Interocular Axial Length Difference Research Articles

Relative corneal refractive power shift and inter-eye differential axial growth in children with myopic anisometropia treated with bilateral orthokeratology

PurposeTo investigate the relationship between relative corneal refractive power shift (RCRPS) and axial length growth (ALG) in bilateral myopic anisometropes treated with orthokeratology.MethodsA total of 102 children with myopic anisometropia in this prospective interventional study were randomly assigned to the spectacle group and orthokeratology group. Axial length (AL) and corneal topography was measured at baseline and the 12-month follow-up visit. ALG was defined as the difference between the two measurements, and RCRPS profiles were calculated from two axial maps obtained.ResultsIn the orthokeratology group, the ALG in the more myopic eye (0.06 ± 0.15 mm) was significantly smaller than that in the less myopic eye (0.15 ± 0.15 mm, p < 0.001), and the interocular difference in AL significantly decreased following 1-year treatment, from 0.47 ± 0.32 to 0.38 ± 0.28 mm (p < 0.001). However, in the spectacle group, the ALG was similar between the two eyes, and the interocular difference in AL did not change significantly over one year (all p > 0.05). The interocular difference in ALG in the orthokeratology group was significantly correlated with the interocular difference in RCRPS (dRCRPS, β=−0.003, p < 0.001) and the interocular difference in baseline AL (β=−0.1179, p < 0.001), with R2 being 0.6197.ConclusionOrthokeratology was effective in decreasing the magnitude of anisometropia. The interocular variation in RCRPS is an important factor accounting for the reduction of interocular ALG difference in anisomyopic children post-orthokeratology. These results provide insight into establishing eye-specific myopia control guidelines during orthokeratology treatment for myopic anisometropes.

Changes in axial length in anisometropic children wearing orthokeratology lenses.

There is a particular anisometropia occurring in one eye with myopia, while the other eye has very low myopia, emmetropia, or very low hyperopia. It is unclear how the binocular axial length changes when these children wear unilateral OK lenses only in the more myopic eyes. This study investigates the changes in the axial elongation of both eyes. This is a 1-year retrospective study. In total, 148 children with myopic anisometropia were included. The more myopic eyes were wearing orthokeratology lenses (treated eyes), whereas the contralateral eyes were not indicated for visual correction (untreated eyes). The untreated eyes were classified into three subgroups based on the spherical equivalent refraction (SER): low myopia (≤ -0.50 D, n = 37), emmetropia (+0.49 to -0.49 D, n = 76), and low hyperopia (≥0.50 D, n = 35). Changes in the axial length (AL) were compared between the untreated and treated eyes and among the three subgroups. The axial elongation was 0.14 ± 0.18 mm and 0.39 ± 0.27 mm in all treated and untreated eyes, respectively (p < 0.001). The interocular AL difference decreased significantly from 1.09 ± 0.45 mm at the baseline to 0.84 ± 0.52 mm at 1 year (p < 0.001). The baseline median (Q1, Q3) SER of the untreated eyes were -0.75 D (-0.56, -0.88 D), 0.00 D (0.00, -0.25 D), and +0.75 D (+1.00, +0.62 D) in low myopia, emmetropia, and low hyperopia subgroups, respectively. The axial elongation was 0.14 ± 0.18 mm, 0.15 ± 0.17 mm, and 0.13 ± 0.21 mm (p = 0.92) in the treated eyes and 0.44 ± 0.25 mm, 0.35 ± 0.24 mm, and 0.41 ± 0.33 mm in the untreated eyes (p = 0.11) after 1 year. Multivariate linear regression analyses only showed significant differences in axial elongation between the emmetropia and low myopia subgroups of untreated eyes (p = 0.04; p > 0.05 between other subgroups). Unilateral orthokeratology lenses effectively reduced axial elongation in the more myopic eyes and reduced interocular AL differences in children with myopic anisometropia. The refractive state of the untreated eyes did not affect the axial elongation of the more myopic eye wearing the orthokeratology lens. In the untreated eyes, AL increased faster in the low myopia subgroup than in the emmetropia subgroup.

Characteristics of the Peripapillary Structure and Vasculature in Patients With Myopic Anisometropia.

To evaluate the interocular differences of the peripapillary structural and vascular parameters and that of association with axial length (AL) in participants with myopic anisometropia using swept-source optical coherence tomography. This prospective cross-sectional study included 90 eyes of 45 participants. Each participant's eyes were divided into the more and less myopic eye respectively according to spherical equivalent. The β- and γ-parapapillary atrophy (PPA) areas, Bruch's membrane opening distance, border length, and border tissue angle were measured manually. Peripapillary choroidal vascularity index and choroidal thickness (CT) values in superior, nasal, inferior, and temporal were calculated using a custom-built algorithm based on MATLAB. The interocular difference in AL and spherical equivalent was 0.62 ± 0.26 mm and -1.50 (-2.13, -1.25) diopters (D), respectively. The interocular difference in spherical equivalent was highly correlated with that of the AL. The β- and γ-PPA areas were significantly greater in more myopic eyes. The mean and inferior peripapillary choroidal vascularity index and all regions of peripapillary CT were significantly lower in the more myopic eyes. The interocular difference in AL was significantly positively correlated with the interocular differences in γ-PPA area and border length and negatively correlated with the interocular differences in temporal choroidal vascularity index and mean, inferior, and temporal peripapillary CT. There was an independent correlation between the interocular differences in AL and the interocular differences in γ-PPA area, inferior, and temporal peripapillary CT. Significant differences between both groups were detected in most peripapillary parameters, especially in peripapillary CT. The γ-PPA area, border length, and peripapillary CT were significantly correlated with the elongation of AL. The current study characterized and analyzed the peripapillary parameters in myopic anisometropia, which helped to monitor myopic progression.

Interocular Symmetry in Retinal Nerve Fiber Layer Thickness in Children: The Hong Kong Children Eye Study.

The aim of this work is to determine the interocular differences in peripapillary retinal nerve fiber layer (p-RNFL) thickness and its associations among school children in Hong Kong. We conducted a population-based study including 4034 children aged 6-8years from the Hong Kong Children Eye Study (HKCES). All participants received comprehensive ocular examinations where p-RNFL thickness was measured using spectral-domain optical coherence tomography (SD-OCT). The degree of symmetry between both eyes was analyzed and represented by intraclass correlation coefficient (ICC) values. Multivariable linear regression analysis was used to investigate the associations between ocular and systemic factors with p-RNFL thickness difference. The study included 4034 children with a mean age of 7.61 ± 0.98years. The mean global p-RNFL thickness was 106.60 ± 9.41μm in right eyes and 105.99 ± 9.30μm in left eyes. The ICC for global p-RNFL difference was 0.866 (95% CI 0.858-0.873, p < 0.001). The symmetry displayed the largest values in nasal inferior quadrant with the ICC value of 0.736 (95% CI 0.721-0.749); and the smallest degree of symmetry was found to be in the superior temporal quadrant with the ICC value of 0.567 (95% CI 0.546-0.588). Axial length (AL) difference was found to have more pronounced correlation to interocular symmetry in p-RNFL thickness with the coefficient of 0.514 (p < 0.001). Normal variation in interocular symmetry exists in children. Our results can contribute to the establishment of a standard reference for interocular differences in OCT parameters in children. The interocular differences in AL should be considered in the interpretation of RNFL symmetry, in terms of identifying children at risk of developing glaucoma or other ocular disorders.

Association of Polymorphisms in ZFHX1B and PAX6 With Anisometropia in Chinese Children: The Hong Kong Children Eye Genetics Study.

To identify gene variants associated with anisometropia development in children. This is a population-based, cross-sectional, and longitudinal genetic association study involving 1057 children aged 6 to 10 years with both baseline and 3-year follow-up data. Six single nucleotide polymorphisms (SNPs), ZC3H11B rs4373767, ZFHX1B rs13382811, KCNQ5 rs7744813, SNTB1 rs7839488, PAX6 rs644242, and GJD2 rs524952 were analyzed in all children. Anisometropia was defined by an interocular difference in SE of ≥1 diopter (D) (Aniso-SE) and an interocular difference in axial length (AL) of ≥0.3 mm (Aniso-AL), respectively. Genetic associations of individual SNPs and joint SNP effects were analyzed. ZFHX1B rs13382811 was associated nominally with Aniso-AL (odds ratio [OR], 1.66; P = 0.003) at baseline. At 3 years, rs13382811 was significantly associated with Aniso-AL (OR, 1.49; P = 0.001) and became nominally associated with Aniso-SE (OR, 1.40; P = 0.01). In addition, PAX6 rs644242 was significantly associated with Aniso-AL at 3 years (OR, 1.45; P = 0.002). At the 3-year follow-up, PAX6 rs644242 was associated significantly with Aniso-AL development (OR, 1.61; P = 0.0003) and nominally with Aniso-SE development (P = 0.03) in children who were not anisometropic at baseline, whereas ZFHX1B rs13382811 was associated nominally with Aniso-AL development (P = 0.02). An additive SNP analysis indicated children carrying the risk allele T of ZFHX1B rs13382811 and allele A of PAX6 rs644242 might have a 4.33- and 6.90-fold of increased risk of Aniso-SE and Aniso-AL development by 3 years, respectively. This study identified two susceptible gene variants, ZFHX1B rs13382811 and PAX6 rs644242, for anisometropia development in Hong Kong Chinese children, implicating their role in imbalanced refractive change and axial elongation between both eyes.

Intravitreal Short-Hairpin RNA Attenuated Adeno-Associated Virus-Induced Knockdown of Amphiregulin and Axial Elongation in Experimental Myopia.

Epidermal growth factor (EGF) and its family members have been reported to be involved in myopic axial elongation. We examined whether short hairpin RNA attenuated adeno-associated virus (shRNA-AAV)-induced knockdown of amphiregulin, an EGF family member, has an influence on axial elongation. Three-week-old pigmented guinea pigs underwent lens-induced myopization (LIM) without additional intervention (LIM group; n = 10 animals) or additionally received into their right eyes at baseline an intravitreal injection of scramble shRNA-AAV (5 × 1010 vector genome [vg]) (LIM + Scr-shRNA group; n = 10) or of amphiregulin (AR)-shRNA-AAV (5 × 1010 vg/5 µL) (LIM + AR-shRNA-AAV group; n = 10), or they received an injection of AR-shRNA-AAV at baseline and three weekly amphiregulin injections (20 ng/5 µL) (LIM + AR-shRNA-AAV + AR group; n = 10). The left eyes received equivalent intravitreal injections of phosphate-buffered saline. Four weeks after baseline, the animals were sacrificed. At study end, interocular axial length difference was higher (P < 0.001), choroid and retina were thicker (P < 0.05), and relative expression of amphiregulin and p-PI3K, p-p70S6K, and p-ERK1/2 was lower (P < 0.05) in the LIM + AR-shRNA-AAV group than in any other group. The other groups did not differ significantly when compared with each other. In the LIM + AR-shRNA-AAV group, the interocular axial length difference increased with longer study duration. TUNEL assay did not reveal significant differences among all groups in retinal apoptotic cell density. In vitro retinal pigment epithelium cell proliferation and migration were the lowest (P < 0.05) in the LIM + AR-shRNA-AAV group, followed by the LIM + AR-shRNA-AAV + AR group. shRNA-AAV-induced knockdown of amphiregulin expression, in association with suppression of epidermal growth factor receptor signaling, attenuated axial elongation in guinea pigs with LIM. The finding supports the notion of EGF playing a role in axial elongation.

Intraocular Amphiregulin antibody and axial elongation in nonhuman primates.

To examine the effect of intraocularly applied amphiregulin antibody on physiological axial elongation in young nonhuman primates. The experimental study included six male 12-months-old macaque nonhuman primates (body weight:2.46 ± 0.25kg;range:2.20-2.90kg). In the experimental group (n=3 animals), three intravitreal injections of amphiregulin antibody (100μg/50μl) were applied to the left eyes at intervals of 4-6 weeks, and injections of phosphate buffered solution (50μl) were applied to the right eyes. Three other animals were assigned to a blank control group. During the study period of 23.6 weeks, axial length in the experimental group did not change in the left eyes (18.91 ± 0.37mm to 18.94 ± 0.67mm;P=0.90), while it linearly increased in the right eyes (18.87 ± 0.38mm to 19.24 ± 0.53mm;P=0.056) and in the control group (left eyes:19.15 ± 0.22mm to 19.48 ± 0.22mm;P=0.009; right eyes:19.17 ± 0.15 mm to 19.46 ± 0.23 mm;P=0.024). The interocular difference in axial elongation increased in the experimental group from -0.11 ± 0.12mm at 4 weeks after baseline to -0.34 ± 0.15mm at the study end, while in the control group, the interocular side difference did not change significantly (from 0.01 ± 0.10 mm to 0.03 ± 0.08 mm;P=0.38). The difference in the interocular difference in axial elongation between the two groups was significant at 8 weeks (P=0.01), 15 weeks (P=0.007), and at study end (P=0.02). The interocular difference in axial length correlated with the interocular difference in vitreous cavity length (standardized regression coefficient beta:0.85;P<0.001). The interocular axial length difference was inversely associated with the interocular refractive error difference (beta:-0.49;P<0.001). Intraocularly applied amphiregulin antibody (100μg) reduced the physiological ocular axial elongation in juvenile nonhuman primates.

Interocular Axial Length Difference and Treatment Outcomes of Anisometropic Amblyopia.

PurposeTo evaluate the effect of interocular axial length (AL) difference on outcomes of treatment for anisometropic amblyopia in comparison with normal participants.Methods In this historical cohort study, 83 patients with anisometropic amblyopia were divided into two age groups, 70 children (mean, 7.86 1.56 and range, 5–15 years) and 13 adults (mean, 26.46 10.87 and range, 16–45 years). The control group consisted of 43 non-amblyopic children and 17 non-amblyopic adults. Treatment outcomes after a period of one year were defined as successful or unsuccessful when posttreatment amblyopic corrected distance visual acuity (CDVA) was reported as 0.9 versus CDVA 0.8, respectively. AL was measured using a Lenstar LS900 (Haag-Streit AG, Switzerland).ResultsFifty-nine patients showed satisfactory treatment outcomes (55 children and 4 adults), while unsuccessful treatment outcomes were observed in 24 patients (15 children and 9 adults). The mean of amblyopia treatment duration was 1.24 0.76 years. The mean of interocular AL difference in all patients, control, successful and unsuccessful treatment outcome groups were 0.49 0.70mm (range, 0.00–3.89 mm), 0.12 0.07 mm (range, 0.02–0.41), 0.33 0.23 mm (range, 0.00–0.99 mm), and 1.81 0.80 mm (range, 1.14–3.89 mm), respectively. In both age groups, the mean of interocular AL difference in patients with unsuccessful treatment outcomes was greater than those with successful treatment outcomes and that of the control group (P 0.001).ConclusionThe results of this study suggest that the outcome of anisometropic amblyopia treatment may depend on the interocular AL difference.

Epiregulin, epigen and betacellulin antibodies and axial elongation in young guinea pigs with lens-induced myopization

BackgroundTo examine an effect of intravitreally applied antibodies against epidermal growth factor family members, namely epiregulin, epigen and betacellulin, on ocular axial elongation.MethodsThe experimental study included 30 guinea pigs (age:3–4 weeks) which underwent bilateral lens-induced myopization and received three intraocular injections of 20 µg of epiregulin antibody, epigen antibody and betacellulin antibody in weekly intervals into their right eyes, and of phosphate-buffered saline into their left eyes. Seven days after the last injection, the animals were sacrificed. Axial length was measured by sonographic biometry.ResultsAt baseline, right eyes and left eyes did not differ (all P > 0.10) in axial length in neither group, nor did the interocular difference in axial length vary between the groups (P = 0.19). During the study period, right and left eyes elongated (P < 0.001) from 8.08 ± 0.07 mm to 8.59 ± 0.06 mm and from 8.08 ± 0.07 mm to 8.66 ± 0.07 mm, respectively. The interocular difference (left eye minus right eye) in axial elongation increased significantly in all three groups (epiregulin-antibody:from 0.03 ± 0.06 mm at one week after baseline to 0.16 ± 0.08 mm at three weeks after baseline;P = 0.001); epigen-antibody group:from -0.01 ± 0.06 mm to 0.06 ± 0.08 mm;P = 0.02; betacellulin antibody group:from -0.05 ± 0.05 mm to 0.02 ± 0.04 mm;P = 0.004). Correspondingly, interocular difference in axial length increased from -0.02 ± 0.04 mm to 0.13 ± 0.06 mm in the epiregulin-antibody group (P < 0.001), and from 0.01 ± 0.05 mm to 0.07 ± 0.05 mm in the epigen-antibody group (P = 0.045). In the betacellulin-antibody group the increase (0.01 ± 0.04 mm to 0.03 ± 0.03 mm) was not significant (P = 0.24).ConclusionsThe EGF family members epiregulin, epigen and betacellulin may be associated with axial elongation in young guinea pigs, with the effect decreasing from epiregulin to epigen and to betacellulin.

Correlation between the increase in corneal higher-order aberrations and the control of children's myopic anisometropia after wearing orthokeratology lenses

Objective: To explore the interocular differences in both the increase of corneal higher-order aberrations (HOAs) and axial length elongation, and the correlation between them after orthokeratology lens (OK lens) wear in children with myopic anisometropia. Methods: It was a prospective cohort study. From 2018 to 2019, 31 children with myopic anisometropia who were fitted with OK lenses initially in the Department of Ophthalmology of Peking University Third Hospital were enrolled, including 15 males (30 eyes) and 16 females (32 eyes). The age was (10.7±1.4) years. Before (baseline) and 12 months after wearing OK lenses, corneal aberrations, corneal relative refractive power (corneal RRP, the difference between peripheral corneal refraction and central corneal refraction) and axial length were measured using the Sirius combining a corneal topographer and a tomographer and an IOL-Master intraocular lens biometer in two eyes. Interocular differences in corneal aberrations, corneal RRP and axial length were analyzed by the paired t test and Wilcoxon rank sum test. The Pearson and Spearman correlation analyses were used to explore the correlation between the increase in corneal HOAs, corneal RRP and axial length elongation. Results: At 12 months after wearing OK lenses, 6 children were lost for follow-up, and the data of the remaining 25 children (50 eyes) were evaluated. With 3.0- and 6.0-mm measuring zones of the total cornea and the anterior surface, the increases in total corneal HOAs, coma, spherical aberration of higher myopic eyes were significantly more than fellow lower myopic eyes (all P<0.05). The corneal RRP with 2.0-mm and 2.5-mm radius in the upper cornea and 2.5-mm radius in the inferior cornea of higher myopic eyes were more than fellow lower myopic eyes (t=-2.06, -2.07, -2.42; P=0.05, 0.049, 0.023), but there was no significant interocular difference in corneal RRP in the horizontal meridian direction of the cornea (both the nasal and temporal sides of the cornea) (both P>0.05). The axial length elongation in higher myopic eyes was 0.14 (0.08, 0.20) mm, which was significantly less than that in the contralateral eyes [0.18 (0.14, 0.35) mm] (Z =-3.21, P= 0.001). The interocular difference in axial length decreased from 0.40 (0.34, 0.54) mm at baseline to 0.33 (0.24, 0.54) mm (Z =-3.21, P = 0.001). The increases in HOAs, coma and spherical aberration of the anterior corneal surface with 3.0-mm measuring zone and the increase in coma of the anterior corneal surface with 6.0-mm measuring zone were all negatively correlated with axial length elongation (r=-0.493, -0.606, -0.500, -0.307; P<0.05). But the corneal RRP had no significant correlation with axial length elongation (r=-0.092, -0.104, -0.230, -0.061; P>0.05). Conclusion: After 12 months of OK lens wear, interocular difference in axial length reduced significantly in children with myopic anisometropia, which was related to the larger increase in corneal HOAs of higher myopic eyes than fellow lower myopic eyes, especially coma.

The iridocorneal angle and related anterior segment structures in pediatric anisohyperopic amblyopic eyes.

Objectives:We aimed at investigating the iridocorneal angle, anterior segment structural differences, and their relationship in pediatric anisohyperopic amblyopic eyes.Methods:This study was designed as an observational case-control study. We prospectively evaluated the pediatric patients who were newly diagnosed with hyperopic anisometropic amblyopia. Iridocorrneal angle in four sectors, axial length, and anterior segment structures were compared to emmetropic fellow and control eyes using Pentacam and IOLMaster 700 devices. The anisohyperopia and iridocorneal angle related factors were determined in hyperopic anisometropic amblyopic eyes.Results:Forty-three hyperopic anisometropic amblyopic eyes, 43 fellow eyes, and 44 control eyes were included. The mean axial length, anterior chamber volume, and anterior chamber depth were significantly reduced in the study eyes compared to the fellow (p < 0.001, p = 0.021, and p = 0.045, respectively) and control eyes (p < 0.001, p = 0.001, and p = 0.009, respectively). The average iridocorneal angle was significantly lower in the study eyes than in the fellow and control eyes (p < 0.001 and p = 0.018, respectively). The iridocorneal angle correlated with anterior chamber depth (r = 0.49, p = 0.013), anterior chamber volume (r = 0.42, p = 0.038), the anterior radius of curvature (r =−0.54, p = 0.005), the posterior radius of curvature (r =−0.58, p = 0.002), and lens thickness (Rho =−0.41, p = 0.033) in the study eyes. Anisohyperopia was related to the interocular difference in axial length (Rho = 0.53, p = 0.005), anterior chamber depth (Rho = 0.53, p = 0.005), and anterior chamber volume (Rho = 0.42, p = 0.031).Conclusion:Pentacam and IOLMaster 700 are suitable for non-contact imaging of iridocorneal angle and anterior segment structures in the pediatric age. These biometric differences and their relationship should be kept in mind whenever anterior or posterior segment surgery is planned for pediatric anisohyperopic amblyopic eyes.

Controlling anisomyopia in children by orthokeratology: A one-year randomised clinical trial

PurposeTo investigate the effects of overnight orthokeratology (OK) lenses wear on the interocular axial length (AL) difference in anisomyopic children. MethodsSixty anisomyopic children (8–14 years old) were enrolled in this one-year prospective, randomised controlled study. Subjects were randomly assigned to wear OK lenses (OK group) or single-vision spectacles (control group). AL was monitored at baseline and every six months using an IOL Master biometer, and axial elongation and interocular AL differences were compared between the groups. ResultsIn the control group, the more myopic eyes had similar axial elongation (0.36 ± 0.17 mm) to the less myopic eyes (0.37 ± 0.17 mm) at the one-year follow-up (P > 0.05). In the OK group, the less myopic eyes exhibited significantly greater axial elongation (0.24 ± 0.17 mm) than the more myopic eyes (0.13 ± 0.13 mm) at the one-year follow-up (P < 0.05). The mean interocular AL difference significantly decreased in the OK group over one year, from 0.47 ± 0.24 mm to 0.35 ± 0.22 mm (P < 0.05). However, the mean interocular AL difference decreased only slightly in the control group, from 0.56 ± 0.28 mm to 0.55 ± 0.28 mm (P > 0.05). ConclusionThis randomised, controlled study demonstrated that OK reduces the interocular AL difference in anisomyopic children due to stronger myopic control of the more myopic eye.

Inter-ocular and inter-visit differences in ocular biometry and refractive outcomes after cataract surgery

This study aimed to determine whether inter-ocular differences in axial length (AL), corneal power (K), and adjusted emmetropic intraocular lens power (EIOLP) and inter-visit differences in these ocular biometric values, measured on different days, are related to refractive outcomes after cataract surgery. We retrospectively reviewed 279 patients who underwent phacoemulsification. Patients underwent ocular biometry twice (1–4 weeks before and on the day of surgery). Patients were divided into three groups: group S (similar inter-ocular biometry in different measurements; n = 201), group P (inter-ocular differences persisted in the second measurement; n = 37), and group D (inter-ocular difference diminished in the second measurement; n = 41). Postoperative refractive outcomes (mean absolute errors [MAEs]) were compared among the groups. Postoperative MAE2, based on second measurement with reduced inter-ocular biometry difference, was smaller than that calculated using the first measurement (MAE1) with borderline significance in group D (MAE1, 0.49 ± 0.45 diopters vs. MAE2, 0.41 ± 0.33 diopters, p = 0.062). Postoperative MAE2 was greater in group P compared to the other two groups (p = 0.034). Large inter-ocular biometry differences were associated with poor refractive outcomes after cataract surgery. These results indicate that measurements with smaller inter-ocular differences were associated with better refractive outcomes in cases with inter-visit biometry differences.

Prevalence and Associations of Myopic Anisometropia in Chinese Adults.

To investigate the prevalence and associations of myopic anisometropia in Chinese adults. A total of 3,791 Chinese refractive surgery candidates with myopia (25.15±7.09 years old, Mean±SD) were recruited. All eyes underwent a standardized ophthalmological examination. Associations between myopic anisometropia and age, gender, spherical ametropia, astigmatism, and axial length (AL) were analyzed by means of the chi-squared test, nonparametric Kruskal-Wallis or Mann-Whitney test, binomial logistic regression analyses, and multivariate logistic regression analysis. The mean myopic anisometropic level was 0.96 D and prevalence of myopic anisometropia was 29.62% (defined as myopic anisometropia ≥1.00 D). The prevalence and severity of myopic anisometropia increased with age, larger interocular AL difference, and higher cylindrical power (all P<0.001). Myopic anisometropia showed a U-shaped correlation with spherical equivalent (SE) refractive error and V-shaped correlations with AL, J0 and J45. Myopic anisometropia was most strongly associated with interocular AL difference (P<0.001). Compared with previous reports, this study revealed an even higher prevalence of myopic anisometropia and showed a U-shaped correlation with SE and a V-shaped correlation with AL. These results indicate that the formation of myopic anisometropia could be related to neural control in the binocular AL growth balance. Further study is needed to clarify this presumption.

Pattern of Axial Length Growth in Children Myopic Anisometropes with Orthokeratology Treatment

ABSTRACT Purpose To compare the pattern of growth in axial length (AL) between children with anisometropia who wear orthokeratology (OK) lenses and those who wear spectacles (SP). Methods A retrospective study was conducted. Data of baseline and 1 year from 252 children (8–14 years old) anisomyopes who sought refraction corrections at the Zhongshan Ophthalmic Center between October 2013 and June 2017 were reviewed. Seventy-nine unilateral myopic anisometropes (UMA) and 98 bilateral myopic anisometropes (BMA) treated with OK lenses were set as study groups (OK-UMA and OK-BMA groups). Age, refraction, and AL-matched unilateral (n = 38) and bilateral myopic anisometropes (n = 37) treated with spectacles were set as control groups (SP-UMA and SP-BMA groups). The 1-year change in AL between the study and control groups (OK-UMA vs. SP-UMA and OK-BMA vs. SP-BMA) was compared. Results There were no significant differences in the baseline of age, refraction, and AL between OK-UMA and SP-UMA or OK-BMA and SP-BMA groups (all P > .05). Compared to the SP-UMA group, annual axial elongation of the myopic eyes of the OK-UMA group was smaller (0.05 ± 0.19 mm vs. 0.33 ± 0.29 mm, P < .001); however, AL elongation in the non-myopic eyes were comparable between SP-UMA and OK-UMA groups (P > .05). At the end of 1 year, the interocular difference in AL (aniso-AL) decreased by 0.29 ± 0.29 mm (P < .001) in the OK-UMA group but remained unchanged in SP-UMA group. Compared to the SP-BMA group, annual axial elongations of both eyes of the OK-BMA group were smaller (the more myopic eye, 0.05 ± 0.17 mm vs. 0.38 ± 0.21 mm; the less myopic eye, 0.15 ± 0.19 mm vs. 0.35 ± 0.28 mm; both P < .001). At the end of 1 year, aniso-AL decreased by 0.10 ± 0.15 mm (P < .001) in the OK-BMA group but remained unchanged in the SP-BMA group. Conclusion Orthokeratology is effective in reducing the interocular difference in AL of children anisomyopes through greater retardation of axial elongation of the more myopic eyes.

Biometry: a tool for the detection of amblyopia risk factor in children

PurposeTo determine optical biometry data criteria for the detection of abnormal refraction in preschool children, and to evaluate the accuracy of these criteria for detecting amblyopia refractive risk factor (ARF), as defined in the 2013 guidelines of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS).MethodsThe present study included 200 eyes of 100 preschool children with normal eyes for the experimental determination of criteria and 142 eyes of 71 preschool children for validation of these criteria. Statistical data from normal eyes were used to determine both “high sensitivity failure criterion” and “high specificity failure criterion” associated with corneal astigmatism, interocular difference in axial length, and the prediction interval of a regression formula for predicting corneal power from axial length. Ophthalmological examination of children for validation included testing cycloplegic refraction and optical biometry testing. Outcomes from optical biometry criteria were compared with determination via ophthalmological examination, and the accuracy of the criteria for detecting ARF was evaluated.ResultsSensitivity of the “high sensitivity failure criterion” for detecting 2013 AAPOS ARF was 100%, while the specificity was 80.5%. The sensitivity of the “high specificity failure criterion” was 93.3%, while the specificity was 95.1%.ConclusionsThe criteria derived from optical biometry data in this study exhibited excellent sensitivity and specificity for detecting ARF. This study may lead to a new approach to vision screening in preschool children.

Effect of Orthokeratology on Axial Length Elongation in Anisomyopic Children.

Anisomyopia is a natural experimental paradigm that compares dose response between fellow eyes. This study is the first to explore whether orthokeratology (ortho-k) has a dose-response effect on axial length growth and reduces the interocular difference in axial length in anisomyopic children. The purpose of this study was to compare the effect of ortho-k on axial length elongation between the fellow eyes of anisomyopic children. In this retrospective study, 49 anisomyopic children who wore ortho-k lenses were assigned to the anisomyopic ortho-k group. Based on the one-to-one match principle (same age and proximate spherical equivalent), high-isomyopic and low-isomyopic groups each enrolled 49 isomyopic children who wore ortho-k lenses with spherical equivalent similar to that of the more myopic eye and the less myopic eye in the anisomyopic ortho-k group, respectively. Forty-nine anisomyopic children who wore spectacles were enrolled in the anisomyopic spectacle group. At baseline and at 1- and 2-year visits, axial length was measured. Axial length elongation and interocular difference in axial length were compared. In the anisomyopic ortho-k group, the less myopic eyes exhibited more axial length elongation than did the more myopic eyes during 1- and 2-year treatment periods (P < .01). However, there was no significant difference in axial length elongation between the fellow eyes in the isomyopic groups and anisomyopic spectacle group. At the 2-year visit, the interocular difference in axial length of children in the anisomyopic ortho-k group significantly decreased from 0.72 ± 0.34 to 0.56 ± 0.38 mm (P < .05). In contrast, ortho-k lens-wearing isomyopic children or spectacle-wearing anisomyopic children did not show a significant change in interocular difference in axial length. Orthokeratology could reduce the amount of anisomyopia in children primarily through stronger myopia control in the more myopic eye.

Factors affecting visual acuity after unilateral cataract extraction in pediatric age group

To evaluate the preoperative risk factors for poor visual outcomes in unilateral pediatric cataract, mainly the interocular axial length difference (IALD).

Interocular Axial Length and Corneal Power Differences as Predictors of Postoperative Refractive Outcomes after Cataract Surgery

To determine whether differences between eyes in axial length (AL) and corneal power (K) on optical biometry are predictive of refractive outcomes. Retrospective cohort study. A total of 729 patients (1458 eyes) who underwent bilateral phacoemulsification at TLC (Mississauga, Ontario, Canada) from September 2013 to August2015. We compared the proportion of patients having >0.5 diopters (D) of refractive error from target stratified by interocular axial length differences (IALDs) and interocular K differences (IKDs) between eyes as measured by optical biometry (IOL-Master, Carl Zeiss Meditec, Oberkochen, Germany). Analysis was repeated for 0.25 D or 1.0 D targets and for patients with uncorrected visual acuity (UCVA) >0.3 logarithm of the minimum angle of resolution (logMAR) postoperatively. Proportions, odds ratios (ORs), and corresponding 95% confidence intervals (CIs) were computed using generalized estimating equations to account for within-patient correlation. Some 79.1% of eyes were ≤0.5 D of refractive target, 47.0% were ≤0.25 D, and 97.2% were ≤1.0 D. The OR of having a refractive outcome >0.5 D from target for IALD cutoff of 0.2 mm was 1.4 (1.1-1.8), of 0.3 mm was 1.6 (1.2-2.1), and of 0.4 mm was 1.8 (1.3-2.5). This translates to 70.0% (63.5-75.7) within target for IALD of ≥0.4 mm versus 80.7% (78.4-82.9) for <0.4 mm. For a given patient with IALD, the chance of being off target was similar for the shorter and longer eye. Eyes outside of target were twice as likely to be <-0.5 D than >0.5 D. Interocular K difference was largely not associated with prediction error, yet larger IKD-flat, steep, and average were associated with increased odds of UCVA >0.3 logMAR postoperatively. Interocular axial length difference of as little as ≥0.2 mm is associated with a higher chance of >0.5 D of refractive error from target and worse UCVA. Interocular K difference was not associated with worse refractive error from target, although a difference of ≥0.4 D was associated with worse UCVA. These cutoffs should be considered in preoperative planning and discussion with patients. Future study is required to assess whether repeating measurements, using adjunctive measurement devices, or attempting to separate true differences from artifact based on preoperative refractive characteristics reduces residual refractive error.

Anisometropia of spherical equivalent and astigmatism among myopes: a 23-year follow-up study of prevalence and changes from childhood to adulthood.

To study anisometropia of spherical equivalent and astigmatism from the onset of myopia at school age to adulthood. A total of 240 myopic schoolchildren (mean age 10.9years), with no previous spectacles, were recruited during 1983-1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Examinations with subjective cyclopedic refraction were repeated 3years later (follow-up 1) for 238 subjects and thereafter at the mean ages of 23.2 (follow-up 2) and 33.9years (follow-up 3) for 178 and 134 subjects. After exclusions, the 102 subjects who attended all three follow-ups were included in the analyses. Corneal refractive power and astigmatism and anterior chamber depth was measured with Pentacam topography and axial length with IOL master at study end. Prevalence and changes in anisometropia of spherical equivalent (AnisoSE) and astigmatism (AnisoAST) and their relationships with refractive and axial measures were studied. Mean (±SD) of spherical equivalent (SE), AnisoSE and AnisoAST increased from baseline to follow-up end from -1.44±0.57 D to -5.11±2.23 D, from 0.28±0.30 D to 0.68±0.69 D and from 0.14±0.18 D to 0.37±0.36 D, respectively. Prevalence of AnioSE, ≥1 D, increased from 5% to 22.6% throughout follow-up. Higher AnisoSE was associated with SE in the less myopic eye at baseline and at follow-up 1, and with SE in the more myopic eye in follow-ups 2 and 3 in adulthood. At study end, AnisoSE was associated with the interocular difference in axial length (AL) (r=0.612, p<0.001) but not with the interocular difference in corneal refraction (CR) (r=-0.122, p=0.266). In cases of low AnisoSE(≤1.00 D), the negative correlation between the real interocular differences (value of right eye minus value of left eye) in CR and AL (r=-0.427, p<0.001) decreased the influence of the interocular difference in AL on AnisoSE, causing emmetropization in AnisoSE. The interocular difference in corneal astigmatism was the main factor associated with AnisoAST (r=0.231, p=0.020). No significant relationship was found between AnisoAST and level of SE. Anisometropia of the spherical equivalent (AnisoSE) increased along with the myopic progression and at study end was mainly associated with the interocular difference in AL. AnisoAST was mainly explained by the interocular difference in corneal astigmatism. In cases with low AnisoSE (≤1.0 D), the interrelationship between CR and AL decreased AnisoSE causing emmetropization in AnisoSE.