Two-year changes in refractive error and related biometric factors in an adult Chinese population

Importance: This article provides, to our knowledge, the first longitudinal population-based data on refractive error (RE) in Chinese persons.

Objective: To study cohort effects and changes associated with aging in REs among Chinese adults.

Design, Setting, and Participants: A 2-year, longitudinal population-based cohort study was conducted in southern China. Participants, identified using cluster random sampling, included residents of Yuexiu District, Guangzhou, China, aged 35 years or older who had undergone no previous eye surgery.

Methods: Participants underwent noncycloplegic automated refraction and keratometry in December 2008 and December 2010; in a random 50% sample of the participants, anterior segment ocular coherence tomography measurement of lens thickness, as well as measurement of axial length and anterior chamber depth by partial coherence laser interferometry, were performed.

Main Outcomes and Measures: Two-year change in spherical equivalent refraction (RE), lens thickness, axial length, and anterior chamber depth in the right eye.

Results: A total of 745 individuals underwent biometric testing in both 2008 and 2010 (2008 mean [SD] age, 52.2 [11.5] years; 53.7% women). Mean RE showed a 2-year hyperopic shift from −0.44 (2.21) to −0.31 (2.26) diopters (D) (difference, +0.13; 95% CI, 0.11 to 0.16). A consistent 2-year hyperopic shift of 0.09 to 0.22 D was observed among participants aged 35 to 64 years when stratifying by decade, suggesting that a substantial change in RE with aging may occur during this 30-year period. Cross-sectionally, RE increased only in the cohort younger than 50 years (0.11 D/y; 95% CI, 0.06 to 0.16). In the cross-sectional data, axial length decreased at −0.06 mm/y (95% CI, −0.09 to −0.04), although the 2-year change in axial length was positive and thus could not explain the cross-sectional difference. These latter results suggest a cohort effect, with greater myopia developing among younger persons.

Conclusions and Relevance: This first Chinese population-based longitudinal study of RE provides evidence for both important longitudinal aging changes and cohort effects, most notably greater myopia prevalence among younger persons.

Determinants and two-year change in anterior chamber angle width in a Chinese population

Objective: To study the population distribution and longitudinal changes in anterior chamber angle width and its determinants among Chinese adults. Design: Prospective cohort, population-based study. Participants: Persons aged 35 years or more residing in Guangzhou, China, who had not previously undergone incisional or laser eye surgery. Methods: In December 2008 and December 2010, all subjects underwent automated keratometry, and a random 50% sample had anterior segment optical coherence tomography with measurement of angle-opening distance at 500 μm (AOD500), angle recess area (ARA), iris thickness at 750 μm (IT750), iris curvature, pupil diameter, corneal thickness, anterior chamber width (ACW), lens vault (LV), and lens thickness (LT) and measurement of axial length (AL) and anterior chamber depth (ACD) by partial coherence laser interferometry. Main Outcome Measures: Baseline and 2-year change in AOD500 and ARA in the right eye. Results: A total of 745 subjects were present for full biometric testing in both 2008 and 2010 (mean age at baseline, 52.2 years; standard deviation [SD], 11.5 years; 53.7% were female). Test completion rates in 2010 varied from 77.3% (AOD500: 576/745) to 100% (AL). Mean AOD500 decreased from 0.25 mm (SD, 0.13 mm) in 2008 to 0.21 mm (SD, 13 mm) in 2010 (difference, -0.04; 95% confidence interval [CI], -0.05 to -0.03). The ARA decreased from 21.5±3.73 10^-2 mm² to 21.0±3.64 10 ^-2 mm² (difference, -0.46; 95% CI, -0.52 to -0.41). The decrease in both was most pronounced among younger subjects and those with baseline AOD500 in the widest quartile at baseline. The following baseline variables were significantly associated with a greater 2-year decrease in both AOD500 and ARA: deeper ACD, steeper iris curvature, smaller LV, greater ARA, and greater AOD500. By using simple regression models, we could explain 52% to 58% and 93% of variation in baseline AOD500 and ARA, respectively, but only 27% and 16% of variation in 2-year change in AOD500 and ARA, respectively. Conclusions: Younger persons and those with the least crowded anterior chambers at baseline have the largest 2-year decreases in AOD500 and ARA. The ability to predict change in angle width based on demographic and biometric factors is relatively poor, which may have implications for screening. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. © 2012 American Academy of Ophthalmology.

Cataract surgery and subtype in a defined, older population: the SEECAT Project

AIM:

To describe the distribution of cataract subtypes present before surgery among a defined population of older, bilaterally pseudophakic individuals.

METHODS:

This was a cohort study of bilaterally pseudophakic individuals participating in the Salisbury Eye Evaluation (SEE), and their locally resident siblings. Subjects underwent slit lamp and retroillumination photography and grading using the Wilmer Cataract Grading System. For all individuals determined to be bilaterally pseudophakic, an attempt was made to determine for each eye the type(s) of cataract present before surgery, based on previous SEE photographs (for SEE participants) and/or medical records obtained from the operating ophthalmologist (for both SEE participants and their siblings).

RESULTS:

The mean age of 223 participants providing data in this study was 78.7 (SD 5.2) years, 19.3% of subjects were black and 60.1% female. The most common surgically removed cataract subtype in this population was pure nuclear (43.5%), followed by nuclear combined with posterior subcapsular cataract (PSC) (20.6%), and nuclear combined with cortical (13.9%); less common types were pure cortical (4.9%), pure PSC (4.5%), and PSC combined with cortical (2.7%). Factors such as sex and source of lens data (study photograph versus clinical record) did not significantly affect the distribution of lens opacity types, while PSC was significantly (p = 0.01) more common among younger people and nuclear cataract was significantly (p = 0.001) more common among white compared to black people.

CONCLUSION:

Epidemiological studies have suggested that the different subtypes of cataract are associated with different risk factors. As studies begin to identify new prevention strategies for cataract, it would appear likely that different strategies will be efficacious against different types of cataract. In this setting, it will be helpful to know which cataract types are most frequently associated with surgery. Among this older, majority white population, nuclear cataract showed a clear predominance among individuals having undergone surgery in both eyes. This may be contrasted with both clinic and population based studies of younger people, which have generally found PSC cataract to predominate.

Familial aggregation of hyperopia in an elderly population of siblings in Salisbury, Maryland.

PURPOSE: To determine whether hyperopia aggregates in families in an older mixed-race population. DESIGN: Cross-sectional familial aggregation study using sibships. METHODS: We recruited 759 subjects (mean age, 73.4 years) in 241 families through the population-based Salisbury Eye Evaluation study. Subjects underwent noncycloplegic refraction if best-corrected visual acuity (BCVA) was <or=20/40, had lensometry to measure their currently worn spectacles if BCVA was >20/40 with spectacles, or were considered to be plano (refraction of zero) if the BCVA was >20/40 without spectacles. Preoperative refraction from medical records was used for bilaterally pseudophakic subjects. RESULTS: Utilizing hyperopia cutoffs from 1.00 to 2.50 diopters, age-, race-, and gender-adjusted odds ratios for hyperopia with an affected sibling ranged from 2.72 (95% confidence interval [CI], 1.84-4.01) to 4.87 (95% CI, 2.54-9.30). The odds of hyperopia increased with age until 75 years, after which they remained relatively constant. Black men were significantly less likely to be hyperopic than white men, white women, or black women. CONCLUSIONS: Hyperopia appears to be under strong genetic control in this older population.

Determinants and heritability of intraocular pressure and cup-to-disc ratio in a defined older population.

PURPOSE:

To investigate the heritability of intraocular pressure (IOP) and cup-to-disc ratio (CDR) in an older well-defined population.

DESIGN:

Family-based cohort study.

PARTICIPANTS:

Through the population-based Salisbury Eye Evaluation study, we recruited 726 siblings (mean age, 74.7 years) in 284 sibships.

METHODS:

Intraocular pressure and CDR were measured bilaterally for all participants. The presence or absence of glaucoma was determined by a glaucoma specialist for all probands on the basis of visual field, optic nerve appearance, and history. The heritability of IOP was calculated as twice the residual between-sibling correlation of IOP using linear regression and generalized estimating equations after adjusting for age, gender, mean arterial pressure, race, self-reported diabetes status, and history of systemic steroid use. The heritability of CDR was calculated using the same model and adjustments as above, while also adjusting for IOP.

MAIN OUTCOME MEASURES:

Heritability and determinants of IOP and CDR, and impact of siblings' glaucoma status on IOP and CDR.

RESULTS:

We estimated the heritability to be 0.29 (95% confidence interval [CI], 0.12-0.46) for IOP and 0.56 (95% CI, 0.35-0.76) for CDR in this population. Mean IOP in siblings of glaucomatous probands was statistically significantly higher than in siblings of normal probands (mean difference, 1.02 mmHg; P = 0.017). The mean CDR in siblings of glaucomatous probands was 0.07 (or 19%) larger than in siblings of glaucoma suspect referrals (P = 0.045) and siblings of normal probands (P = 0.004).

CONCLUSIONS:

In this elderly population, we found CDR to be highly heritable and IOP to be moderately heritable. On average, siblings of glaucoma patients had higher IOPs and larger CDRs than siblings of nonglaucomatous probands.

Comparison of anterior ocular biometry between optical low-coherence reflectometry and anterior segment optical coherence tomography in an adult Chinese population.

PURPOSE: To evaluate the agreement between optical low-coherence reflectometry (OLCR) and anterior segment optical coherence tomography (AS-OCT) for biometry of the anterior segment. SETTING: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. DESIGN: Evaluation of diagnostic technology. METHODS: A series of OLCR (Lenstar LS 900) and AS-OCT measurements of the anterior segment were taken for consecutive subjects aged 35 years and older in a population-based study. The differences and correlations between the 2 methods of ocular biometry were assessed. Agreement was calculated as the 95% limits of agreement (LoA). RESULTS: The mean age of the 776 subjects was 55.2 years ± 12.0 (SD); 54.6% were women. The mean central corneal thickness (CCT) was smaller with OLCR than with AS-OCT (537.84 ± 31.46 μm versus 559.39 ± 32.02 μm) as was anterior chamber depth (ACD) (2.60 ± 0.37 mm versus 2.72 ± 0.37 mm) and anterior chamber width (ACW) (11.76 ± 0.47 mm versus 12.04 ± 0.55 mm) (all P<.001). The 95% LoA between the 2 instruments were -44.80 to 1.71 μm for CCT, -0.17 to -0.06 mm for ACD, and -1.28 to 0.72 mm for ACW. CONCLUSION: Optical low-coherence reflectometry and AS-OCT yielded potentially interchangeable ACD measurements, while the CCT and ACW measurements acquired by the 2 devices showed clinically significant differences.

Statistical Tests for Joint Analysis of Performance Measures

Recently there has been an increasing interest in the development of new methods using Pareto optimality to deal with multi-objective criteria (for example, accuracy and architectural complexity). Once one has learned a model based on their devised method, the problem is then how to compare it with the state of art. In machine learning, algorithms are typically evaluated by comparing their performance on different data sets by means of statistical tests. Unfortunately, the standard tests used for this purpose are not able to jointly consider performance measures. The aim of this paper is to resolve this issue by developing statistical procedures that are able to account for multiple competing measures at the same time. In particular, we develop two tests: a frequentist procedure based on the generalized likelihood-ratio test and a Bayesian procedure based on a multinomial-Dirichlet conjugate model. We further extend them by discovering conditional independences among measures to reduce the number of parameter of such models, as usually the number of studied cases is very reduced in such comparisons. Real data from a comparison among general purpose classifiers is used to show a practical application of our tests.

Do Gifts Increase Consent to Home-based HIV Testing? A Difference-in-differences Study in Rural KwaZulu-Natal, South Africa

Background Despite the importance of HIV testing for controlling the HIV epidemic, testing rates remain low. Efforts to scale-up testing coverage and frequency in hard-to-reach and at-risk populations commonly focus on home-based HIV testing. This study evaluates the effect of a gift (a food voucher for families, worth US$ 5) on consent rates for home-based HIV testing.
Methods We use data on 18,478 men and women who participated in the 2009 and 2010 population-based HIV surveillance carried out by the Wellcome Trust Africa Centre for Health and Population Studies in rural KwaZulu-Natal, South Africa. Our quasi-experimental difference-in-differences approach controls for unobserved confounding in estimating the causal effect of the intervention on HIV testing consent rates.
Results Allocation of the gift to a family in 2010 increased the probability of family members consenting to test in 2010 by 25 percentage points (95% CI 21-30; p<0.001). The intervention effect persisted, slightly attenuated, in the year following the intervention (2011), further increasing intervention value for money.
Conclusions In HIV hyperendemic settings a gift can be highly effective at increasing consent rates for home-based HIV testing. Given the importance of HIV testing for treatment uptake and individual health, as well as for HIV treatment-and-prevention strategies and for monitoring the population impact of the HIV response, gifts should be considered as a supportive intervention for HIV testing initiatives where consent rates have been low.