This article is more than 5 years old. Information may no longer be current.
Approaches to macular degeneration include surgery, laser options
Our Spotlight on Vitreoretinal Surgery examines current thinking on treatment options.
Click Here to Manage Email Alerts
| Surgical tip |
| Submacular surgery is still a viable option in patients with subchoroidal neovascularization, said Mark W. Johnson, MD. When asked about his technique, he said he made a small retinotomy with a 36-gauge perforator. If there is minimal subretinal fluid, he inflates the area with a 33-gauge cannula. Typically, these types of patients do not have much fluid, he said. “Balloon the retina off the membrane, and then use horizontal forceps,” he said. “I never try to put forceps or a pick under the membrane, but I do try to with sort of a lateral teasing of the anterior surface, try to separate as much as I can from the RPE, and then rock it … until I remove it.” He applies 25% air to the bubble but no laser, he said. Intraoperatively, he applies 50% air. He positions patients face down for the first day postoperatively. By then, the patient can already see under the bubble, he said. |
Since its introduction in the late 1990s, photodynamic therapy has caused a revolution in the treatment of subfoveal choroidal neovascularization in age-related macular degeneration. But surgeons are still learning where PDT best fits into their arsenal of treatments for AMD.
Questions remain: How many times should the procedure be repeated, and how often? When is traditional argon laser photocoagulation a better option than PDT? When should the surgeon consider submacular surgery instead of repeating PDT?
The studies highlighted in this Spotlight on Vitreoretinal Surgery attempt to address these questions and more. One study suggests that PDT can be an effective treatment for some juxtafoveal lesions in addition to subfoveal choroidal neovascularization (CNV). Pneumatic displacement can also be a treatment alternative in the management of subretinal hemorrhages, another says. A surgeon suggests that submacular surgery can be a viable alternative when PDT fails. Another reminds us that, as beneficial as PDT has been shown to be, it will not replace the argon laser in all cases of CNV.
In this Spotlight on Vitreoretinal Surgery, Ocular Surgery News provides a summary of these and other recent studies concerning PDT and other treatment options for CNV in AMD and related retinal conditions.
Intravitreal gas displacement of subretinal hemorrhage
Pneumatic displacement of subretinal blood can be a viable treatment for moderate subretinal hemorrhages, said Mark W. Johnson, MD. Outcomes with the procedure have improved with the advent of PDT and antiangiogenesis drugs, he said.
In the past, surgeons surgically removed subretinal blood after hemorrhage but often without visual improvement, Dr. Johnson said. Thick blood and AMD are two risk factors for poor treatment results, he said
Since the introduction of PDT and antiangiogenesis, however, pneumatic displacement of blood may produce more favorable outcomes, he said. The displacement of blood has more consistent and longer-term results, rather than just short-term improvement that requires re-treatment to maintain a favorable outcome, Dr. Johnson said.
In a retrospective study in patients with lesions greater than 2 disc diameters, Dr. Johnson said, 13% of patients achieved visual acuities of 20/80 or better with observation alone. With surgical removal, 16% achieved the same outcome, but with pneumatic displacement, twice as many achieved that visual outcome, he said.
Important to success of the procedure is patient selection, according to Dr. Johnson. Good candidates should have had adequate reading vision prior to the hemorrhage, he said. Too much blood can also be a problem; he does not perform the procedure on large hemorrhages, he said.
PDT cannot replace argon laser
Standard argon lasers are still a necessity for treating some cases of CNV even in the era of PDT, said Andrew P. Schachat, MD, of Baltimore.
The argon laser is ideal for treating lesions that are far enough from the central fovea, while PDT is suited for treating lesions close to the macula, Dr. Schachat said. However, a patient is more likely to vision loss without argon laser treatment than with it, he added.
There is a 75% chance that subfoveal CNV will recur in 5 years after argon laser photocoagulation, Dr. Schachat said. To monitor the patient and to be aware of recurrences he recommends seeing patients at least six times a year and ordering a fluorescein angiography each time to catch recurrences as quickly as possible.
Physicians should be aware of the predictors that most often dictate whether a patient may experience recurrence, Dr. Schachat said. A main factor is the condition of the fellow eye, he said. If there is CNV already in the second eye, the chances of recurrence are greater. Other risk factors include high blood pressure and smoking, he added.
Submacular surgery may help when PDT did not
Submacular surgery may be an effective option for certain patients with subchoroidal neovascularization who have not benefitted from PDT, according to Dr. Johnson. Patients who have been unresponsive to PDT and other therapies, such as triamcinolone, could experience improved reading vision after submacular surgery, he said.
In a small case series, Dr. Johnson and colleagues observed how well surgery performed in patients who did not respond to PDT. Diagnoses included presumed ocular histoplasmosis syndrome, myopia, multifocal choroiditis and idiopathic conditions. The study found that the outcome of the surgery was not affected by prior PDT treatments, Dr. Johnson said. In addition, recurrent membranes also seemed to respond well to the surgery.
Dr. Johnson observed patients who had fewer PDT sessions had an increased chance of success with the surgery. He said patients who underwent only one session preoperatively had the best outcomes.
Additionally, he noted that patients with focal RPE appeared to have more successful outcomes than those with AMD.
Even with surgery, Dr. Johnson noted that recurrences were still possible. Even patients with good outcomes still experience recurrence, he added.
PDT effective for some juxtafoveal lesions
Lesions close to the fovea are not appropriate for treatment with argon laser photocoagulation for fear of damaging the fovea. Dr. Schachat said the application of PDT can be effective in stopping leakage in some juxtafoveal lesions. He noted that in a study by Michael Blair, MD, and colleagues, visual acuity deteriorated in about one-third of the cases, he said, and in some of these cases the lesions progressed to the subfoveal area. But in two-thirds of the eyes vision stabilized or improved.
The researchers found that PDT can halt leakage progression in juxtafoveal lesions, but patients should be informed of the possibility of recurrence. Dr. Schachat said PDT may be an acceptable strategy when dealing with juxtafoveal lesions.
“We think this is an acceptable strategy as long as you expect that about one-third of the time the lesion is going to become subfoveal anyway,” he said.
Dr. Schachat said he typically applies three to five PDT treatments to retard CNV.