Refractive error, ocular and general parameters and ophthalmic diseases. The Beijing Eye Study

Myopia is associated with education: Results from NHANES 1999-2008

Purpose

Myopia is increasing worldwide and possibly linked to education. In this study, we analyse the association of myopia and education in the U.S. and investigate its age-dependency.

Methods

We conducted a secondary data analysis using the public use files from the cross-sectional study National Health and Nutrition Examination Survey of the period from 1999 to 2008. 19,756 participants aged 20 to 85 years were included with data on education and ophthalmic parameters (distance visual acuity, objective refraction and keratometry). Spherical equivalent, astigmatism, corneal power and corneal astigmatism were evaluated for an association with education using linear regression analysis with adjustment of potential confounders.

Results

Analysis revealed an association between spherical equivalent and educational level in the univariate analysis (P < .001), and in the adjusted model (P < .001). Subjects who attend school to less than 9th grade had a mean spherical equivalent of 0.34 D, subjects with 9-11th grade -0.14 D, subjects that finished high school -0.33 D, subjects with partial college education -0.70 D, subjects that graduated from college or a higher formal education -1.22 D. Subjects that graduated from college or above were -1.47 D more myopic compared to subjects that completed less than 9^th grade school in the adjusted analyses. Astigmatism and corneal curvature was not associated with education.

Conclusions

Myopia is associated with higher education in the U.S. Our analysis shows that corneal curvature does not contribute to this association, therefore axial elongation or lens power are likely to contribute to myopia.

Effect of refractive status on Valsalva-induced anterior segment changes

PURPOSE

To evaluate the effect of the Valsalva maneuver (VM) on anterior segment parameters and its association with refractive status.

METHOD

In this prospective study, 120 eyes of 120 subjects were evaluated. Subjects were divided into three groups: myopic (n = 40 patients), hyperopic (n = 40 patients), and emmetropic (control group, n = 40 subjects). The anterior segment parameters, including keratometric, pachymetric, and anterior chamber parameters, were measured using the Sirius System (Costruzione Strumenti Oftalmici, Florence, Italy) before and during VM.

RESULTS

There was no statistically significant difference in corneal parameters including keratometric and pachymetric values at rest or during VM in myopic, hyperopic, and control groups (p > 0.05 for all). In the myopic and control groups, anterior chamber depth, anterior chamber volume (ACV), and anterior chamber angle (ACA) were significantly decreased during VM. In the hyperopic group, only anterior chamber depth was significantly decreased during VM, while ACV and ACA did not significantly change.

CONCLUSION

The Valsalva maneuver may cause significant narrowing in anterior chamber depth, anterior chamber volume, and anterior chamber angle in the myopic and emmetropic groups, whereas it may affect only anterior chamber depth in the hyperopic group.

Refractive error change and its association with ocular and general parameters in junior high school students in Taiwan

PURPOSE

To assess the relationships between refractive error and ocular and general parameters in Taiwanese junior high school students and to identify the predictive factors associated with the changes in refractive error.

METHODS

This was a prospective, school-based study. A total of 687 students (357 boys and 330 girls) from a municipal junior high school in Taipei were enrolled. The students' refractive status, intraocular pressure, and ocular parameters were measured first in 2010 and again 1 year later. Data were analyzed using multiple linear regression models and generalized estimating equations (GEEs).

RESULTS

Significant differences were found between the baseline (2010) and 1-year follow-up (2011) mean anterior chamber depths, mean axial lengths, and mean horizontal and vertical corneal refractive powers. GEE models revealed that vertical and horizontal corneal refractive powers, axial length, and anterior chamber depth were significantly associated with refractive error change.

CONCLUSIONS

Students with a longer axial length, steeper corneal radius, and shallower anterior chamber depth had an increased risk of myopic refractive errors.

Intraocular pressure and central corneal thickness in the COMET cohort

PURPOSE

To describe intraocular pressure (IOP) and central corneal thickness (CCT) in ethnically diverse, myopic young adults enrolled in COMET (the Correction of Myopia Evaluation Trial) and their association with ocular and demographic factors.

METHODS

IOP (Goldmann tonometry), CCT (handheld pachymetry), refractive error (cycloplegic autorefraction), and ocular components (A-scan ultrasonography) were measured in 385 of the original 469 subjects (mean age = 20.3 ± 1.3 years). Summary statistics for descriptive analysis, Pearson correlation coefficients, and linear regression models to formally test the association of IOP and CCT with other covariates were used.

RESULTS

Mean IOP was 15.1 ± 0.1 mm Hg and differed by ethnicity and CCT but did not vary by gender, magnitude of myopia, or vitreous chamber depth (VCD). Adjusting for CCT, IOP in black participants was 1.8 mm Hg higher than in Hispanics (p = 0.0001) and 0.8 mm Hg higher than in whites (p = 0.03). Mean CCT was 562.4 ± 1.8 μm and differed by ethnicity, VCD, and IOP after adjusting for covariates. Blacks had thinner corneas than Asians, whites, and Hispanics, with adjusted differences of 15.4, 11.8, and 15.3 μm (p = 0.03, < 0.01 and < 0.01), respectively. Eyes with shorter VCD (<17.8 mm) had 8.0-μm thinner CCT (p = 0.03). CCT did not vary by gender or magnitude of myopia. Overall, a modest positive correlation (r = 0.25, P < 0.0001) was found between IOP and CCT, which varied by ethnicity in Asians (r = 0.47; p = 0.008), blacks (r = 0.29; p = 0.002), and whites (r = 0.24; p = 0.002).

CONCLUSIONS

Myopic, black young adults had higher IOP and thinner corneas relative to other ethnic groups, suggesting that evaluation of these parameters during routine examination of these individuals should begin at a young age. Their thinner CCT should also be considered in evaluations for refractive surgery.

Asian Age-Related Macular Degeneration: Current Concepts and Gaps in Knowledge

Data on the epidemiology and treatment of age-related macular degeneration (AMD) in Asian populations have been scarce. Recently, significant advances in the current knowledge of AMD in Asia have been made, but deficiencies in important areas remain. Epidemiological data on AMD in those 80 years or older are lacking.There are also few incidence data on AMD or polypoidal choroidal vasculopathy (PCV), an important variant of AMD that seems to be more common in Asia. The risk factors for PCV have not been clearly defined to the extent that those for AMD have. No trials of nutritional supplementation for AMD prevention in Asia exist, and there is also a lack of long-term clinical trial data on combination therapy for PCV and indeed very few trial data on PCV. These represent opportunities for future research. With aging populations in Asia, increased data on the prevalence, risk factors, prevention, and treatment of AMD and PCV in Asian populations will be needed to formulate evidence-based public health and clinical guidelines.

Predictive Factors Within the Optic Nerve Complex for Glaucoma Progression: Disc Hemorrhage and Parapapillary Atrophy

The optic nerve complex (ONC) is a new term we have created to describe the clinically and non-clinically visible portions of the optic nerve and surrounding tissues. Recent advances in imaging technologies have created a need to provide a unified and comprehensive view of the structure and function of the components of ONC to assess various risk factors for glaucoma development and progression. Despite a great deal remaining to elucidate their underlying pathogenesis, disc hemorrhages and β-zone parapapillary atrophy have been consistently shown in different study designs to be significant risk factors for glaucoma progression. Given their easy visibility as components of the ONC, disc hemorrhage and β-zone parapapillary atrophy are widely underscored glaucoma features that should be thoroughly investigated and documented with the purpose of stratifying patients under risk categories along with other intraocular pressure-dependent and -independent factors. This review provides an update on these 2 features and their relationship to glaucoma progression.

Beta-zone parapapillary atrophy and multifocal visual evoked potentials in eyes with glaucomatous optic neuropathy

We investigated changes in multifocal visual evoked potential (mfVEP) responses due to beta-zone parapapillary atrophy (ßPPA). Patients with glaucomatous optic neuropathy (GON) with or without standard achromatic perimetry (SAP) abnormalities were referred for mfVEP testing during a 2-year period. Eyes with good quality optic disc stereophotographs and reliable SAP results were included. The mfVEP monocular mean latency delays (ms) and amplitudes (SNR) were analyzed. Age, SAP mean deviation (MD), pattern standard deviation (PSD), and spherical equivalent (SE) were analyzed in the multivariate model. Generalized estimated equations were used for comparisons between groups after adjusting for inter-eye associations. Of 394 eyes of 200 patients, 223 (57%) had ßPPA. The ßPPA eyes were older (59.6 ± 13.7 vs. 56.5 ± 13.7 year, P = 0.02), more myopic (-4.0 ± 3.5 vs. -1.3 ± 3.5 D, P < 0.01), and had poorer SAP scores (MD: -4.9 ± 5.2 vs. -2.6 ± 5.2 dB, P < 0.01; PSD: 4.3 ± 2.9 vs. 2.5 ± 3.0 dB, P < 0.01). By univariate analysis, mean latencies were longer in ßPPA eyes (6.1 ± 5.3 vs. 4.0 ± 5.5 ms, P < 0.01). After adjusting for differences in SE, age, and SAP MD, there was no significant difference between the two groups (P = 0.09). ßPPA eyes had lower amplitude log SNR (0.49 ± 0.16 vs. 0.56 ± 0.15, P < 0.01), which lost significance (P = 0.51) after adjusting for MD and PSD. Although eyes with ßPPA had significantly lower amplitudes and prolonged latencies than eyes without ßPPA, these differences were attributable to differences in SAP severity, age, and refractive error. Thus, ßPPA does not appear to be an independent factor affecting mfVEP responses in eyes with GON.