Modern phacoemulsification cataract surgery does not appear to increase the progression age-related macular degeneration (AMD) in patients with the retinal disease who might benefit from cataract removal, according to a new Australian study.
AMD and cataract surgery: Study design and methods
Patients with cataracts and early macular degeneration who were deemed to be at high risk of having their AMD progress to a more serious and more vision-threatening form of the disease were randomly assigned to two groups:
- The study group (27 patients) underwent immediate phacoemulsification-style cataract surgery.
- The control group (29 patients) had cataract surgery deferred for six months.
At both the beginning of the study and six months after the study group had their cataract surgery (before the control group did), all subjects were assessed using the following criteria:
- visual acuity
- quality of life (measured via questionnaire)
- fundus fluorescein angiography (FFA)
FFA is a diagnostic test that uses an injected dye to determine if there is any leakage of retinal blood vessels or abnormal new blood vessel growth in the choroid — the layer of the eye that underlies the cornea and nourishes it.
Such blood vessel growth is called choroidal neovascularization, or CNV, and this represents the beginning of a more advanced stage of macular degeneration called “wet” AMD. New blood vessels formed by CNV can leak into the retina and cause severe vision loss.
Eyes with unsuspected pre-existing CNV that was detected by fluorescein angiography were disqualified from the study.
AMD and cataract surgery: Study results
Findings of the study at the 6-month mark included:
- Of the 27 eyes that underwent cataract surgery, one eye (3.7 percent) developed CNV, compared with none in the control group of 29 eyes that did not have surgery.
- The mean visual acuity improvement among study eyes that underwent cataract surgery was a 2.8-line improvement on a standardized eye chart.
- AMD patients who underwent cataract surgery reported more than a two-fold average improvement in quality of life scores, as measured by a standardized questionnaire.
The development of CNV in one eye among the study group compared with no eyes in the control group did not meet the criterion of statistical significance.
Conclusions
The researchers concluded there is no increased short-term risk of progression of AMD to CNV in high-risk individuals following uncomplicated phacoemulsification cataract surgery.
Also, provided there is no CNV, there are distinct quality of life benefits of cataract surgery in people with early AMD, the researchers said.
It should be noted that the follow-up period of this study was six months. Studies with longer follow-up periods are needed to determine long-term risks of cataract surgery among patients with early AMD.
SOURCE: Cataract surgery in high-risk age-related macular degeneration: a randomized controlled trial. Clinical & Experimental Ophthalmology. August 2009.
Tags: cataracts, macular degeneration