Xiaohu Ding

Use of Eye Care Services among Diabetic Patients in Urban and Rural China

OBJECTIVE To assess the use of eye care and its predictors among diabetic patients in China. DESIGN Cross-sectional, clinic-based study. PARTICIPANTS Diabetic patients 18 years of age or older were recruited consecutively from an urban tertiary and community hospitals and from a rural clinic in Guangdong, China. METHODS Information obtained by questionnaire and chart review included: demographic and socioeconomic status, knowledge about diabetic retinopathy (DR), and ocular and medical history. MAIN OUTCOME MEASURES Self-reported or chart history of an eye examination ever or within the preceding 12 months. RESULTS The participation rate among 889 eligible subjects was 92.7%. Among 824 participants (mean age, 62.6+/-12.9 years; 58.8% female), 550 (66.7%) had not been examined in the last year as recommended by the American Academy of Ophthalmology, and 356 (43.2%) had never been examined. For the rural hospital, these figures were 81.1% and 68.7%, respectively. In regression analyses, factors associated with having an eye examination in the last year were: attendance at urban hospitals (odds ratio [OR], 3.46 [P<0.001] and 1.76 [P = 0.021] for the tertiary and community hospitals, respectively, compared with the rural clinic), higher DR knowledge score (OR, 1.24; P = 0.001), greater concern about vision loss (OR, 1.22; P = 0.007), and recommendation of regular eye examinations by the provider (OR, 2.36; P = 0.011). Predictors of ever having an eye examination were similar. Monthly income and health insurance status were not predictive of being examined. CONCLUSIONS These results suggest that the low proportion of diabetic receiving recommended annual eye examinations in China may be improved through patient and physician education.

High Prevalence of Demodex brevis Infestation in Chalazia

PURPOSE To investigate the correlation between demodicosis and chalazia in patients with the latter. DESIGN Prospective, observational, comparative study. METHODS Forty-four adult and 47 pediatric patients with chalazia and 34 adult and 30 pediatric age- and sex-matched patients without chalazia treated at an institutional referral eye center were included. All 155 patients underwent lash sampling followed by microscopic identification and counting of Demodex mites. All 91 patients with chalazia underwent surgical removal, and among them, 74 were followed up for 18 ± 4.3 months after surgery. Statistical correlation between ocular demodicosis and chalazia and its postoperative recurrence was performed. RESULTS Demodicosis was significantly more prevalent in chalazia patients than in control patients as a group (69.2% vs 20.3%) and when separated into pediatric (70.2% vs 13.3%) and adult (68.2% vs 26.5%) subgroups (all P < .001). Demodicosis was associated strongly with chalazia (odds ratio, 4.39; 95% confidence interval, 2.17 to 8.87; P < .001). D. brevis was significantly more prevalent (odds ratio, 18.21; 95% confidence interval, 2.22 to 149.74; P = .01) than D. folliculorum (odds ratio, 2.82; 95% confidence interval, 1.16 to 6.84, P = .02) in patients with chalazia. Patients with demodicosis tended to demonstrate recurrence (33.3% vs 10.3%; P = .02), especially in those with D. brevis (35.1% vs 13.5%; P = .03). CONCLUSIONS There is a high prevalence of demodicosis, especially cases of caused by D. brevis, in adult and pediatric patients with chalazia, suggesting that ocular demodicosis is a risk factor for chalazia.

Shared Genetic Determinant of Axial Length, Anterior Chamber Depth, and Angle Opening Distance: The Guangzhou Twin Eye Study

PURPOSE To estimate the extent to which common genetic and environmental effects contribute to covariances among axial length, anterior chamber depth, and angle-opening distance. METHODS The study participants were recruited from the Guangzhou Twin Registry. Anterior segment optical coherence tomography and custom software were used to quantify the angle opening distance (AOD) at the location 500 microm anterior to the scleral spur. Anterior chamber depth (ACD) and axial length (AL) were measured using laser interferometry. Cross-trait, cross-twin correlations for monozygotic (MZ) and dizygotic (DZ) twins and the Cholesky model were used to quantify shared genetic and environmental effects for AL, ACD, and AOD after adjusting for age and sex. RESULTS A group of 459 pairs of twins (304 MZ and 155 DZ) aged 8 to 16 years were available for analysis. The phenotypic correlations among AL, ACD, and AOD ranged from 0.39 to 0.64. Cross-twin, cross-trait correlations for these three phenotypes for MZ twins were consistently greater than the corresponding correlations for DZ twins. The results of the Cholesky model-fitting analyses can be summarized as follows: first, of 70% of additive genetic factors for AOD, 23% and 13% were those shared with ACD and AL, respectively, whereas the remaining 34% were those unique to AOD. Second, of 89% of additive genetic factors for ACD, 25% were those shared with AL, whereas 64% were those unique to ACD. Third, random environmental influences on covariances among AL, ACD, and AOD were very small. CONCLUSIONS Analyses of Chinese children twin data suggest that shared genes are responsible for the significant phenotypic correlations found for AL ACD, and AOD.

Shared genetic determinants of axial length and height in children: the Guangzhou twin eye study.

OBJECTIVES To describe the association between axial length (AL) and height and to estimate the extent to which shared genetic or environmental factors influence this covariance. METHODS Study participants were recruited from the Guangzhou Twin Registry. Axial length was measured using partial coherence laser interferometry. Height was measured with the participants standing without shoes. We computed twin pairwise correlations and cross-twin cross-trait correlations between AL and height for monozygotic and dizygotic twins and performed model-fitting analyses using a multivariate Cholesky model. The right eye was arbitrarily selected to represent AL of participants. RESULTS Five hundred sixty-five twin pairs (359 monozygotic and 206 dizygotic) aged 7 to 15 years were available for analysis. Phenotypic correlation between AL and height was 0.46 but decreased to 0.19 after adjusting for age, sex, and age × sex interaction. Bivariate Cholesky model-fitting analyses revealed that 89% of phenotypic correlation was due to shared genetic factors and 11% was due to shared random environmental factors, which includes measurement error. CONCLUSIONS Covariance of AL and height is largely attributable to shared genes. Given that AL is a key determinant of myopia, further work is needed to confirm gene sharing between myopia and stature.

Longitudinal Changes of Axial Length and Height Are Associated and Concomitant in Children

PURPOSE To examine the association between the longitudinal changes of axial length (AL) and height in Chinese children. METHODS The study participants were recruited from the Guangzhou Twin Registry. AL and height were measured every year from 2006 to 2008. AL was measured using partial coherence laser interferometry. Height was measured with the participants standing without shoes. Bivariate correlation coefficients and a multivariate generalized regression model were used to calculate the association between the changes of AL and height. Data from the first-born twins were selected to present the results: The right eye was arbitrarily selected to represent AL of the specific individual. RESULTS Mean annual increases of AL and height were 0.22 (SD, 0.17) mm and 3.93 (SD, 3.02) cm, respectively. Correlations between AL and height were 0.47 (95% CI, 0.40-0.52) in 2006. The correlation between AL at 2006 and height at 2008 was 0.44 (95% CI, 0.37-0.51); the correlation between AL at 2008 and height at 2006 was 0.38 (95% CI, 0.32-0.45). These cross-trait cross-time correlation coefficients remained statistically significant after adjusting for age and sex. Plotting the changes of AL and height suggested that the changes of AL and height with age were concomitant; greater changes were observed in younger children. CONCLUSIONS The association between AL and height in cross-sectional analysis and longitudinal changes may suggest common pathways for the development of eye size and body size in children.

Biometric measurements in highly myopic eyes

Purpose To assess the repeatability and accuracy of optical biometry (Lenstar LS900 optical low‐coherence reflectometry [OLCR] and IOLMaster partial coherence interferometry [PCI]) and applanation ultrasound biometry in highly myopic eyes. Setting Division of Preventive Ophthalmology, Zhongshan Ophthalmic Center, Guangzhou, China. Design Comparative evaluation of diagnostic technology. Methods Biometric measurements were taken in highly myopic subjects with a spherical equivalent (SE) of −6.00 diopters (D) or higher and an axial length (AL) longer than 25.0 mm. Measurements of AL and anterior chamber depth (ACD) obtained by OLCR were compared with those obtained by PCI and applanation A‐scan ultrasound. Right eyes were analyzed. Repeatability was evaluated using the coefficient of variation (CoV) and agreement, using Bland‐Altman analyses. Results The mean SE was −11.20 D ± 4.65 (SD). The CoVs for repeated AL measurements using OLCR, PCI, and applanation ultrasound were 0.06%, 0.07%, and 0.20%, respectively. The limits of agreement (LoA) for AL were 0.11 mm between OLCR and PCI, 1.01 mm between OLCR and applanation ultrasound, and 1.03 mm between PCI and ultrasound. The ACD values were 0.29 mm, 0.53 mm, and 0.51 mm, respectively. These repeatability and agreement results were comparable in eyes with extreme myopia (AL ≥27.0 mm) or posterior staphyloma. The mean radius of corneal curvature was similar between OLCR and PCI (7.66 ± 0.24 mm versus 7.64 ± 0.25 mm), with an LoA of 0.12 mm. Conclusion Optical biometry provided more repeatable and precise measurements of biometric parameters, including AL and ACD, than applanation ultrasound biometry in highly myopic eyes. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Effect of Ginkgo Biloba on Visual Field and Contrast Sensitivity in Chinese Patients With Normal Tension Glaucoma: A Randomized, Crossover Clinical Trial

PURPOSE We evaluated the effect of ginkgo biloba extract on visual field defect and contrast sensitivity in a Chinese cohort with normal tension glaucoma. METHODS In this prospective, randomized, placebo-controlled crossover study, patients newly diagnosed with normal tension glaucoma, either in a tertiary glaucoma clinic (n = 5) or in a cohort undergoing routine general physical examinations in a primary care clinic (n = 30), underwent two 4-week phases of treatment, separated by a washout period of 8 weeks. Randomization determined whether ginkgo biloba extract (40 mg, 3 times per day) or placebo (identical-appearing tablets) was received first. Primary outcomes were change in contrast sensitivity and mean deviation on 24-2 SITA standard visual field testing, while secondary outcomes included IOP and self-reported adverse events. RESULTS A total of 35 patients with mean age 63.7 (6.5) years were randomized to the ginkgo biloba extract-placebo (n = 18) or the placebo-ginkgo biloba extract (n = 17) sequence. A total of 28 patients (80.0%, 14 in each group) who completed testing did not differ at baseline in age, sex, visual field mean deviation, contrast sensitivity, IOP, or blood pressure. Changes in visual field and contrast sensitivity did not differ by treatment received or sequence (P > 0.2 for all). Power to have detected a difference in mean defect as large as previously reported was 80%. CONCLUSIONS In contrast to some previous reports, ginkgo biloba extract treatment had no effect on mean defect or contrast sensitivity in this group of normal tension glaucoma patients. (http://www.chictr.org number, ChiCTR-TRC-08000724).

The epidemics of myopia: Aetiology and prevention

&NA; There is an epidemic of myopia in East and Southeast Asia, with the prevalence of myopia in young adults around 80–90%, and an accompanying high prevalence of high myopia in young adults (10–20%). This may foreshadow an increase in low vision and blindness due to pathological myopia. These two epidemics are linked, since the increasingly early onset of myopia, combined with high progression rates, naturally generates an epidemic of high myopia, with high prevalences of “acquired” high myopia appearing around the age of 11–13. The major risk factors identified are intensive education, and limited time outdoors. The localization of the epidemic appears to be due to the high educational pressures and limited time outdoors in the region, rather than to genetically elevated sensitivity to these factors. Causality has been demonstrated in the case of time outdoors through randomized clinical trials in which increased time outdoors in schools has prevented the onset of myopia. In the case of educational pressures, evidence of causality comes from the high prevalence of myopia and high myopia in Jewish boys attending Orthodox schools in Israel compared to their sisters attending religious schools, and boys and girls attending secular schools. Combining increased time outdoors in schools, to slow the onset of myopia, with clinical methods for slowing myopic progression, should lead to the control of this epidemic, which would otherwise pose a major health challenge. Reforms to the organization of school systems to reduce intense early competition for accelerated learning pathways may also be important. HighlightsThere is an epidemic of myopia in the developed countries of East and Southeast Asia.A related epidemic of high myopia is due to early onset myopia and rapid myopic progression.There is a new and highly prevalent form of high myopia, which is acquired rather than genetic.Intense education and limited time outdoors play major causal roles in both epidemics.These modifiable risk factors are already being used in schools to contain the epidemics.

The Guangzhou twin project: An update

The Guangzhou Twin Registry is a population-based registry of twins residing in Guangzhou City. The initial registry database included 9,700 pairs of young twins recruited from the Official Household Registry of Guangzhou City. The registry is designed to provide a resource to identify the genetic and environmental causes of common diseases with an initial focus on eye diseases. From 2006 onward, phenotype and DNA collection have been completed for more than 1,200 twin pairs and their parents or siblings. Most of the young twins have come back for an annual examination of the progressive traits, such as refraction, ocular biometry, weight, and height. Genome-wide association scans have been completed recently. This article gives an update of the study design, cohort profile, previous findings, and future directions. Results from the Guangzhou Twin Project may contribute to the understanding of gene-environmental interplay for complex diseases in both adults and children.

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

PURPOSE 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.