Refractive error and smoking habits in exudative age-related macular degeneration in a hospital-based setting

Ocular Axial Length and Diabetic Retinopathy: The Kailuan Eye Study

Purpose

To examine the role of ocular axial length as an ocular parameter for the prevalence and severity of diabetic retinopathy (DR).

Methods

The cross-sectional Kailuan Diabetic Retinopathy Study included patients with diabetes who participated in the community-based longitudinal Kailuan Study and who had undergone ocular fundus photography. The fundus photographs were graded using the Early Treatment of Diabetic Retinopathy Study criteria.

Results

The study included 1096 patients with diabetes (mean age: 60.8 ± 9.4 years; axial length: 23.37 ± 0.92 mm). In binary regression analysis, a higher DR prevalence was associated with shorter axial length (P = 0.007; odds ratio [OR]: 0.81; 95% confidence interval [CI]: 0.70, 0.95) after adjusting for longer known duration of diabetes (P = 0.02; OR: 1.13; 95%CI: 1.02, 1.24) and higher fasting blood glucose concentration (P < 0.001; OR: 1.38; 95%CI: 1.26, 1.52). A more severe DR stage was associated (regression coefficient r: 0.46) with shorter ocular axial length (P = 0.047; standardized regression coefficient β: -0.06) after adjusting for higher fasting blood glucose (P < 0.001; β: 0.41) and longer known duration of diabetes (P = 0.045; β: 0.07). Longer axial length was associated with a lower DR prevalence (P = 0.003; β: -0.10) after adjusting for younger age (P < 0.001), male sex (P < 0.001), higher body mass index (P = 0.016), and lower fasting blood glucose concentration (P = 0.036).

Conclusions

After adjusting for systemic risk factors, DR prevalence decreased by 19% (95%CI: 5, 30) for each millimeter increase in axial length. With longer axial length being a surrogate for axial myopia, the marked increase in myopia prevalence worldwide may lead to a relative decrease in the prevalence and incidence of DR in future.

Intravitreal vascular endothelial growth factor concentration and axial length

BACKGROUND

To examine the intravitreal concentration of vascular endothelial growth factor (VEGF) in dependence of the axial length in eyes without intraocular neovascularization.

METHODS

The concentrations of VEGF in vitreous samples and blood samples of patients undergoing pars plana vitrectomy for treatment of idiopathic macular holes or epiretinal membranes were examined using enzyme-linked immunosorbent assay. Axial length was determined by biometry.

RESULTS

The study included 34 patients with macular holes (n = 21) or epiretinal membranes (n = 13) with a mean age of 62.4 ± 10.5 years (range: 35-76 years) and a mean axial length of 24.1 ± 1.8 mm (range: 21.0-29.1 mm). The intravitreal VEGF concentration (mean: 71.0 ± 63.2 pg/mL) was significantly (P < 0.001) lower than the VEGF concentration in the blood (830 ± 585 pg/mL). Both parameters were significantly associated with each other (P = 0.04; correlation coefficient r = 0.35). The intravitreal VEGF concentration was not significantly associated with gender (P = 0.25) or age (P = 0.48). A higher intravitreal VEGF concentration was significantly associated with a shorter axial length (P = 0.025; r = -0.39) or a higher hyperopic refractive error (P = 0.04; r = 0.35). Neither plasma concentration of VEGF nor the ratio of plasma VEGF concentrations to intravitreal VEGF concentration was significantly associated with axial length (P = 0.89 and P = 0.22, respectively) or with refractive error (P = 0.89 and P = 0.26, respectively).

CONCLUSION

Intravitreal VEGF concentration decreased with increasing axial length. It suggests a diluting effect in eyes with larger intraocular volume and/or a faster turnover rate of VEGF in axially myopic eyes with vitreous liquefaction.

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

Objective

To 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.

Methods

The 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).

Results

The 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.

Conclusions

Higher 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.

Prevalence, racial variations, and risk factors of age-related macular degeneration in Singaporean Chinese, Indians, and Malays

OBJECTIVE

To describe the prevalence and risk factors for age-related macular degeneration (AMD) in a multiethnic Asian cohort of Chinese, Malay, and Indian persons.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

A total of 10 033 persons (3280 Malay, 3400 Indian, and 3353 Chinese; response rate, 75%) 40 years of age or older residing in Singapore.

METHODS

We performed comprehensive systemic and ocular examinations, retinal photography, and laboratory investigations for all participants. We graded early and late AMD signs from retinal photographs using the modified Wisconsin AMD grading scale. We calculated the age-standardized prevalence of AMD using the 2010 Singapore adult population and analyzed risk factors for AMD using logistic regression models.

MAIN OUTCOME MEASURES

Early and late AMD.

RESULTS

Of the 9799 participants with gradable photographs, 588 had early AMD and 60 had late AMD. The age-standardized prevalence was 5.1% (95% confidence interval [CI], 4.6-5.5) for early AMD and 0.5% (95% CI, 0.4-0.6) for late AMD. The prevalence of early AMD was similar between Chinese (5.7%) and Indian (4.5%; P = 0.27) persons and lower in Malays (3.5%; P = 0.002 compared with Chinese; P = 0.09 compared with Indians); in contrast, the prevalence for late AMD was similar across ethnic groups (Chinese, 0.6%; Indian, 0.3%; and Malay, 0.3%; P = 0.20). Risk factors for early AMD were older age (odds ratio [OR], 1.40 per 5-year increase in age; 95% CI, 1.33-1.47), male gender (OR, 1.81; 95% CI, 1.43-2.29), hypertension (OR, 1.28; 95% CI, 1.02-1.61), and hyperopic refraction (OR, 1.17 per 1-diopter increase in spherical equivalent; 95% CI, 1.11-1.24). Risk factors for late AMD include older age (OR, 1.87 per 5-year increase in age; 95% CI, 1.54-2.19), smoking more than 5 packs per week (OR, 3.63; 95% CI, 1.34-9.80), and presence of chronic kidney disease (OR, 2.17; 95% CI, 1.22-3.88).

CONCLUSIONS

Early AMD is more common in Chinese and Indians than in Malays, but there were no racial variations in the prevalence of late AMD.

Refractive error and risk of early or late age-related macular degeneration: a systematic review and meta-analysis

OBJECTIVE

To summarize relevant evidence investigating the associations between refractive error and age-related macular degeneration (AMD).

DESIGN

Systematic review and meta-analysis.

METHODS

We searched Medline, Web of Science, and Cochrane databases as well as the reference lists of retrieved articles to identify studies that met the inclusion criteria. Extracted data were combined using a random-effects meta-analysis. Studies that were pertinent to our topic but did not meet the criteria for quantitative analysis were reported in a systematic review instead.

MAIN OUTCOME MEASURES

Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between refractive error (hyperopia, myopia, per-diopter increase in spherical equivalent [SE] toward hyperopia, per-millimeter increase in axial length [AL]) and AMD (early and late, prevalent and incident).

RESULTS

Fourteen studies comprising over 5800 patients were eligible. Significant associations were found between hyperopia, myopia, per-diopter increase in SE, per-millimeter increase in AL, and prevalent early AMD. The pooled ORs and 95% CIs were 1.13 (1.06-1.20), 0.75 (0.56-0.94), 1.10 (1.07-1.14), and 0.79 (0.73-0.85), respectively. The per-diopter increase in SE was also significantly associated with early AMD incidence (OR, 1.06; 95% CI, 1.02-1.10). However, no significant association was found between hyperopia or myopia and early AMD incidence. Furthermore, neither prevalent nor incident late AMD was associated with refractive error. Considerable heterogeneity was found among studies investigating the association between myopia and prevalent early AMD (P = 0.001, I2 = 72.2%). Geographic location might play a role; the heterogeneity became non-significant after stratifying these studies into Asian and non-Asian subgroups.

CONCLUSION

Refractive error is associated with early AMD but not with late AMD. More large-scale longitudinal studies are needed to further investigate such associations.

Prevalence and risk factors for age-related macular degeneration in Indians: a comparative study in Singapore and India

PURPOSE

To compare the prevalence and risk factors for age-related macular degeneration (AMD) in 2 Indian populations, 1 living in urban Singapore and 1 in rural central India.

DESIGN

Population-based, cross-sectional studies of Indians aged 40+ years.

METHODS

Our analysis included 3337 Singapore-residing participants and 3422 India-residing participants. All participants underwent comprehensive systemic and ocular examinations and retinal photography. AMD was graded from retinal photographs according to the Wisconsin Age-Related Maculopathy Grading System. Systemic and ocular risk factors were assessed for association with AMD.

RESULTS

Singapore-residing participants were older (mean age 57.8 years vs 53.8 years) and, after adjusting for age and sex, were more likely to have previous cataract surgery, higher body mass index, hypertension, diabetes, previous myocardial infarction, higher cholesterol, and lower creatinine levels, but less likely to be current smokers, than India-residing participants. The age-standardized prevalence of early and late AMD was 4.45% and 0.34%, respectively, in Singapore and 5.80% and 0.16%, respectively, in India. Shorter axial length was associated with early AMD in both Singapore and India, whereas previous cataract surgery, higher body mass index, hypertension, and lower cholesterol were associated with early AMD in Singapore but not in India.

CONCLUSION

The prevalence of AMD was similar among Indian adults living in urban Singapore and rural India, despite differences in cardiovascular risk factor profile and demographics.

Drusen prevalence and pigmentary changes in Caucasians aged 18-54 years

AIMS AND PURPOSE

The aim of this study was to describe the prevalence and characteristics of drusen and pigmentary changes in a middle-aged population.

METHODS

Retinal images from 500 individuals aged 18-54 years were included. The source of participants was two UK optometry practices. Retinal images were graded using the Wisconsin Age-Related Maculopathy Grading System. However, owing to the relatively young age of the population studied, a new category of drusen of smaller size (<31.5 μm) was introduced.

RESULTS

Drusen were identified within the central macular grid in 91.48% of all gradable eyes and in 444 subjects. Drusen sized <31.5 μm were present in 89.7% of eyes, drusen sized >31.5 μm and <63 μm were present in 45.9% of all eyes and drusen >63 μm and <125 μm were present in only 1.7% of eyes. No eye had drusen larger or equal to 125 μm. Very few eyes (1.2%) showed pigmentary changes within the grid. Drusen load increased with increasing age, P <0.001.

CONCLUSIONS

The frequency of drusen in a younger Caucasian population aged 18-54 years is high, with 91.48% of all gradable eyes having drusen. The most frequent drusen subtype was hard distinct drusen <31.5 μm. No druse greater or equal in size to 125 μm was seen. Pigmentary changes are rare.

Associations of early age-related macular degeneration with ocular and general parameters. The Central India Eyes and Medical Study

PURPOSE

To assess associations between age-related macular degeneration (AMD) and ocular and general parameters.

METHODS

The Central India Eye and Medical Study, a population-based study performed in rural Central India, included 4711 subjects (aged 30+ years) out of 5885 eligible subjects (response rate: 80.1%). Fundus photographs were assessed using the Wisconsin Age-Related Maculopathy Grading system.

RESULTS

Fundus photographs were available for 4542 (96.4%) subjects. Early AMD was present in 215/4542 subjects (4.7 ± 0.3%), and late AMD was detected in 8/4542 (0.2 ± 0.03%) subjects. After adjustment for age, prevalence of AMD was significantly associated with hyperopic refractive error (p = 0.001), shorter axial length (p = 0.01), and higher corneal refractive power (p = 0.02). Each dioptre increase in hyperopic refraction or each millimetre decrease in axial length was associated with a 15% [odds ratio (OR):1.15; 95% confidence interval (CI): 1.06, 1.24] and 19% (OR: 0.81; 95%CI: 0.69, 0.95) increased probability of early AMD, respectively. AMD was not significantly associated with blood pressure, serum concentration of cholesterol, glycosylated haemoglobin Hb1Ac, high-density lipoproteins and postprandial glucose, gender, level of education, any parameter of smoking, alcohol consumption, psychiatric depression or of daily activities, anterior chamber depth, lens thickness, intraocular pressure, size of the optic disc, neuroretinal rim and parapapillary atrophy, nor amount of nuclear cataract and status after cataract surgery. If the statistical analysis was adjusted for age and refractive error, age-related macular degeneration was marginally significantly associated with a low intake of fruits (p = 0.06).

CONCLUSIONS

Hyperopia (and short axial length) besides age was the single most important associated factor for AMD in adult Indians.

Prevalence and progression of myopic retinopathy in Chinese adults: the Beijing Eye Study

PURPOSE

To determine the prevalence and progression of myopic retinopathy in Chinese adults.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

The Beijing Eye Study 2001 included 4439 subjects of 5324 individuals who were invited to participate (response rate, 83.4%); the eligibility criterion was an age of 40+ years. The study was repeated in 2006, with 3251 subjects (73.2%) participating.

METHODS

The participants underwent a detailed eye examination, including fundus photography. Myopic retinopathy was defined by posterior staphylomata, lacquer cracks, Fuchs' spot of the macula, and myopic chorioretinal atrophy at the posterior pole. Parapapillary atrophy was assessed separately.

MAIN OUTCOME MEASURES

Prevalence of myopic retinopathy and its change during a follow-up of 5 years.

RESULTS

After exclusion of pseudophakic or aphakic eyes, and eyes without assessable fundus photographs, 4319 subjects (97.3%) were included in the present study. Myopic retinopathy was present in 198 eyes (2.3%+/-0.2%; 95% confidence interval [CI], 2.0-2.6) of 132 participants (3.1%). Myopic retinopathy was significantly associated with higher age (P<0.001), worse best-corrected visual acuity (P<0.001), deeper anterior chamber (P = 0.04), larger optic disc (P<0.001), less age-related macular degeneration (P = 0.02; odds ratio [OR] 0.90), and greater prevalence of open-angle glaucoma (P<0.001; OR 4.42). Myopic retinopathy was not associated significantly (P>0.20) with body height and weight, gender, rural versus urban region of residence, level of education, intraocular pressure, or central corneal thickness. The prevalence of myopic retinopathy increased significantly (P<0.001) with increasing myopic refractive error, from 3.8% in eyes with a myopic refractive error of < -4.0 diopters to 89.6% in eyes with a myopic refractive error of at least -10.0 diopters. At the 5-year follow-up examination, enlargement of the chorioretinal atrophy at the posterior fundus was observed in 9% of the eyes.

CONCLUSIONS

Myopic retinopathy was present in 3.1% of subjects aged 40+ years who resided in the Greater Beijing area. Myopic retinopathy was associated with increased age, worse best-corrected visual acuity, deeper anterior chamber, larger optic disc, less age-related macular degeneration, and higher prevalence of open-angle glaucoma.