Orthokeratology Research Articles

Difference in choroidal thickness of Danish children, after treatment with Ortho-k measured using Swept-source OCT

Purpose: The purpose of this study was to investigate, whether there was a difference in choroidal thickness on Danish Caucasian children wearing ortho-k(OK) and single vision lenses (SVL). Furthermore, if there was a difference in choroidal thickness between sex, and if there was a correlation on choroidal thickness for age and spherical equivalent.

Comparative analysis of treatment zone diameter, location and amount of maximum defocus and pupil size with orthokeratology

Purpose: The purpose of this study was to retrospectively examine data from young patients who had undergone orthokeratology (OK) for myopia control to quantify the size and amount of central (treatment zone) and mid-perpheral (reverse zone) total refractive power (TRP) changes and compare where these changes occur with respect to the pupil size (PS) and location.

Orthokeratology and Low-Intensity Laser Therapy for Slowing the Progression of Myopia in Children.

Orthokeratology (OK) is widely used to slow the progression of myopia. Low-level laser therapy (LLLT) provides sufficient low energy to change the cellular function. This research is aimed at verifying the hypothesis that LLLT treatment could control myopia progression and comparing the abilities of OK lenses and LLLT to control the refractive error of myopia. Eighty-one children (81 eyes) who wore OK lenses, 74 children (74 eyes) who underwent LLLT treatment, and 74 children (74 eyes) who wore single-vision distance spectacles for 6 months were included. Changes in axial length (AL) were 0.23 ± 0.06 mm for children wearing spectacles, 0.06 ± 0.15 mm for children wearing OK lens, and −0.06 ± 0.15 mm for children treated with LLLT for 6 months. Changes in subfoveal choroidal thickness (SFChT) observed at the 6-month examination were −16.84 ± 7.85 μm, 14.98 ± 22.50 μm, and 35.30 ± 31.75 μm for the control group, OK group, and LLLT group, respectively. Increases in AL at 1 month and 6 months were significantly associated with age at LLLT treatment. Changes in AL were significantly correlated with the baseline spherical equivalent refraction (SER) and baseline AL in the OK and LLLT groups. Increases in SFChT at 1 month and 6 months were positively associated with age at enrolment for children wearing OK lens. At 6 months, axial elongation had decelerated in OK lens-wearers and LLLT-treated children. Slightly better myopia control was observed with LLLT treatment than with overnight OK lens-wearing. Evaluations of age, SER, and AL can enhance screening for high-risk myopia, improve the myopia prognosis, and help determine suitable control methods yielding the most benefits.

Multifocal Orthokeratology versus Conventional Orthokeratology for Myopia Control: A Paired-Eye Study

We conducted a prospective, paired-eye, investigator masked study in 30 children with myopia (−1.25 D to −4.00 D; age 10 to 14 years) to test the efficacy of a novel multifocal orthokeratology (MOK) lens compared to conventional orthokeratology (OK) in slowing axial eye growth. The MOK lens molded a center-distance, multifocal surface onto the anterior cornea, with a concentric treatment zone power of +2.50 D. Children wore an MOK lens in one eye and a conventional OK lens in the fellow eye nightly for 18 months. Eye growth was monitored with non-contact ocular biometry. Over 18 months, MOK-treated eyes showed significantly less axial expansion than OK-treated eyes (axial length change: MOK 0.173 mm less than OK; p < 0.01), and inner axial length (posterior cornea to anterior sclera change: MOK 0.156 mm less than OK, p < 0.01). The reduced elongation was constant across different baseline progression rates (range −0.50 D/year to −2.00 D/year). Visual acuity was less in MOK vs. OK-treated eyes (e.g., at six months, MOK: 0.09 ± 0.01 vs. OK: 0.02 ± 0.01 logMAR; p = 0.01). We conclude that MOK lenses significantly reduce eye growth compared to conventional OK lenses over 18 months.

Comparison of the Clinical Efficacies of 0.01% Atropine and Orthokeratology in Controlling the Progression of Myopia in Children

ABSTRACT Purpose : To compare the clinical efficacies of 0.01% atropine and orthokeratology (OK) in slowing the development of myopia, and to evaluate their effects on basal tear secretion and tear film stability. Methods : A prospectively, randomised study. A total of 120 children aged 8–14 years with myopia were included; of these, 60 participants were randomly assigned to use spectacles and 0.01% atropine (SA) and the remaining 60 wore OK lenses (OK). Comprehensive ophthalmologic examinations were performed before and after treatment every 3 months. Results : The primary outcomes include the changes of spherical equivalent refraction (SE) and axial length (AL). After one-year, the SE and AL in participants aged ≤10 years were better controlled in the SA in low-myopia group (P < .05), whereas those aged ≥11 years were better controlled in the OK in high-myopia group (P < .05). Secondary outcomes include Schirmer’s test and tear film break-up time (TBuT). A statistically significant difference was found in TBuT between the SA and OK in the first 3 months and there was a statistically significant difference in TBuT in the OK between before and after 3 months; however, no statistically significant difference was observed after 6 months. Conclusion : Both 0.01% atropine and OK lenses effectively retarded myopia progression; however, different effects were found in different ages and refractions. 0.01% atropine had no evident effect on Schirmer’s test and TBuT results. Furthermore, OK lenses had no effect on Schirmer’s test, whereas it had a significant effect on TBuT after only the first 3 months.

The Role of Back Optic Zone Diameter in Myopia Control with Orthokeratology Lenses.

We compared the efficacy of controlling the annual increase in axial length (AL) in myopic Caucasian children based on two parameters: the back optic zone diameter (BOZD) of the orthokeratology (OK) lens and plus power ring diameter (PPRD) or mid-peripheral annular ring of corneal steepening. Data from 71 myopic patients (mean age, 13.34 ± 1.38 years; range, 10–15 years; 64% male) corrected with different BOZD OK lenses (DRL, Precilens) were collected retrospectively from a Spanish optometric clinic. The sample was divided into groups with BOZDs above or below 5.00 mm and the induced PPRD above or below 4.5 mm, and the relation to AL and refractive progression at 12 months was analyzed. Three subgroups were analyzed, i.e., plus power ring (PPR) inside, outside, or matching the pupil. The mean baseline myopia was −3.11 ± 1.46 D and the AL 24.65 ± 0.88 mm. Significant (p < 0.001) differences were found after 12 months of treatment in the refractive error and AL for the BOZD and PPRD. AL changes in subjects with smaller BOZDs decreased significantly regarding larger diameters (0.09 ± 0.12 and 0.15 ± 0.11 mm, respectively); in subjects with a horizontal sector of PPRD falling inside the pupil, the AL increased less (p = 0.035) than matching or outside the pupil groups by 0.04 ± 0.10 mm, 0.10 ± 0.11 mm, and 0.17 ± 0.12 mm, respectively. This means a 76% lesser AL growth or 0.13 mm/year in absolute reduction. OK corneal parameters can be modified by changing the OK lens designs, which affects myopia progression and AL elongation. Smaller BOZD induces a reduced PPRDs that slows AL elongation better than standard OK lenses. Further investigations should elucidate the effect of pupillary diameter, PPRD, and power change on myopia control.

Effects of orthokeratology lenses and frame glasses on anisometropia in primary and middle school students with low myopia in one eye

Objective To investigate the effects of orthokeratology lenses and frame glasses on anisometropia in children with low myopia in one eye. Methods Between January 2017 and January 2018, 120 children of primary and secondary school age with myopic anisometropia low myopia in one eye presenting to the Second People’s Hospital of Yunnan Province were selected as research objects, with average refractive error of (–1.00, –2.50) D in one eye and (–0.50, 0.50) D in another eye. Participants were divided into an experimental group and a control group (60 cases per group), according to a random number grouping method. The control group were given frame glasses, while the experimental group were given orthokeratology lenses. A prospective study was conducted to compare and analyze the lengths of the posterior eye axis (AL) and spherical equivalent (SE), measured at different time intervals between the two groups. Results There were some initial differences in AL and SE between the two groups before the experiment began; however, this difference was not statistically significant ( P >0.05). After 12 months, participants myopic eyes given the orthokeratology lenses had shorter AL [(24.91±0.11) mm] compared to the control group [(25.02±0.09) mm], participants health eyes had longer AL [(24.58±0.24) mm] compared to the control group [(24.20±0.13) mm]. One month after the subjects stopped wearing plastic mirrors, participants myopic eyes had higher SE [(–2.22±0.78) D] compared to the control group [(–2.64土 0.21) D], and had lower that in the control group [(–0.96±0.84) (–0.37±0.54) D] ( t = 4.02, –4.58, P 0.05);配戴12个月后, 试验组戴镜眼AL[(24.91±0.11)mm]较对照组 [(25.02±0.09)mm]短, 对侧眼AL [(24.58±0.24) mm]较对照组[(24.20±0.13) mm]长。停戴塑形镜1月后, 试验组戴镜眼 SE[(–2.22±0.78)D]较对照组[(–2.64±0.21)D]高, 对侧眼 SE [(–0.96±0.84)D]较对照组[(–0.37±0.54) D]低, 差异均有 统计学意义（ t 值分别为4.02, –4.58, P 值均<0.05)。 结论 与佩戴框架镜相比, 配戴角膜塑形镜可有效抑制单眼近视患儿 患眼AL延长、控制患眼近视进展, 促进对侧健眼眼轴延长及屈光度增加, 降低屈光参差值, 在一定程度上解决双眼视轴发 育不平衡的问题, 促进双眼协调发展。

Repeatability of pupil size measurements with NIDEK OPD‐Scan III in myopic children

AbstractObjectiveTo investigate the repeatability of pupil size measurements, determined from the NIDEK OPD‐Scan III, of myopic eyes in children wearing single‐vision spectacles (SVS), undergoing orthokeratology (OK) and receiving combined treatment of 0.01% atropine and orthokeratology (AOK).MethodsA single examiner took two sets of mesopic pupil size measurements from the right eyes of 80 children (SVS:16, OK: 34, AOK: 30) (mesopic 1 and mesopic 2) and two sets of photopic (photopic 1 and photopic 2) pupil size measurements (internal light source) using the NIDEK OPD‐Scan III. Each set was taken at a single visit, 15 min apart. Subjects in the OK and AOK groups had undergone treatment for at least 6 months, and the SVS subjects had no previous myopia treatment other than wearing spectacles. Repeatability of measurements was analysed using intraclass correlation coefficient (ICC), Bland‐Altman (BA) plot, and coefficient of repeatability (CoR).ResultsMesopic 1 and 2 values were not significantly different among the three groups (p = 0.56, 0.77), hence the data were pooled for each set of measurements (mean [±S.D.] values were 7.09 ± 0.61 and 7.12 ± 0.61 mm, respectively) for further analyses. ICC for repeated mesopic pupil size measurements was 0.98 (95% CI, 0.98–0.99). No significant correlation was found between the means of the mesopic 1 and 2 measurements and their differences (Pearson's r = −0.02, p = 0.83). A BA plot also demonstrated narrow 95% limits of agreement, with a CoR of 0.28 mm.Mean photopic 1 and 2 measurements for the AOK group (3.74 ± 0.46; 3.73 ± 0.43 mm, respectively) were significantly larger (p = 0.01; 0.009) than those of the SVS and OK groups, but no significant difference was found between the latter two groups (p &gt; 0.05). Hence, photopic 1 and 2 measurements for the SVS and OK groups were pooled (SVS‐OK) for further analyses. ICC for repeatability of the photopic measurements was 0.98 (95% CI, 0.96 to 0.99) for the SVS‐OK and AOK groups. The differences between photopic 1 and 2 measurements were not significantly correlated with their means, either in the AOK group (Pearson's r = −0.25, p = 0.19), or in the pooled SVS‐OK group (Pearson's r = −0.04, p = 0.78). BA plots also showed narrow 95% limits of agreement, and CoR was 0.25 mm and 0.23 mm in the AOK and pooled SVS‐OK groups, respectively.ConclusionMesopic and photopic pupil size measurement using the NIDEK OPD‐Scan III was highly repeatable and suitable for use on children.

Clinical efficacy of 0.01% atropine in retarding the progression of myopia in children

PurposeTo investigate the clinical efficacy of 0.01% atropine in slowing the progression of myopia in children and to evaluate the influence of 0.01% atropine on secretion of basal tear and stability of tear film.MethodsEighty children aged 5–14 years with myopia, 40 were randomly divided into two groups consisting of those who received spectacles in addition to 0.01% atropine (SA group) and those who received only spectacles (S group). The remaining 40 children who were wearing orthokeratology (OK) lenses for 3 months were randomly divided into two groups comprising those who received OK lenses in addition to 0.01% atropine (OKA group) and those who received only OK lenses (OK group). Comprehensive ophthalmologic examinations, including slit-lamp examination, visual acuity testing, autorefraction, intraocular pressure, axial length (AL), corneal topography, Schirmer’s test, and tear film break-up time (TBuT), were performed before treatment and after every 3 months treatment.ResultsDuring the follow-up visits, evidently better spherical equivalent (SE) control over 3, 6 and 12 months was observed in the SA and OKA groups compared with the S and OK groups. The AL over 3, 6, and 12 months was evidently inhibited in the SA and OKA groups compared with the S and OK groups. No statistically significant differences in Schirmer’s test and TBuT results were observed between the S and SA groups and between the OK and OKA groups. However, statistically significant differences were found in TBuT results between before treatment and after 3 months treatment in the OK group (P < 0.05, paired t test) and the OKA group (P < 0.05, paired t test).Conclusions0.01% atropine can effectively control myopia progression and axial elongation regardless of combined treatment with spectacles or OK lenses. And 0.01% atropine has no evident effect on Schirmer’s test and TBuT results; however, researchers also found that Schirmer’s test and TBuT results showed a tendency to reduce after treatment with 0.01% atropine.

The Impact of Overnight Orthokeratology on Accommodative Response in Myopic Subjects.

This study aimed to evaluate the effects of two months of orthokeratology (OK) treatment in the accommodative response of young adult myopes. Twenty eyes (21.8 ± 1.8 years) were fitted with the Paragon CRT® 100 LENS to treat myopia between −1.00 and −2.00 D. Low- and high-contrast visual acuity (LCDVA and HCDVA), central objective refraction, light disturbance (LD), and objective accommodative response (using the Grand Seiko WAM-5500 open-field autorefractometer coupled with a Badal system) were measured at baseline (BL) before lens wear and after 1, 15, 30, and 60 nights of OK. Refractive error correction was achieved during the first fifty days of OK lens wear, with minimal changes afterwards. LD analysis showed a transient increase followed by a reduction to baseline levels over the first 30 nights of treatment. The accommodative response was lower than expected for all target vergences in all visits (BL: 0.61 D at 1.00 D to 0.96 D at 5.00 D; 60 N: 0.36 D at 1.00 D to 0.79 D at 5.00 D). On average, the accommodative lag decreases over time with OK lens wear. However, these differences were not statistically significant (p > 0.050, repeated-measures ANOVA and Friedman test). This shows that overnight OK treatment does not affect objectively measured the accommodative response of young, low myopic eyes after two months of treatment stabilization.

Structural changes associated to orthokeratology: A systematic review

PurposeTo summarize the peer-reviewed literature on corneal structural changes after orthokeratology (OK) and to analyze the quality of the studies published. MethodsAn exhaustive search was carried out in the databases Pubmed MEDLINE, Web of Science and Scopus. Original studies in English, with a cohort or experimental design and analyzing the cellular and structural changes of the cornea after OK fitting for myopia correction were selected. The NewCastle-Ottawa Assessment Scale (NOS) tool was used to analyze the quality of the studies selected. ResultsThe search provided a total of 1837 articles, of which 12 were selected following the inclusion and exclusion criteria. All studies had good quality according to the NOS tool (mean 7.58 ± 1.31). The mean ± standard deviation follow-up period of lens wear in the studies evaluated was 19.27 ± 33.97 months. The following reversible changes after OK have been reported: reduction in central epithelial basal cells, an increase in height and especially in width of superficial epithelial cells, as well as an increase in central stromal thickness and in the number of active keratocytes. Concerning corneal endothelium, only changes in terms of polymegathism were reported that were compatible with those observed for other types of contact lens wear. In relation to corneal sensitivity, there was a reduction during the use of OK, as well as in the nervous density of the sub-basal plexus at the central level, with some contradictory outcomes concerning the reversibility of these changes. ConclusionOK produces reversible structural changes in the central epithelium and central anterior corneal stroma, as well as a decrease in the nerve density of the sub-basal plexus and corneal sensitivity. The quality of published studies evaluating these aspects is good, although more studies are needed to evaluate longer follow-up changes.

Practice of orthokeratology in Algeria: a retrospective study

PurposeTo report the practice of orthokeratology (OK) in Algeria and to investigate the visual outcomes, safety and subjective responses with this technique in myopes. MethodsA retrospective chart review of 48 participants using OK lenses since January 2010 were included in the study. Lenses were selected and fitted according to the manufacturer’s recommendations using their respective software and the number of lenses required for a successful fit was recorded. Visual acuity (VA) in logMAR units and biomicroscopic findings were recorded for each visit. Subjective ratings was determined with analogue rating scale was filled in by the investigator, the participants were divided into Group 1 (> 4.00D) and Group 2 (< 3.75D) myopic groups for analysis. ResultsFirst lens fitting success rate of 64.58%. There was also a significant difference between the BCVA at baseline and VA at Day 1 (P < 0.05), and no significant difference at Day 7, Day 30 and the final visit (P = 0.51, P = 0.93, P = 0.62, respectively), for Group 2. There was a significant difference between the BCVA at baseline and VA at Day 1, 7, 30 and the final visit (P < 0.05), for Group 1. the patients of the second group were happier but the results from the survey were not statistically significant (P = 0.10), no serious complication was reported. Conclusionthe technique was efficient and safe as we didn’t have any serious complication, with a high success rate for first lens fitting.

Retinal Response of Low Myopes during Orthokeratology Treatment.

The aim of this study was to evaluate the changes in retinal activity during orthokeratology (OK) treatment in 20 myopic eyes. Pattern electroretinography (PERG) and visual evoked potential (VEP) were assessed with the RETI-port/scan21 (Roland Consult, Wiesbaden, Germany). Measurements were taken at baseline (BL) and 1 night (1N), 15 nights (15N), 30 nights (30N), and 60 nights (60N) of OK lens wear. Repeated measures analysis of variance (ANOVA) and the Friedman test were used. Twenty eyes (23.20 ± 3.46 years, 70% female) with visual acuity ≤ 0.00 logMAR in post-treatment showed that despite a slight increase in retinal and cortical response amplitude, observed with both PERG and VEP, respectively, immediately after the initial treatment, these differences found were not statistically significant during the 60 days of OK treatment, despite a statistically significant increase in N95 response with PERG. This shows that retinal and cortical visual-related electrical activity is maintained or slightly increased during OK treatment.

Combined Orthokeratology with Atropine for Children with Myopia: A Meta-Analysis

Background: Myopia has become a worldwide public health issue, which is occurring at a younger age, leading to an increased risk of high myopia. Ocular complications associated with high myopia can lead to irreversible vision loss. It is urgent and critical to explore effective treatment to slow down or even stop the progression of myopia in young children. Objective: The aim of the study was to evaluate the additive effects of orthokeratology (OK) and 0.01% atropine ophthalmic solution for myopia in children. Methods: We searched PubMed, Cochrane Library, EMBASE, MEDLINE, Web of science, Ovid, EBSCO host, CNKI, and CBM to collect eligible studies. Efficacy and safety were evaluated in terms of the axial length (AL), uncorrected distant visual acuity (UCVA), corneal endothelial cell density (CECD), and intraocular pressure (IOP). We calculated the weighted mean difference (WMD) and the 95% confidence intervals (CIs) of all outcomes and plotted on forest plots. Results: Four studies were ultimately included, involving a total of 267 subjects. This meta-analysis revealed that the mean AL of the subjects in the experimental group was 0.09 mm less than that of subjects in the control group (WMD = −0.09, 95% CI [−0.15, −0.03], p = 0.003). There was no significant difference in UCVA, CECD, and IOP between the 2 groups (WMD was −0.01 [95% CI: −0.03, 0.01], 11.75 [95% CI: −4.09, 27.58], 0.12 [95% CI: −0.40, 0.63], respectively). None of the studies reported severe adverse events. Conclusion: Our study suggests that the combination of OK and 0.01% atropine is more effective in slowing axial elongation than OK monotherapy in children with myopia in a relatively short duration of treatment. In addition, the combination therapy has no negative influence on UCVA, CECD, and IOP.

Efficacy of combined orthokeratology and 0.01% atropine solution for slowing axial elongation in children with myopia: a 2-year randomised trial

Eighty Japanese children, aged 8–12 years, with a spherical equivalent refraction (SER) of − 1.00 to − 6.00 dioptres (D) were randomly allocated into two groups to receive either a combination of orthokeratology (OK) and 0.01% atropine solution (combination group) or monotherapy with OK (monotherapy group). Seventy-three subjects completed the 2-year study. Over the 2 years, axial length increased by 0.29 ± 0.20 mm (n = 38) and 0.40 ± 0.23 mm (n = 35) in the combination and monotherapy groups, respectively (P = 0.03). Interactions between combination treatment and age or SER did not reach significance level (age, P = 0.18; SER, P = 0.06). In the subgroup of subjects with an initial SER of − 1.00 to − 3.00 D, axial length increased by 0.30 ± 0.22 mm (n = 27) and 0.48 ± 0.22 mm (n = 23) in the combination and monotherapy groups, respectively (P = 0.005). In the − 3.01 to − 6.00 D subgroup, axial length increased by 0.27 ± 0.15 mm (n = 11) and 0.25 ± 0.17 mm (n = 12) in the combination and monotherapy groups, respectively (P = 0.74). The combination therapy may be effective for slowing axial elongation, especially in children with low initial myopia.

Short-term effects of atropine combined with orthokeratology (ACO) on choroidal thickness

PurposeTo analyse the one-month change in subfoveal choroidal thickness (SFChT) of myopic children treated with 0.01 % atropine, orthokeratology (OK), or their combination. MethodsThis is a prospective, randomized controlled trial. One hundred fifty-four children aged between 8 and 12 years with a spherical equivalent (SE) of -1.00 to -6.00 diopters were enrolled. Subjects were randomly assigned to receive 0.01 % atropine and orthokeratology (ACO, n = 39), 0.01 % atropine and single vision glasses (atropine, n = 42), orthokeratology and placebo (OK, n = 36), or placebo and single vision glasses (control, n = 37). SFChT was assessed using optical coherence tomography (OCT). Ocular parameters, including axial length (AL), were measured using a Lenstar LS 900. ResultsSFChT significantly increased in the ACO (14.12 ± 12.88 μm, p < 0.001), OK (9.43 ± 9.14 μm, p < 0.001) and atropine (5.49 ± 9.38 μm, p < 0.001) groups, while it significantly decreased in the control group (-4.81 ± 9.93 μm, p = 0.006). The one-month change in SFChT was significantly different between the control and treatment groups (p < 0.001). The results of pairwise comparisons among the treatment groups showed that the magnitude of the SFChT change was larger in the ACO group than in the atropine group (p = 0.002). The changes in the ACO and OK groups were not significantly different (p = 0.326). ConclusionThe combination of OK and atropine induced a greater increase in SFChT than monotherapy with atropine, which might indicate a better treatment effect for childhood myopia control.

Thickness profiles of the corneal epithelium along the steep and flat meridians of astigmatic corneas after orthokeratology

BackgroundThe aim of this study was to investigate the changes in corneal epithelial thickness along the principle meridians of astigmatic corneas after six months of overnight spherical myopic orthokeratology (OK) lens wear.MethodsThis is a prospective study. Fifty-seven subjects with up to 1.50 diopters (D) of corneal toricity wore spherical OK lenses for 6 months. Evaluations of OK lens fit, visual acuity, refractions and corneal toricity (CT) were performed. Fourier-domain optical coherence tomography (FD-OCT) was conducted to measure the corneal epithelial thickness (ET) along the principle meridians of corneal toricity over a diameter of 6 mm. The means of △ET of the same diameter at individual meridians (△ETSm and △ETFm) were calculated and compared.ResultsVisual acuity and refraction improved significantly after OK lens wear. △ETFm thinned more than △ETSm (P = 0.027) at 1.5 mm in radius. △ETSm thickened more than △ETFm at 2.5 mm (P = 0.019) and 3.0 mm (P = 0.036).∣△ETSm - △ETFm∣ were significantly correlated with the baseline central CT at 2.0 mm, 2.5 mm and 3.0 mm. ∣△ETSm - △ETFm∣was significantly correlated with the baseline peripheral CT at 2.5 mm.ConclusionsOvernight wear of spherical OK lenses resulted in differential changes in the thickness profiles of the corneal epithelium between the steep and flat meridians in eyes with corneal toricity.

Myopia Control: A Citation Network Study

Background: According to the World Health Organization, myopia is already one of the major causes of vision impairment and blindness. It is predicted to affect almost a half of the world's population within the next years. A lot of researches around the world have been performed on myopia, there is no clear overview of these researchers. In this manuscript, we analyzed the main connections between the most cited researchers, to build a citation network to evaluate the impact of different authors, journals, and subjects in the field of myopia control. Methods: A search using the keywords “myopia control” was made through Web of Science. Extracted data was analyzed using CitNetExplorer® software obtaining a visual evaluation of the most cited publications. A subnet analysis was made by adding the keywords “myopia control" AND ("orthokeratology" OR "corneal refractive therapy”), “myopia control" AND ("soft contact lens*" OR "multifocal contact lens*”), and “myopia control" AND "atropine”. The most important publications of the network and subnetworks were analyzed using the "core" function. Results: This study showed 228 references that generated 1087 citations across the network. 2013 was the most important year for myopia control, with most publications and citations. Optometry and Vision Science journal has published the most cited papers. Regarding the authors, Walline ranked the first of the most cited articles on myopia control. Conclusion: This study analyzed the associations between the authors, journals and subjects in myopia control, highlighting the great importance of this area in the recent years. More than 50% of the papers in the network were published after 2013.

Two-dimensional peripheral refraction and retinal image quality in orthokeratology lens wearers.

Orthokeratology (O-K) is a common procedure that uses rigid contact lenses to reshape the cornea while worn overnight. Beyond the correction of refractive error, it has been suggested that this approach can also be used to reduce myopia progression, possibly because it induces changes in peripheral optics. As this hypothesis remains unproven, the aim of the present study was to explore changes in peripheral retinal optical quality in a group of myopic children following O-K treatment. We provide a comprehensive description of optical characteristics in a group of myopes before and after achieving stable corneal reshaping using overnight O-K lenses. These characteristics extended across the central visual field (60° horizontal x 36° vertical) as measured with a custom Hartmman-Shack wavefront sensor. After corneal reshaping, peripheral refraction was found to be asymmetrically distributed, with a myopic relative refraction of approximately 3D in the temporal retina. Astigmatism and higher order aberrations also increased in the temporal side. Based on corneal topography following treatment, subjects were divided into two groups: Centred Treatment (CT, decentration ∈ [-0.5 + 0.5] mm) and Slightly Decentred Treatment (subjects with more decentred lenses). The process was also modelled by ray-tracing simulation. The results indicate that increased myopia in the temporal retina is caused by the decentration of lenses towards the temporal side. Peripheral optics differ significantly following O-K lens treatment, but further research is required to determine whether this is likely to affect myopia progression.

Mid-peripheral corneal steepening after orthokeratology

Purpose:&#x0D; The purpose of this study was to retrospectively examine data from patients who had undergone orthokeratology (OK) to quantify the amount of mid-perpheral steeping in tangential curvature (MP-TC) and total refractive power (TRP) changes.&#x0D; Methods:&#x0D; Charts were reviewed from participants and data from the Pentacam instrument were collected prior to OK and after the final visit. Variables included central flattening (C-TC), the e-value, the mid-peripheral tangential curvatures (MP-TC), total corneal refractive power (TRP), the initial Rx (sphere) and initial corneal curvature (flat K). The group was further subdivided into high and low myopia for comparison. All participants were fitted with the Paragon CRT lenses. Data analysis was conducted to analyse the effects of lenses on TC and TRP.&#x0D; Results:&#x0D; A total of 40 patients (80 eyes) age13.95±6.80, 34 M and 46 F, were successfully fitted with CRT lenses. The average sphere was -4.23±0.90D for Group 1 and -1.89±0.62D for Group 2 The changes in TC and TRP from baseline were significant (both P&lt;0.0001). The difference between the amount of C-TC and the maximum area of MPTC was ≈4.00D in the horizontal meridian and ≈3.00 in the veritcal meridian. The amount of MP-TC change from baseline was ≈2.00D in both meridians. There was a similar change in TRP: the distance from the centre to mid-periphery ≈2.50D. For C-TC, C-TRP, MP-TC, MP-TRP there was no significant difference between the 2 groups, overall (P=0.541 (TC) and P=0.321(TRP)).&#x0D; Conclusion:&#x0D; Results from this study should provide valuable insights into the topographic and refractive changes occurring with orthokeratology.