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

PURPOSE: To 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. METHOD: A 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. RESULTS: A 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. CONCLUSION: The 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.

Evaluation of early period changes in intraocular pressure, ocular biometry and anterior segment after upper eyelid blepharoplasty.

PURPOSE: To investigate the acute effects of upper eyelid blepharoplasty on intraocular pressure (IOP) and ocular biometric parameters. METHOD: This prospective cross sectional study examined the eyes of 49 patients with dermatochalasis. Following a detailed ophthalmological examination, corneal topography was used to evaluate the eyes mesopic and photopic pupil diameter, anterior chamber depth, and corneal astigmatism on the day of surgery and on days first and seventh postoperatively. Ocular biometry was used to assess axial length and intraocular lens power. Goldmann applanation tonometry was used to measure intraocular pressure. RESULTS: Forty-nine eyes (26 males and 23 females) of 49 patients aged between 44 and 76 years (mean 61 ± 7.9) were included in our study. The mean anterior chamber depth (ACD) was 2.90 ± 0.37 mm preoperatively, 3.00 ± 0.29 mm at postoperative day first, and 3.04 ± 0.29 mm at postoperative day seventh, and the increase in anterior chamber depth was statistically significant (p < 0.001). The mean astigmatism values were measured as preoperative 0.73 ± 0.69 D, postoperative first day 0.93 ± 0.81 D, and postoperative seventh day 1.26 ± 0.90 D. The increase in astigmatism values was statistically significant (p < 0.001). The mean pupil diameter measurements in the mesopic environment were 4.20 ± 0.61 mm preoperatively, 4.40 ± 0.59 mm on the first postoperative day, and 4.39 ± 0.57 mm on the seventh postoperative day, and there was a statistically significant difference between the three measurements (p = 0.03). The mean IOP measurements of the patients were 15.91 ± 3.51 mmHg preoperatively, 16.81 ± 3.36 mmHg on the first postoperative day, and 16.97 ± 3.13 mmHg on the seventh postoperative day. The increase between these three measurements was statistically significant (p = 0.013). CONCLUSION: This study includes important insights into the potential acute phase impact of blepharoplasty surgery on ocular findings. Patients undergoing upper eyelid surgery should be informed about the possible change in ocular biometric parameters, intraocular pressure, and pupil diameter.

Correlation between refractive errors and ocular biometric parameters in children and adolescents: a systematic review and meta-analysis.

BACKGROUND: Refractive errors are one of the most common ocular conditions among children and adolescents, with myopia showing an increasing prevalence and early onset in this population. Recent studies have identified a correlation between refractive errors and ocular biometric parameters. METHODS: A systematic search was conducted in electronic databases including PubMed, EMBASE, Cochrane Library, Web of Science, and Medline from January 1, 2012, to May 1, 2023. Various ocular biometric parameters were summarized under different refractive states, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), corneal curvature (CC), Corneal curvature radius (CR),axial length-to-corneal radius ratio (AL/CR ratio), choroidal thickness (ChT), retinal thickness (RT), retinal nerve fiber layer thickness (RNFL), and retinal blood density (VD). The differences in these parameters among different refractive states were analyzed using Stata software with fixed or random-effects models, taking into account the assessed heterogeneity level. RESULTS: This meta-analysis included a total of 69 studies involving 128,178 eyes, including 48,795 emmetropic eyes, 60,691 myopic eyes, 13,983 hyperopic eyes, 2,040 low myopic eyes, 1,201 moderate myopic eyes, and 1,468 high myopic eyes. The results of our study demonstrated that, compared to the control group (emmetropic group), the myopic group and low, moderate, and high myopic groups showed significant increases in AL, AL/CR ratio, and ACD, while the hyperopic group exhibited significant decreases. Compared to the control group, the myopic group had a significantly increase for CC, while CR, CCT, perifoveal RT, subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal (except nasal) ChT, and pRNFL (except temporal) significantly decreased. Compared to the control group, the hyperopic group had a significantly increase for subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal ChT, and nasal pRNFL. Compared to the control group, the low and moderate myopic groups had a significantly decreases for the CCT, parafoveal RT (except nasal), perifoveal RT (except nasal), and pRNFL (except superior and temporal). Compared to the control group, the high myopic group had a significantly increase for CR, while LT, perifoveal ChT (except nasal), parafoveal RT, perifoveal RT, and pRNFL (except temporal) had significant decreased. CONCLUSION: The changes of ocular biometric parameters in children and adolescents are closely related to refractive errors. Ocular biometric parameters devices, as effective non-invasive techniques, provide objective biological markers for monitoring refractive errors such as myopia.

Characteristics and influencing factors of corneal higher-order aberrations in patients with cataract.

PURPOSE: To observe the distribution characteristics of corneal higher-order aberrations (HOAs) in cataract patients, and analyze the relationship of HOAs with patients' age and ocular biometric parameters. METHODS: This retrospective study reviews the patients with cataract in Wuhan Aier Eye Department from January to August 2022. Root mean square (RMS) of the total HOA (tHOA), spherical aberration (SA), coma and trefoil aberration of the anterior cornea at central 4 and 6 mm optic zone were measured by the Wavefront Aberrometer (OPD-Scan III; Nidek Inc, Tokyo, Japan). The biometric parameters including axial length (AL), keratometry (K), central corneal thickness (CCT) and lens thickness (LT) were measured by swept-source coherence laser interferometry (OA-2000; TOMEY Corp, Aichi, Japan). Subgroup analyses and multiple linear regression analyses were used to determine whether HOAs were associated with age and ocular biometric parameters. RESULTS: A total of 976 patients (976 eyes) were included, averagely aged 65 years. At central 4 and 6 mm optic zone, the mean RMS of tHOA were respectively 0.20 and 0.65 µm, the SA were 0.06 and 0.30 µm, the coma aberration were 0.11 and 0.35 µm, and the trefoil aberration were 0.12 and 0.30 µm. The tHOA decreased with age until 60 years and then started to increase afterwards. The tHOA, coma and trefoil aberration increased with corneal astigmatism. The tHOA, SA, and coma aberration differ among different AL groups, and emmetropes had the smallest tHOA, SA, and coma aberration. CONCLUSIONS: With increasing age, the value of tHOA decrease first and started increasing at 60 years. The trends of corneal HOAs are consistent with corneal low-order aberrations. The values of tHOA, SA and coma aberration were the smallest in emmetropic eyes.

Effects of prematurity and retinopathy of prematurity on refractive errors and biometric optic components in school children: results of a tertiary center from Turkey.

PURPOSE: To reveal refractive errors, the relationship between refractive errors and optical parameters, and the effect of prematurity and retinopathy of prematurity (ROP) on ocular development in school children with a history of prematurity. METHODS: Premature children aged 8-12 years were divided into 3 groups as those without ROP (Group 1), with ROP that did not require treatment (Group 2), and with laser-treated ROP (Group 3). Age-matched full-term healthy children were included in the control group. Demographic features were recorded. A detailed ophthalmologic examination was performed. Anterior chamber depth (ACD), trabecular-iris angle (TIA), iris thickness (IT), lens thickness (LT), vitreous body length (VBL), axial length (AL) were measured by ultrasound biomicroscopy (UBM). The results were compared between groups. RESULTS: Group 3 had the lowest best corrected visual acuity (0.81 ± 0.31 SL), the highest rates of myopia (55.9%) and astigmatism (50.0%). In the premature groups, ACD (p < 0.001), TIA (p < 0.001), IT (p = 0.016), VBL (p < 0.001) and AL (p < 0.001) were lower; LT (p < 0.001) was higher than in the control group. As birth weight (BW) and gestational age (GA) increased, ACD, TIA, VBL and AL increased, and LT decreased (p < 0.001). In the group 3, 35.2% anisometropia, 17.6% of esotropia and 5.9% of exotropia were detected. CONCLUSIONS: The frequency of myopia, astigmatism, hyperopia and anisometropia is increasing in premature children, especially in cases with laser-treated ROP. Premature cases are characterized by thicker lens, shallower ACD, narrower TIA and shorter AL. Refractive errors, anisometropia, amblyopia and strabismus are important causes of visual impairment in children with laser-treated ROP.

Development pattern of ocular biometric parameters and refractive error in young Chinese adults: a longitudinal study of first-year university students.

BACKGROUND: The increase in the prevalence of myopia has become a matter of serious public health concern, and few studies to date have examined the ocular biometric parameters of myopia in young Chinese adults. This study aimed to investigate the longitudinal ocular biometric and refractive development of first-year university students and the influence of near work. METHODS: This study included 526 first-year university students from Tianjin Medical University (mean age, 18.34 years; 313 females and 213 males). From 2016 to 2018, participants underwent ocular biometry measurements and subjective refraction annually. Near-work activities such as the use of electronic devices, online games, reading, and writing as well as demographic data were recorded by questionnaires. RESULTS: The prevalence of myopia in this population from 2016 to 2018 was 92.40%, 92.59%, and 92.97%, respectively. Importantly, the prevalence of high myopia increased significantly from 20.91% to 28.33% (P < .001). The spherical equivalent refraction was significantly more myopic by approximately - 0.38 D (from - 4.18 ± 2.44 to - 4.56 ± 2.57 D; P < .001) during the period. The axial length, central corneal thickness, and lens thickness became significantly different (all P < .05), and the axial length significantly increased by 0.12 mm during 2 years (P < .001). Using binary logistic regression analysis, the data indicated that spending more time on online games (odds ratio, 2.09; 95% confidence interval, 1.33-3.29) could speed up the progression of myopia (P < .05). CONCLUSIONS: This study showed that the prevalence of high myopia continued to increase in undergraduate students over 2 years. Baseline myopia correlated with myopic shift, the time spent on online games, and parental myopia were significantly associated with an increase in myopia in these young adult populations.

Changes in ocular biometric parameters after renal transplantation.

PURPOSE: This study aimed to investigate the changes in postoperative ocular biometric parameters in end-stage renal disease patients who underwent renal transplantation. MATERIAL AND METHODS: This retrospective study included a total of 33 eyes of 33 patients. The ocular biometric measurements which were evaluated were axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), corneal keratometry (K1 and K2), degree of astigmatism, lens thickness (LT), and intraocular pressure (IOP). Refractive prediction error (RE) was calculated before and after renal transplantation using the same diopter (D) for intraocular lens (IOL) power calculation and evaluated for potential cataract surgery. RESULTS: The study included 15 male (45%) and 18 female (55%) patients. Mean patient age was 31.55 ± 8.24 (range: 18-49 years). In the comparison of preoperative and 1-month postoperative measurements, there was a statistically significant difference in AL, LT, ACD, and CCT (p < 0.001). There was no statistically significant difference between K1, K2, and astigmatism measurements (p = 0.72; p = 0.35; p = 0.62, respectively). There was no statistically significant difference in RE (p = 0.61-Holladay 2). CONCLUSION: While renal transplantation surgery does not lead to significant changes in astigmatism, predicted refractive error, corneal keratometry, or intraocular pressure, it causes significant decrease in axial length, lens thickness, and central corneal thickness and significant increase in anterior chamber depth. However, these changes do not result in significant changes in IOL power calculation in planned cataract surgery.

Effect of hemodialysis on intraocular lens power calculation.

BACKGROUND: To evaluate changes in ocular biometric parameters after hemodialysis (HD) in patients with end-stage renal disease (ESRD). METHODS: Forty eyes of 40 patients undergoing HD were included in this cross-sectional study. Keratometry (K) readings, white-to-white (WTW) distance, central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter, lens thickness (LT), axial length (AL), and intraocular lens (IOL) power calculation were measured with Lenstar LS 900 (Haag Streit AG, Koeniz, Switzerland) before and after hemodialysis. Intraocular pressure (IOP) was measured with a non-contact tonometer (Tonopachy NT-530P, Nidek Co., LTD, Tokyo, Japan). Main outcomes were changes in biometric parameters after HD. Reliability of the measurements (intraclass correlation coefficients (ICCs)) and the effect size (Cohen's d) were also calculated. RESULTS: Mean difference in AL before and after HD was -0.041 ± 0.022 mm with ICCs > 0.90 (p < 0.001 and Cohen's d = 0.06). Pupil diameter was also significantly different before (4.28 ± 0.81 mm) and after (4.44 ± 0.79 mm) HD with ICCs > 0.90 (p = 0.041 and Cohen's d = 0.20). Hemodialysis had no significant effect on K readings, WTW distance, CCT, ACD, LT, or IOP. CONCLUSION: Axial length and pupil diameter increase after HD with small effect size, while HD does not significantly affect IOL power calculations.

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

AIM: To analyze and compare the differences among ocular biometric parameters in Han and Uyghur populations undergoing cataract surgery. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Agreement between a new optical low coherence reflectometry biometer and an anterior segment optical coherence tomographer.

BACKGROUND: To assess agreement of measurements between a new optical low coherence reflectometry (OLCR) biometer (SW-9000, Suoer, Tianjin, China) and a spectral-domain optical coherence tomographer (SD-OCT)/Placido topographer (MS-39, CSO, Florence, Italy) in healthy subjects. METHODS: A total of 66 right eyes from 66 healthy subjects were enrolled in this prospective study. Three consecutive measurements were randomly obtained with both devices by the same experienced operator to assess agreement. Bland-Altman plots and 95% limits of agreement (LoA) were used to verify the agreement between the devices. Results are presented as mean ± standard deviation (SD). RESULTS: The SD-OCT/Placido tomographer showed high agreement with the OLCR biometer for all parameters included in this study. The mean differences of central corneal thickness (CCT), anterior chamber depth (ACD), aqueous depth (AQD), mean keratometry (Km) and corneal diameter (CD) were 2.21 ± 2.67 µm (P < 0.001), - 0.10 ± 0.03 mm (P < 0.001), - 0.10 ± 0.04 mm (P < 0.001), - 0.01 ± 0.22 D (P = 0.773) and 0.20 ± 0.16 mm (P < 0.001), respectively. This implies that the inter-device difference in Km was not statistically significant, while the differences in CCT, ACD, AQD, CD were statistically but not clinically significant. The 95% LoAs of CCT, ACD, AQD, Km and CD were - 3.01 to 7.44 µm, - 0.16 to - 0.05 mm, - 0.18 to - 0.03 mm, - 0.45 to 0.43 D, and - 0.12 to 0.51 mm, respectively. CONCLUSIONS: For CCT, ACD, AQD, Km, and CD in healthy subjects, the new OLCR biometer has high agreement with the SD-OCT/Placido tomographer and can be used interchangeably due to the narrow range of 95% LoAs.

Relatively anterior lens position in primary angle-closure glaucoma eyes with long axial length.

Purpose: To evaluate the refractive status and ocular biometric parameters in primary angle-closure glaucoma (PACG) eyes with different axial lengths (ALs). Methods: In total, 742 Chinese PACG subjects with complete ophthalmic examinations were enrolled. The refractive status was categorized as myopia (spherical equivalent [SE] ≤-0.5 D), emmetropia (-0.5 D < SE < +0.5 D), and hyperopia (SE ≥+0.5 D), whereas the AL was divided into short (AL <22.5 mm), regular (22.5 ≤ AL <23.5 mm), and long (AL ≥23.5 mm). The refractive status and ocular biometric parameters were compared among different AL groups. Results: The mean AL of the PACG eyes was 22.53 ± 0.84 mm (range: 19.68-25.57 mm). The refractive status was significantly different among different AL groups (P < 0.001). Also, 92.6% of hyperopic PACG eyes showed AL <23.5 mm, and 19.0% of myopic PACG eyes showed AL ≥23.5 mm. The SE showed significant differences among different AL groups only in the hyperopic subjects (P = 0.012). The AL was significantly longer in myopic eyes (P < 0.001). The PACG eyes with longer AL exhibited lower keratometry, longer central anterior chamber depth and corneal diameter, and lens position and relative lens position closer to the anterior (P < 0.001). Conclusion: Axial hyperopia was common in PACG eyes, and axial myopia was not uncommon. Relatively anterior lens position could explain the occurrence of PACG in the eyes with long AL.

Distribution and Characteristics of Ocular Biometric Parameters among a Chinese Population: A Hospital-Based Study.

INTRODUCTION: This study aimed to describe the distribution and characteristics of ocular biometric parameters among a large Chinese population. METHODS: This retrospective cross-sectional study included 146,748 subjects whose ocular biometric parameters were measured at the ophthalmology clinic of West China Hospital, Sichuan University, and recorded in the hospital database. Ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, were recorded. Only monocular data for each subject were analyzed to avoid bias. RESULTS: Valid data from 85,770 subjects (43,552 females and 42,218 males) aged 3-114 years were included in this study. The mean axial length, mean anterior chamber depth, average corneal keratometry, and mean keratometric astigmatism were 24.61 mm, 3.30 mm, 43.76 D, and 1.19 D, respectively. The stratification of the ocular parameters by age and gender showed significant inter-gender and inter-age differences. CONCLUSIONS: Analysis of a large population of subjects in western China aged 3-114 years showed that the distribution and characteristics of ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, differed by age and gender. This study is the first to describe ocular biometric parameters in subjects aged > 100 years.

Long-term Visual and Refractive Outcomes of Argon Laser-treated Retinopathy of Prematurity.

Purpose: In this case-control study, we measured visual acuity, objective refraction, ocular biometric parameters, and strabismus in premature cases classified according to the following categories: argon laser-treated retinopathy of prematurity (ROP), untreated spontaneously regressed ROP, no ROP, and full-term controls. Methods: Cases with a history of prematurity at six years of age were categorized into the following groups: patients with a history of treated type 1 ROP using argon laser (group I), untreated spontaneously regressed ROP (group II), and no history of ROP (group III). Group IV included age-matched healthy full-term controls. Funduscopy was performed for all the cases and the control group. Results: In total, 24 eyes of 12 laser-treated ROP cases, 186 eyes of 93 spontaneously regressed ROP patients, 74 eyes of 37 premature cases with no history of ROP, and 286 eyes of 143 controls were included in the study. The mean spherical equivalent in the treated cases was not significantly different from that in the untreated cases and patients in group III. However, the average cylindrical power was significantly different among the groups (P < 0.004). Furthermore, anisometropia ( ≥ 1.5 diopters) was diagnosed with a higher rate in the treated cases (P = 0.03). The corneal curvature of the laser-treated eyes was significantly steeper and the axial length was significantly shorter than those in the other groups (P < 0.002 and P < 0.001, respectively, for multivariate analysis). Strabismus was found in three treated patients (25%). Additionally, there were three treated eyes (12.5%) diagnosed with macular dragging. Conclusion: Premature cases including those who had a history of argon laser-treated ROP and those with untreated spontaneously regressed ROP showed acceptable long-term visual and refractive outcomes along with a fairly low rate of ocular disorders.

Ocular biometric parameters of mild hyperopia to mild myopia children aged 6-14 years from Wenzhou optometry center: A cross-sectional study.

Introduction: Myopia is the most common visual disorder in school-aged children and adolescents worldwide. This study aimed to explore the ocular biometric characteristics of children aged 6-14 years from the Wenzhou optometry center and to determine the relationship between spherical equivalent refraction (SER) and macular pigment optical density (MPOD). Subjects and methods: Participants underwent a full-scale ophthalmic examination anteriorly and posteriorly. Relevant parameters were documented, such as axial length (AL), anterior chamber depth (ACD), SER and lens thickness (LT), corneal curvature radius (CCR), and MPOD. Lens power (LP) was calculated using Bennett's formula. Shapiro-Wilk tests and histograms were used to check the normality of the distribution of refractive and ocular biometric parameters. Scatter diagrams were adopted to analyze the relationships between refraction and parameters of ocular biometry. Multiple linear regression models were employed to fit the associated factors of AL, AL/CCR, and LP. Results: A total of 902 mild hyperopia to mild myopia (+3.00 D ≤ SE ≤ -3.00 D) children aged 6-14 years were included. The mean age of participants was 10.03 ± 2.47 years, and the prevalence of mild hyperopia, emmetropia, and myopia was 5.65, 27.05, and 67.30%, respectively. The prevalence of mild myopia increased from 30.53% at 6 years of age to 93.62% at 14 years of age. Overall, AL, ACD, and AL/CCR increased, but LP declined from 6 to 14 years of age, whereas CCR and MPOD remained stable. An increase of 1 mm in AL was associated with -0.69 D of myopic change. A unit increase in AL/CCR was associated with -7.87 D in SER. As for the SER variance, AL explained 30.5% and AL/CCR explained 51.1%, whereas AL/CCR and LP accounted for 59.2%. Discussion: In this work, we have studied the distributions of ocular biometric characteristics of mild hyperopia to mild myopia children from the perspective of an optometry center rather than a sampling survey. In addition, we found that children from the optometry center had a slower progression toward myopia than those from previous sampling surveys, which was an informative finding for future myopia prevention. In addition, we have made a correlation analysis between the macular pigment optical density and spherical equivalent refraction. Though, no correlation was found.

Comprehensive comparisons of ocular biometry: A network-based big data analysis.

PURPOSE: To systematically compare and rank ocular measurements with optical and ultrasound biometers based on big data. METHODS: PubMed, Embase, the Cochrane Library and the US trial registry ( www. CLINICALTRIAL: gov ) were used to systematically search trials published up to October 22nd, 2020. We included comparative studies reporting the following parameters measured by at least two devices: axial length (AL), flattest meridian keratometry (Kf), steepest meridian keratometry (Ks), mean keratometry (Km), astigmatism (AST), astigmatism vectors J0 and J45, anterior chamber depth (ACD), aqueous depth (AQD), central corneal thickness (CCT), corneal diameter (CD) and lens thickness (LT). A network-based big data analysis was conducted using STATA version 13.1. RESULTS: Across 129 studies involving 17,181 eyes, 12 optical biometers and two ultrasound biometers (with both contact and immersion techniques) were identified. A network meta-analysis for AL and ACD measurements found that statistically significant differences existed when contact ultrasound biometry was compared with the optical biometers. There were no statistically significant differences among the four swept-source optical coherence tomography (SS-OCT) based devices (IOLMaster 700, OA-2000, Argos and ANTERION). As for Ks, Km and CD, statistically significant differences were found when the Pentacam AXL was compared with the IOLMaster and IOLMaster 500. There were statistically significant differences for CCT when the OA-2000 was compared to Pentacam AXL, IOLMaster 700, Lenstar, AL-Scan and Galilei G6. CONCLUSION: For AL and ACD, contact ultrasound biometry obtains the lower values compared with optical biometers. The Pentacam AXL achieves the lowest values for keratometry and CD. The smallest value for CCT measurement is found with the OA-2000.

Comparison of uveal parameters between acute primary angle-closure eyes and fellow eyes in South Indian population.

Purpose: : To analyze the ocular biometric parameters of eyes with acute primary angle closure (APAC) as compared to fellow eyes. Methods: : A cross-sectional study was conducted on 27 patients presenting with recent onset APAC to a tertiary eye institute in India. Anterior and posterior ocular biometric parameters were measured simultaneously by anterior segment optical coherence tomography (AS-OCT), A-scan, ultrasound biomicroscopy (UBM), and B-mode ultrasonogram (USG). The parameters measured were anterior chamber depth (ACD), anterior chamber angle (ACA), angle opening distance (AOD500, AOD750), lens vault (LV), axial length (AL), ciliary body thickness maximum (CBTmax) and at the point of scleral spur (CBT0), anterior placement of the ciliary body (APCB), and retinochoroidal thickness (RCS). Results: Mean age ± SD of patients with APAC was 55.66 ± 7.2 years with female preponderance (21:6 patients). Mean presenting IOP ± SD of the affected eye and fellow eye were 54.74 ± 11.67 mm Hg and 18.7 ± 11.67 mm Hg, respectively. Eyes with APAC had statistically significant narrower anterior ocular biometric parameters, higher LV, decreased ciliary body thickness, more APCB, and longer AL than the fellow eyes. CBTmax is the only variable that had significance (ß = -0.421,95% CI: -0.806 to - 0.035, P = 0.034) in the univariate analysis with RCS thickness in APAC eyes. Further, there was a correlation between CBT0 and APCB with CBTmax both in univariate (ß = 0.894, P < 0.0001 and ß = -0.351, P = 0.039) and multivariable analysis (ß = 0.911, P < 0.0001 and ß = -0.416, P = 0.016). Conclusion: Compared to the fellow eyes, APAC eyes had different ocular biometric parameters. In addition to known biometric parameters associated with pupillary block (narrower anterior biometric parameters-ACA, ACD, and AOD), our study found multiple nonpupillary block factors such as higher lens vault and thinner and more anteriorly placed ciliary body to be associated with APAC.

Effects of diode laser photocoagulation treatment on ocular biometric parameters in premature infants with retinopathy of prematurity.

AIM: To investigate the effects of diode laser treatment on ocular biometric parameters in premature infants with retinopathy of prematurity (ROP). METHODS: Premature infants who received diode laser treatment for ROP (n=68) and premature infants with spontaneous regressed ROP without treatment (n=50) were performed longitudinal ocular biometric measurements including anterior chamber depth, lens thickness and axial length as follows: 1d prior to laser treatment, and 3, 6, 9, and 12mo after the laser treatment. RESULTS: The mean birth weight, gestational age and initial examination time values were 936.53±302.07 g, 26.66±2.42wk, 36.26±2.73wk in the treatment group and 959.78±260.08 g, 27.28±2.10wk, 36.56±2.54wk in the control group. There was no statistically significant difference in these demographic characteristics of the groups. Anterior chamber depth, lens thickness and axial length demonstrated statistically significant linear increases during the study period in the two groups (P<0.001 for each). There were no statistically significant differences between the two groups in terms of anterior chamber depth after laser treatment. Measurements of the lens thickness at 9th and 12th months (9th month 3.70±0.22 vs 3.60±0.21 mm, P=0.017; 12th month 3.81±0.21 vs 3.69±0.22 mm, P=0.002) and the axial length at 12th month (19.35±0.79 vs 19.13±0.54 mm, P=0.031) after laser treatment were statistically higher in the treatment group. CONCLUSION: Diode laser retinal photocoagulation treatment in premature infants seems to increase the lens thickness and axial length.

Inter-eye Differences in Ocular Biometric Parameters of Concomitant Exotropia.

Purpose: To evaluate the ocular biometric parameters in patients with constant and intermittent exotropia by the measurement of swept-source optical coherence tomography (SS-OCT) optical biometer OA-2000 and comparing it with the normal control subjects. Design: Cross-sectional case-control study. Participants: Fifty-five constant and 24 intermittent patients with exotropia with central fixation and 77 orthotropic normal control participants aged 4-18 years old. Methods: Non-contact and high-resolution optical biometric OA-2000 measurements were conducted under uniform ambient light conditions. The statistical analysis included intraclass correlation coefficient (ICC), Bland-Altman plot, and independent t-tests. Main Outcome Measures: Spherical equivalent (SE), ocular biological parameters such as pupil diameter (PD), anterior chamber depth (ACD), lens thickness (LT), and axial lengths (AL). The absolute values of inter-eye differences for SE, PD, ACD, LT, and AL were recorded as AnisoSE, AnisoPD, AnisoACD, AnisoLT, and AnisoAL, respectively. Results: AnisoSE (0.878 vs. 0.577, P = 0.019), AnisoAL (0.395 vs. 0.208, P = 0.001), AnisoACD (0.060 vs. 0.032, P < 0.001), AnisoLT (0.060 vs. 0.031, P = 0.002), and AnisoPD (0.557 vs. 0.340, P = 0.002) were significantly larger in concomitant patients with exotropia. The SE, AL, ACD, LT, and PD showed excellent binocular correlation with ICC values that ranged from 0.943 to 0.987 in control participants and from 0.767 to 0.955 in concomitant exotropia patients. Bland-Altman plots showed the wider range of agreement in patients with concomitant exotropia than the control participants (SE: 5.0288 vs. 3.3258; AL: 2.2146 vs. 1.3172; ACD:0.3243 vs. 0.1682; PD: 2.4691 vs. 1.9241; and LT:0.3723 vs 0.1858). Conclusion: Patients with concomitant exotropia showed larger inter-eye differences in SE, ACD, LT, PD, and AL. Advice should be given to suspicious children to avoid or delay the development of concomitant exotropia.

The Stabilization Time of Ocular Measurements after Cataract Surgery.

PURPOSE: To determine the stabilization time of automated refraction, ocular biometric parameters, keratometry, and central corneal thickness (CCT) and to find the optimal time for glasses' prescription after cataract surgery. METHODS: This was a prospective, case series study of 62 consecutive eyes with senile cataracts. Patients undergoing uncomplicated phacoemulsification surgery were included in the study. Automated refraction, keratometry, ocular biometric parameters, and CCT were recorded at baseline before cataract surgery and at follow-up visits at one day, one week, two weeks, and four weeks after surgery. RESULTS: The study was composed of 62 eyes of 62 patients with a mean age of 66±12.38 (range, 40 to 84 years). The automated refraction stabilized one week after surgery and changed minimally between the first week and the first month after cataract surgery. The stabilization of average keratometric corneal astigmatism in keratometry, average anterior chamber depth, and CCT was achieved after the second postsurgical week. CONCLUSION: It may be possible to prescribe glasses starting from two weeks after an uneventful phacoemulsification cataract surgery for most patients.