Risk of AMD Progression After Cataract Surgery

Patients with existing dry age-related macular degeneration (dAMD) had a small but statistically increased risk of conversion to neovascular age-related macular degeneration (nvAMD) after cataract surgery, data from a national ophthalmology registry showed.

A propensity-matched analysis involving 80,000 eyes showed a hazard ratio of 1.22 for nvAMD conversion among patients who had cataract surgery compared with those who did not. Much of the risk accumulated during the first year after a cataract procedure, then declined steadily and became nonsignificant after 4 years. After 6 years, the absolute difference between groups was less than 3%.

The findings suggest a need for careful perioperative evaluation of patients with dAMD but do not clearly implicate cataract surgery as a long-term factor in neovascular conversion, reported Grayson Armstrong, MD, MPH, of Massachusetts Eye and Ear in Boston, and colleagues in Ophthalmology.

“In clinical settings, the potential risk of AMD progression is a significant concern for patients with dAMD undergoing CS [cataract surgery],” they wrote. “Although each patient should be considered individually, the findings of this study demonstrated a slight increased risk of conversion to nvAMD after CS. Although this [observational] finding does not establish a causal relationship between CS and nvAMD conversion, it may inform clinical decision-making and patient counseling when considering CS in the context of AMD.”

Small Association, Potential Explanations

The “rather small association” between cataract and nvAMD probably can be explained by increased surveillance after cataract surgery, according to the authors of an invited commentary.

“Patients with existing AMD, especially those with intermediate AMD, which can be quite heterogeneous, are at high risk of developing late AMD,” wrote Emily Y. Chew, MD, of the National Eye Institute in Bethesda, Maryland, and colleagues. “It is important to inform patients with coexisting AMD and cataract that vigilant follow-up is key for the management of their AMD after cataract surgery because the risk of progression may be inherently high and coincidental.”

The study confirms the low likelihood of an association between cataract surgery and acceleration of progression to late AMD, especially nvAMD, Chew told MedPage Today.

“The key take-home message is to provide vigilant and meticulous follow-up of patients with AMD following cataract surgery to ensure good visual acuity results,” she said.

Regarding implications for ophthalmology practice, Chew said the study supports a need to inform patients about a potential risk of AMD progression but that the association is not necessarily due to cataract surgery.

“Removing the cataract may sometimes give a better view for a more precise diagnosis,” she said. “There is good treatment for neovascular AMD, and it is important that the patient be followed regularly and more frequently following surgery.”

Background, Key Findings

About 80% of patients with AMD have dry, or non-neovascular, AMD, associated with gradual vision loss. Cataract surgery can substantially improve vision, even in patients with AMD at the time of surgery. However, understanding of the effects of cataract surgery on progression from dAMD to nvAMD remains incomplete, Armstrong and colleagues noted.

Prior studies of cataract surgery and AMD progression have yielded mixed results, they continued. Large population-based studies conducted more than 20 years ago showed an increased risk of late AMD after surgery; smaller cross-sectional studies showed no association. A systematic review showed a significant correlation between cataract surgery and risk of AMD progression, with a more pronounced risk with longer follow-up.

“Considerable variation across studies may explain these conflicting findings,” the authors noted. “Differences in study design, sample size, follow-up duration, and statistical approaches all contribute to the heterogeneity of reported results. Moreover, advances in CS techniques over time may explain the heterogeneity further.”

In an effort to bring some clarity to the issue, investigators analyzed data from the American Academy of Ophthalmology IRIS registry of eye disease. The review encompassed data from January 2016 through December 2022, involving patients 55 or older with early or intermediate dAMD and phakic status at baseline. After propensity matching, two groups of 40,053 eyes were compared according to whether the patient underwent cataract surgery. The primary outcome was the rate of conversion from dry to nvAMD between the two groups.

The key finding was a significant association between cataract surgery and conversion to nvAMD (HR 1.22, 95% CI 1.16-1.30, P<0.001). A time-varying analysis showed a stronger association early in follow-up after surgery, reaching a hazard ratio of 2.5 during the first year, followed by a steady decline to statistical nonsignificance. At year 6, the surgery group had a cumulative nvAMD incidence of 17.7% as compared with 15.2% in the group without surgery. Baseline AMD status moderated the impact of cataract surgery, which had a weaker effect on eyes with intermediate-stage AMD.

The observation of apparently greater risk of conversion during early follow-up suggests the overall risk might be driven by eyes with more advanced or symptomatic AMD at baseline, the authors stated. Those patients might have undergone cataract surgery earlier because of vision loss “incorrectly attributed to cataract, with increased postoperative surveillance unmasking pre-existing or incipient nvAMD, rather than indicating a sustained biological effect of surgery itself.”