Does Cataract Surgery Really Increase the Risk for AMD Progression?

Cataract Does cataract surgery really increase the risk for AMD progression?

Nadja Geipert The fourth analysis involved identifying “Patients come in with decreased vision, The NEI’s Age-related Eye Disease Study in San Francisco matched cases and controls, taking the cases drusen near the fovea, but without definite is a multi-centre cohort study designed to that had cataract surgery, and if both eyes advanced AMD.There is a tendency to say, assess the clinical progression, prognosis CATARACT surgery may not increase the had cataract surgery, looking at the eye that ‘Let’s take the cataract out and see what and risk factors of both AMD and cataracts risk of developing neovascular age-related had cataract surgery first.Then, the happens.’ What happens sometimes is and to evaluate the effects of high macular degeneration (AMD) after all, new researchers compared these eyes to the advanced AMD develops, not because of the antioxidant intake on the progression of findings from the Age-Related Eye Disease control eyes that didn’t have cataract cataract extraction but because early both diseases. From 1990 to 1998 more Study (AREDS) suggest. surgery while matching for age,AMD advanced AMD was the cause of the vision than 4,500 participants were recruited for The results could stir controversy in the severity and AREDS treatment groups. Here loss to start with. It’s easy for us to think the the study, and findings continue to be ophthalmic community because they the odds ration was less than 1.0, which cataract extraction caused the AMD, when published. contradict earlier findings by other significant indicates a trend in the direction of actually the early changes of the advanced studies, which found a two-to-five-fold protection, but again the results were not AMD caused the cataract extraction,” he [email protected] increased risk of developing AMD in patients statistically significant. said. [email protected] who had undergone cataract surgery, “We worked hard to look every way we according to Frederick Ferris MD, lead could because when you don’t have Some studies support AREDS findings investigator on the new study and director consistent findings, it makes it hard to know of the division of epidemiology and clinical But other studies have supported the recent what the truth is,” said Dr Ferris. research at the National Eye Institute in findings by AREDS.The Blue Mountain Eye Bethesda, Maryland. Study – a large Australian population-based Contradictions with previous studies “If we look at all of the evidence, we do study conducted during the 1990s in more not find clear evidence of an association The results are surprising because of the than 3,500 individuals aged 49 years and between cataract surgery and neovascular above-mentioned earlier findings and the older – concluded after five- and 10-year AMD, and most patients can be re-assured,” strong biological plausibility of an association follow-ups that there was no evidence of a he said, during his presentation of the study between cataract surgery and AMD clear association that could not be explained at the annual ASCRS meeting. progression, he told EuroTimes during a by the age-related increase in prevalence in In the new study, researchers closely follow-up interview. both conditions (Wang JJ; Ophthalmic examined 8,200 eyes, taking fundus photos The Beaver Dam Eye study, which began Epidemiol; 1999 Dec;6(4):317-26). every 12 months over 10 years. Some 1,700 in 1987 and was funded by the NEI, enrolled And a recent review of the current of these eyes underwent cataract surgery more than 6,000 participants aged between literature concluded that there was no and 603 eyes developed neovascular AMD 43 and 84 years of age in Beaver Dam, conclusive evidence to support a clear over the course of the study. Wisconsin.The researchers examined the association between cataract extraction and The researchers defined AMD based on association between cataract surgery and progression of AMD (Smith BT; Curr Opin fundus photographic evidence of lesions the incidence of age-related maculopathy Ophthalmol. 2005 Jun; 16(3):166-9). associated with advanced neovascular AMD (ARM) in this population and concluded that Regarding the biological plausibility, it is or geographic atrophy, or a clinical history of signs of geographic atrophy were four times expected that cataract surgery would result having had photocoagulation for AMD. as likely to occur in an eye that had in the release of cytokines and potentially In the data analysis, Dr Ferris and his undergone cataract surgery. In addition, signs create an atmosphere where AMD risk colleagues used four different statistical of exudative macular degeneration were increases, Dr Ferris told EuroTimes. Stirring approaches to test for an association three times as likely to develop after up an inflammatory response in a patient between cataract surgery and AMD and also cataract surgery (Klein et al;Arch who already has large drusen might tip the used the common co-variants for AMD Ophthalmol; Nov 2002;120:1551-1558). balance, he also said. progression such as age, smoking, gender, In part because of the biological race and if the patients took any antioxidant It’s easy for us to think the plausibility, Dr Ferris is still awaiting the supplements. results of further analysis that focuses on Disease severity was rated on a nine-point cataract extraction caused patients with geographic atrophy and other scale that has been associated with disease subgroups that might face an increased risk. outcome. the AMD, when actually Preliminary results from this geographic The first analysis used ordinary logistic atrophy subgroup indicate this may be so. progression.After adjusting for age, which is the early changes of the “We looked at the most severe eyes, crucial because the risk for both cataract particularly those eyes that already had de- and AMD increases with age, the researchers advanced AMD caused the pigmentation and geographic atrophy away found a risk ratio of 1.0. In other words, from the centre and in that subgroup there there was no increase in risk associated with cataract extraction” may be an increased risk. However, this is cataract surgery in this analysis. Frederick Ferris MD the group that is potentially subject to In the second analysis, Dr Ferris and decreased vision from AMD.Then they have colleagues focused on the first five years Furthermore, data from three large cataract surgery, and the AMD does what it after cataract surgery, which reduced the population-based studies concluded that a would have done anyway; it progresses and total number of eyes that underwent the history of cataract surgery might be it would have done so without the cataract procedure from 1,700 to 579. Here the associated with a higher prevalence of AMD surgery,” he said. findings were inconclusive, but if there was (Freeman EE et al,Am J Ophthalmol; Nov “Whether there is an increased risk an increased risk, it was small and not 2003; 136 (5):961). through cataract surgery or not, you have statistically significant. These studies made a strong case for an to tell patients who have fundus changes Thirdly, another analysis evaluated the association between cataract extraction and putting them at high risk for progression to time until development of neovascularisation AMD progression largely because they are advanced AMD that they may develop using the Cox proportional hazard model. population based, said Dr Ferris. But, there is advanced AMD in the next few years, and While this analysis found a slight increase in also a possible confounding factor involved because of that they should be seen risk, it was not statistically significant. in the findings. regularly,” he added.