and in the morning after lens removal after the seventh night of lens wear for both lens designs. TZ diameter and decentration was calculated from corneal topography.

RESULTS

After 7-nights of wear both lens designs created -2.00D refraction effect with no significant difference in refractive effect or change to BCVA between the designs. The Test design created a significantly smaller horizontal (4.78 ± 0.37 vs 5.70 ± 0.37 mm, p < 0.001) and vertical (5.09 ± 0.51 vs 5.92 ± 0.51 mm p < 0.001) TZ diameter. The TZ was decentered inferior temporal with no significant difference between designs. There was no significant difference between the lens designs in RPR along the horizontal and vertical meridians at any measurement period.

CONCLUSIONS

OK induced TZ diameter can be reliably reduced by altering OK lens design without detrimentally effecting lens centration or refractive effect. Reducing TZ diameter did not alter RPR, though measurement artifacts could be responsible for masking an effect. Longitudinal studies are needed to assess whether smaller TZ OK lens designs increase efficacy for slowing progression of myopia.

Efficacy of Trial Fitting and Software Fitting for Orthokeratology Lens: One-Year Follow-Up Study

OBJECTIVE

To observe and compare the clinical efficacy of 1-year trial fitting and software fitting orthokeratology lenses.

METHODS

One hundred myopes who received vision correction with the use of orthokeratology lenses form July 2016 to September 2017 were included in this study. Subjects were assigned randomly into the two groups: the trial fitting group (group A) and the software fitting group (group B). For the right eye of each subject, measurements, such as uncorrected visual acuity (UCVA, logarithm of minimal angle of resolution), refractive error, corneal topography, ocular health status, and the fitting situation, were obtained at baseline, 1 week, 1 month, 3 months, 6 months, and 12 months after lens wear. Axial length and corneal endothelium cells (CECs) were also measured at baseline and 12 months after wearing the lens.

RESULTS

Compared with the baseline, the spherical equivalent refraction, UCVA, and central corneal curvature changed significantly after orthokeratology (OK) lens wear (all P<0.05). Between groups A and B, the parameters aforementioned were insignificant at each time point (all P>0.05). Axial length and CECs showed no significant changes during the first year of OK treatment (all P>0.05). Rate of corneal staining between two groups revealed no difference during 1-year visit (P<0.05).

CONCLUSION

Both the trial lens fitting and software fitting approaches were effective in temporarily reducing myopia, providing good UCVA and delaying the elongation of axial length for moderate and high myopic adolescents. Both the two approaches can be combined in OK lens fitting.

Utility of orthokeratology contact lenses; efficacy of myopia correction and level of patient satisfaction in Iranian myopic/myope-astigmatic patients

Purpose

To investigate the medical profiles of patients referred to Iran Lens Clinic with myopic/myope-astigmatic refractive errors.

Methods

Medical records of 182 patients (364 eyes) with myopic/myope-astigmatic refractive errors that underwent orthokeratology contact lens wear and fulfilled a 6-month period of follow-up were recruited. Efficacy and safety of these contact lenses in improving the visual acuity and correction of the refractive errors were investigated. Time needed to achieve final targeted visual acuity and association of various factors in this time course and level of acuity were investigated. Complications related to these lenses that were recorded in the medical profiles were studied.

Results

In manifest refraction, the amount of spherical equivalent and myopia decreased significantly after orthokeratology contact lens wear (P < 0.001). A significant negative association was found between amount of mean baseline spherical equivalent and final achieved mean uncorrected visual acuity (P < 0.001). None of the parameters of age, gender, and keratometric findings influenced the outcomes significantly (P > 0.1).

Conclusion

Patients with myopic refractive error lower than −5.0 Diopters achieved higher final visual acuities rather than patients with higher amounts of myopic refractive errors.

Refractive error, visual acuity, and corneal-curvature changes in high and low myopes with orthokeratology treatment: A Malaysian study

Background/Purpose:

The effect of orthokeratology (OK) on low myopia is well known, but there are a few reports on its effect on high myopia. In this study, the parametric changes in high and low myopia as results of wearing OK lenses for a period of 6 months have been analyzed.

Methods:

Records of schoolchildren (age 7–17 years) undergoing OK treatment from an optometry clinic were retrospectively reviewed. Data involving refractive errors, uncorrected visual acuity, and corneal curvatures at baseline and after 1 day, 1 week, 1 month, 3 months, and 6 months of OK treatment from 25 patients who fulfilled the inclusion criteria were examined. For the analysis, the participants were arbitrarily divided into two groups comprising high myopia (< −6.00 D) and low to moderate myopia (from −1.00 D to −6.00 D).

Results:

Significant reductions of refractive error, improvement in visual acuity, and corneal-curvature flattening were found in all participants after 6 months of OK lens wear compared to the baseline. No significant changes were found in corneal toricity in both high and low to moderate myopic groups. Almost all of these occurred after one night of lens wear in both the high- and low-myopia groups.

Conclusion:

The OK lens wear significantly reduced the refractive error and corneal curvature that results in the improvement in visual acuity in both high- and low-myopia groups, and the reduction seemed to occur nearly at the same time despite the difference in initial myopic power. High myopes with refractive power up to −8.25 D would benefit significantly from OK lenses.

Peripheral optics with bifocal soft and corneal reshaping contact lenses

PURPOSE

To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses.

METHODS

Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, and inferiorly while wearing Proclear Multifocal "D" contact lenses with a +2.00-diopter add power (CooperVision, Fairport, NY) and after wearing Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lenses for 2 weeks.

RESULTS

Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were white. The average (± SD) spherical equivalent noncycloplegic manifest refraction for the right eye was -2.84 ± 1.29 diopters. The average logMAR best-corrected, binocular, high-contrast visual acuity was -0.17 ± 0.15 while wearing the bifocal soft contact lenses and -0.09 ± 0.16 after corneal reshaping contact lens wear (analysis of variance, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity.

CONCLUSIONS

Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in the peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina.

Gas permeable and soft contact lens wear in children

PURPOSE

To compare children's reports of comfort, vision, and contact lens-related issues in gas permeable (GP) and soft (SCL) contact lens wearers.

METHODS

Subjects were 116 8- to 11-year old children in the Contact Lenses and Myopia Progression Study. Aspects of contact lens wear were compared for children remaining in their original treatment group (either GPs or SCLs) for 3 years. Questionnaires were completed at every visit, as was visual acuity. Comparisons were made between the two groups using logistic regression or mixed linear models analyses as appropriate to examine the contact lens wearing experience. Additionally, children crossing over from GP wear to SCLs were compared with children remaining in GP lenses to determine the potential factors related to GP dissatisfaction.

RESULTS

Seventy percent of GP wearers and 93% of SCL wearers wore their assigned lenses every visit. GP wearers wore their lenses significantly fewer hours per week than the SCL wearers (76.2 h/week vs. 86.8 h/week, respectively, p = 0.003). GP wearers had statistically significantly better visual acuity though the difference was not clinically meaningful (p < 0.001). Comfort was poorer among the GP wearers using the Ocular Pain subscale (p < 0.001) but did not differ using a subjective question about comfort. Symptoms were more frequent in GP wearers than SCL wearers (p = 0.002) and were related to reports of discomfort. Significant factors relating to crossing over from GPs to SCLs were lower wearing time with GPs and itching.

CONCLUSIONS

Children are able to successfully wear GP and soft contact lenses. Long-term adaptation occurred more frequently to SCLs than to GPs. The amount of time GP lens wearers are able to comfortably wear their contact lenses and the amount of itching may help determine whether they will remain in that modality.

Epithelial, stromal, and corneal pachymetry changes during orthokeratology

PURPOSE

To describe epithelial, stromal, and corneal thickness profile changes induced by orthokeratology treatment.

METHODS

This is a case report of a mild myopic patient (OD -3.25/-0.50 x 172 and OS -3.25/-0.50 x 45) treated with orthokeratology lenses. The patient was assessed before treatment (following 2 weeks of no orthokeratology contact lens wear) and during treatment (after 30 consecutive nights of wearing orthokeratology lenses). Epithelial, stromal, and corneal thickness profile in vivo was measured by Artemis very high-frequency digital ultrasound scanning across the central 10 mm diameter of the cornea before and during orthokeratology treatment. Manifest refraction, contrast sensitivity, corneal topography, and corneal front surface aberrations were also measured before and during orthokeratology treatment. Thickness changes were correlated with corneal topography changes and corneal front surface aberrations changes. The effects of these changes on the patient's quality of vision were measured with manifest refraction and contrast sensitivity.

RESULTS

Orthokeratology lenses effectively corrected the patient's myopic refraction. Corneal topography demonstrated typical central flattening and an annulus of mid-peripheral steepening in both the eyes. The epithelial thickness profile was altered, with up to 18 microm of central epithelial thinning and up to 16 microm of annular mid-peripheral epithelial thickening. There also appeared to be a degree of stromal changes, with central stromal thickening and mid-peripheral stromal thinning, in particular in the left eye. There was a large increase in higher order aberrations, in particular in the left eye. This was associated with a decrease in contrast sensitivity in both the eyes.

CONCLUSIONS

Refractive changes during orthokeratology treatment are mainly induced by changes in epithelial thickness profile, while stromal changes may also contribute to a small extent.

Long-term clinical outcomes for overnight corneal reshaping in children and adults

PURPOSE

To retrospectively evaluate outcomes of overnight corneal reshaping (OCR) in children aged 12 years or younger compared to children older than 12 years and adults at one practice to establish the efficacy and safety of OCR during a period of 51 months.

METHODS

Examination records of OCR patients were reviewed for pretreatment data, including manifest refraction, keratometric readings, topography, corneal staining, and age at beginning OCR. Posttreatment records were reviewed for manifest refraction, unaided visual acuity, keratometric readings, topography, corneal staining, adverse events, and duration of OCR lens wear.

RESULTS

Records of 296 OCR patients were evaluated. One hundred fifty-four (52.0%) patients were 12 years old or younger. Sixty-eight percent of all patients in the study were Asian, and almost 95% of the patients aged 12 years or younger were Asian. The patients aged 12 years or younger had a mean original spherical equivalent refractive error of -3.50 +/- 1.50 diopters (D). The patients older than 12 years had a mean original spherical equivalent refractive error of -3.20 +/- 1.50 D. Refractive changes were similar between the group aged 12 years or younger and the group older than 12 years (3.30 +/- 1.40 D vs. 3.10 +/- 1.40 D) (P=0.14). The mean unaided, binocular logMAR visual acuity was 0.03 +/- 0.06 (i.e., 20/20) for the group aged 12 years or younger and 0.02 +/- 0.07 (i.e., 20/20) for the group older than 12 years. There were three adverse events during the study that did not result in a loss of best-corrected visual acuity. A total of 507 patient-years of wear was represented in the study.

CONCLUSIONS

OCR resulted in comparable safety and efficacy in temporarily reducing myopia for children younger than 12 years as it is for children older than 12 years and adults.

Contact Lenses in Pediatrics (CLIP) Study: Chair Time and Ocular Health

PURPOSE

Despite several studies that show 8- to 11-year-old children are capable of wearing a various contact lens modalities, parents often report that their eye care practitioner would not fit their child with contact lenses until the child was about 13 years old. We conducted the Contact Lenses in Pediatrics (CLIP) Study to compare contact lens fitting and follow-up between 8- to 12-year-old children and 13- to 17-year-old teenagers.

METHODS

At the baseline visit, all subjects underwent a contact lens fitting, including visual acuity, a manifest refraction, autorefraction, and biomicroscopy. Subjects then underwent contact lens insertion and removal training, which 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, and visual acuity, contact lens fit assessment, and biomicroscopy were performed. The time of the fitting, the insertion and removal training, and each follow-up visit were measured individually and added for a total chair time. Biomicroscopy examinations were conducted according to a standardized protocol.

RESULTS

We enrolled 84 children and 85 teens in the study. Of the 169 subjects, 93 (55.0%) were female, 78 (46.2%) were white, 44 (23.3%) were Hispanic, and 28 (17.6%) were black. The mean (+/- SD) total chair time for children was 110.6 +/- 39.2 min, significantly more than 95.3 +/- 25.2 min for teens (Student's t-test, p = 0.003). Most of the difference was caused by insertion and removal training, which lasted 41.9 +/- 32.0 min for children and 30.3 +/- 20.2 min for teens (Student's t-test, p = 0.01). The presence of conjunctival staining increased from 7.1% of the subjects at baseline to 19.9% of the subjects at 3 months (chi2, p = 0.0006), but the changes were similar between children and teens. No other biomicroscopy signs increased significantly over the 3-month period.

CONCLUSIONS

The total chair time for children is approximately 15 min longer than teens, but most of that difference is explained by longer time spent teaching children insertion and removal. Because insertion and removal is generally taught by staff members, the eye care practitioner's time with the patient is similar between children and teens. Furthermore, neither children nor teens experienced problems related to contact lens wear during the study. Eye care practitioners should consider routinely offering contact lenses as a treatment option, even for children 8 years old.

Empirical Advanced Orthokeratology Through Corneal Topography: The University of Houston Clinical Study

PURPOSE

Traditionally, orthokeratology has used diagnostic lenses to determine the best fit. The purpose of this study was to determine the efficacy of fitting empirically from corneal topography, without the use of diagnostic lenses.

METHODS

Twenty-nine subjects, 18 to 37 years old, with myopia of 1.00 to 4.00 diopters (D) and astigmatism of no more than 1.50 D, were entered into this 6-month study. Corneal topography, scanning slit topography and corneal thickness (Orbscan), confocal microscopy, ultrasound corneal thickness, aberrometry, and biomicroscopy were used to assess corneal changes. Unaided logMAR high-contrast visual acuity, subjective refraction, and questionnaires were used to monitor vision and symptoms. Follow-up visits were scheduled after 1 day, 1 week, 2 weeks, 1 month, 3 months, and 6 months.

RESULTS

For 6-month data, unaided logMAR acuity improved from 0.78 +/- 0.26 in the right eye and 0.75 +/- 0.22 in the left eye to 0.06 +/- 0.18 in the right eye and 0.04 +/- 0.16 in the left eye. Myopia decreased from -2.55 +/- 0.87 D in the right eye and -2.47 +/- 0.89 D in the left eye to +0.45 +/- 0.74 D in the right eye and -0.17 +/- 0.69 D in the left eye. Shape factor, using corneal topography, increased from 0.85 +/- 0.13 in the right eye and 0.85 +/- 0.15 in the left eye to 1.28 +/- 0.32 in the right eye and 1.30 +/- 0.29 in the left eye. Both eyes showed a decrease in lower-order aberrations (i.e., defocus) and an increase in higher-order aberrations (i.e., spherical aberrations and coma).

CONCLUSIONS

Myopia reduction after 1 week was clinically insignificant from the 1-month results, indicating that the full effect is achieved by 1 week. Neither total nor epithelial corneal thickness varied significantly from baseline measurements.

Orthokeratology review and update

Orthokeratology (OK) is a clinical technique that uses specially designed rigid contact lenses to reshape the cornea to temporarily reduce or eliminate refractive error. This article reviews the history of traditional daily-wear OK (1960s to 1980s) and discusses the reasons for the recent resurgence in interest in the new modality of overnight OK, using reverse-geometry lens designs (1990s to the present). The clinical efficacy of the current procedure is examined and outcomes from clinical studies in terms of refractive error change and unaided visual acuity are summarised. Onset of the effects of overnight OK lens wear is rapid, with most change after the first night of lens wear and stability of refractive change after seven to 10 days. Mean reductions in myopic refractive error of between 1.75 and 3.33 D and individual reductions of up to 5.00 D have been reported. There appear to be slight reductions or minimal changes in astigmatism with the use of reverse-geometry lenses and most patients are reported to achieve 6/6 unaided vision or better. The induction of higher order aberrations, in particular, spherical aberration, has been reported and this may affect subjective vision under conditions of low contrast and pupil dilation. Patient satisfaction with overnight OK has been reported as similar to or better than with other popular modalities of contact lens wear. Available evidence suggests that the corneal changes induced by overnight OK are fully reversible. The refractive effect in OK is achieved by central epithelial thinning and this has raised concerns about compromise of the epithelial barrier to microbial infection. Recent reports of microbial keratitis in the modality are reviewed and the overall safety of the procedure is examined critically. Recent research on stromal contributions to the OK effect, particularly relating to overnight oedema, is summarised. Emerging issues in OK, including myopic control, correction of other refractive errors and permanency of the OK effect, are discussed.

The Effect of Overnight Contact Lens Corneal Reshaping on Refractive Error-Specific Quality of Life

PURPOSE

The purpose of this study is to determine the effect of corneal refractive therapy (CRT) on refractive error-specific quality of life.

METHODS

The National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) was administered to 20 myopic patients (mean spherical equivalent -3.11 D +/- 0.96 D) between the ages of 21 and 37 years both before and 1 month after being successfully fit with Paragon CRT lenses. High- and low-contrast best-corrected visual acuity (BCVA) and higher-order aberrations were also measured. Scores for the 13 NEI RQL-42 subscales were calculated and a Wilcoxon sign rank test was used to determine whether there was a significant change in each of the subscale scores. Post hoc power analyses were also performed.

RESULTS

Statistically significant changes were found in three of the 13 NEI RQL-42 subscales. Significant improvements in subscale score were found for the symptoms (mean +/- standard deviation, 10.18 +/- 10.57, p = 0.0007) and dependence on correction (43.13 +/- 27.42, p < 0.0001) subscales. A significant reduction was found in the glare subscale (-32.50 +/- 35.22, p = 0.001). No significant changes were found in the clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, worry, suboptimal correction, appearance, or satisfaction with correction subscales.

CONCLUSIONS

CRT may improve a patient's perception of their visual independence, decrease the amount of ocular symptoms they report, and increase symptoms of glare. A larger, well-controlled clinical trial is necessary to verify these results. An increase in patient-reported glare is likely the result of measured increases in higher-order aberrations after CRT, especially spherical aberration under mesopic and scotopic conditions.

Study design issues in a corneal reshaping contact lens myopia progression study

Advances in contact lens design have led to corneal reshaping contact lenses that can be worn at night to temporarily reduce myopia so that patients can see clearly without glasses or contact lenses. Children are able to wear corneal reshaping contact lenses, but we do not know how they may affect the progression of myopia. A myopia control study with corneal reshaping contact lenses poses study design problems that other studies do not encounter because they temporarily reduce the refractive error. A discussion of the choice of primary outcome and control group will highlight some of these unique study design issues.

Adverse Corneal Events Associated With Corneal Reshaping

PURPOSE

This case series presents the first documented cases of infectious ulcers associated with overnight orthokeratology in North America and other less serious complications associated with overnight corneal reshaping.

CASE REPORTS

Five cases of adverse corneal events associated with corneal refractive therapy are described: two cases of microbial keratitis, one case of infiltrates, one case of toxic keratitis, and one corneal abrasion.

CONCLUSIONS

Corneal compromise and poor compliance can cause adverse events with corneal reshaping. The need for ongoing patient education is important not only for pediatric contact lens patients, but also for adults.

Daily Disposable Contact Lens Wear in Myopic Children

PURPOSE

To determine whether 8- to 11-year-old myopic children are able to wear daily disposable contact lenses.

METHODS

Subjects were examined for eligibility and fitted with 1-Day Acuvue contact lenses at the baseline visit. They underwent noncycloplegic manifest refraction, keratometry, slitlamp biomicroscopic examination, contact lens fitting, standardized visual acuity measurement, and contact lens application and removal training. The subjects attended visits 1 week, 1 month, and 3 months after the initial dispensing visit. At each of these visits, the subjects underwent spherical over-refraction, keratometry, slitlamp examination, and standardized visual acuity measurement, and they completed surveys about contact lens wear. The contact lens with the base curve that exhibited the most appropriate amount of movement and centration or the contact lens with the flatter base curve, if the movement and centration of the two contact lenses were similar, was dispensed.

RESULTS

Ten of the 12 subjects completed the 3-month investigation. One subject decided not to wear contact lenses before the 1-week visit, and one subject moved from the area after the 1-month visit. At the 3-month visit, 6 (60%) of the 10 subjects wore the 9.0 mm base curve contact lens, and 6 (60%) of the 10 subjects required one power change to optimize vision. At the 3-month visit, all subjects but one reported that their vision was "pretty good" or "perfect." All subjects also reported that their eyes were "always comfortable" or "usually comfortable." Eighty percent of the subjects reported that they "never had a problem" or "usually did not have a problem" putting on their contact lenses. All subjects reported that they "usually did not have a problem" or "never had a problem" taking out their contact lenses, and 90% of the subjects reported that they "usually did not have a problem" or "never had a problem" handling their contact lenses.

CONCLUSION

Eight- to 11-year-old subjects are able to independently care for daily disposable contact lenses and wear them successfully. Daily disposable contact lenses eliminate the need for cleaning and disinfecting contact lenses, so they should be strongly considered as a contact lens treatment option for children.