The efficacy of orthokeratology lenses with smaller back optic zone diameter in myopia control. A meta-analysis.

PURPOSE: This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects. METHOD: A meta-analysis was registered in PROSPERO (CRD42023408184). A comprehensive systematic database search was conducted, encompassing PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Ovid, CNKI and CBM, to identify relevant studies up to 25 March 2023. The primary inclusion criteria for this meta-analysis were studies that investigated the myopia control effect of OK lenses with a small optical treatment area (≤5 mm). To assess the quality of the retrieved articles, two researchers evaluated them using the Cochrane bias risk assessment criteria. The primary outcome measures were the changes in axial length (AL) and refractive error, using the weighted mean differences (WMD) and 95% confidence intervals (CI) to assess differences between small and traditional back optical treatment zone groups in terms of these outcomes. RESULTS: The analysis encompassed five eligible studies, with a 1 year duration. The average difference in AL between the groups was 0.12 mm (WMD = -0.12, 95% CI [-0.16, -0.09], p < 0.00001). Likewise, the average difference in refractive error between the two groups was 0.44 D (WMD = 0.44, 95% CI [0.30, 0.57], p < 0.00001). None of the studies reported severe adverse events. CONCLUSIONS: Current evidence suggests that OK lenses with smaller back optical treatment zone are more effective in preventing myopia progression than traditional lenses. However, a longer-term evaluation is warranted.

Exploring the impact of optical corrections on visual functions in myopia control-a scoping review.

PURPOSE: Myopia is controlled optically with peripheral defocus spectacles, multifocal contact lenses, or orthokeratology lenses. However, it is unknown which optical correction will improve visual performance. This scoping review aimed to identify and summarize studies on various visual functions using optical corrections for myopia control. METHODS: To develop the search strategy, population (Myopia), concept (visual performance), and context (unrestricted race/region) were used. PubMed, SCOPUS, Cochrane Library, and Web of Science databases were searched using the keywords myopia, contrast sensitivity, high and low contrast visual acuity, stereopsis, and optical correction of myopia control. This scoping review protocol was registered in the Open Science Framework registry and followed the framework for scoping review outlined by the Joanna Briggs Institute. RESULTS: Eight studies (n = 8) met the inclusion criteria and were included in the review. Four were conducted in Europe, two were conducted in China, and one was conducted in Japan and Singapore. Five studies were randomized controlled trials, out of which three used contact lenses and two studies used peripheral defocus spectacles lenses. Studies ranged from one day to 2 years. Three studies that used orthokeratology lenses were prospective study designs. Among the studies that used orthokeratology lenses and contact lenses, two studies measured the contrast sensitivity function with CSV1000 (Vector Vision) under mesopic and photopic conditions, with and without glare. Two studies measured the central and peripheral contrast sensitivity using psychophysics experiments. High and low contrast visual acuity was measured using the Freiburg Vision Test (n = 1) and ETDRS charts (n = 3), and stereopsis was assessed using a random dot stereogram (n = 1). The studies showed a reduction in central and peripheral contrast sensitivity function and low contrast acuity when treated with multifocal contact lenses, orthokeratology lenses, and peripheral defocus lenses compared with single-vision lenses. CONCLUSION: This scoping review found a reduction in central and peripheral contrast sensitivity function, as well as low contrast visual acuity when using various optical corrections for myopia control, while high-contrast visual acuity remained the same. The impact of visual functions may not influence the effectiveness of myopia control. Eye care practitioners should provide awareness to the parent and patient population about the potential visual impact of recent designs for optical corrections of myopia control.

Alterations of conjunctival microbiota associated with orthokeratology lens wearing in myopic children.

BACKGROUND: Orthokeratology (OK) lens wear increases the risk of bacterial infection, but little is known about the microbiota of the conjunctival sac in myopic children wearing OK lenses. This study aimed to investigate the changes of conjunctival microbiota in children after treatment with OK lenses using 16 S rDNA sequencing. METHODS: Twenty-eight myopic children who had been continuously wearing OK lenses for 12 to 13 months were enrolled in this prospective study. Twenty-two gender- and age-matched myopic children who had not worn OK lenses or discontinued OK lens wear at least 1 year ago were recruited as controls. Conjunctival swabs from each participant were collected for exploration of the microbiota profiles, targeting the V3-V4 regions of the 16 S rRNA gene by MiSeq sequencing. The differences in the microbial community structure and diversity were also compared between groups. RESULTS: The bacterial alpha diversity indices in the OK lens group were not different from those in the non-wearer group (P > 0.05, Wilcoxon test), while beta diversity examined using principle coordinate analysis of unweighted UniFrac divided the two groups into different clusters. Proteobacteria, Bacteroidetes, and Firmicutes were the abundant phyla in the conjunctival sac microbiota in both groups (P < 0.05, Mann-Whitney U test). Among children in the OK lens group, the Linear discriminant analysis Effect Size identified the compositional changes in OK lens-associated bacteria. Key functional genera such as Blautia, Parasutterella, and Muribaculum were enriched, whereas Brevundimonas, Acinetobacter, Proteus, and Agathobacter decreased significantly (P < 0.05, Mann-Whitney U test). Phylogenetic investigation of communities by reconstruction of unobserved states also showed altered bacterial metabolic pathways in OK lens-associated microbiota. Moreover, using receiver operating characteristic curves, Brevundimonas, Acinetobacter, Proteus, and Agathobacter alone (the area under the curve was all > 0.7500) or in combination (the area under the curve was 0.9058) were revealed to discriminate OK lens wearers from controls. CONCLUSIONS: The relative abundance of the microbial community in the conjunctival sac of myopic children can alter after OK lens wear. Brevundimonas, Acinetobacter, Proteus, and Agathobacter may be candidate biomarkers to distinguish between OK lens wearers and non-wearers.

Influence of overnight orthokeratology on tear film and meibomian glands in myopic children: a prospective study.

BACKGROUND: Orthokeratology lenses, which are worn overnight, are recommended for reducing myopia progression. They lie on the cornea and can influence the ocular surface by temporarily reshaping the corneal surface through a reverse geometry design. This study investigated the effect of overnight orthokeratology lenses on tear film stability and meibomian gland status in children aged 8-15 years. METHODS: This prospective, self-controlled study included 33 children with monocular myopia who were prescribed orthokeratology lenses for at least one year. The experimental group (ortho-k group) comprised 33 myopic eyes. The control group comprised the emmetropic eyes of the same participants. Tear film stability and meibomian gland status were measured using a Keratograph 5M (Oculus, Wetzlar, Germany). Paired t-tests and Wilcoxon signed-rank tests were used to compare the data between the two groups. RESULTS: At the one-year visit, the non-invasive first tear film break-up time (NIBUTf) values were 6.15 ± 2.56 s and 6.18 ± 2.61 s in the experimental and control groups, respectively. The lower tear meniscus height was 18.74 ± 0.05 µm and 18.65 ± 0.04 µm in these groups, respectively. No significant difference was observed in loss of meibomian glands or non-invasive average tear film break-up time between the experimental and control groups using Wilcoxon signed-rank tests. CONCLUSIONS: The stability of the tear film and meibomian gland status were not significantly affected by wearing orthokeratology lenses overnight, indicating that continuous use of orthokeratology lenses for 12 months has a minimal effect on the ocular surface. This finding can help guide the clinical management of tear film quality with respect to the use of orthokeratology contact lenses.

Preventing the Progression of Myopia in Children-A Review of the Past Decade.

The growing incidence of myopia worldwide justifies the search for efficient methods of myopia prevention. Numerous pharmacological, optical, and lifestyle measures have already been utilized, but there remains a need to explore more practical and predictable methods for myopia control. This paper presents a review of the most recent studies on the prevention of myopia progression using defocus-incorporated multiple-segment spectacle lenses (DIMSsl), repeated low-level red-light (RLRL) therapy, and a combination of low-dose atropine (0.01%) with orthokeratology lenses.

The relationship between corneal biomechanical parameters and treatment outcomes of orthokeratology lenses.

BACKGROUND: To evaluate changes in corneal biomechanical properties after long-term orthokeratology (OK) treatment and the factors affecting treatment outcomes. METHODS: Twenty-four myopic teenagers who wore OK lenses for more than 1 year were included. Twenty-three individuals of the same age and with the same spherical equivalent wearing single-vision spectacles (SVS) were enrolled as controls. After routine eye examinations, corneal biomechanical properties and axial length were measured. Parameters were compared between groups. RESULTS: Less axial elongation (AE) occurred in the OK group (P = 0.021). The OK group experienced a statistically significant decrease in the A1 deformation amplitude (P = 0.02), whole eye movement maximum (P = 0.026), and Ambrósio's relational thickness to the horizontal profile (ARTh) (P < 0.001), and a statistically significant increase in the pachyslope (P < 0.001) and Corvis biomechanical index (P < 0.001). Smaller ARTh and a larger highest concavity deflection area resulted in a better refractive state. The inhibitory effect of AE was better for older patients with smaller ARTh. CONCLUSIONS: Long-term OK treatment slowed myopia progression by reshaping the cornea. Smaller ARTh after OK lens wear indicated a better refractive state and slower AE and could predict OK lens treatment outcomes.

Effects of orthokeratology on corneal reshaping and the delaying of axial eye growth in children.

Purpose: To investigate the inhibition of myopia progression and axial elongation in children wearing orthokeratology (OK) lenses, as well as to evaluate the status of corneal reshaping, this study explores the relationship between changes in central corneal curvature (K-value) and e-value induced by OK lenses and axial elongation. Methods: In this study, it is planned to select children aged 8-15 who wear orthokeratology lenses at the Pediatric Ophthalmology and Strabismus Clinic of the Second Affiliated Hospital of Dalian Medical University. All children will undergo slit lamp examination, visual acuity assessment, computerized refraction, intraocular pressure measurement, biometry, and corneal topography examination before lens wear and at 1 month, 3 months, and 6 months after lens wear in the pediatric ophthalmology clinic. Based on age (lower age group (8 < age ≤12 years); higher age group (12 < age ≤15 years)) and baseline equivalent spherical (SE) value (mild myopia group (-1.00 D < SE ≤ -3.25D); moderate myopia group (-3.25 D < SE ≤ -6.00 D)), four groups will be formed by pairing these factors. Suitable data will be selected according to inclusion and exclusion criteria, and different groups will be included. Data will be organized, and statistical analysis will be performed using SPSS software to obtain the results. The expected results will be discussed and analyzed. Results: After wearing OK lenses, all four groups achieved good visual acuity at follow-up. At 6 months, there were no significant differences in visual acuity among the four groups (P = 0.149, >0.05). There were no significant differences in refractive error among the four groups (P = 0.066, >0.05). Baseline axial length differed significantly among the four groups (P = 0.000, <0.001), with the LM group having longer axial length than the LL group (P < 0.001, paired samples t-test), and the HM group having longer axial length than the HL group (P < 0.001, paired samples t-test). However, there were no significant differences in axial length change compared to baseline among the groups at 1 month, 3 months, and 6 months (P 1 = 0.053; P 3 = 0.557; P 6 = 0.329, >0.05). Significant differences were observed in corneal flat K-value change compared to baseline among the four groups at 1 month, 3 months, and 6 months (P 1 = 0.001, P 3 = 0.001, P 6 = 0.004, <0.05). There were no significant differences in e-value change among the groups at 1 and 3 months (P 1 = 0.205, P 3 = 0.252, >0.05), but significant differences were found in e-value change compared to baseline at 6 months (P 6 = 0.010, <0.05). Multiple regression analysis with changes in central corneal flat K-value and e-value as independent variables and axial elongation as the dependent variable showed a correlation between e-value change at 6 months and axial elongation (P = 0.004, <0.05), indicating a negative correlation. Conclusion: Orthokeratology (OK) lenses effectively improve myopic children's vision by reshaping the cornea, leading to reduced central corneal curvature and flattening of its anterior surface. The effectiveness of OK lenses is not significantly affected by age or initial myopia severity. Children of varying ages and myopia levels experience similar levels of axial length control with OK lens wear. Changes in corneal shape due to OK lenses affect axial elongation, with greater changes in corneal morphology associated with smaller increases in axial length.

Comparison of the clinical efficacy of orthokeratology and 0.01% atropine for retardation of myopia progression in myopic children.

OBJECTIVE: To compare the clinical efficacy of orthokeratology (ortho-k) and 0.01% atropine for retardation of myopia progression in myopic children. METHODS: This was a retrospective cohort study. A total of 282 patients, aged 8-17 years, were enrolled, including 100 children treated with ortho-k, 84 with 0.01% atropine, and 98 with single-vision spectacles. During the follow-up of 1 year, ortho-k wearers were examined at 1 day, 1 week, 1 month, 3 months after treatment, and thereafter every 3 months, while the others were examined every 3 months by measurements of uncorrected vision, intraocular pressure, refractive power, slit-lamp microscopy, corneal topography, and the lens fitting when necessary. The axial length was measured every 6 months. RESULTS: Patients with ortho-k had stable uncorrected vision after 1 month of lens wear, all reaching 0 logMAR. The annual axial elongation was 0.23 ± 0.19 mm, 0.22 ± 0.20 mm, and 0.39 ± 0.27 mm in the ortho-k, atropine, and spectacle groups, respectively, with significant difference (F = 23.251, P = 0.000). The axial length was delayed to increase by 41.03% and 43.59% within a year in patients with ortho-k and atropine, respectively, as compared to patients with spectacles (F = 0.006, P = 0.936). The elongation was ≤ 0.3 mm in 69.0% and 66.7% of patients in the two groups, respectively, versus 38.8% in the spectacle group (χ2 = 17.251, P = 0.000). During the follow-up, the rate of corneal staining was 11.0% and 2.0% in the ortho-k and spectacle groups, respectively (χ2 = 8.076, P = 0.003). The use of atropine did not increase corneal staining, but the incidence of related photophobia was 4.8%. No other serious complications were observed. CONCLUSION: Ortho-k lenses and 0.01% atropine can achieve similar efficacy of myopia retardation, which was significantly better than that obtained with single-vision spectacles, in myopic children. The risk of corneal staining after ortho-k wear may be slightly higher than that with spectacles, but could be well controlled.

Vision-related quality of life in children: Cross-cultural adaptation and test-retest reliability of the Danish version of the paediatric refractive error profile 2.

PURPOSE: To translate and cross-culturally adapt PREP2 into Danish and to investigate the face validity and reliability of Danish PREP2 through cognitive interviewing, Rasch and reliability analyses. METHODS: The Danish PREP2 was translated using a standardized procedure and then pretested following the Three-Steps-Interviews (TSTI) process. A total of 15 myopic children aged 7-14 wearing either orthokeratology lenses (ortho-k) or single-vision spectacles (SVS) were included in pretesting comprising cognitive interviews and Rasch analysis. Data from cognitive interviewing was analysed thematically according to Collins. Rasch analysis was used to pretest the psychometric properties in terms of person- and item-fit statistics. Reliability was assessed via test-retest using Intra-class correlation coefficient (ICC) in the CONTROL study population, which consisted of 60 Danish children aged 7-14 years wearing either ortho-k or SVS. RESULTS: Fifteen children participated in pilot studies comprising of cognitive interviewing and Rasch analysis and 44 out of 60 CONTROL children participated in test-retest reliability analysis. The translation process resulted in a Danish version of PREP2 corroborating the original. Pretesting highlighted issues in the contextualization of items and in marking responses. Thus, we introduced a digital format with help texts. Cognitive interviewing identified issues in the following Collins' themes: comprehension (understanding of concepts), judgement (ambiguity of items) and response (selecting answers). Rasch analysis indicated that help texts were useful for clarifying context. The ICC was 0.77 (95% CI: 0.66-0.85). CONCLUSIONS: The cross-cultural adaptation of PREP2 was satisfactory and issues were identified and corrected through pretesting. The test-retest reliability showed substantial consistency. The instrument could be validated in a more generalizable setting in future studies. TRIAL REGISTRATION: NCT03246464 (CONTROL study).

The effect of orthokeratology lenses on optical quality and visual function in children.

Purpose: To assess changes in optical quality and visual function in children after 3 months of wearing orthokeratology (OK) lenses. Methods: A total of 25 myopic children aged 8-12 years were recruited and completed the follow-up study. Optical quality, visual function and corneal morphology were assessed at baseline and at follow-ups 1 and 3 months after wearing OK lenses. Optical quality parameters mainly included the modulation transfer function (MTF) cutoff, objective scattering index (OSI), Strehl ratio (SR) and the predicted visual acuities (PVAs). Visual function was assessed by visual acuity, monocular contrast sensitivity function (CSF) across five spatial frequencies and the area under the log contrast sensitivity function (AULCSF) that was also computed as an index for overall CSF. Results: The MTF cutoff and SR values both increased after 1 month of wearing the OK lenses (baseline vs. 1 month: P MTF = 0.008 and P SR = 0.049); this improvement plateaued after 3 months of lens wear (1 month vs. 3 months: P MTF = 0.626, P SR = 0.428). The corneal morphology also showed the similar change trend. The OSI showed the opposite change trend (baseline vs. 1 month: P OSI < 0.001; 1 month vs. 3 months: P OSI = 0.720). The mean CSF at 1.5 cpd decreased significantly after 1 month of wearing the lenses (baseline vs. 1 month: p = 0.001) and recovered after 3 months of lens wear (baseline vs. 3 months: p = 0.076). CSF at spatial frequencies of 3, 6, 12 and 18 cpd as well as the AULCSF did not significantly differ between any two timepoints (all Ps > 0.05). Conclusion: After 3 months of wearing OK lenses, the subjects exhibited a decrease in optical quality, similar to corneal morphology, whereas their visual function remained largely unchanged. Thus, the optical quality was more susceptible to OK lenses than visual function in children. The initial month of OK treatment of children is a key period to be paid close attention to deterioration of optical quality and visual function.

Control of myopia using orthokeratology lenses in Scandinavian children aged 6 to 12 years. Eighteen-month data from the Danish Randomized Study: Clinical study Of Near-sightedness; TReatment with Orthokeratology Lenses (CONTROL study).

PURPOSE: To investigate the efficacy of myopia control defined by axial elongation and safety of orthokeratology lenses (OKL) in a Scandinavian (Danish) population. METHODS: Sixty Danish children aged 6-12 years with myopia ranging from 0.5 to 4.75 dioptres (D) spherical component and refractive astigmatism ≤2.5 D in both eyes were randomly assigned to either OKL or single-vision spectacles (SVS). Study duration was 18 months. Outcome measures were axial length (AL) measured with Lenstar LS900 (Haag-Streit, Koeniz, Switzerland) and adverse events graded with Efron Grading Scale for Contact Lens Complications. RESULTS: Nineteen participants completed the 18-month follow-up in the OKL group and 28 in the SVS group. The average AL elongation in the OKL group was 0.24 mm smaller as compared to the SVS group (95% confidence interval 0.12-0.36, mixed model adjusted for baseline sex, age and AL). There were no fast progressors (>0.75 D/year) in the OKL group during the follow-up period in contrast to 22% in the SVS group. No treatment-requiring or vision-threatening adverse events were observed. CONCLUSION: Orthokeratology lenses reduced AL elongation in myopic Scandinavian children by 59%, with no treatment-requiring or vision-threatening adverse events. The results align with outcomes of previous clinical trials.

Repeatability and inter-observer variation of choroidal thickness measurements using swept-source optical coherence tomography in myopic danish children aged 6-14 years.

PURPOSE: To estimate repeatability and inter-observer variation of choroidal thickness measurements in myopic Danish children aged 7-14 years using swept-source optical coherence tomography (SS-OCT). METHODS: Thirty-nine children were enrolled. Optical correction was single-vision spectacles (SVS) or orthokeratology lenses (OKL). Three repeated 7 × 7 mm 3-dimensional SS-OCT macula scans and three repeated 9 mm SS-OCT line scans were collected for each child using a DRI OCT Triton. Choroidal thickness was measured using three different methods: line scan method 1 (LM1), line scan method 2 (LM2) and 3D macula scan method (3DM). Segmentation was adjusted if needed. Coefficients of repeatability (CR) and limits of agreement (LoA) were calculated. RESULTS: The CRs ranged from 13.4 to 23.9 µm, 14.5 to 26.2 µm and 5.2 to 10.7 µm for LM1, LM2 and 3DM, respectively. The LoA ranged from -22.9 to +31.5 µm, -23.3 to +32.2 µm and -10.2 to +12.4 µm for LM1, LM2 and 3DM, respectively. Segmentation was adjusted in most scans (63%-92%). Mean choroidal thickness ranged from 142.2 ± 47.2 to 253.8 ± 60.9 µm and 190.1 ± 64.0 to 299.0 ± 55.8 µm for the SVS and OKL groups, respectively, measured by 3DM. CONCLUSION: The 3DM was the most repeatable method in this paediatric population. It yielded a CR of 10.7 µm, confidence interval 2.4 µm, which makes the minimal detectable difference between two measurements 13.1 µm. Most inter-observer variation could be explained by the intramethod variation. Segmentation adjustment on 3D macula scans did not increase CR on a group level.

Study on the control effect of orthokeratology lenses on children with differ-ent types of myopic anisometropia / 眼科新进展

Objective To explore the effect of the orthokeratology lenses on the control of different types of aniso-metropia in myopic children.Methods A total of 99 myopic children aged 8 to 16 years who got the orthokeratology len-ses at the Department of Ophthalmology,Heping Hospital Affiliated to Changzhi Medical College from September 2020 to November 2022 with complete data were included.These children were divided into the simple myopic anisometropia group(monocular myopia,binocular diopter difference ≥ 1.00 D,n=39)and the compound myopic anisometropia group(binoc-ular myopia,binocular diopter difference ≥ 1.00 D,n=60).The children with higher anisometropia(binocular diopter difference ≥ 2.50 D)in the two groups were set as the high anisometropia subgroup(n=18 and 29,respectively),and chil-dren with lower anisometropia(1.00 D≤ binocular diopter difference＜2.50 D)were set as the low anisometropia subgroup(n=21 and 31,respectively).In each group,eyes with a higher diopter were set as the high diopter eyes,and the contra-lateral eyes with a lower diopter were set as the low diopter eyes.Diopter,corneal topography,intraocular pressure,cor-neal endothelium and axial length of children in the two groups were examined and recorded.The changes in axial length before and after wearing orthokeratology lenses for 1 year were compared between the two groups,analyzing the correla-tion between the degree of anisometropia and changes in the binocular axial length.Results After wearing orthokeratolo-gy lenses for 1 year,children in both groups had an increase in the axial length with a lower increase in the axial length of the high diopter eyes compared to the low diopter eyes;before and 1 year after wearing orthokeratology lenses,the axial length of high diopter eyes was greater than that of the low diopter eyes in both groups,and the differences were statistical-ly significant(all P＜0.05).Both groups of children showed a decrease in the binocular axial length difference after wear-ing the orthokeratology lenses for 1 year;before and 1 year after wearing orthokeratology lenses,the binocular axial length difference of children in the simple myopic anisometropia group was greater than that in the compound myopic anisometro-pia group,and the differences were statistically significant(t=4.903 and 2.670;both P＜0.05).The changes in binocular axial length difference before and after wearing the orthokeratology lenses of children in the high anisometropia subgroup and low anisometropia subgroup of the simple myopic anisometropia group were greater than those in the high anisometro-pia subgroup and low anisometropia subgroup of the compound myopic anisometropia group,respectively,and the differ-ences were statistically significant(both P＜0.05).In the simple myopic anisometropia and compound myopic anisometro-pia groups,the degree of anisometropia was positively correlated with the binocular axial length changes before and 1 year after wearing the orthokeratology lenses(r=0.423 and 0.510,both P＜0.05).Conclusion Orthokeratology lenses can effectively reduce the difference in binocular axial length of children with myopic anisometropia,and their control effect on simple myopic anisometropia is better than that of compound myopic anisometropia.

Efficacies of different correction methods on adolescents with low-to-moderate unilateral myopia / 局解手术学杂志

Objective To compare the prevention and control effects of binocular myopia after wearing orthokeratology lenses or glasses for correction in adolescents with low-to-moderate unilateral myopia.Methods The clinical data of 46 adolescents with unilateral myopia treated in First Affiliated Hospital of Army Medical University were retrospectively analyzed,the patients were divided into the orthokeratology lenses group and spectacles group according to the correction methods,with 23 cases in each group.The axial length(AL),changes in spherical diopter(SD)and anisometropia between the myopic eye and the control eye with orthokeratology lenses spectacles for unilateral myopia correction,and orthokeratology lenses for unilateral and binocular myopia were compared.Results There was no significant difference in baseline AL,SD or anisometropia between the two groups(P>0.05).One year after unilateral myopia correction,the increase of SD for the myopic eye in the orthokeratology lenses group was less than that in the spectacles group(P<0.05),and there was no significant difference in the AL elongation of myopic eyes between the two groups(P>0.05);the elongation of AL for the control eyes in the orthokeratology lenses group was more than that in the spectacles group;the increase of SD for the myopic eyes in the orthokeratology lens group was lower than that in the spectacles group(P<0.05),and there was no significant difference in the increase of SD for the control eyes between the two groups(P>0.05);the anisometropia of patients in the orthokeratology lenses group was less than that in the spectacles group(P<0.05).The biological parameters of the eyes before and after wearing orthokeratology lenses in the patients with monocular and binocular myopia in the orthokeratology lens group were compared,the elongation of AL for the myopic eyes with lens in one eye was less than that with lenses in both eyes(P<0.05),and the elongation of AL for the control eye was more than that with lenses in both eyes(P<0.05),the increases of SD in both myopic eyes and control eyes were more than those with lenses in both eyes(P<0.05),and the anisotropia was more than that with lenses in both eyes(P<0.05).Conclusion Orthokeratology lenses is better than spectacles in controlling the increase of myopia in low-to-moderate unilateral myopia,which can reduce anisometropia between eyes.However,the AL of the emmetropic eye increases rapidly during unilateral myopia correction by orthokeratology lenses,and the progression of binocular myopia can be significantly delayed after wearing orthokeratology lenses.

Peripheral retinal defocus in myopic children wearing orthokeratology lenses / 眼科新进展

Objective To analyze the peripheral defocus of the retina in myopic children wearing orthokeratology lenses(OK lenses)using multispectral refraction topography(MRT).Methods A retrospective study was conducted.A total of 128 eyes of 128 myopic children(right eye)who got OK lenses in Ineye Hospital of Chengdu University of TCM from January to April 2021 were included.The steep keratometry(Ks),flat keratometry(Kf),eccentricity at the meridian of Ks and eccentricity at the meridian of Kf were measured by corneal topography before wearing OK lenses.The central corneal thickness before wearing OK lenses,baseline axial length(AL1)and axial length(AL2)after wearing OK lenses for 1 year were measured by optical biometer,and retinal defocus value(RDV)after wearing OK lenses for 1 year was meas-ured by MRT.According to the change in axial length(CAL)after wearing OK lenses for 1 year,subjects were divided into the SAL group(CAL≤0.3 mm)and LAL group(CAL＞0.3 mm).The peripheral RDV in the range of 0°-10°,＞10°-20°,＞20°-30°,＞30°-40°,and＞40°-53°(RDV0°-10°,RDV10°-20°,RDV20°-30°,RDV30°-40°,RDV40°-53°),av-erage RDV in the range of 0°-53°,and average RDVs in the superior,inferior,temporal and nasal quadrants(RDV-S,RDV-I,RDV-T and RDV-N)of both groups were compared after wearing OK lenses for 1 year.In addition,the effect of RDV in different peripheral retinal regions on AL growth was analyzed.Results After wearing OK lenses for 1 year,the peripheral RDV20°-30°,RDV30°-40°,RDV40°-53°,TRDV,RDV-I and RDV-T were higher in the LAL group than those in the SAL group(all P＜0.05).Correlation analysis showed that AL1 was negatively correlated with CAL(P＜0.05),whereas age,peripheral RDV0°-10°,RDV-S,RDV-N and other ocular biological parameters were not correlated with CAL(all P＞0.05).The peripheral RDV10°-20°,RDV20°-30°,RDV30°-40°,RDV40°-53°,TRDV,RDV-I and RDV-T were positively correlated with CAL(all P＜0.05).Conclusion Peripheral retinal defocus in the range of 10°-53° in myopic children is closely related to AL growth.The lower the RDV,the slower the AL growth.

Observation on the long - term effectiveness and safety of juvenile myopia patients wearing orthokeratology / 国际眼科杂志(Guoji Yanke Zazhi)

coefficient of variation, corneal endothelium hexagonal cell ratio, anterior corneal surface curvature ratio of horizontal(HK) and vertical curvature(VK) were not statistically significant before and after wearing for 6mo, 1, and 2a (P > 0. 05). The uncorrected visual acuity increased significantly, and the diopter decreased significantly after their wearing (P<0.05). There was no significant difference in axial length after wearing OK lens for 6mo,1,and 2a (P>0.05). CONCLUSION: The orthokeratology lenses can significantly increase uncorrected visual acuity and improve refractive power for juvenile myopia without severe corneal or conjunctival complications occurred, which has little influence on corneal endothelial cells and corneal thickness with a certain degree of safety.

Attempts to reduce the progression of myopia and spectacle prescriptions during childhood: a survey of eye specialists.

PURPOSE: To determine methods tried in clinical trials to reduce the progression of myopia in children, and spectacle prescribing patterns of hospital ophthalmologists. METHODS: A multi-sectioned survey composed of Likert items relating to the methods of reducing myopia progression (orthokeratology lenses [O-K lenses], undercorrected glasses, and topical atropine) and the patterns of prescribing spectacles for children (including two cases involving a 5-year-old girl and an 8-year-old boy) were distributed to members of the Korean Ophthalmological Society, and the collected data was statistically analyzed. RESULTS: A total of 78 out of 130 ophthalmologists returned the survey. On a scale of 1 to 5, the mean rates of whether the ophthalmologists think O-K lenses arrest myopia progression, and whether they recommend their patients to wear O-K lenses if indicative, were 3.06 and 2.75, respectively. Moreover, the mean rates of whether they consider that wearing glasses which are undercorrected would slow down the progression of the myopia, or if they think topical atropine helps in arresting myopia progression in children, were 2.34 and 1.27, respectively. In response to the case studies, the majority of practitioners preferred to prescribe the full amount found in cycloplegic refraction to pediatric patients with myopia. CONCLUSIONS: Ophthalmologists in clinical practice encouraged children to wear O-K lenses more than undercorrected glasses as a way to retard myopia progression. However, the application of atropine is rarely tried in clinical trials. In managing pediatric patients with myopia (case specific), the majority of the practitioners chose to prescribe glasses with full cycloplegic correction.

Effect of Toric Orthokeratology Lenses in Patients with Limbus to Limbus Corneal Astigmatism

PURPOSE: To report the efficacy of toric orthokeratology lenses in patients with astigmatism within 1.5 D having difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. METHODS: Twenty-three eyes of 16 patients with limbus-to-limbus corneal astigmatism who had been wearing toric orthokeratology lenses for more than 6 months were recruited. The uncorrected visual acuity (UCVA), refractive error, and keratometric changes including eccentricity before and after wearing lenses were compared, and the correlations between corneal astigmatism as well as refractive astigmatism and lens toricity were assessed. RESULTS: After wearing the lens, UCVA (log MAR) significantly improved from 0.61 +/- 0.22 to 0.05 +/- 0.08 (p < 0.001). Myopia and spherical equivalent were also reduced significantly (p < 0.001 and p < 0.001, respectively). While Simulated K (Sim K) tended to be more flattened (p < 0.001) and the eccentricity showed significant decrease (p < 0.001), corneal and refractive astigmatism were not changed significantly (p = 0.330 and p = 0.124, respectively). Correlations between corneal and refractive astigmatism and lens toricity were not statistically significant (r = 0.244, p = 0.300; r = -0.051, p = 0.832). No patients showed lens decentration or visual discomfort. CONCLUSIONS: Corneal topography was essential in patients who had difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Toric orthokeratology lenses may be an effective treatment option in patients with limbus-to-limbus corneal astigmatism.

Effect of Toric Orthokeratology Lenses in Patients with Limbus to Limbus Corneal Astigmatism

PURPOSE: To report the efficacy of toric orthokeratology lenses in patients with astigmatism within 1.5 D having difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. METHODS: Twenty-three eyes of 16 patients with limbus-to-limbus corneal astigmatism who had been wearing toric orthokeratology lenses for more than 6 months were recruited. The uncorrected visual acuity (UCVA), refractive error, and keratometric changes including eccentricity before and after wearing lenses were compared, and the correlations between corneal astigmatism as well as refractive astigmatism and lens toricity were assessed. RESULTS: After wearing the lens, UCVA (log MAR) significantly improved from 0.61 +/- 0.22 to 0.05 +/- 0.08 (p < 0.001). Myopia and spherical equivalent were also reduced significantly (p < 0.001 and p < 0.001, respectively). While Simulated K (Sim K) tended to be more flattened (p < 0.001) and the eccentricity showed significant decrease (p < 0.001), corneal and refractive astigmatism were not changed significantly (p = 0.330 and p = 0.124, respectively). Correlations between corneal and refractive astigmatism and lens toricity were not statistically significant (r = 0.244, p = 0.300; r = -0.051, p = 0.832). No patients showed lens decentration or visual discomfort. CONCLUSIONS: Corneal topography was essential in patients who had difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Toric orthokeratology lenses may be an effective treatment option in patients with limbus-to-limbus corneal astigmatism.

Correction of Limbus-to-Limbus Corneal Astigmatism with Toric Orthokeratology Lenses

PURPOSE: To report the efficacy of toric orthokeratology lenses in a patient with corneal astigmatism within 1.5 D having difficulty wearing spherical orthokeratology lenses because of limbus-to-limbus corneal astigmatism. CASE SUMMARY: An 11-year-old boy who wanted to wear orthokeratology lenses had a refractive error of -4.75 D sph = -1.00 D cyl 180 in the right eye and -4.50 D sph = -1.25 D cyl 180 in the left eye. The corneal astigmatism was 1.19 D and 1.19 D, respectively, and limbus-to-limbus corneal astigmatism was observed in topography. After wearing spherical orthokeratology lenses, the patient complained of monocular diplopia and both lenses were found to be displaced nasally. Toric orthokeratology lenses were prescribed for centration of lenses and resulted in significant improvement of uncorrected visual acuity of 20/20, refractive error of +0.75 D sph = -0.50 D cyl 170 in the right eye and +0.50 D sph = -0.50 D cyl 160 in the left eye, and centration of lenses for the 12-month follow-up period. CONCLUSIONS: Toric orthokeratology lenses should be considered if spherical orthokeratology lenses are not effective even in patients having less than 1.5 D of corneal astigmatism because of limbus-to-limbus corneal astigmatism.