Ocular Biometric Parameters Research Articles

Relative peripheral refractive errors in Chinese children with myopic anisometropia.

To compare relative peripheral refractive errors (RPREs) in Chinese children with and without myopic anisometropia (MAI) and to explore the relationship between RPRE and myopia. This observational cross-sectional study included 160 children divided into two groups according to the interocular spherical equivalent refraction (SER) difference ≥1.0 D in the MAI group (n=80) and <1.0 D in the non-MAI group (n=80). The MAI group was further divided into two subgroups: ∆SER<2.0 D group and ∆SER≥2.0 D group. Basic ocular biometric parameters of axial length (AL), average keratometry (Ave K), cylinder (CYL), surface regularity index (SRI), and surface asymmetry index (SAI) were recorded. In addition, multispectral refraction topography was performed to measure RPRE, and the parameters were recorded as total refraction difference value (TRDV), refraction difference value (RDV) 0-10, RDV10-20, RDV20-30, RDV30-40, RDV40-53, RDV-superior (RDV-S), RDV-inferior (RDV-I), RDV-temporal (RDV-T) and RDV-nasal (RDV-N). In the non-MAI group, the interocular differences of all parameters of RPRE were not significant. In the MAI group, the interocular differences of TRDV, RDV10-53, RDV-S, RDV-I, RDV-T, and RDV-N were significant. In subgroup analysis, the interocular differences of TRDV, RDV30-53, RDV-I, and RDV-T were significant in ∆SER<2.0 D group and ∆SER≥2.0 D group, but the interocular differences of RDV10-30, RDV-S and RDV-N were only significant in the ∆SER≥2.0 D group. In correlation analysis, ∆TRDV, ∆RDV 10-53, ∆RDV-S, and ∆RDV-N were negatively correlated with ∆SER but positively correlated with ∆AL. The more myopic eyes have larger hyperopic RPRE in Chinese children with MAI in certain retinal range, and partial ∆RPRE is closely associated with ∆SER and ∆AL.

Association between myopia and sleep duration among primary school students in minority regions of Southwest China: a school-based cross-sectional research.

To investigate the relationship between sleep duration and myopia among primary school students in minority regions of Southwest China. The school-based, cross-sectional study was conducted from October 2020 to January 2021. All participants underwent a comprehensive ocular examination and completed a questionnaire on demographic characteristics, ophthalmological history and major environmental factors for myopia. Spherical equivalent (SE) and ocular biometric parameters were measured after cycloplegia, with myopia being defined as SE ≤-0.5 D (Diopter). Multivariate regression models were used to examine the association of sleep duration with myopia, SE and axial length (AL). A total of 857 students from grades 2 to 4 were included in the analysis, of which 63.6% were myopic and 62.0% belonged to ethnic minorities. Boys had a slightly higher prevalence of myopia compared with girls (66.7% vs 60.6%, p=0.06). Myopic students had longer AL, deeper anterior chamber depth and thinner central corneal thickness compared with non-myopic students (all p<0.05). There was no significant association between sleep duration and myopia in both boys and girls (p=0.319 and 0.186, respectively). Moreover, girls with a sleep duration of 8-9 hour/day had higher SE and shorter AL compared with those with less than 8 hour/day of sleep (β=0.41 and -0.32, respectively, all p<0.05). This cross-sectional study did not find a significant association between sleep duration and myopia. However, it suggests that 8-9 hours of sleep per day may have a protective effect on SE progression and AL elongation in girls. Future studies with objectively measured sleep duration are needed to validate the findings.

Refractive Status Occurrence And Correlation With Anthropometry And Ocular Biometric Parameters In Students In North Indian University

Refractive Status Occurrence And Correlation With Anthropometry And Ocular Biometric Parameters In Students In North Indian University

Quantitative Evaluation of the Effects of Blepharoplasty on Visual Field, Corneal Changes, and Cosmetic Appearance.

Blepharoplasty is an important eyelid surgical procedure, involving aesthetic and functional changes to the eyelids. The aim of this study is to investigate the effects of upper eyelid blepharoplasty on changes in the visual field, corneal changes, and cosmetic appearance. This study was performed with preoperative and postoperative facial photographs of 32 patients who underwent bilateral blepharoplasty. Marginal reflex distance (MRD1), percentage of corneal exposure area (CEA), and brow height (BH) were obtained from photographs. intraocular pressure (IOP) and ocular biometric parameters were also obtained. The morphometric and ocular parameters obtained from preoperative, postoperative first-month, and postoperative third-month patients were compared using repeated measures ANOVA test. Significant differences in MRD1, CEA, and BH were observed between preoperative, postoperative first-month, and postoperative third-month patients. Improvements were observed in left axis and right corneal astigmatism axis measurements in the postoperative third month compared with preoperative measurements, and the positive change was statistically significant (P=0.020, P=0.036). Upper eyelid blepharoplasty could provide satisfactory functional and aesthetic outcomes by contributing to the improvement of pseudoptosis and reduction in eyebrow height postoperatively.

Distribution of Ocular Biometry and Intraocular Lens Power in Patients Undergoing Cataract Surgery in an Eye Camp in Northern Pakistan

Purpose: To report ocular biometric data of patients undergoing cataract surgery in an eye camp in a city of Northern area of Pakistan. Design: Cross-sectional descriptive study. Place and Duration of Study: A surgical eye camp was set up in the month of September 2022 for 6 days in a private hospital in Skardu. Methods: A total of 119 patients were selected with a non-probability consecutive sampling technique. Ocular biometry of permanent local residents with significant cataractswas included. Incomplete biometry data and coexisting diseases like corneal opacity, pterygium, and severe dry eye causing errors in biometry were excluded. Keratometry was done with an automated refractor-keratometer. Axial length was calculated with an A-scan (ultrasound contact method) and intraocular lens (IOL) power was calculated. Results: A total of 119 patients were selected for biometry among 3908 individuals visiting an eye camp. The mean axial length was 22.13 ± 1.25 SD mm. The mean keratometry readings (K1) was 43.28 ± 1.83 Diopter and (K2) 44.26 ± 1.67 D. The mean intraocular lens (IOL) power was 24.78 ± 3.43 D. The mean K readings were more in males as compared to females (p-value &lt;0.005). There was no significant difference in axial length and IOL power among genders. Conclusion: This study gives normative data on ocular biometric parameters of patients undergoing cataract surgery at high altitudes in Skardu, Pakistan. These biometric values can be used as reference values in the local population

Ocular biometric parameters in South-Indian children with myopia - A hospital-based retrospective descriptive analysis.

This study aims to profile the ocular biometric parameters in a large group of children of South-Indian ethnicity who visited our outpatient children's department and were diagnosed with myopia. Children <15 years old diagnosed with myopia (Jan 2022-Oct 2023) and who had ocular biometry readings recorded were included. Their demographics, axial length (AL), anterior chamber depth (ACD), spherical equivalent (SE), corneal radius of curvature (CR), and AL/CR ratio were analyzed. The study included 3728 myopic children; the mean age was 11.85 (4-15) years, and 52.8% were girls. Mean SE was -3.98 D. The mean (SD) AL, ACD, CR, and AL/CR ratio were 24.64 (1.32), 3.73 (0.40), 7.61 (0.27), and 3.24 (0.16), respectively. Female gender was associated with shorter AL, ACD, CR, and AL/CR ratios (P < 0.001) across all age groups. There was a significant increase in ACD with age in both sexes (P < 0.001). A 1-unit (mm) increase in AL was associated with an SE increase of -1.65 D (CL: -1.70 to -1.60). AL/CR ratio could explain 71% of the total variance in SE (P < 0.001). SE showed a mild correlation with age (rho = 0.14, P < 0.001) and ACD (rho = -0.03, P = 0.041) and a stronger correlation with AL (rho = -0.68, P < 0.001) and AL/CR (rho = -0.83, P < 0.001). In this hospital-based study, AL and AL/CR ratios strongly correlate with SE, and the AL/CR better explains the total variance in SE than AL alone in children with myopia.

Lens Power and Associated Factors in Nonhuman Primate Subjects: A Cross-sectional Study.

We aimed to examine the normative profile of crystalline lens power (LP) and its associations with ocular biometric parameters including age, axial length (AL), spherical equivalent refraction (SE), corneal radius (CR), lens thickness, anterior chamber depth, and AL/CR ratio among a cynomolgus monkey colony. This population-based cross-sectional Non-human Primate Eye Study recruited middle-aged subjects in South China. All included macaques underwent a detailed ophthalmic examination. LP was calculated using the modified Bennett's formula, with biometry data from an autorefractometer and A-scan. SPSS version 25.0 was used for statistical analysis. A total of 301 macaques with an average age of 18.75 ± 2.95years were collected in this study. The mean LP was 25.40 ± 2.96 D. Greater LP was independently associated with younger age, longer AL, and lower SE (P = 0.028, P = 0.025, and P = 0.034, respectively). LP showed a positive correlation with age, SE, CR, AL, lens thickness, and anterior chamber depth, whereas no correlation was observed between LP and AL/CR ratio. Our results suggested the LP distribution in the nonhuman primate colony and indicated that AL and SE strongly influenced the rate of LP. Therefore, this study contributed to a deeper understanding of the relative significance of the LP on the optics of the crystalline lens study.

Ocular biometry parameters in mobile cataract surgery camp: a large-scale report from Nigeria

Background: Humanitarian missions and mobile camp surgeries have pivotal roles in cataract surgery in areas with limited resources. Ocular biometry is an important preoperative evaluation tool for cataract surgery candidates. Herein, we report the distributions of ocular biometric values among cataract surgery candidates in camp settings in southern Nigeria. Methods: In this cross-sectional study, we retrieved data from consecutive patients scheduled for cataract surgery. All patients underwent a full ophthalmic examination using a slit-lamp biomicroscope. Age, sex, and preoperative biometric values, including anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL), together with intraocular lens (IOL) power, were documented. Biometric values were obtained using A-mode ultrasonography. Results: Records of 567 patients with a mean (standard deviation) age of 66.0 (13.4) years revealed a male-to-female sex ratio of 1:1.24. Most participants were in the 66–70-year age group. Mean IOL power was significantly different between males and females (P &lt; 0.001). However, the biometric values were comparable between sexes (all P &gt; 0.05). There were significant differences in the mean IOL power (P &lt; 0.001) and ACD (P &lt; 0.05) between the age groups, indicating a decrease in ACD with age. However, the other biometric parameters were comparable between the age groups (all P &gt; 0.05). ACD had a significant weak negative correlation with LT (r = - 0.16; P &lt; 0.001) and IOL power (r = - 0.22; P &lt; 0.001) and a positive correlation with AL (r = + 0.24; P &lt; 0.001). LT had a significant weak negative correlation with VCD (r = - 0.16; P &lt; 0.001) and a positive correlation with AL (r = + 0.09; P &lt; 0.05). VCD had significant moderate positive and negative correlations with AL (r = + 0.39; P &lt; 0.001) and IOL power (r = - 0.34; P &lt; 0.001), respectively. AL had a significant strong negative correlation with IOL power (r = - 0.78; P &lt; 0.001). Conclusions: This study presents the mean distributions of ocular biometric parameters among cataract surgery candidates in camp settings in southern Nigeria. Age and sex were important determinants of IOL power and should be considered when planning eye camp supplies. AL had a strong inverse correlation with IOL power. Further multicenter national studies are required to verify these preliminary findings.

Comparison of ocular biometric parameters between two swept-source optical coherence tomography devices and Scheimpflug tomography in patients with cataract.

To assess and compare the variations and agreements across different ocular biometric parameters using swept-source optical coherence tomography (SS-OCT) and Scheimpflug tomography in patients diagnosed with cataract. This prospective case series was conducted at Tianjin Medical University Eye Hospital. In total, 212 eyes from 212 patients scheduled for phacoemulsification were included. Eyes were evaluated preoperatively using two SS-OCT devices (IOLMaster700 and CASIA2) and Scheimpflug tomography (Pentacam). Central corneal thickness (CCT), anterior chamber depth (ACD), aqueous depth (AQD), white-to-white distance (WTW), flat simulated keratometry (Kf), steep simulated keratometry (Ks), mean keratometry (Km), and total corneal keratometry (TKm) were measured. Intraclass correlation coefficient (ICC), 95% confidence intervals (CI) and limits of agreement (LoA) widths were conducted to assess differences and correlations between devices. All parameters, except for Ks, were significantly different. Pairwise comparison revealed no significant differences between keratometry obtained by IOLMaster 700 and Pentacam. LoA widths of all paired comparisons for Ks were >0.80 D. Except for WTW between IOLMaster 700 and CASIA2 and between CASIA2 and Pentacam, other Pearson's coefficients between devices showed a strong correlation (all r>0.95). The ICC of WTW (ICC=0.438, 95%CI 0.167-0.625) showed poor reliability. The reliability of CCT, ACD, and AQD was excellent (all ICC>0.95), whereas that of TKm was good (ICC=0.827, 95%CI 0.221-0.939). A significant linear correlation was also observed among devices. The ocular parameters derived from the use of IOLMaster700, CASIA2, and Pentacam exhibit significant discrepancies; as such, measurements from these devices should not be deemed as interchangeable.

An Analysis of Ocular Biometrics: A Comprehensive Retrospective Study in a Large Cohort of Pediatric Cataract Patients.

Objectives: This study aims to provide a comprehensive analysis of ocular biometric parameters in pediatric patients with cataracts to optimize surgical outcomes. By evaluating various biometric data, we seek to enhance the decision-making process for intraocular lens (IOL) placement, particularly with advanced technologies like femtosecond lasers. Methods: This retrospective comparative study included pediatric patients with cataracts who underwent ocular biometric measurements and cataract extraction with anterior vitrectomy at the Medical University of Vienna between January 2019 and December 2021. Parameters measured included corneal diameter (CD), axial length (AL), corneal thickness (CT) and flat and steep keratometry (Kf and Ks). The study explored the correlations between these parameters and IOL placement. Results: A total of 136 eyes from 68 pediatric patients were included in the study. Significant positive correlations were found between corneal diameter, age and AL. The mean CD was 11.4 mm, mean AL was 19.5 mm, CT was 581.2 ± 51.8 µm, Kf was 7.76 ± 0.55 mm and Ks 7.41 ± 0.59 mm, respectively. Older pediatric patients with larger corneal diameters and longer ALs were more likely to receive in-the-bag IOL implantation. Conversely, younger patients often required alternative IOL placements or remained aphakic. Our data indicated that over 95% of the study population and all patients aged one year and older had a corneal diameter of 10 mm or larger. Conclusions: Detailed ocular biometric analysis is crucial for optimizing both surgical outcomes and postoperative care in pediatric cataract patients. The positive correlations between CD, age and AL underline the importance of individualized surgical planning tailored to each patient's unique anatomical features. Additionally, our findings suggest that the use of a femtosecond laser is both feasible and safe for pediatric patients aged one year and older, potentially offering enhanced surgical precision and improved outcomes.

Distribution of angle alpha and angle kappa offsets among adult candidates for cataract surgery.

The current study aimed to describe the distribution of angle alpha and angle kappa offsets as well as their associated ocular biometric parameters in a large population of candidates for cataract surgery. This cross-sectional retrospective study included 8,119 eyes of 4,781 candidates for cataract surgery (mean age 70.7 ± 12.9 years). There were 49.9% right eyes, and 53.0% patients were females. The angles offset and ocular biometric parameters were measured by the IOLMaster 700 (Carl Zeiss Meditec, AG, Germany). Patient's age and gender, and most of their ocular biometric measurements were similar for the right and left eyes except for pupil diameter (4.01 ± 1.18 vs. 3.92 ± 1.14 mm, respectively, P< 0.001). The angle alpha offset magnitude was similar for the right and left eyes (0.50 ± 0.20 and 0.51 ± 0.21 mm, P= 0.08), whereas the angle kappa offset magnitude was greater in the right eyes (0.37 ± 0.21 vs. 0.33 ± 0.20 mm, P< 0.001). The angle kappa offset magnitudes were greater in the right eyes compared to the left eyes for both males (0.36 ± 0.21 vs. 0.33 ± 0.21 mm, respectively, P< 0.001) and females (0.37 ± 0.20 vs. 0.34 ± 0.20 mm, respectively, P< 0.001). The offset magnitudes of both angles varied significantly according to gender, eye laterality, angle location, and biometric parameters (e.g., axial length). The offset magnitudes of both angles were positively correlated in both right and left eyes. The offset magnitudes of both the angle alpha and angle kappa present significant variations according to gender, eye laterality, angle location, and biometric parameters, such as AL. These values are also population-specific.

Refractive and ocular biometric characteristics of non-myopic and pseudomyopic eyes in mild hyperopic Chinese children aged 3–12 years

PurposeTo investigate the refractive and ocular biometric characteristics of children with mild hyperopia and distinguish between non-myopic and pseudomyopic eyes before cycloplegia. MethodsThe eligible children underwent refractive error measurements using a NIDEK autorefractor before and after the administration of 0.5 % tropicamide. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT), were measured using the IOLMaster 700 before cycloplegia. We performed comparative analyses between the non-myopic and pseudomyopic groups, categorized based on whether the spherical equivalent (SE) before cycloplegia exceeded −0.50 diopters (D). Univariable and multivariable regression analyses were performed to control for confounding factors. ResultsThe final analysis included 968 eyes. The participants with pseudomyopia were more likely to be boys (P = 0.029), younger (P = 0.004), less hyperopic (P < 0.001) after cycloplegia, and exhibit a higher delta SE (P < 0.001) compared to the non-myopic participants. Pseudomyopic eyes were associated with a shallower ACD (P = 0.004) and thicker LT (P < 0.001) than non-myopic eyes. After adjusting for sex, age, and SE, pseudomyopic eyes showed increased AL (P = 0.001) and LT (P < 0.001) and decreased ACD (P = 0.005) compared with non-myopic eyes before cycloplegia. ConclusionsAmong the children with mild hyperopia, pseudomyopia was more common in younger boys with a lower cycloplegic SE and higher delta SE. A thicker LT, shallower ACD, and increased AL may indicate the presence of pseudomyopia, which may provide insights into the rapid progression of myopia in children with pseudomyopia.

Choroidal vascularity index in patients with computer vision syndrome combined with accommodative lead

BackgroundThis study aimed to investigate the choroidal vascularity index (CVI) in patients with computer vision syndrome (CVS) combined with accommodative lead. MethodsThis retrospective case-control study enrolled patients diagnosed with CVS and accommodative lead at University-Town Hospital of Chongqing Medical University between July 2022 and May 2023. The control group included individuals without any ocular diseases. Ophthalmic assessments included basic visual acuity, refraction, ocular biometric parameters, and CVI. ResultsA total of 85 participants were included in the study, with 45 in the CVS group and 40 in the control group. The central corneal thickness of CVS group was found to be significantly thinner compared to the control group in both the right eye (532.40±30.93 vs. 545.78±19.99 µm, P = 0.019) and left eye (533.96±29.57 vs. 547.56±20.39, P = 0.014). In comparison to the control group, the CVS group exhibited lower CVI in the superior (0.40±0.08 vs. 0.43±0.09, P = 0.001), temporal (0.40±0.08 vs. 0.44±0.10, P < 0.001), inferior (0.41±0.08 vs. 0.46±0.08, P < 0.001), and nasal (0.41±0.08 vs. 0.44±0.08, P = 0.001) quadrants. Similar differences were observed in all four quadrants within the 1–3 mm radius, and in the temporal (P = 0.004) and inferior (P = 0.002) quadrants within the 1–6 mm and 3–6 mm radii (all P < 0.05). ConclusionCompared to individuals without ocular issues, patients with CVS and accommodative lead were found to have thinner corneal central thickness and lower CVI.

Influence of Ocular Biometric Parameters on Intraocular Lens Position: A Prospective Cohort Study.

To assess the influence of ocular biometric parameters on intraocular lens (IOL) tilt and decentration after cataract surgery. Patients scheduled for cataract surgery were screened for inclusion in this prospective cohort study. Tilt and decentration of the crystalline lens and IOL were measured using the CASIA2 (Tomey). Anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were preoperatively measured by the IOLMaster 700 (Carl Zeiss Meditec AG). Multivariate regression analysis was performed to assess the influence of ocular biometric parameters on IOL tilt and decentration after cataract surgery. In total, 191 eyes of 120 patients were included. Age was positively correlated with IOL tilt, whereas ACD and AL were negatively correlated with IOL tilt. A strong positive correlation was found between preoperative crystalline lenses and postoperative IOLs in tilt magnitude (r = 0.769, P < .001) and tilt direction (r = 0.688, P < .001). A positive correlation was found between preoperative and postoperative lens decentration magnitude and decentration direction. Greater postoperative IOL tilt and decentration were significantly associated with greater preoperative crystalline lens tilt (P < .001) and decentration (P = .027). IOL tilt was greater in older patients. Shorter AL and shallower ACD contributed to greater IOL tilt. The tilt and decentration of the IOL will be greater in patients with greater tilt and decentration of the crystalline lens. [J Refract Surg. 2024;40(7):e438-e444.].

Ocular biometric characteristics of Han ethnicity in Tianjin and Uyghur ethnicity in Xinjiang undergoing cataract surgery.

To analyze and compare the differences among ocular biometric parameters in Han and Uyghur populations undergoing cataract surgery. In this hospital-based prospective study, 410 patients undergoing cataract surgery (226 Han patients in Tianjin and 184 Uyghur patients in Xinjiang) were enrolled. The differences in axial length (AL), anterior chamber depth (ACD), keratometry [steep K (Ks) and flat K (Kf)], and corneal astigmatism (CA) measured using IOL Master 700 were compared between Han and Uyghur patients. The average age of Han patients was higher than that of Uyghur patients (70.22±8.54 vs 63.04±9.56y, P<0.001). After adjusting for age factors, Han patients had longer AL (23.51±1.05 vs 22.86±0.92 mm, P<0.001), deeper ACD (3.06±0.44 vs 2.97±0.37 mm, P=0.001), greater Kf (43.95±1.40 vs 43.42±1.69 D, P=0.001), steeper Ks (45.00±1.47 vs 44.26±1.71 D, P=0.001), and higher CA (1.04±0.68 vs 0.79±0.65, P=0.025) than Uyghur patients. Intra-ethnic male patients had longer AL, deeper ACD, and lower keratometry than female patients; however, CA between the sexes was almost similar. In the correlation analysis, we observed a positive correlation between AL and ACD in patients of both ethnicities (rHan =0.48, rUyghur =0.44, P<0.001), while AL was negatively correlated with Kf (rHan =-0.42, rUyghur =-0.64, P<0.001) and Ks (rHan =-0.38, rUyghur =-0.66, P<0.001). Additionally, Kf was positively correlated with Ks (rHan =0.89, rUyghur =0.93, P<0.001). There are differences in ocular biometric parameters between individuals of Han ethnicity in Tianjin and those of Uyghur ethnicity in Xinjiang undergoing cataract surgery. These ethnic variances can enhance our understanding of ocular diseases related to these parameters and provide guidance for surgical procedures.

Ocular Biometric Components in Hyperopic Children and a Machine Learning-Based Model to Predict Axial Length.

The purpose of this study was to investigate the development of optical biometric components in children with hyperopia, and apply a machine-learning model to predict axial length. Children with hyperopia (+1 diopters [D] to +10 D) in 3 age groups: 3 to 5years (n=74), 6 to 8years (n=102), and 9 to 11years (n=36) were included. Axial length, anterior chamber depth, lens thickness, central corneal thickness, and corneal power were measured; all participants had cycloplegic refraction within 6 months. Spherical equivalent (SEQ) was calculated. A mixed-effects model was used to compare sex and age groups and adjust for interocular correlation. A classification and regression tree (CART) analysis was used to predict axial length and compared with the linear regression. Mean SEQ for all 3 age groups were similar but the 9 to 11year old group had 0.49D less hyperopia than the 3 to 5year old group (P < 0.001). With the exception of corneal thickness, all other ocular components had a significant sex difference (P < 0.05). The 3 to 5year group had significantly shorter axial length and anterior chamber depth and higher corneal power than older groups (P < 0.001). Using SEQ, age, and sex, axial length can be predicted with a CART model, resulting in lower mean absolute error of 0.60 than the linear regression model (0.76). Despite similar values of refractive errors, ocular biometric parameters changed with age in hyperopic children, whereby axial length growth is offset by reductions in corneal power. We provide references for optical components in children with hyperopia, and a machine-learning model for convenient axial length estimation based on SEQ, age, and sex.

Accuracy of 14 intraocular lens power calculation formulas in extremely long eyes.

To compare the accuracy of 14 formulas in calculating intraocular lens (IOL) power in extremely long eyes with axial length (AL) over 30.0mm. In this retrospective study, 211 eyes (211 patients) with ALs > 30.0mm were successfully treated with cataract surgery without complications. Ocular biometric parameters were obtained from IOLMaster 700. Fourteen formulas were evaluated using the optimized A constants: Barrett Universal II (BUII), Kane, Emmetropia Verifying Optical (EVO) 2.0, PEARL-DGS, T2, SRK/T, Holladay 1, Holladay 2, Haigis and Wang-Koch AL adjusted formulas (SRK/Tmodified-W/K, Holladay 1modified-W/K, Holladay 1NP-modified-W/K, Holladay 2modified-W/K, Holladay 2NP-modified-W/K). The mean prediction error (PE) and standard deviation (SD), mean absolute errors (MAE), median absolute errors (MedAE), and the percentage of prediction errors (PEs) within ± 0.25 D, ± 0.50 D, ± 1.00 D were analyzed. The Kane formula had the smallest MAE (0.43 D) and MedAE (0.34 D). The highest percentage of PE within ± 0.25 D was for EVO 2.0 (37.91%) and the Holladay 1NP-modified-W/K formulas (37.91%). The Kane formula had the highest percentage of PEs in the range of ± 0.50, ± 0.75, ± 1.00, and ± 2.00 D. There was no significant difference in PEs within ± 0.25, ± 0.50 ± 0.75 and ± 1.00 D between BUII, Kane, EVO 2.0 and Wang-Koch AL adjusted formulas (P > .05) by using Cochran's Q test. The Holladay 2modified-W/K formula has the lowest percentage of hyperopic outcomes (29.38%). The BUII, Kane, EVO 2.0 and Wang-Koch AL adjusted formulas have comparable accuracy for IOL power calculation in eyes with ALs > 30.0mm.

Refraction and ocular biometric parameters in 3-to 6-year-old preschool children : a large-scale population-based study in Chengdu, China

PurposeTo understand the ocular biometric parameters characteristics and refractive errors in 3-to 6-year-old preschool children in Chengdu, China, and to investigate the prevalence of refractive errors.MethodA school-based cross-sectional study was conducted in Chengdu from 2020 to2022 with a total of 666 kindergartens. All children were measured by non-cycloplegic autorefraction and uncorrected visual acuity (UCVA) and ocular biometric parameters. Finally, univariate linear regression models were used to analyze the relationship between ocular biometric parameters and refraction.ResultsA total of 108,578 preschool children aged 3–6 underwent examinations, revealing a myopia prevalence of 6.1%. The mean axial length (AL), keratometry (K), corneal radius (CR), axial length/corneal radius (AL/CR) Ratio, central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were 22.35 ± 0.69 mm, 43.35 ± 1.58 D, 7.80 ± 0.28 mm, 2.87 ± 0.08, 533.31 ± 32.51 μm, 2.70 ± 0.28 mm, 3.91 ± 0.27 mm, and 15.20 ± 0.68 mm, respectively. With increasing age, AL, CR, AL/CR ratio, CCT, ACD, LT, and VCD also increased. Regardless of age, males consistently exhibited longer AL, flatter corneal curvature, shallower ACD, thicker CCT, thinner LT, and longer VCD compared to females. AL, K, CR, LT, and VCD all showed significant linear relationships with SE (all P < 0.001) in univariate linear regression analysis after adjusting for gender and age.ConclusionThe prevalence of myopia among preschool children aged 3–6 in Chengdu is relatively low. Ocular biometric parameters affecting refractive errors include AL, K, CR, LT, and VCD. The preschool period serves as a critical phase for myopia prevention and control.

The influence of variations in ocular biometric and optical parameters on differences in refractive error.

To present a paraxial method to estimate the influence of variations in ocular biometry on changes in refractive error (S) at a population level and apply this method to literature data. Error propagation was applied to two methods of eye modelling, referred to as the simple method and the matrix method. The simple method defines S as the difference between the axial power and the whole-eye power, while the matrix method uses more accurate ray transfer matrices. These methods were applied to literature data, containing the mean ocular biometry data from the SyntEyes model, as well as populations of premature infants with or without retinopathy, full-term infants, school children and healthy and diabetic adults. Applying these equations to 1000 SyntEyes showed that changes in axial length provided the most important contribution to the variations in refractive error (57%-64%), followed by lens power/gradient index power (16%-31%) and the anterior corneal radius of curvature (10%-13%). All other components of the eye contributed <4%. For young children, the largest contributions were made by variations in axial length, lens and corneal power for the simple method (67%, 23% and 8%, respectively) and by variations in axial length, gradient lens power and anterior corneal curvature for the matrix method (55%, 21% and 14%, respectively). During myopisation, the influence of variations in axial length increased from 54.5% to 73.4%, while changes in corneal power decreased from 9.82% to 6.32%. Similarly, for the other data sets, the largest contribution was related to axial length. This analysis confirms that the changes in ocular refraction were mostly associated with variations in axial length, lens and corneal power. The relative contributions of the latter two varied, depending on the particular population.

Correlation analysis of angles κ and α with the refraction and anterior segment parameters in children

AimTo investigate the correlation of angles α and κ with the refractive and biological parameters in children.MethodsThis case-series study included 438 eyes of 219 children (males/females = 105/114, age: 3–15 years). Ocular biometric parameters, including axial length, corneal radius of curvature (CR), white-to-white distance (WTW), angle κ and angle α, were measured using IOL Master 700; auto-refraction were assessed under cycloplegia. The eyes were assigned to different groups based on CR, WTW, and gender to compare the angles α and κ, and analyze the correlations between the differences of biological parameters on angles α and κ.ResultsThe means of axial length, CR, WTW, angle α, and angle κ were 23.24 ± 1.14 mm, 7.79 ± 0.27 mm, 11.68 ± 0.41 mm, 0.45 ± 0.25 mm, and 0.27 ± 0.22 mm, respectively. Angle α was correlated with CR and WTW (fixed effect coefficient [FEC] = 0.237, p = 0.015; FEC = -0.109, p = 0.003; respectively), and angle κ also correlated with CR and WTW (FEC = 0.271, p = 0.003; FEC = -0.147, p < 0.001, respectively). Comparing subgroups, the large CR and small WTW group had larger angles α (0.49 ± 0.27 vs. 0.41 ± 0.21, p < 0.001; 0.46 ± 0.27 vs. 0.44 ± 0.21, p < 0.05, respectively) and κ (0.29 ± 0.25 vs. 0.24 ± 0.15, p < 0.01; 0.29 ± 0.25 vs. 0.26 ± 0.19, p < 0.05, respectively). The differences in interocular angles α and κ showed correlation with interocular WTW (r = − 0.255, p < 0.001; r = − 0.385, p < 0.001). Eyes with smaller WTW tended to have larger angle κ (0.28 ± 0.27 vs. 0.25 ± 0.15, p < 0.05).ConclusionThe size of angle α/κ may be correlated to CR and WTW, and a larger WTW eye may suggest a smaller angle κ compared with the fellow eye.