Late stage AMD
There have been major advances in the treatment of new blood vessels
in the late stage of AMD that have enabled many patients with this type of complication to regain lost vision. The majority of patients with active new blood vessels can now be offered treatment with drugs that are injected into the vitreous cavity of the eye. These drugs reduce leakage from the abnormal blood vessels under the retina when they are administered regularly at monthly intervals. Once OCT scans show absence of fluid
in the macula, the time between retreatments may gradually extend by one to two weeks until the 12 week interval is reached. In many patients, lifelong treatment every 12 weeks may be sufficient to keep the vision stable. In a significant proportion of patients, a prolonged course of four to six weekly retreatment regimens may be required because retinal fluid returns or vision loss occurs when the retreatment interval is extended. Your doctor will discuss possible alternative treatments in such situations with you. There are also new drugs being developed for treating new blood vessels that may have stronger action or longer-lasting effects.
The results of large, multi-centre randomised controlled trials demonstrated that up to half of all patients treated with intravitreal injections achieve improvement in vision. Ranibizumab (Lucentis®) and Aflibercept (Eylea®) treatment achieved similar results in vision gain. Bevacizumab (Avastin®) was developed as an intravenous infusion to treat patients with advanced bowel cancer. Its potential for treating patients with eye diseases was recognised early. It has been used to successfully treat patients with abnormal new vessels in the macula and other eye diseases by injection of a far smaller dose into the vitreous cavity of the eye. However, several studies have demonstrated that Lucentis® is superior to Avastin® in AMD so that Lucentis® and Eylea® are now accepted worldwide as the gold standard treatments for patients with wet form of late AMD, and their use has given patients with this disease real hope of retained or even improved vision.
In patients who have new blood vessels due to myopic macular degeneration, retinal inflammation and other similar conditions not classified as AMD, Avastin remains the only available drug to treat abnormal blood vessels. Myopic macular degeneration complicated by new blood vessels tends to respond differently compared with AMD and hence monthly monitoring and a “treat-as-required” regimen may be more suitable than an “injection at every visit” approach.
A major drawback of intravitreal drug treatment is the need for continuous multiple injections in order to maintain vision. Most patients with abnormal blood vessels due to AMD are judged to be suitable for treatment and they will receive an initial loading dose of three or more injections, once per month. The retreatment interval will be determined based on assessment of fluid status on the OCT scan by your ophthalmologist at each treatment visit. If there is no fluid, your doctor may decide to extend the interval by one to two weeks. If there is recurrence of fluid, your doctor may shorten the interval by one to two weeks or go back to a monthly loading regimen to control the leakage aggressively.
A significant proportion of patients may not achieve a fluid-free macula on OCT even with 4-weekly injections. It is important that you discuss with your ophthalmologist alternative treatment strategies if this situation persists into the second year of treatment. One option for treatment resistance or failure to extend retreatment interval is to switch from Eylea® to Lucentis® or vice versa. In some patients, switching drugs may be the solution to successfully extending the retreatment interval.
In situations where choroidal polyps or central serous retinopathy are suspected based on FAF photography or OCT scans, further investigation using indocyanine green (ICG) angiography may be required to confirm these diagnoses. Both choroidal polyps and central serous retinopathy can mimic the wet form of AMD but, unlike AMD, they can be effectively treated by photodynamic therapy (PDT) with verteporfin, or sometimes laser photocoagulation alone. Both treatments are performed as an outpatient procedure. Neither treatment is suitable for every patient with choroidal polyps or central serous retinopathy, and your retinal specialist will determine if any treatment can be recommended after examination and review of the OCT scan, FAF photograph and ICG angiography. Neither treatment is a cure, and both aim to preserve central vision for as long as possible.
In PDT, a drug called verteporfin (Visudyne®) is infused into the patient’s bloodstream. The drug has been designed to selectively target the
leaky abnormal blood vessels under the macula. A non-thermal laser (a laser that does not burn the retina) is directed at the leaky blood vessels and activates the drug. This in turn seals the leaky vessels without causing damage to other parts of the retina. Because of its selectivity, PDT with verteporfin is typically used when the leaky blood vessel is underneath the centre of the macula. PDT may become a course of therapy, and sometimes several treatments are needed to keep the leaking blood vessels closed and stop the progression of choroidal polyps or recurrence of central serous retinopathy. Close follow-up evaluations with your retinal specialist are needed to determine if retreatment is required. Sometimes, reactivation of the new blood vessels may respond to another course of injections and therefore combining PDT with injections may be necessary to achieve long-term control of the leakage particularly in choroidal polyps.