Fangjun Bao

Efficacy Comparison of 16 Interventions for Myopia Control in Children: A Network Meta-analysis

PURPOSE To determine the effectiveness of different interventions to slow down the progression of myopia in children. METHODS We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov from inception to August 2014. We selected randomized controlled trials (RCTs) involving interventions for controlling the progression of myopia in children with a treatment duration of at least 1 year for analysis. MAIN OUTCOME MEASURES The primary outcomes were mean annual change in refraction (diopters/year) and mean annual change in axial length (millimeters/year). RESULTS Thirty RCTs (involving 5422 eyes) were identified. Network meta-analysis showed that in comparison with placebo or single vision spectacle lenses, high-dose atropine (refraction change: 0.68 [0.52-0.84]; axial length change: -0.21 [-0.28 to -0.16]), moderate-dose atropine (refraction change: 0.53 [0.28-0.77]; axial length change: -0.21 [-0.32 to -0.12]), and low-dose atropine (refraction change: 0.53 [0.21-0.85]; axial length change: -0.15 [-0.25 to -0.05]) markedly slowed myopia progression. Pirenzepine (refraction change: 0.29 [0.05-0.52]; axial length change: -0.09 [-0.17 to -0.01]), orthokeratology (axial length change: -0.15 [-0.22 to -0.08]), and peripheral defocus modifying contact lenses (axial length change: -0.11 [-0.20 to -0.03]) showed moderate effects. Progressive addition spectacle lenses (refraction change: 0.14 [0.02-0.26]; axial length change: -0.04 [-0.09 to -0.01]) showed slight effects. CONCLUSIONS This network analysis indicates that a range of interventions can significantly reduce myopia progression when compared with single vision spectacle lenses or placebo. In terms of refraction, atropine, pirenzepine, and progressive addition spectacle lenses were effective. In terms of axial length, atropine, orthokeratology, peripheral defocus modifying contact lenses, pirenzepine, and progressive addition spectacle lenses were effective. The most effective interventions were pharmacologic, that is, muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including orthokeratology and peripheral defocus modifying contact lenses, had moderate effects, whereas specially designed spectacle lenses showed minimal effect.

Evaluation of the relationship of corneal biomechanical metrics with physical intraocular pressure and central corneal thickness in ex vivo rabbit eye globes

The relationship of corneal biomechanical metrics provided by the Ocular Response Analyzer (ORA) and Corvis ST (CVS) with physical intraocular pressure (IOPp) and central corneal thickness (CCT) was evaluated. Thirty fresh enucleated eyes of 30 rabbits were used in ex vivo whole globe inflation experiments. IOPp was measured with a pressure transducer and increased from 7.5 to 37.5 mmHg in steps of 7.5 mmHg while biomechanical data was acquired using the ORA and CVS. At least 3 examinations were performed at each pressure level, where CCT and twelve biomechanical metrics were recorded and analyzed as a function of IOPp. The biomechanical metrics included corneal hysteresis (CH) and corneal resistance factor (CRF), obtained by the ORA. They also included the applanation times (A1T, A2T), lengths (A1L, A2L) and velocities (A1V, A2V), in addition to the highest concavity time (HCT), peak distance (PD), radius (HR) and deformation amplitude (DA), obtained by the CVS. The variation of CCT and the twelve biomechanical metrics for the 30 rabbit eyes tested across the 5 pressure stages considered (inter-pressure differences) were statistically significant (P = 0.00). IOPp was highly to moderately correlated with most biomechanical metrics, especially CRF, A1T, A1V, A2V, PD and DA, while the relationships with CH, A2T, A1L and HCT were poor. IOP has important influences on most corneal biomechanical metrics provided by CVS and ORA. Two biomechanical metrics A1V and HR were influenced by CCT after correcting for the effect of IOP in most pressure stages, while the correlation with others were weak. Comparisons of research groups based on ORA and CVS with different IOPs and CCTs may lead to possible misinterpretations if both or one of which are not considered in the analysis.

Comparison and evaluation of central corneal thickness using 2 new noncontact specular microscopes and conventional pachymetry devices.

Purpose: The aim of this study was to evaluate the repeatability of central corneal thickness (CCT) measurements in normal eyes using 2 new noncontact specular microscopes (NCSMs) EM-3000 (Tomey, Japan) and SP-02 (CSO, Italy) and to compare the results with those obtained from an SP-3000P NCSM (Topcon, Japan) and ultrasound pachymetry (USP). Methods: Seventy subjects were enrolled in a prospective study. A single experienced ophthalmologist performed tests with each of the 4 instruments. Measurements were obtained in the right eye during the same session. The testing sequence of the NCSM was randomly selected. After performing noncontact examinations, the USP was performed to derive the CCT measurements. Intraoperator repeatability was analyzed using within-subject coefficient of variation and intraclass correlation coefficients. The agreement between NCSMs or NCSM and USP was assessed with Bland–Altman plots and 95% limits of agreement (LoA). Results: The mean CCT values measured by SP-3000P, EM-3000, SP-02, and USP were 513.66 ± 33.14 &mgr;m, 529.12 ± 33.22 &mgr;m, 549.06 ± 40.27 &mgr;m, and 539.01 ± 35.73 &mgr;m, respectively. All coefficients of variation were <1.3%, and the intraclass correlation coefficients were >0.95. There were statistically significant differences between any 2 devices as determined by CCT measurements. The mean difference between paired comparisons was >9 &mgr;m. The 95% LoA ranges were broad, and the greatest 95% LoA was found to exist between SP-3000P and SP-02. Conclusions: The new NCSMs and USP all show a high intraoperator repeatability for CCT measurements in normal eyes. However, interdevice agreement was poor and prevented the comparison of CCT measurements taken with different instruments.

Correlation Among Lens Opacities Classification System III Grading, Visual Function Index-14, Pentacam Nucleus Staging, and Objective Scatter Index for Cataract Assessment

PURPOSE To investigate the relationship among Lens Opacities Classification System III (LOCS III) grading score, Visual Function Index-14 (VF-14) score, average lens density by the Pentacam Nucleus Staging system, and the objective scatter index measured by the Optical Quality Analysis System in age-related cataract patients. DESIGN Prospective, single-center, cross-sectional study. METHODS Thirty-six subjects (60 eyes) with age-related cataract were recruited. Subjects with any corneal anomaly potentially affecting intraocular scatter were excluded. The best-corrected visual acuity (BCVA), LOCS III nuclear opalescence score and cortical cataract score, VF-14 score, average lens density, and objective scatter index were obtained. Correlations among these parameters were analyzed. RESULTS The LOCS III nuclear opalescence score was correlated with the BCVA (r = 0.438; P = .001), objective scatter index (r = 0.543; P < .001), and average lens density (r = 0.621; P < .001). The objective scatter index was also correlated with the BCVA (r = 0.779; P < .001) and the average lens density (r = 0.320; P = .013). The VF-14 score had the strongest correlation with the objective scatter index (r = -0.712; P < .001). The difference between groups with objective scatter index<3.0 and ≥3.0 was significant with regard to BCVA, average lens density, LOCS III nuclear opalescence score, and VF-14 score. CONCLUSIONS LOCS III grading remains an economical and effective method to assess lens opacities, especially in the formation of early cortex cataracts. The objective scatter index can be a useful parameter to objectively analyze the correlation between ocular examination findings and patient concerns. Furthermore, the objective scatter index scores ≥3.0 can be a possible objective cut-off for preoperative decision making.

Efficacy and Acceptability of Orthokeratology for Slowing Myopic Progression in Children: A Systematic Review and Meta-Analysis

Background. To evaluate the efficacy and acceptability of orthokeratology for slowing myopic progression in children with a well conducted evidence-based analysis. Design. Meta-analysis. Participants. Children from previously reported comparative studies were treated by orthokeratology versus control. Methods. A systematic literature retrieval was conducted in MEDLINE, EMBASE, Cochrane Library, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. The included studies were subjected to meta-analysis using Stata version 10.1. Main Outcome Measures. Axial length change (efficacy) and dropout rates (acceptability) during 2-year follow-up. Results. Eight studies involving 769 subjects were included. At 2-year follow-up, a statistically significant difference was observed in axial length change between the orthokeratology and control groups, with a weighted mean difference (WMD) of −0.25 mm (95% CI, −0.30 to −0.21). The pooled myopic control rate declined with time, with 55, 51, 51, and 41% obtained after 6, 12, 18, and 24 months of treatment, respectively. No statistically significant difference was obtained for dropout rates between the orthokeratology and control groups at 2-year follow-up (OR, 0.79; 95% CI, 0.52 to 1.22). Conclusions. Orthokeratology is effective and acceptable for slowing myopic progression in children with careful education and monitoring.

Posterior scleral reinforcement on progressive high myopic young patients.

Purpose To evaluate the effect of posterior scleral reinforcement in controlling high myopic axial progression in young patients. Methods Only one eye of each patient had posterior scleral reinforcement surgery. Before surgery and at each postoperative follow-up, the best corrected visual acuity, intraocular pressure, refractive errors, indirect ophthalmoscopy, B-type ultrasonography, and IOLMASTER reflected light biometry were performed on both eyes. The changes of axial length and the changes of refractive errors from the baseline were compared between the surgery eyes and the contralateral eyes. Results Thirty patients had a mean age of 7.5 years and a mean spherical equivalent of −9.72 diopters. The mean elongation of axial length was significantly less in the surgery eye group than that in the contralateral eye group (0.75 mm vs. 0.94 mm, p < 0.0001, paired t test) after a mean follow-up of 895 days. The surgical effect was mild but maintained during the follow-up. The eyes with staphyloma gained less surgical effect when compared with the eyes without staphyloma (p = 0.0036). There was also a notable nonstatistically significant trend for younger patients to gain a larger surgical effect (p = 0.0986). Conclusions Posterior scleral reinforcement surgery was found effective in slowing down high myopic axial progression in young patients within the study period, but the size of the effect was small. The surgical procedure is well tolerated without vision-threatening complications.

Axial Length Measurement Failure Rates with the IOLMaster and Lenstar LS 900 in Eyes with Cataract

Purpose To evaluate axial length (AL) measurement failure rate with the IOLMaster (Carl Zeiss AG, Germany) and Lenstar LS 900 (Haag-Streit AG, Switzerland) in eyes with cataract. Methods Two hundred and ninety-six eyes of 170 patients with cataract were enrolled. Cataract type and severity were graded using the Lens Opacities Classification System III (LOCS III) and AL measurements were attempted with IOLMaster (version 5.4) and Lenstar LS 900 (version 1.1). Chi-squared analysis was used to assess if the difference in AL measurement acquisition rate was statistically significant between the two devices. The association of the different cataract types and severity with the AL measurement acquisition rate was evaluated with logistic regression analysis. Results AL measurements were obtained in 184 eyes (62.16%) using the IOLMaster and 191 eyes (64.53%) using the Lenstar, which corresponds to a failure rate of 37.84% and 35.47% respectively. Chi-square analysis indicated no significant difference between the Lenstar and IOLMaster for AL measurement failure rate (x2 = 0.356, P = 0.550). Logistic regression analysis indicated no association between acquisition rates and cortical or nuclear cataracts with either device. There was a statistically significant association between acquisition rates and increasing severity of posterior subcapsular cataracts with the IOLMaster (β = -1.491, P<0.001) and Lenstar LS 900 (β = -1.507, P<0.001). Conclusion The IOLMaster and Lenstar LS 900 have similar AL measurement failure rates (35–38%) for Chinese public hospital cataract patients. Increasing severity of posterior subcapsular cataracts was problematic for both devices.

Repeatability and interobserver reproducibility of a new optical biometer based on swept-source optical coherence tomography and comparison with IOLMaster

Objective To evaluate the precision of the measurements in healthy subjects obtained with a new optical biometer (OA-2000, Tomey, Nagoya, Japan) using swept-source optical coherence tomography (SS-OCT) and compare these measurements with those provided by the IOLMaster v5.4 (Carl Zeiss Meditec AG, Jena, Germany) using partial coherence interferometry (PCI). Methods Axial length (AL), keratometry (K) over 2.5 mm and 3.0 mm diameters, anterior chamber depth (ACD) (corneal epithelium to lens), lens thickness (LT), central corneal thickness and corneal diameter (CD) were measured with SS-OCT by two experienced operators. Intraobserver repeatability and interobserver reproducibility were assessed. AL, ACD, K and CD were also measured with PCI for agreement analysis using Bland-Altman plots. Results Sixty-five eyes of 65 normal subjects were enrolled in the prospective study. The SS-OCT measurements revealed high repeatability and reproducibility with low test-retest repeatability, low within-subject coefficient of variation (CoV) and high intraclass correlation coefficients. Bland-Altman analysis showed narrow 95% limits of agreement for most parameters indicating excellent agreement for AL (−0.05 mm to 0.07 mm), K values both at 2.5 mm (−0.42 D to 0.20 D) and 3.0 mm (−0.42 D to 0.08 D) and ACD (−0.19 mm to 0.22 mm) except for the CD (−1.11 mm to −0.01 mm). Conclusions The repeatability and reproducibility of SS-OCT were excellent for all parameters including AL, K, ACD, LT and CD values. High agreement was shown between SS-OCT and PCI for most biometrical parameters.

Ex vivo testing of intact eye globes under inflation conditions to determine regional variation of mechanical stiffness

BackgroundThe eye globe exhibits significant regional variation of mechanical behaviour. The aim of this present study is to develop a new experimental technique for testing intact eye globes in a form that is representative of in vivo conditions, and therefore suitable for determining the material properties of the complete outer ocular tunic.MethodsA test rig has been developed to provide closed-loop control of either applied intra-ocular pressure or resulting apical displacement; measurement of displacements across the external surface of the eye globe using high-resolution digital cameras and digital image correlation software; prevention of rigid-body motion and protection of the ocular surface from environmental drying. The method has been demonstrated on one human and one porcine eye globe, which were cyclically loaded. Finite element models based on specimen specific tomography, free from rotational symmetry, were used along with experimental pressure-displacement data in an inverse analysis process to derive the mechanical properties of tissue in different regions of the eye’s outer tunic.ResultsThe test method enabled monitoring of mechanical response to intraocular pressure variation across the surface of the eye globe. For the two eyes tested, the method showed a gradual change in the sclera’s stiffness from a maximum at the limbus to a minimum at the posterior pole, while in the cornea the stiffness was highest at the centre and lowest in the peripheral zone. Further, for both the sclera and cornea, the load–displacement behaviour did not vary significantly between loading cycles.ConclusionsThe first methodology capable of mechanically testing intact eye globes, with applied loads and boundary conditions that closely represent in vivo conditions is introduced. The method enables determination of the regional variation in mechanical behaviour across the ocular surface.

Fast segmentation of anterior segment optical coherence tomography images using graph cut.

BackgroundOptical coherence tomography (OCT) is a non-invasive imaging system that can be used to obtain images of the anterior segment. Automatic segmentation of these images will enable them to be used to construct patient specific biomechanical models of the human eye. These models could be used to help with treatment planning and diagnosis of patients.MethodsA novel graph cut technique using regional and shape terms was developed. It was evaluated by segmenting 39 OCT images of the anterior segment. The results of this were compared with manual segmentation and a previously reported level set segmentation technique. Three different comparison techniques were used: Dice’s similarity coefficient (DSC), mean unsigned surface positioning error (MSPE), and 95% Hausdorff distance (HD). A paired t-test was used to compare the results of different segmentation techniques.ResultsWhen comparison with manual segmentation was performed, a mean DSC value of 0.943 ± 0.020 was achieved, outperforming other previously published techniques. A substantial reduction in processing time was also achieved using this method.ConclusionsWe have developed a new segmentation technique that is both fast and accurate. This has the potential to be used to aid diagnostics and treatment planning.