Partial Coherence Laser Interferometry Research Articles

Association between body stature with ocular biometrics and refraction among Chinese preschoolers

PurposeTo evaluate the association of body stature with ocular biometrics and refraction in preschool children.MethodsA cross-sectional, school-based study was conducted in Shenzhen, China. Preschool children aged 3 to 6 from 10 randomly-selected kindergartens were recruited. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), corneal radius curvature (CR), axial length to corneal radius ratio (AL-to-CR ratio) and lens thickness (LT) were measured using non-contact partial-coherence laser interferometry. Cycloplegic refractions were obtained by a desktop autorefractor. Body height and weight were measured using standard procedures. The association between body stature and ocular biometrics were analyzed with univariable and multivariable regression model.ResultsA total of 373 preschoolers were included. AL, ACD, VCD, CR, and AL-to-CR ratio, were positively associated with height and weight (p < 0.05), whereas LT was negatively associated with height and weight (p < 0.01). No association was observed between stature and central cornea thickness and refraction. After adjusted for age and gender in a multivariable regression model, AL had positive associations with height (p < 0.01) and weight (p < 0.01). However, refraction had no significant association with stature parameters.ConclusionTaller and heavier preschoolers had eyes with longer AL, deeper vitreous chamber, and flatter cornea. The significant associations between body stature and ocular biometric parameters reveal the driving influence of body development on the growth of eyeballs in preschoolers.

Partial Coherence Laser Interferometry Versus Conventional A-Scan Acoustic Biometry in Intraocular Lens Power Calculation – Comparison of Postoperative Refractive Error

Purpose: To compare the post-operative residual refractive error in patients undergoing cataract surgery using partial coherence laser interferometry (PCLI) versus A-scan Applanation acoustic biometry. Study Design: Quantitative experimental research. Place and Duration of Study: Shifa International Hospital (SIH), Islamabad from November 2018 to August 2019. Methods: Total 254 patients were selected. Group A included patients whose biometry was done using PCLI method and group B included patients who had A-Scan acoustic biometry. Intraocular lens power calculation was done using SRK/T formula. Phacoemulsification surgery with foldable Intraocular lens was performed. Patients were called for follow-up visit the next day and then one month after surgery. Postoperative refractive error was checked after one month. All data were entered and analyzed using SPSS version 21.0. Descriptive statistics were used for qualitative as well as quantitative variables. We applied independent samples t-test to compare the mean postoperative refractive error in both groups. A p-value of less than 0.05 was considered significant. Results: The mean age of patients was 65 ± 9.37 years. The preoperative mean axial length was 20.35 ± 1.1 mm in the PCLI group and 21.54 ± 1.2 mm in the ultrasound group. Mean Absolute Error (MAE) of postoperative residual refractive error in the PCLI group was 0.12 ± 0.13 mm (P = 0.003). The MAE in the ultrasound group was 0.18 ± 0.12 mm (P = 0.02). Conclusion: The non-contact optical biometry improves the mean absolute error for postoperative refraction and is a reliable tool for biometry in phakic eyes before surgery. Key Words: Partial coherence laser interferometry; Ultrasound A scan; Biometry; A-constant; Intraocular lens.

Compare the Accuracy of IOL Power Calculations Using Ultrasound Biometry and Partial Coherence Laser Interferometry based Optical Biometry

Aims: To compare the accuracy of IOL power calculations using ultrasound biometry and partial coherencelaser interferometry based optical biometryMaterial and Methods: All cases of cataract with no other pathology involved presenting to, ophthalmologydepartment at RNT Medical College and Hospital, Udaipur from august 2018 to December 2019.The patientsare divided into two group 1st group IOL power calculated by optical biometer and 2nd group IOL powercalculated by ultrasound biometry.Results: Significant p-value (0.01) was observed between Group 1 and Group 2 among pre operative andpost-operative VS patients.Conclusion: optical biometry with the AL scan (Nidek) proved to be slightly more accurate than ultrasoundbiometry for IOL power calculation

Proportion and characteristic of emmetropia in schoolchildren aged 6-11y: the Shenzhen elementary school eye study.

To investigate the proportion and characteristic of emmetropia in schoolchildren aged 6-11, especially estimate the normal value of ocular biometric parameters of emmetropia. A population-based cross-sectional study was conducted on children aged 6-11y in Shenzhen. Totally, 2386 schoolchildren from two primary schools were involved. The axial length (AL) and the corneal radius of curvature (CRC) were measured by partial coherence laser interferometry. Noncycloplegic refraction and refractive astigmatism (RA) was measured using autorefraction. The axial length-to-corneal radius of curvature ratio (AL/CRC), corneal astigmatism (CA) and spherical equivalent refraction (SER) were calculated. The proportion of emmetropia in elementary school students was 41.30%. This percentage decreased gradually from 6 to 11 years of age and decreased rapidly after 9 years of age. The mean and 95%CI of each parameter were provided for boys and girls aged 6 to 11 years of age with emmetropia according to each age group. The change trend of parameters of boys and girls are similar. After 7 years of age, the AL of non-emmetropia started to increase faster than that of emmetropia. The change trend of AL/CRC was the same as that of AL. The other parameters tend to be stable after 7 years of age. The age of 7-9 is an important period for the changes of refractive state and ocular biometric parameters of primary school students, and it is a special focus period for children myopia prevention. The normal value and variation of ocular biometric parameters of emmetropia can provide the basis for the clinical judgment of whether or not children's ocular biometric parameters obtained by single measurement and changes obtained by multiple measurements are abnormal.

Comparison of optical biometry based on partial coherence laser interferometry (PCLI) principle to conventional applanation ultrasonic biometry

Purpose: Our aim was to compare the accuracy of intraocular lens (IOL) power calculation with two techniques namely optical biometry based on partial coherence laser interferometry (PCLI) principle and conventional ultrasound biometry. Materials and Methods: A comparative study was done in our hospital wherein 100 eyes of 100 patients undergoing phacoemulsification cataract surgery were recruited into it. Out of them, 50 eyes underwent optical biometry and 50 eyes underwent conventional applanation ultrasound biometry. Eyes were grouped according to axial length into long (>24.50), normal (22 to Results: The MAE calculated was 0.60 +/- 0.40D and 0.20+/- 0.30D with the conventional applanation ultrasound and optical biometry respectively. It was found that the optical biometry gives more accurate values for eyeball with small and large axial length. Conclusion: The optical biometry parameters which uses the partial coherence laser interferometry (PCLI) principle happens to be the more precise method in IOL power calculation. Keywords: Axial length, Optical, Partial coherence laser interferometry, Ultrasound A scan.

Comparison of Ocular Biometry Profiles in Urban and Rural Cataract Candidates in Eastern China.

Purpose To compare ocular biometric parameters between urban and rural cataract patients in Shanghai, China. Methods A study of ocular biometry records from urban and rural hospitals was performed for cataract patients at least 50 years of age. The ocular biometrical parameters, which were measured with partial coherence laser interferometry (IOL Master, Zeiss), were axial length (AL), anterior chamber depth (ACD), radius of corneal curvature (K, including steep/flat/average K), astigmatism, and axis. Only the right eye record of each patient was analysed. Results Ocular biometric data included 2839 urban patients (73.15 ± 9.54 years) and 2646 rural patients (73.64 ± 7.32 years). Mean AL, ACD, and K were 24.35 ± 2.34 mm, 3.14 ± 0.58 mm, and 44.38 ± 1.52 D, respectively, in urban patients and 23.58 ± 1.70 mm, 3.08 ± 0.57 mm, and 44.53 ± 1.50 D, respectively, in rural patients. The urban subjects had significantly longer axial lengths (in both univariate and multivariate linear regression analyses) and deeper ACDs (in univariate analysis) than rural subjects (p < 0.01). There was no significant difference in steep K, flat K, and average K between the two groups. With-the-rule (WTR) corneal astigmatism was found in 1787 eyes (32.58%), against-the-rule (ATR) corneal astigmatism was found in 2727 eyes (49.72%), and oblique corneal astigmatism was found in 971 eyes (17.70%). Conclusions We report biometry and astigmatism data in a large cohort of urban and rural adult subjects for the first time. In our study, a short AL, shallow ACD, and axis turned in an ATR direction had higher prevalence rates in the rural subjects. This profile of ocular biometric data and corneal astigmatism will be helpful in planning for intraocular lens (IOL) power calculations and astigmatism correction in subjects in different locations.

Ocular biometry characteristics and corneal astigmatisms in cataract surgery candidates at a tertiary care center in North-East India.

Purpose:The purpose of this study is to determine the ocular biometry characteristics and corneal astigmatisms using partial coherence laser interferometry in patients aged 40 years or above undergoing cataract surgery in a medical college in North-East India.Methods:In a hospital-based cross-sectional study, ocular biometry characteristics such as axial length (AL), anterior chamber depth (ACD), white-to-white (WTW) diameter, corneal power (K), and corneal astigmatisms (D) of consecutive eligible cataract patients in a medical college in North-East India between January 2015 and December 2017 were determined using the intraocular lens (IOL) master. Height and weight were also measured.Results:A cross-sectional study evaluated ocular biometry characteristics of 641 eyes in 641 eligible patients. The mean age was 64.04 ± 10.81 years. The mean AL, ACD, WTW, corneal power, IOL power, and body mass index (BMI) were 23.34 ± 1.12 mm, 3.12 ± 0.39 mm, 11.92 ± 0.54 mm, 44.41 ± 1.50 diopter (D), 20.53 ± 2.79 D, and 26.12 ± 4.32, respectively. Against-the-rule, with-the-rule, and oblique astigmatisms were 48.4%, 33.2%, and 18.4%, respectively. Corneal astigmatism of ≥1 D was found in 292 eyes (45.55%) and >1.5 D in 182 eyes (28.39%). AL had statistically significant correlation with ACD, WTW, K, IOL power, height and weight but not with age. By multivariate analysis, AL was found to be associated with ACD, WTW, K and IOL power (P ≤ 0.05). The mean AL was negatively correlated with the mean K (R-square 0.138).Conclusion:This study is likely to provide the initial normative data for ocular biometry values in Indian adults 40 years or above, because such data is lacking in Indians using the IOL master. This will also help ophthalmologists in planning and improving the quality of surgical outcomes in phacoemulsification and phacorefractive surgeries by choosing the appropriate IOL and incision location.

Refractive error in Chinese with type 2 diabetes and its association with glycaemic control

BackgroundThe aim of this study was to determine the prevalence of refractive errors and their association with glycaemic control among adults with type 2 diabetes mellitus (T2DM) in eastern China.MethodsA community‐based survey, including 913 adults with T2DM aged 30 to 89 years, was conducted. Refractive error was assessed by autorefraction, after which subjective refraction was performed. Ocular biometric parameters were measured by non‐contact partial coherence laser interferometry. Myopia was defined as spherical equivalent (SE) less than −0.50 dioptres (D), high myopia as SE less than −5.00 D, hyperopia as SE greater than 0.50 D and astigmatism as cylinder less than −0.50 D.ResultsAfter excluding participants who had undergone cataract surgery, 839 were included in the data analyses and 96.1 per cent were found to have refractive errors. The overall prevalences of myopia, high myopia, hyperopia and astigmatism were 28.2 per cent (95 per cent confidence interval [CI] 25.2–31.3), 6.3 per cent (95 per cent CI 4.7–8.0), 46.4 per cent (95 per cent CI 43.0–49.7) and 81.0 per cent (95 per cent CI 78.4–83.7) with no gender differences observed (all p > 0.10). In multivariate analysis, myopia was associated with decreasing age (odds ratio [OR] = 0.86, p = 0.01; per year increase), higher blood levels of haemoglobin A1c (HbA1c) (OR = 1.12, p = 0.05; per unit increase), higher education levels (OR = 5.10, p < 0.001; university or college versus illiterate or primary school) and the presence of nuclear cataract (OR = 2.36, p < 0.001).ConclusionsRefractive errors may be associated with glycaemic control among T2DM patients. Longitudinal analyses are warranted to examine the relationship between changes in HbA1c and the development of refractive errors.

Six-year changes in refraction and related ocular biometric factors in an adult Chinese population.

PurposeTo investigate longitudinal changes in refraction and biometry in Chinese adults.DesignPopulation-based prospective cohort study.Methods1817 subjects aged ≥ 35 years were randomly recruited from Yuexiu district, Guangzhou, China in 2008. Of which 1595 (87.8%) were reexamined in 2010 and 1427 (78.5%) were reexamined in 2014. Non-cycloplegic automated refraction and visual acuity test were performed at baseline and the 6-year follow-up examination for all participants. In addition, 50% of the participants were randomly selected for axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) measurements using non-contact partial coherence laser interferometry. Lens power (LP) was calculated with the Bennett’s equation.ResultsA total of 1300 participants were included in current analysis (2008 mean [SD] age, 51.4 [10.6] years; 54.5% women). Mean change in spherical equivalence (SE) was +0.24 (95% confidence interval [CI], +0.19 to +0.30), +0.51 (95% CI, +0.46 to +0.57), +0.26 (95% CI, +0.15 to +0.38) and -0.05 (95% CI, -0.21 to +0.10) diopters (D) for individuals in the age groups of 35 to 44, 45 to 54, 55 to 64 and 65+ years at baseline, respectively. Corneal power, AL and LT increased while ACD and LP decreased during the follow-up. Baseline SE and changes in biometric factors could explain 97.2% of the variance in longitudinal SE change while LP solely could explain 65.2%. Six-year mean change in cylinder power was -0.16 (95% CI, -0.19 to -0.13) D, the axis of astigmatism changed from “with-the-rule” to “against-the-rule” in 16.4% of the participants and to “oblique” in 0.9%.ConclusionsThis study confirms a hyperopic shift in the elderly before 65 years old and a myopic shift thereafter. Longitudinal refraction change could be well explained by corresponding biometry changes, especially LP. There is also a shift to “against-the-rule” astigmatism for the adult population.

Significant Axial Elongation with Minimal Change in Refraction in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study

To document the distribution of ocular biometry and to evaluate its associations with refraction in a group of Chinese preschoolers. Population-based cross-sectional study. A total of 1133 preschoolers 3 to 6 years of age from 8 representative kindergartens. Biometric measurements including axial length (AL), anterior chamber depth (ACD), and corneal radius of curvature (CR) were obtained from partial-coherence laser interferometry (IOL Master; Carl Zeiss Meditec, Oberkochen, Germany) before cycloplegia. Lens power (LP) and AL-to-CR ratio were calculated. Cycloplegic refraction (3 drops of 1% cyclopentolate) was measured using an autorefractor (KR8800; Topcon Corp., Tokyo, Japan), and spherical equivalent refraction (SER) was calculated. Biometric and refractive parameters were assessed as a function of age and gender. Multiple regression analysis was performed to explore the associations between refraction and ocular biometry. Ocular biometric distributions and their relationships to refraction. Among the 1127 children (99.5%) with successful cycloplegic refraction, mean SER was 1.37±0.63 diopters (D). Prevalence of myopia increased from 0% at 3 years of age to 3.7% (95% confidence interval, 1.0%-6.5%) at 6 years of age. Biometric parameters followed Gaussian distributions with means of 22.39±0.68 mm for AL, 7.79±0.25 mm for CR, and 24.61±1.42 D for calculated LP; and non-Gaussian distributions with means of 3.34±0.24 mm for ACD and 2.88±0.06 for AL-to-CR ratio. Axial length, ACD, and AL-to-CR ratio increased from 3 to 6 years of age, CR remained stable, whereas LP declined. Overall, SER declined slightly. For the SER variance, AL explained 18.6% and AL-to-CR ratio explained 39.8%, whereas AL, CR, and LP accounted for 80.0% after adjusting for age and gender. Young Chinese children are predominantly mildly hyperopic, with a low prevalence of myopia by the age of 6 years. An increase of 1 mm in AL was associated with only 0.45 D of myopic change. Decreases in LP reduce the myopic shifts that normally would be associated with increases in AL, and thus play a key role in refractive development in this age group.

Incidence of Complications in Cataract Surgery according to the Availability of Partial Coherence Laser Interferometry

Incidence of Complications in Cataract Surgery according to the Availability of Partial Coherence Laser Interferometry

Factors influencing the pupillary light reflex in healthy individuals.

To determine the ocular anatomical factors influencing the pupillary light reactions to different wavelengths of light, measured with chromatic pupillometry. Community-based, cross-sectional study including subjects with normal ocular health (ages 50-79years). Direct pupillary responses to continuously increasing irradiances (6.8 to 13.8 log photons cm(-2) s(-1)) of red (631nm) and blue (469nm) light were measured, using a dedicated infrared pupillometer. All subjects underwent swept source optical coherence tomography (SS-OCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan) and noncontact partial coherence laser interferometry (Lenstar LS900, Haag-Streit AG, Switzerland). Univariate and multivariable regression analyses were performed to determine the anatomical features influencing pupillographic parameters. Among the 177 included subjects, 167 (94.4%) were Chinese and 116 (65.5%) female. The average baseline pupil diameter in darkness (β = -0.080, p < 0.001) and the amplitude of the relative pupillary constriction (β = -0.233, p = 0.006) to blue light decreased with age. The amplitude of pupillary constriction was significantly larger in patients with a thinner iris, in response to stimulation with blue (β = -0.321, p < 0.001) and red light (β = -0.336, p < 0.001). Other ocular parameters (i.e., lens vault, anterior chamber depth width, iris volume, iris curvature, and lens thickness) were not significantly associated with pupillometric outcomes. The amplitude of the pupillary light constriction to chromatic photic stimuli is reduced with increasing age and iris thickness in subjects with normal ocular health, a finding which needs to be integrated into future pupillometric studies.

Intracameral interleukin 1β, 6, 8, 10, 12p, tumor necrosis factor α and vascular endothelial growth factor and axial length in patients with cataract.

ObjectiveTo assess associations between the aqueous humour concentration of interleukin IL-1β, IL-6, IL-8, IL-10 and IL-12p, tumor necrosis factor α (TNF-α) and vascular endothelial growth factor (VEGF) and axial length in eyes with cataract.MethodsThe hospital-based investigation included patients who underwent cataract surgery between March 2014 and April 2014. Using aqueous humour collected at the start of cataract surgery, the interleukins IL-1β, IL-6, IL-8, IL-10 and IL-12p, TNF-α and VEGF were examined using a cytometric bead array. Axial length was determined by partial coherence laser interferometry (IOL Master).ResultsThe study included 33 patients with cataract (33 eyes) with a mean age of 69.2±10.8 years (range:50–87 years) and a mean axial length of 24.7±1.9 mm (range:22.6–31.5 mm). Lower aqueous concentration of VEGF was significantly associated with longer axial length (VEGF concentration (pg/mL) = -5.12 x Axial Length (mm) + 163; correlation coefficient r = -0.41; P<0.001) and more myopic refractive error (VEGF concentration (pg/mL) = 1.27xspherical equivalent (diopters)+44.8; r = 0.383; P = 0.002). The aqueous concentrations of all other substances were not significantly (all P>0.10) associated with axial length or refractive error.ConclusionsHigher intravitreal concentrations of VEGF were measured in eyes with a longer axial length, while the intraocular concentrations of IL-1β, IL-6, IL-8, IL-10, IL-12p and TNF-α were not correlated with axial length. The lower concentration of VEGF in axially elongated eyes may be one of the reasons for the lower prevalence of age-related macular degeneration and diabetic retinopathy in myopic eyes.

Study of impact of diabetes mellitus on anterior chamber depth as detected by partial coherence laser interferometry

Study of impact of diabetes mellitus on anterior chamber depth as detected by partial coherence laser interferometry

한국 어린이의 안축장과 신체 계측치와의 관련성

목적: 본 연구는 한국 어린이를 대상으로 안축장과 신체 계측치와의 관련성을 조사하였다. 방법: 서울지역에서 11-12세(평균 연령: <TEX>$11.95{\pm}0.22$</TEX>세, 여학생: 45.0%)의 초등학생 40명을 대상으로 하였다. 부분 간섭측정법에 의한 안축장, 각막 곡률반경, 굴절이상도, 신장(m), 그리고 체중(kg)을 측정하였고, 체질량지수(BMI <TEX>$[kg/m^2]=weight/[height]^2$</TEX>)와 비만정도지수(DO[%]=[actual weightstandard weight]/standard weight)는 계산하였다. 근업 활동으로 1일 평균 독서시간, TV 시청시간, 그리고 컴퓨터 사용시간에 대하여 설문하였다. 결과: 전체 대상자의 평균 굴절이상도는 <TEX>$1.06{\pm}0.84D$</TEX>였고, 이들의 안축장과 몸무게(r=0.427, p=0.006), 체질량지수(r=0.508, p=0.001), 비만정도지수(r=0.371, p=0.018)는 유의한 양의 상관관계를 보였다. 또한 안축장은 체중(p=0.041)과 체질량지수(p=0.015)의 1사분위수, 그리고 비만정도지수가 가장 높은 그룹(p=0.042)에서 유의하게 길었다. 연령, 성별, 그리고 근업 활동을 보정한 후에 다중회귀분석에서 체중, 체질량지수 그리고 비만정도지수는 안축장과 유의한 관련성을 보였고, 특히, 근업 활동에서 1일 독서시간은 안축장과 유의한 관련성을 보였다. 결론: 한국 초등학생의 안축장은 체중과 관련이 있었다. 특히, 긴 안축장과 1일 독서시간은 유의한 관계를 보였다. Purpose: To investigate the relationship between axial length (AL) and anthropometric parameters in Korean children. Methods: This study included 40 urban school children aged 11-12 years (mean age, <TEX>$11.95{\pm}0.22$</TEX> years; 45.0% girls) residing in Seoul, South Korea. AL (using partial coherence laser interferometry), corneal radius, refractive error, height (m), and weight (kg) were measured. Body mass index (BMI <TEX>$[kg/m^2]=weight/[height]^2$</TEX>) and degree of obesity (DO[%]=[actual weight standard weight]/standard weight) were calculated. Furthermore, the number of hours spent reading, watching television, and using a computer every day was determined using a detailed questionnaire. Results: The students had a mean spherical equivalent refraction of <TEX>$1.06{\pm}0.84$</TEX> D. Weight (r=0.427, p=0.006), BMI (r=0.508, p=0.001), and DO (r=0.371, p=0.018) showed a significant positive correlation with AL. Furthermore, longer AL was significantly associated with heavier weight (p=0.041), and higher BMI (p=0.015), and higher DO quartiles (p=0.042). After adjust for age, sex, and near-work activities, multivariate linear regression models showed that weight, BMI, and DO were still significantly associated with AL. Among the near-work activities, daily reading time was significantly associated with AL. Conclusions: AL was positively related to weight as well as daily reading time in Korean urban school children.

Effect of axial length reduction after trabeculectomy on the development of hypotony maculopathy

To measure changes in axial length before and after trabeculectomy with noncontact, partial coherence laser interferometry and identify patient factors that lead to the development of hypotony maculopathy and axial length shortening in 25 eyes with intraocular pressure (IOP) ≤ 6 mmHg at 4 weeks after mitomycin C-augmented trabeculectomy. A retrospective comparative case series. Hypotony maculopathy was identified with both ophthalmoscopy and spectral-domain optical coherence tomography. Axial length and IOP were serially measured pre- and postoperatively. Logistic regression analysis was performed to identify factors associated with the presence of hypotony maculopathy at 4 weeks after trabeculectomy and multiple regression analysis to identify factors associated with axial length changes. Ten eyes exhibited hypotony maculopathy, whereas the remaining 15 did not. Patients with hypotony maculopathy were significantly younger (47.7 ± 6.2 years) compared with those without it (63.3 ± 9.6 years, P = 0.0002, unpaired t test). The percent reduction of axial length after trabeculectomy was significantly larger in the former group (5.91 ± 2.76 %) compared with the latter group (1.51 ± 0.91 %) (P = 0.0001, Mann-Whitney U test). Multivariate analyses showed that only age was associated with the presence of hypotony maculopathy, with an odds ratio of 0.82 (P = 0.0075), when age, sex, type of glaucoma, lens status, percent changes in axial length and IOP before and after trabeculectomy, and central corneal thickness were included as independent variables (R (2) = 0.543, P = 0.003). Age-dependent axial length reduction is a risk factor for the development of hypotony maculopathy after trabeculectomy.

Distribution and Heritability of Peripheral Eye Length in Chinese Children and Adolescents: The Guangzhou Twin Eye Study

Peripheral eye length (PEL) provides a measure of overall eye shape, which may play a role in the development of myopia. The current study explores the distribution and heritability of PEL, relative PEL (RPEL, defined as PEL minus axial eye length) and relative ratio PEL (RRPEL, defined as PEL divided by axial eye length) in Chinese children and adolescents. Subjects included both male and female youths participating in the Guangzhou Twin Eye Study. Eye length was measured by partial coherence laser interferometry axially, 40° temporally (PEL-T(40)) and 40° nasally (PEL-N(40)). Structural equation modeling (SEM) was used to estimate the relative contribution of genetic and environmental factors on PEL, RPEL, and RRPEL, adjusting for age and sex. We examined 104 monozygotic (MZ) and 54 dizygotic (DZ) twins aged 8 to 20 years old. The intraclass correlation coefficients were 0.89 for PEL-T(40), 0.92 for PEL-N(40), 0.80 for RPEL-T(40), 0.73 for RPEL-N(40), 0.77 for RRPEL-T(40), and 0.73 for RRPEL-N(40) in MZ pairs, and 0.52, 0.50, 0.39, 0.58, 0.37, and 0.58 in DZ pairs, respectively. The best fit adjusted models estimated that additive genetic effects accounted for approximately 86.2%, 89.8%, 79.9%, 75.5%, 77.1%, and 74.5% of the variance for the above mentioned traits, respectively, while dominant genetic effects and shared environmental factors were negligible. Additive genetic effects had a substantial influence on phenotypic variation in PEL and RPEL, suggesting genetic rather than environmental factors play a major role in determining eye shape.

Differential Associations of Myopia with Major Age-related Eye Diseases: The Singapore Indian Eye Study

To determine the associations of myopia and axial length (AL) with major age-related eye diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), age-related cataract, and primary open-angle glaucoma (POAG). Population-based, cross-sectional study. A total of 3400 Indians (75.6% response rate) aged 40 to 84 years in Singapore. Refractive error was determined by subjective refraction, and AL was determined by noncontact partial coherence laser interferometry. Age-related macular degeneration and DR were defined from retinal photographs according to the Wisconsin Age-Related Maculopathy Grading System and Airlie House classification system, respectively. Age-related cataract was diagnosed clinically using the Lens Opacity Classification System (LOCS) III system. Glaucoma was defined according to International Society for Geographical and Epidemiological Ophthalmology criteria. Age-related macular degeneration, DR, age-related cataract, and POAG. Myopic eyes (spherical equivalent [SE] <-0.5 diopter [D]) were less likely to have AMD (early plus late AMD) (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.25-0.79) or DR (OR, 0.68; 95% CI, 0.46-0.98) compared with emmetropic eyes; each millimeter increase in AL was associated with a lower prevalence of AMD (OR, 0.76; 95% CI, 0.65-0.89) and DR (OR, 0.73; 95% CI, 0.63-0.86). Myopic eyes were more likely to have nuclear (OR, 1.57; 95% CI, 1.13-2.20) and posterior subcapsular (OR, 1.73; 95% CI, 1.10-2.72) cataract, but not cortical cataract (P = 0.64); each millimeter increase in AL was associated with a higher prevalence of posterior subcapsular cataract (PSC) (OR, 1.29; 95% CI, 1.07-1.55), but not nuclear (P = 0.77) or cortical (P = 0.39) cataract. Eyes with high myopia (SE <-6.0 D) were more likely to have POAG (OR, 5.90; 95% CI, 2.68-12.97); each millimeter increase in AL was associated with a higher prevalence of POAG (OR, 1.43; 95% CI, 1.13-1.80). Myopic eyes are less likely to have AMD and DR but more likely to have nuclear cataract, PSC, and POAG. The associations of myopia with AMD, DR, and POAG are mostly explained by longer AL. However, the association between myopia and nuclear cataract is explained by lens refraction rather than AL.

Changes in choroidal thickness and optical axial length accompanying intraocular pressure increase

To measure changes in choroidal thickness (CT), retinal thickness (RT), and axial length (AL) accompanying intraocular pressure (IOP) increase and to investigate the changes in axial eye dimensions induced by IOP increase. Thirty-four eyes of 34 patients undergoing a diagnostic provocative test for primary angle closure (PAC). Patients with other macular diseases were excluded. Patients underwent the darkroom prone provocative test (DR-PPT) for 1 h. We measured CT and RT at the fovea by optical coherence tomography with the enhanced depth imaging method and AL with noncontact, partial coherence laser interferometry before and after the DR-PPT. There was a statistically significant increase in the mean (SD) IOP of 7.3 (9.2) mmHg and the mean (SD) AL of 0.06 (0.12) mm after the DR-PPT (P < 0.001 and P = 0.014, respectively). There was a statistically significant decrease in the mean (SD) subfoveal CT of 30.0 (36.8) μm (P < 0.001), while there was no significant change in the mean foveal RT. The change in subfoveal CT was negatively correlated with the changes in IOP (r = -0.71, P < 0.001) and AL (r = -0.54, P = 0.004). In eyes suspected of having PAC, acutely increased IOP accompanies choroid thinning and corresponding elongation of the optical axis.

Prevalence of Primary Angle Closure and Primary Angle-Closure Glaucoma in a Southwestern Rural Population of Japan: The Kumejima Study

To determine the prevalence and ocular biometry of primary angle closure (PAC) and primary angle-closure glaucoma (PACG) in a rural population in southwestern Japan. Population-based cross-sectional study. All residents aged 40 years or older in Kumejima, Okinawa, Japan. Of the 4632 residents 40 years of age or older, 3762 (participation rate, 81.2%) underwent a detailed ocular examination, including measurement of the best-corrected visual acuity, slit-lamp examination, Goldmann applanation tonometry, static and dynamic gonioscopy, undilated stereoscopic optic fundus photographs, autorefractometry, partial coherence laser interferometry, noncontact specular microscopy, and screening visual field (VF) testing using frequency-doubling technology. If glaucoma or related or other ocular disorders were suspected, the subject was referred for a definitive examination including VF testing with the 24-2 Swedish Interactive Thresholding Algorithm Standard program of the Humphrey Field Analyzer (Carl Zeiss Meditec, Dublin, CA). Prevalence rates of primary angle-closure suspects (PACS), PAC, PACG, and PACG suspects. Under the standard definitions of the International Society of Geographical and Epidemiological Ophthalmology, the prevalence rates of PACS, PAC, and PACG were 8.8%, 3.7%, and 2.0%. Extending the diagnosis of PAC and PACG to include people with narrow but open angles and primary peripheral anterior synechiae, the prevalence rates of PAC and PACG increased to 6.0% and 2.2%, respectively. Hence, broadening the diagnostic categories in PAC and PACG increased the prevalence rates by 62% and 10%. Twenty-three subjects (0.6%; 95% confidence interval, 0.4%-0.9%) had a history of or were diagnosed with acute PAC. Older age, female gender, hyperopic refractive error, short axial length, and shallow anterior chamber depth were independent predictors of an occludable angle. The prevalence of PACG in Kumejima (2.2%) was one of the highest reported in population-based studies, that is, 3.7 times higher than in the Tajimi Study carried out in an urban center located in the central area of the main island of Japan. The author(s) have no proprietary or commercial interest in any materials discussed in this article.