L. Robman

External factors in the development of cataract

AimsTo provide an update on the risk factors for cataract development.MethodsReview of the literature.ResultsAge and heredity are the most important risk factors associated with the different types of cataract. While the hereditary component is self-explanatory, increasing age serves as a surrogate for a number of potential external risk factors, the effect of which is cumulative. Identification of the risk factors that have a causal effect on cataract development may provide means for cataract prevention. There are only a few risk factors that satisfy the criteria for causal effect: smoking, which results in the increased risk of nuclear cataract, excessive UV-B exposure and diabetes that increase the risk of cortical cataract, and steroidal treatment, diabetes and ionising radiation that lead to the formation of posterior subcapsular opacity. The effect of medications on cataract development requires further study, since the effect of the diseases should be distinguished from that of treatment. ‘Stop Smoking’ and ‘UV-B protection’ campaigns are gaining momentum as preventative measures, while the attempts to actively prevent cataract with antioxidants have not been successful. Cataract research has been facilitated lately by improvements of precision and standardisation in measuring lens opacities. However, measurement precision on its own cannot give us a solution to this problem.ConclusionThe major studies repeatedly measure the exposure to the traditional health hazards, while the missing parts in the equation are those risk factors that we do not know about and therefore do not measure. New approaches and new hypotheses are needed.

Red Meat and Chicken Consumption and Its Association With Age-related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness among older people, and diet has been postulated to alter risk of AMD. To evaluate associations between red meat and chicken intake and AMD, the authors conducted a cohort study of 6,734 persons aged 58-69 years in 1990-1994 in Melbourne, Australia. Meat intake was estimated from a food frequency questionnaire at baseline. At follow-up (2003-2006), bilateral digital macular photographs were taken and evaluated for AMD (1,680 cases of early AMD, 77 cases of late AMD). Logistic regression was used to estimate odds ratios, adjusted for age, smoking, and other potential confounders. Higher red meat intake was positively associated with early AMD; the odds ratio for consumption of red meat > or =10 times/week versus <5 times/week was 1.47 (95% confidence interval: 1.21, 1.79; P-trend < 0.001). Similar trends toward increasing prevalence of early AMD were seen with higher intakes of fresh and processed red meat. Conversely, consumption of chicken > or =3.5 times/week versus <1.5 times/week was inversely associated with late AMD (odds ratio = 0.43, 95% confidence interval: 0.20, 0.91; P-trend = 0.007). These results suggest that different meats may differently affect AMD risk and may be a target for lifestyle modification.

Characteristics of progression of early Age-related macular degeneration: the Cardiovascular Health and Age-related maculopathy Study

AimsTo determine the risk of age-related macular degeneration (AMD) progression posed by the presence of each early AMD characteristic.MethodsA prospective cohort study of 254 participants aged 50 years and older, all with early AMD features at their baseline visit followed for an average of 7 years. Stereoscopic colour fundus photographs were graded for early AMD features using the International Classification System. AMD status was stratified into six exclusive levels along a continuum of disease severity according to drusen type, pigmentary abnormalities, or late AMD. Progression was assessed according to three definitions: a change between or within a severity level, or by side by side grading.ResultsThe progression rate of early AMD ranged between 3.4 and 4.67% per annum depending upon the definition used. In total, 15 (6%) cases progressed from early AMD to the late complication of AMD. After controlling for age and smoking, cases with soft indistinct drusen at baseline were at a greater risk of progressing from early to late AMD than were cases without this characteristic (OR=3.72, 95%CI 1.20–11.54; P=0.02).ConclusionOur proposed definitions of AMD progression give rates that are consistent with current knowledge of progression and its determinants. Each early AMD characteristic conveys its own risk of progression to an eye, with soft indistinct drusen carrying the greater risk. An international consensus on what defines AMD progression would greatly help the research community when trying to assess the importance of new risk factors and the effectiveness of novel interventions.

Does dietary lutein and zeaxanthin increase the risk of age related macular degeneration? The Melbourne Visual Impairment Project

Age related macular degeneration (AMD) was one of the five main causes of vision impairment in the combined study of the Melbourne Visual Impairment Project (MVIP) and the Blue Mountains Eye Study (BMES).1 A higher dietary intake of lutein/zeaxanthin was significantly associated with lower risk of having exudative age related macular degeneration in the Eye Disease Case-Control Study, but there was no association between lutein/zeaxanthin (LZ) intake and either early or neovascular age related maculopathy in the combined prospective US study.2,3 Also, a higher fish intake has been associated with a lower risk of progression to advanced AMD among those with low (below median) linoleic acid intake, whereas there was no significant association among those with higher linoleic acid intake.4 The aim of this paper is to examine the association of AMD with dietary intake of the carotenoids lutein/zeaxanthin in conjunction with linoleic acid intake in the follow up population based sample of the MVIP. ### Study design Of 3040 permanent residents recruited in 1992–4, 2594 (85%) of them attended the follow up examinations in 1997–9.5 At both time points of the study, participants signed an informed consent and underwent a standard procedure including an ophthalmic examination and an interview regarding socioeconomic and demographic characteristics, historic and current symptoms of eye diseases, medical history, and medication use. The follow up survey also included a …

Age-related macular degeneration and mortality: the Melbourne Collaborative Cohort Study

AimsTo assess associations between features of age-related macular degeneration (AMD) and mortality.MethodsA total of 21 129 participants from the Melbourne Collaborative Cohort Study aged 47-85 years (60% female) were assessed for AMD (2003-2007). Mortality data to December 31, 2012 were obtained through linkage with the National Death Index. Associations were assessed using Cox regression, adjusting for age, sex, smoking, region of birth, education, physical activity, diet and alcohol.ResultsLate AMD was identified in 122 (0.6%) participants, including those with choroidal neovascularisation (n=55, 0.3%), geographic atrophy (n=87, 0.4%) and reticular pseudodrusen (n=87, 0.4%). After a median follow-up period of 8.1 years, 1669 (8%) participants had died, including those from cardiovascular diseases (386), tobacco-related cancers (179), and neurodegenerative disease (157). There was evidence of an increased rate of all-cause mortality for those with choroidal neovascularisation (Hazard Ratio (HR) 1.71 95% CI 1.06-2.76) and geographic atrophy (HR 1.46 95% CI 0.99-2.16). Choroidal neovascularisation was also associated with an increased rate of cardiovascular mortality (HR 3.16 95% CI 1.62-6.15) and geographic atrophy was associated with an increased rate of death from tobacco-related cancer (HR 2.86 95% CI 1.15-7.09). Weak evidence was also present for an association between choroidal neovascularisation and death from neurodegenerative disease (HR 2.49 95% CI 0.79-7.85). Neither reticular pseudodrusen nor the earlier stages of AMD were associated with mortality.ConclusionsLate AMD is associated with an increased rate of all-cause mortality. Choroidal neovascularisation and geographic atrophy were associated with death from cardiovascular disease and tobacco-related cancer, respectively.AimsTo assess associations between features of age-related macular degeneration (AMD) and mortality.MethodsA total of 21 129 participants from the Melbourne Collaborative Cohort Study aged 47–85 years (60% female) were assessed for AMD (2003–2007). Mortality data to December 31, 2012 were obtained through linkage with the National Death Index. Associations were assessed using Cox regression, adjusting for age, sex, smoking, region of birth, education, physical activity, diet and alcohol.ResultsLate AMD was identified in 122 (0.6%) participants, including those with choroidal neovascularisation (n=55, 0.3%), geographic atrophy (n=87, 0.4%) and reticular pseudodrusen (n=87, 0.4%). After a median follow-up period of 8.1 years, 1669 (8%) participants had died, including those from cardiovascular diseases (386), tobacco-related cancers (179), and neurodegenerative disease (157). There was evidence of an increased rate of all-cause mortality for those with choroidal neovascularisation (Hazard Ratio (HR) 1.71 95% CI 1.06–2.76) and geographic atrophy (HR 1.46 95% CI 0.99–2.16). Choroidal neovascularisation was also associated with an increased rate of cardiovascular mortality (HR 3.16 95% CI 1.62–6.15) and geographic atrophy was associated with an increased rate of death from tobacco-related cancer (HR 2.86 95% CI 1.15–7.09). Weak evidence was also present for an association between choroidal neovascularisation and death from neurodegenerative disease (HR 2.49 95% CI 0.79–7.85). Neither reticular pseudodrusen nor the earlier stages of AMD were associated with mortality.ConclusionsLate AMD is associated with an increased rate of all-cause mortality. Choroidal neovascularisation and geographic atrophy were associated with death from cardiovascular disease and tobacco-related cancer, respectively.

Dietary lutein and zeaxanthin : authors' response

We were interested to see the letter by Mitchell,1 written in response to our earlier publication.2 Mitchell raises several points, the first of which is the way one handles missing data. Age related macular degeneration (AMD) can be assessed either clinically or photographically. Rather than throw away data and run the potential of bias by excluding patients who did not have a retinal photograph, we chose to include in our analysis those people for whom we did not have a retinal photograph for one reason or another but for whom we had clinical macular grading. In separate analyses …