Rate Of Myopia Progression Research Articles

Time and Factors Affecting the Direction of Re-drift in Essential Infantile Esotropia.

To investigate the development pattern and related factors of postoperative re-drift in infantile esotropia. A total of 112 patients with infantile esotropia who underwent surgery before 3 years of age were included. Surgical outcomes were divided into (1) consecutive exotropia: more than 8 prism diopters (PD) of exodeviation; (2) recurrent esotropia: more than 8 PD of esodeviation; and (3) monofixation syndrome: maintenance of deviations within 8 PD. The occurrence rate, time of onset, and associated factors of the re-drift were evaluated. At a mean follow-up of 9.5 years, consecutive exotropia developed in 37 patients (33.0%) and recurrent esotropia in 43 patients (38.4%). Whereas 76.7% of total recurrent esotropia cases were identified within postoperative 1 year, consecutive exotropia occurred constantly over 10 years postoperatively. The mean time to consecutive exotropia development from surgery was 78.6 months, greater than that of recurrent esotropia development (8.9 months) (P < 0.001). In multinomial logistic regression using monofixation syndrome as the reference category, fixation preference before surgery (odds ratio [OR]: 6.64, 95% confidence interval [CI]: 2.07 to 21.32) and the rate of myopic progression (OR: 15.07 per -1.00 D/year, 95% CI: 1.23 to 184.86) were associated with consecutive exotropia, whereas increase in the angle of esodeviation on postoperative day 1 (OR: 1.15, 95% CI: 1.04 to 1.26) was correlated with recurrent esotropia. This study demonstrates a difference between the development pattern of exotropic and esotropic drift after infantile esotropia surgery. Detailed preoperative assessment and close postoperative observation of deviations and refractive status will help to determine surgical outcomes of infantile esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(2):128-134.].

Refractive changes after lens-sparing vitrectomy for macular hole and epiretinal membrane.

PurposeCataract progression after lens-sparing vitrectomy might differ according to original posterior segment diseases. Our objective was to analyze the refractive values after lens-sparing vitrectomy for macular hole (MH) and epiretinal membrane (ERM).Materials and methodsWe reviewed the medical records of 25 MH patients (25 eyes) and 23 ERM patients (23 eyes) who underwent lens-sparing vitrectomy. Refractive changes in both groups were compared. All patients underwent 20-gauge three-port pars plana vitrectomy. Fluid–air exchange was performed during vitrectomy only in the MH group. The results were analyzed using the unpaired t-test, chi-square test, or Fisher exact probability test, and multivariate analysis.ResultsThere were no significant differences in the patient’s age (P=0.45). The myopia progression rate (D/month) was higher in the MH group after surgery than that in the ERM group (P=0.035). MH group had more females (P=0.043), longer surgical time (P<0.001), and higher frequencies of surgical adjuvants use (triamcinolone acetonide, P=0.019; brilliant blue G, P<0.001). The myopia progression rate in the MH group (R=0.568, P<0.001) correlated with female gender. However, no correlation was observed between longer surgical time and the use of surgical adjuvants.ConclusionThe rate of myopia progression was higher in the MH group. Fluid–air exchange and gender may affect the rate of myopia progression.

Efficacy and Adverse Effects of Atropine in Childhood Myopia

Some uncertainty about the clinical value and dosing of atropine for the treatment of myopia in children remains. To evaluate the efficacy vs the adverse effects of various doses of atropine in the therapy for myopia in children. Data were obtained from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials, from inception to April 30, 2016. The reference lists of published reviews and clinicaltrials.gov were searched for additional relevant studies. Key search terms included myopia, refractive errors, and atropine. Only studies published in English were included. Randomized clinical trials and cohort studies that enrolled patients younger than 18 years with myopia who received atropine in at least 1 treatment arm and that reported the annual rate of myopia progression and/or any adverse effects of atropine therapy were included in the analysis. Two reviewers independently abstracted the data. Heterogeneity was statistically quantified by Q, H, and I2 statistics, and a meta-analysis was performed using the random-effects model. The Cochrane Collaboration 6 aspects of bias and the Newcastle-Ottawa Scale were used to assess the risk for bias. The primary outcome was a difference in efficacy and the presence of adverse effects at different doses of atropine vs control conditions. The secondary outcomes included the differences in adverse effects between Asian and white patients. Nineteen unique studies involving 3137 unique children were included in the analysis. The weighted mean differences between the atropine and control groups in myopia progression were 0.50 diopters (D) per year (95% CI, 0.24-0.76 D per year) for low-dose atropine, 0.57 D per year (95% CI, 0.43-0.71 D per year) for moderate-dose atropine, and 0.62 D per year (95% CI, 0.45-0.79 D per year) for high-dose atropine (P < .001), which translated to a high effect size (Cohen d, 0.97, 1.76, and 1.94, respectively). All doses of atropine, therefore, were equally beneficial with respect to myopia progression (P = .15). High-dose atropine were associated with more adverse effects, such as the 43.1% incidence of photophobia compared with 6.3% for low-dose atropine and 17.8% for moderate-dose atropine (χ22 = 7.05; P = .03). In addition, differences in the incidence of adverse effects between Asian and white patients were not identified (χ21 = 0.81; P = .37 for photophobia). This meta-analysis suggests that the efficacy of atropine is dose independent within this range, whereas the adverse effects are dose dependent.

Current approaches to myopia control

Myopia is a global problem, being particularly prevalent in the urban areas of east and southeast Asia. In addition to the direct economic and social burdens, associated ocular complications may lead to substantial vision loss. With prevalence of myopia above 80% and high myopia over 20%, it is crucial to control myopia. The aim of this review to is provide an update on the interventions to slow the onset of myopia and retard its progression. The epidemic of myopia is characterized by increasingly early onset, combined with high myopia progression rates. There are two pathways for myopia control: firstly to slow the onset of myopia and secondly to reduce or prevent progression. Increased time outdoors can reduce the onset of myopia. Atropine 0.01% dose offers an appropriate risk-benefit ratio, with no clinically significant visual side effects balanced against a significant 50% reduction in myopia progression. Orthokeratology contact lenses can slow axial length elongation, but infective keratitis is a risk. Peripheral defocussing lenses may both have a role in slowing myopic progression in a subset of children and further help our understanding of the physiologic control of ocular growth. Myopia control can be achieved by slowing the onset of myopia, which now appears to be possible through increasing time outdoors and slowing the progression of myopia with interventions like atropine and orthokeratology.

The Response AC/A Ratio Before and After the Onset of Myopia.

PurposeTo investigate the ratio of accommodative convergence per diopter of accommodative response (AC/A ratio) before, during, and after myopia onset.MethodsSubjects were 698 children aged 6 to 14 years who became myopic and 430 emmetropic children participating in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error. Refractive error was measured using cycloplegic autorefraction, near work by parent survey, and the AC/A ratio by simultaneously monitoring convergence and accommodative response. The response AC/A ratios of children who became myopic were compared with age-, sex-, and ethnicity-matched model estimates for emmetropic children from 5 years before through 5 years after the onset of myopia.ResultsThe response AC/A ratio was not significantly different between the two groups 5 years before onset, then increased monotonically in children who became myopic until reaching a plateau at myopia onset of about 7 Δ/D compared to about 4 Δ/D for children who remained emmetropic (differences between groups significant at P < 0.01 from 4 years before onset through 5 years after onset). A higher AC/A ratio was associated with greater accommodative lag but not with the rate of myopia progression regardless of the level of near work.ConclusionsAn increasing AC/A ratio is an early sign of becoming myopic, is related to greater accommodative lag, but does not affect the rate of myopia progression. The association with accommodative lag suggests that the AC/A ratio increase is from greater neural effort needed per diopter of accommodation rather than change in the accommodative convergence crosslink gain relationship.

Effect of homoeopathic preparation of Ruta graveolens on the progression of childhood myopia before, during and after cessation of treatment: A retrospective study

Background: Increased incidence and progression of myopia, especially in Asian countries, have been attributed to excess near work. Topical use of Atropine was effective in controlling myopia but has got side effects and rebound effect after stopping the treatment. Homoeopathy mentions Ruta graveolens (Ruta) for myopia with its action on accommodation. Aim: The aim of the study is to evaluate the effect of Ruta on annual myopia progression rate (AMPR) before, during and after stopping treatment in childhood myopia. Materials and Methods: Ten cases of simple myopia in progressive stage aged 11–16 years were studied retrospectively. Myopia or spherical equivalent of refraction (SER) and AMPR in diopters (D) before treatment were assessed from the previous refraction reports. Ruta 3C was used in BD dose orally for 2 years with a gap of 7 days after every 21 days, and thereafter, treatment was discontinued. Subjective refraction on Snellen's chart at the start, during and after stopping treatment was recorded. From SER values, AMPR at different phases of study was assessed and analysed with paired t-test. Results: Mean AMPR before treatment was −1.10 D (±0.53). After Ruta treatment, there was a significant reduction of −0.27 D (±0.32) in AMPR (t = −4.13, P = 0.003). After stopping the treatment for an average of 10 months, mean AMPR was −0.46 D (±0.49), but this change was insignificant (t = 1.21, P = 0.26). Conclusion: Homoeopathic Ruta 3C was effective in controlling AMPR with no major progression after stopping the treatment.

O uso terapêutico do colírio de atropina para retardar a progressão de miopia em crianças é reconhecido cientificamente e possui eficácia comprovada?

The prevalence of myopia worldwide has been increasing significantly over the past decades, and it is currently a leading cause of visual impairment worldwide. This severe and significant public health problem has been addressed at the community level with the use of atropine eye drops at a concentration of 0.01% (one drop daily). This regimen appears to offer an appropriate balance between costs and benefits, indicated by a 50% reduction in the annual myopia progression rate in children without resulting in clinically significant adverse effects. The therapeutic use of atropine eye drops to slow myopia progression in children is scientifically recognized and it has been proven to be effective.

Relationship between Reduced Accommodative Lag and Myopia Progression.

To determine the relationship between accommodative lag and rate of myopia progression when Ghanaian myopic school children are either undercorrected or fully corrected with single vision lenses. A 2-year single masked randomized control trial was conducted using 150 Ghanaian myopic children aged 10 to 15 years with mean baseline myopia of -1.98 ± 0.50D. The children were randomly assigned to wear either a full correction (n = 75) or +0.50D undercorrection (UC) (n = 75) single vision lenses. Repeated measurements which included refractive error and accommodative response at 33 and 28.6 cm for FC and UC, respectively, were performed using Open-Field Autorefractor whereas ocular biometry results were obtained using A-Scan ultrasonography. Results were based on the right eye and analyzed using STATA 11. After 24 months, the mean myopia progression of children in the FC group (-0.54 ± 0.26D) was not significantly different from that of the children in the UC group (-0.5 ± 0.22D) (p = 0.31). There was no significant difference between the mean values of the initial near lag and the average lag measured 24 months later in both groups (FC: initial lag -0.74 ± 0.17D, average lag -0.72 ± 0.15D, p = 0.44; UC: initial lag -0.57 ± 0.14D, average lag -0.58 ± 0.15D; p = 0.67). Also, there was no significant correlation between refractive change seen in 24 months and either the first near lag for both FC (r = -0.05, p = 0.43) and UC (r = -0.08, p = 0.43) or the average near lag of accommodation for both FC (r = -0.02, p = 0.49) and UC (r = -0.04, p = 0.49). This study showed no relationship between lag of accommodation and rate of myopia progression in children with progressing myopia. Different ethnic groups may respond differently to the same size of hyperopic blur.

Visual performance with multifocal soft contact lenses in non-presbyopic myopic eyes during an adaptation period.

PurposeMultifocal soft contact lenses (MFCLs) have been proposed and used for controlling the rate of myopia progression; however, little is known on the performance and adaptation with MFCLs in non-presbyopes. This study aims to evaluate the visual performance of four commercially available MFCLs in non-presbyopic myopic eyes during an adaptation period.MethodsFifty-two experienced myopic contact lens wearers (67% female; mean age 21.4±2.0 years) were enrolled in this trial and 40 completed the trial. Twenty-six participants (Group 1) wore Lotrafilcon B single vision (SV, control), Omafilcon A MFCL center-distance (D) and center-near (N) and the other 26 participants (Group 2) wore Lotrafilcon B SV, Lotrafilcon B MFCL N, and Balafilcon A MFCL N. Lens order was randomized. Participants wore each allocated lens for a minimum of 8 days over four scheduled visits (dispensing and three follow-up visits) with a 1-week washout period between the lens types. At each visit, high-contrast visual acuity (HCVA) (in logarithm of the minimum angle of resolution [logMAR]) and seven subjective performance variables (via questionnaire) were obtained. Power profiles of each lens type, pupil size, and contact lens centration, with lens placed on the eye, were measured.ResultsThe SV control outperformed the MFCLs in all variables (P<0.05). There were no significant differences in HCVA over time, with the exception of monocular HCVA with Omafilcon A MFCL N, which at the end of the adaptation period had significantly (P<0.05) improved by 0.10 logMAR. No differences were found between visits for any subjective variables. Subjectively, Lotrafilcon B MFCL N performed best and was the only lens that did not decenter significantly compared to the SV control. Conversely, Omafilcon A MFCL N was the worst performing and most decentered lens (P<0.05, y=−0.39 mm), with the greatest plus area under the power profile.ConclusionMFCLs with greatest power variation across the optic zone, a greater plus area under the distance labeled power profile, and/or lenses that were significantly decentered resulted in the lowest subjective ratings. Over time, quality of vision with MFCLs did not change in non-presbyopic myopic participants, with the exception of Omafilcon A MFCL N, which showed some adaptation effects.

Refraction data survey: 2nd generation correlation of myopia.

The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st and 2nd generation correlations, relevant to whether myopia is random or inherited. First- and second-generation ocular refraction data are assembled from N=34 families, average of 2.8 children per family. From this group, data are available from N=165 subjects. Inter-generation regressions are performed on all the data sets, including correlation coefficient r, and myopia prevalence [%]. Prevalence of myopia is [M]=38.5%. Prevalence of high myopes with |R|>6 D is [M-]=20.5%. Average refraction is<R>=-1.84 D±3.22 (N=165). For the high myopes, |R|>6 D, prevalence for the parents is [M-]=25%, for the 2nd generation [M-]=16.5%. Average myopia level for the high myopes, both generations, is<S>=-7.52 D±1.31 D (N=33). Regression parameters are calculated for all the data sets, yielding correlation coefficients in the range r=0.48-0.72 for some groups of myopes and high myopes, fathers to daughters, and mothers to sons. Also of interest, some categories show essentially no correlation, -0.20<r<0.20, indicating that the refractive errors occur randomly. Time series results show myopia diopter rates=-0.50 D/year.

Use of Atropine for Prevention of Childhood Myopia Progression in Clinical Practice.

The most effective strategy to reduce myopia-related complications is to prevent myopia progression during childhood. This review article examines the latest published evidence on the use of atropine in childhood myopia control and discusses practical aspects of applying the findings to clinical practice. Future directions including possible forms of combination therapy are examined. A literature search with a focus on randomized controlled trials (RCTs) and meta-analyses on the subject was conducted. Observational studies with control groups were also reviewed to discuss issues regarding feasibility of using atropine for myopia control in clinical practice. Five RCTs and 2 meta-analyses were found. The studies all found beneficial effects of atropine in myopia control, as well as a clear but perhaps clinically insignificant dose-response relationship between atropine and myopia progression rates. Available evidence however is focused on predominantly Chinese populations, and there is a current lack of guidance on timing of therapy initiation, duration of therapy, and treatment cessation. For future directions, combining atropine with other forms of myopia control would be worth considering. Atropine is robust option for childhood myopia control. Further evidence including RCTs in different populations as well as the upcoming 5-year atropine for the treatment of myopia 2 trial results will provide much needed answers for wider acceptance of its use.

Atropine 0.01% Eyedrops Significantly Reduce the Progression of Childhood Myopia.

Atropine 0.01% eyedrops have been shown to slow childhood myopic progression in primarily Asian populations. We studied its effects on an ethnically diverse population over a broad range of myopia. A retrospective case-control study was performed on 60 children (6-15 years) with initial myopic spherical equivalents from -0.25 to -8.00 diopters (D). The primary outcome was the rate of myopic progression per year. Secondary outcomes were the proportion of subjects with slow or rapid myopic progression, atropine-related side effects, and rates of myopic progression for subgroups with low, moderate, or higher initial myopia. The average initial age (10.2 years) and refraction (-2.0 D) were identical between groups. After 1.1±0.3 years follow-up, atropine subjects had significantly lower rates of myopic progression (-0.1±0.6 D/year) than controls (-0.6±0.4 D/year) (P=0.001), including 24 of 32 (75%) with slow progression ≤-0.25 D/year versus only 5 of 28 (18%) controls. Three atropine and 4 control subjects had rapid progression ≥-1.00 D/year. For subjects with low initial myopia (≤-1.00 D), 9 of 11 (82%) atropine subjects had plano or slightly hyperopic refractive changes after 1 year, while 8 of 8 (100%) controls were more myopic. Only 3 atropine subjects complained of intermittent blur or light sensitivity, not symptomatic enough to discontinue treatment. Atropine 0.01% significantly reduced the rate of myopic progression over 1 year with minimal side effects. It appears most effective in children with low initial myopia and may not control rapid myopic progression in some patients. Stronger concentrations of atropine may be required to slow rapid myopic progression.

High magnitude with-the-rule astigmatism and myopic progression in children

Purpose: To investigate high magnitude with-the-rule astigmatism (WTRA, plus cylinder with axis between 75 and 105 degrees) as a risk factor for myopic progression in children.Methods: Retrospective case-control study. Medical records were screened using CPT codes and age of visit. Subjects were included if the age at initial and final refractive visits were 10 years, respectively, and had at least five years of follow up. Exclusion criteria include a history of intraocular/oculoplastic pathologies, surgeries, lasers, presence of pathologic myopia (magnitude > 8 diopters). Eyes were categorized based on the initial refraction: no astigmatism (NA), non-WTRA (cylinder outside of 75-105 degree range), low-WTRA (cylinder 2 D). Results: A total of 2974 records were screened. 202 eyes of 110 patients were included; 79 (39%) were NA, 81 (40%) were low-WTRA, 24 (12%) eyes were high-WTRA, and 18 (9%) were non-WTRA. High-WTRA had the least hyperopic initial spherical equivalence (0.5 +/- 6.4 D) compared to NA (2.2 +/- 3.0 D), non-WTRA (2.3 +/- 3.2 D), and low-WTRA (3.2 +/- 2.7 D, P = 0.009). When comparing the rates of myopic refractive change per year, patients with high-WTRA demonstrated a significantly greater rate (-0.24 +/- 0.21 D/year) than those without high-WTRA (-0.13 +/- 0.22 D/year, P = 0.0041).Conclusions: Compared to cohorts with NA, non-WTRA or low-WTRA, children with high-WTRA show a significantly higher rate of myopic progression when followed for five or more years.

Analysis of the Prevalence and Situation of Myopia in Adolescents from South China.

To conduct dynamic detection of refraction changes in adolescents with myopia and analyze the correlation between different reexamination times and factors that included age of onset, initial refractive power, and rate of myopia progression. A total of 900 adolescents (aged 6-15 years) with myopia admitted to Zhongshan Ophthalmic Center between 2009 and 2013 were randomly selected in this investigation. All participants underwent objective refraction measurement with an autorefractometer (Topcon 8900) or streak retinoscopy and subjective refraction detection with an autorefractor (Nidek) or minus-lens procedures at different time intervals (6 months, 1, and 2 years). Accurate refractive power was obtained. All data were analyzed with SPSS 18.0 statistical software. The mean refractive power was increased by 0.56 ± 0.37 diopters(D) after 6 months, by 0.83 ± 0.45 D after 1 year, and by 1.50 ± 0.70 D after 2 years. Among the 900 adolescents, the most rapid increase in refractive power was observed at the age of 8 years at the 6-month reexamination, at the age of 8 and 9 years at the 1-year reexamination, and at the age of 7-9 years at the 2-year reexamination. The increase in index of refraction tended to diminish with aging. The different cycles of reexamination revealed a slowing of the rate of myopia progression along with the increase in the initial index of refraction. The highest rate of myopia progression was noted in low-myopic adolescents with initial refractive power ranging from -0.25 to 2.75 D. No positive correlation was documented between different cycles of reexamination and the refractive power. The increase in refractive power was associated with factors that included the reexamination cycle, age of onset, and initial refractive power.

Influence of indoor and outdoor activities on progression of myopia during puberty.

The purpose of this study was to investigate whether time spent on indoor and outdoor activities or the other possible risk factors including age, gender, parental history, and initial refraction was associated with progression of myopia, during puberty. Fifty eyes of 50 myopic children aged 9-14 years were enrolled in the study. The parents were interviewed to determine the amounts of time in hours per day spent on reading and writing, using computer, watching TV, and outdoor activities (i.e., sports, games, or being outdoor with no activities) on an average day. The annual myopia progression rate (diopters per year) was calculated for each subject and was used in the statistical analyses. The mean initial age of the subjects was 10.9 ± 1.5 (ranging from 9 to 14) years. The mean follow-up period was 33.3 ± 10.3 (ranging from 17 to 55) months. There was a significant increase in the mean myopia value of the subjects after follow-up period (p < 0.001). The mean daily time spent on reading and writing and initial refraction value were independently associated with annual myopic progression rate. On the other hand, age, gender, parental myopia, and the mean daily times spent on computer use, watching TV, and outdoor activities had no correlations with annual myopia progression rate. The present study showed that myopia progression was associated with time spent on reading and writing and initial refraction value, during puberty. However, myopia progression was not associated with parental myopia, age, gender, and daily times spent on using computer, watching TV, and outdoor activities.

Changes in refractive error in patients with accommodative esotropia after being weaned from hyperopic correction

BackgroundTo determine the long-term changes in refractive error and ocular alignment in patients with accommodative esotropia (AET) who were able to discontinue wearing hyperopic glasses because of emmetropisation.MethodsForty-seven patients with...

The impact of intermittent exotropia and surgery for intermittent exotropia on myopic progression among early school-aged children with myopia

AimTo investigate the relationship between myopic progression and intermittent exotropia, and the impact of surgery for exotropia on myopic progression in early school-aged children (from 7 years to 12 years...

Effect of Bifocal and Prismatic Bifocal Spectacles on Myopia Progression in Children

Myopia is a significant public health problem, making it important to determine whether a bifocal spectacle treatment involving near prism slows myopia progression in children. To determine whether bifocal and prismatic bifocal spectacles control myopia in children with high rates of myopia progression and to assess whether the treatment effect is dependent on the lag of accommodation and/or near phoria status. This 3-year randomized clinical trial was conducted in a private practice. A total of 135 (73 female and 62 male) Chinese-Canadian children (aged 8-13 years; mean [SE] age, 10.29 [0.15] years; mean [SE] myopia, -3.08 [0.10] D) with myopia progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments. A total of 128 (94.8%) completed the trial. Single-vision lenses (control, n = 41), +1.50-D executive bifocals (n = 48), and +1.50-D executive bifocals with 3-Δ base-in prism in the near segment of each lens (n = 46). MAIN OUTCOMES AND MEASURES Myopia progression (primary) measured using an automated refractor following cycloplegia and increase in axial length (secondary) measured using ultrasonography at intervals of 6 months for 36 months. RESULTS Myopia progression over 3 years was an average (SE) of -2.06 (0.13) D for the single-vision lens group, -1.25 (0.10) D for the bifocal group, and -1.01 (0.13) D for the prismatic bifocal group. Axial length increased an average (SE) of 0.82 (0.05) mm, 0.57 (0.07) mm, and 0.54 (0.06) mm, respectively. The treatment effect of bifocals (0.81 D) and prismatic bifocals (1.05 D) was significant (P < .001). Both bifocal groups had less axial elongation (0.25 mm and 0.28 mm, respectively) than the single-vision lens group (P < .001). For children with high lags of accommodation (≥ 1.01 D), the treatment effect of both bifocals and prismatic bifocals was similar (1.1 D) (P < .001). For children with low lags (<1.01 D), the treatment effect of prismatic bifocals (0.99 D) was greater than of bifocals (0.50 D) (P = .03). The treatment effect of both bifocals and prismatic bifocals was independent of the near phoria status. Bifocal spectacles can slow myopia progression in children with an annual progression rate of at least 0.50 D after 3 years. These results suggest that prismatic bifocals are more effective for myopic children with low lags of accommodation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00787579.

Visual regulation of refractive development: insights from animal studies

Investigations employing animal models have demonstrated that ocular growth and refractive development are regulated by visual feedback. In particular, lens compensation experiments in which treatment lenses are used to manipulate the eye's effective refractive state have shown that emmetropization is actively regulated by signals produced by optical defocus. These observations in animals are significant because they indicate that it should be possible to use optical treatment strategies to influence refractive development in children, specifically to slow the rate of myopia progression. This review highlights some of the optical performance properties of the vision-dependent mechanisms that regulate refractive error development, especially those that are likely to influence the efficacy of optical treatment strategies for myopia. In this respect, the results from animal studies have been very consistent across species; however, to facilitate extrapolation to clinical settings, results are presented primarily for nonhuman primates. In agreement with preliminary clinical trials, the experimental data show that imposed myopic defocus can slow ocular growth and that treatment strategies that influence visual signals over a large area of the retina are likely to be most effective.

Factors Preventing Myopia Progression with Orthokeratology Correction

To examine which baseline measurements constitute predictive factors for axial length growth over 2 years in children wearing orthokeratology contact lenses (OK) and single-vision spectacles (SV). Sixty-one children were prospectively assigned to wear either OK (n = 31) or SV (n = 30) for 2 years. The primary outcome measure (dependent variable) was axial length change at 2 years relative to baseline. Other measurements (independent variables) were age, age of myopia onset, gender, myopia progression 2 years before baseline and baseline myopia, anterior chamber depth, corneal power and shape (p value), and iris and pupil diameters as well as parental refraction. The contribution of all independent variables to the 2-year change in axial length was assessed using univariate and multivariate regression analyses. After univariate analyses, smaller increases in axial length were found in the OK group compared to the SV group in children who were older, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had less myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris diameter, had larger pupil sizes, and had lower levels of parental myopia (all p < 0.05). In multivariate analyses, older age and greater corneal power were associated with smaller increases in axial length in the OK group (both p < 0.05), whereas in SV wearers, smaller iris diameter was associated with smaller increases in axial length (p = 0.021). Orthokeratology is a successful treatment option in controlling axial elongation compared to SV in children of older age, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had lower myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris and pupil diameters, and had lower levels of parental myopia.