Biometrie Features Research Articles

Ocular Biometry Features and Their Relationship with Anterior and Posterior Segment Lengths among a Myopia Population in Northern China.

Objectives: The study aims to explore the ocular biometry of a myopic population in Northern China, focusing specifically on anterior and posterior segment lengths. Methods: This is a cross-sectional study. The medical records of 3458 myopic patients who underwent refractive surgery were evaluated. Axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and other biometric parameters were measured using the IOL Master 700. The study determined the anterior segment length (ASL = ACD + LT), the posterior segment length (PSL = AL - ASL) and the ratio of ASL to PSL (ASL/PSL). Results: This study included 3458 eyes from 3458 myopic patients (1171 men and 2287 women). The mean age was 27.38 ± 6.88, ranging from 16 to 48 years old. The mean ASL was 7.35 ± 0.27 mm, and the mean PSL was 18.39 ± 1.18 mm. The ASL and PSL trends demonstrate an age-related increase for both genders, with notable gender-specific variations. Across most age groups, males typically exhibited higher ASLs and PSLs than females, with the exception of the 35-40 and 40-45 age groups. The ASL and PSL consistently increased with a rising AL. The AL strongly correlates with the PSL and negatively correlates with the ASL/PSL ratio. The ACD and LT moderately correlate with the ASL, but an increased LT does not imply a longer posterior segment. The CCT and SE show little correlation with axial eye parameters. Conclusions: Among Chinese myopic patients, a longer ASL and PSL were correlated with older age and the male gender. The AL strongly correlates positively with the PSL and negatively correlates with the ASL/PSL ratio. An elongation of the posterior segment may primarily account for an eyeball's lengthening.

Development of glaucoma predictive model and risk factors assessment based on supervised models

ObjectivesTo develop and to propose a machine learning model for predicting glaucoma and identifying its risk factors.MethodData analysis pipeline is designed for this study based on Cross-Industry Standard Process for Data Mining (CRISP-DM) methodology. The main steps of the pipeline include data sampling, preprocessing, classification and evaluation and validation. Data sampling for providing the training dataset was performed with balanced sampling based on over-sampling and under-sampling methods. Data preprocessing steps were missing value imputation and normalization. For classification step, several machine learning models were designed for predicting glaucoma including Decision Trees (DTs), K-Nearest Neighbors (K-NN), Support Vector Machines (SVM), Random Forests (RFs), Extra Trees (ETs) and Bagging Ensemble methods. Moreover, in the classification step, a novel stacking ensemble model is designed and proposed using the superior classifiers.ResultsThe data were from Shahroud Eye Cohort Study including demographic and ophthalmology data for 5190 participants aged 40-64 living in Shahroud, northeast Iran. The main variables considered in this dataset were 67 demographics, ophthalmologic, optometric, perimetry, and biometry features for 4561 people, including 4474 non-glaucoma participants and 87 glaucoma patients. Experimental results show that DTs and RFs trained based on under-sampling of the training dataset have superior performance for predicting glaucoma than the compared single classifiers and bagging ensemble methods with the average accuracy of 87.61 and 88.87, the sensitivity of 73.80 and 72.35, specificity of 87.88 and 89.10 and area under the curve (AUC) of 91.04 and 94.53, respectively. The proposed stacking ensemble has an average accuracy of 83.56, a sensitivity of 82.21, a specificity of 81.32, and an AUC of 88.54.ConclusionsIn this study, a machine learning model is proposed and developed to predict glaucoma disease among persons aged 40-64. Top predictors in this study considered features for discriminating and predicting non-glaucoma persons from glaucoma patients include the number of the visual field detect on perimetry, vertical cup to disk ratio, white to white diameter, systolic blood pressure, pupil barycenter on Y coordinate, age, and axial length.

Myopia Prevalence and Ocular Biometry Features in a General Japanese Population: The Nagahama Study

To describe the distribution of ocular biometry and refraction in Japanese adults. Cross-sectional analysis of a prospective cohort study. A total of 9850 individuals participated in the first follow-up of the Nagahama Prospective Cohort for Comprehensive Human Bioscience (the Nagahama Study) conducted between 2013 and 2016. Participants were between 34 and 80 years of age. All participants underwent axial length (AL; in millimeters), anterior chamber depth (ACD; in millimeters), corneal diameter (white to white; in millimeters), and central corneal thickness (CCT; in micrometers) measurement (IOL Master; Carl Zeiss Meditec, Dublin, CA) and refraction (spherical equivalent [SE]; in diopters [D]) and corneal curvature (CC; in millimeters) measurement (ARK-530A; Nidek, Aichi, Japan). Distribution of these ocular biometric parameters and prevalence of myopia, high myopia, and extreme myopia were summarized. Distribution of ocular biometry and refraction. After standardization to the national population of 2015, estimates of mean AL and SE were 24.21 mm and -1.44 D, respectively. Estimates of mean CC, corneal diameter, CCT, and ACD were 7.69 mm, 12.01 mm, 543.96 μm, and 3.21 mm, respectively. After standardization of age and gender, the prevalence of myopia (SE, ≤-0.5 D) and high myopia (SE, ≤-6.0 D) were 49.97% and 7.89%, respectively. Approximately 70% of the younger participants (34-59 years of age) showed myopia, whereas high myopia was observed in approximately 10%. Although the number of individuals with myopia or high myopia was higher in the younger age groups, the prevalence of more extreme phenotypes remained stable across all ages, especially in women. Axial length of more than 30 mm was observed only in older women (n= 5 [0.05%]). We showed detailed distributions of various ocular biometry and refraction parameters using a large general Japanese cohort. Prevalences of myopia and high myopia from 2013 through 2016 were higher thanthose in earlier studies, which reflects recent environmental change. However, constant prevalence of extreme myopia across all ages suggests high genetic predisposition of the extreme phenotype.

Dietary ecology of the Portunus segnis (Forskal, 1775) in the coastal waters of Hormozgan Province, Iran

In this study, the feeding habits of blue swimming crab (Portunus segnis) from Hormozgan province (south of Iran) were investigated. A total of 722 specimens were collected using bottom trawl from June 2011 to May 2012. The samples were transferred to the laboratory in order to further analysis after freezing. At first, the biometry features such as body weight (BW) and carapace width (CW) were measured and then all individuals were dissected and their stomach was removed. The results showed that the vacancy index of stomach (CV) was 34.5 during sampling. This finding indicated that this species is a gluttonous crab. Also the analysis of its feeding habits showed that this species is carnivorous. The principal food items included crustacean, fish and mollusks. Diet varied seasonally. Crustaceans were more important in summer whereas fish and mollusks were more important during autumn and winter, respectively. The crustacean included shrimp and crab. The dominant mollusks were the bivalves such as Marcina hiantina, Circentia callipyga, Tellina sp., Cardita bicolor and gastropods Cerithium erythraeonese, Atys sp. There was significant difference in the frequency of occurrence of food items among sexes.

Optical biometry features in silicon oil filled eyes

Background. The article presents results of axial length (AL) measurement in eyes filled with silicone oil and in those without silicone oil with IOLMaster and Lenstar LS 900 optical biometry methods.
 Materials and methods. The anteroposterior axis was measured in 27 eyes of 27 patients with silicone oil tamponade after surgical treatment of several vitreoretinal conditions. Using IOLMaster, the AL of eyes without silicone oil tamponade varied from 21.99 mm to 29.38 mm, Lenstar LS 900 biometry gave results from 21.96 mm to 29.41 mm.
 Results. According to data obtained and to their distribution, all cases were divided into 2 groups: I group eyes with AL less than 23.63 mm, and II group eyes with AL more than 23.63 mm. In the group II, the disparity of consecutive measurements was reliable and amounted to 0.28 0.46 mm (р = 0.024) for IOLMaster and 0.23 0.44 mm (р = 0.029) for Lenstar LS 900.
 Conclusion. So AL values at IOLMaster and Lenstar LS 900 biometry of silicone oil filled eyes may significantly overestimate the real ones when exceeding 23.63 mm. In case of simultaneous phacoemulsification with IOL implantation, this could lead to hypermetropic shift of postoperative refraction. Lenstar LS 900 measurement error in silicon oil filled eyes is less than that of IOLMaster, thus making the first biometry method preferable. In eyes with AL shorter than 23.63 mm, the measurement difference was not reliable, thus the biometry accuracy in silicone oil filled short eyes becomes higher.

Comparison of anterior ocular segment biometry features and related factors among American Caucasians, American Chinese and mainland Chinese

To compare the anterior segment biometric parameters amongst adult American Caucasians, American Chinese and mainland Chinese, in order to determine parameters that may contribute to increased risk for angle closure in Chinese. Cross-sectional clinic-based study Four gender- and age-matched cohorts included Caucasians, American Chinese, Southern and Northern mainland Chinese. Anterior segment optical coherence tomography was utilized to image the anterior chamber. Customized software was used to calculate the anterior segment parameters. Anterior chamber depth, anterior chamber width, lens vault and corneal arc depth. Data from 121, 124, 121 and 120 subjects were available for American Caucasian, American Chinese, and Southern and Northern Mainland Chinese subjects, respectively. Caucasians had significantly greater anterior chamber depth, anterior chamber width and corneal arc depth than all Chinese groups even after adjustment for refractive status and axial length. In multiple regression analysis, predictors of greater lens vault were female gender, older age and more hyperopic/less myopic status for both racial groups. It was found only in Chinese that female and older subjects tended to have smaller anterior chamber depth, anterior chamber width and corneal arc depth. The shallower anterior chamber in Chinese than Caucasians is likely attributable to the shorter corneal arc depth in the former group. Moreover, the smaller anterior chamber width contributes to more crowded anterior chambers in Chinese than in Caucasians. The more anteriorly located lens under a less vaulted cornea in Chinese females compared with Chinese males may account for the higher risk of angle closure in this subpopulation.