Thermotherapy for Age-Related Macular Degeneration
ALI, MD, FRCS(C)
Figure 1. Red-free photo at initial presentation.
HISTORY AND DIAGNOSTIC EVALUATION
A white female patient, 68 years of age,
presented with a 3-week history of sudden onset of decrease in vision in her left
eye with progressive deterioration. On presentation her vision was 20/30 OD and
20/400 OS. The right eye had dry age-related macular degeneration (AMD). The left
eye had thick subretinal blood in the center of the macula with diffuse retinal
edema and a visible subfoveal vascular membrane (Figure 1). Fluorescein angiography
showed significant blockage due to subretinal blood with a small area of poorly-defined
late leakage under the fovea (Figure 2). Optical coherence tomography (OCT) showed
significant diffuse subretinal fluid and retinal edema (Figure 3). A diagnosis of
an occult subretinal neovascular membrane in her left eye due to exudative AMD was
options were discussed with the patient. It was explained that without any treatment,
a 70% chance of progressive and significant vision loss existed. At the time of
presentation, anti-VEGF therapies were not available. Additionally, photodynamic
therapy (PDT) with verteporfin (Visudyne, Novartis) was an uninsured service for
occult membranes and the patient was unwilling and unable to pay for the cost of
this therapy. Transpupillary thermotherapy (TTT) was discussed with the patient.
It was explained that TTT had a 75% chance of preventing further significant visual
loss, a 10% chance of noticeable vision improvement, and required only a single
treatment in 80% of patients. The patient agreed to treatment with TTT.
Figure 2. Late-phase fluorescein angiogram at initial presentation.
Transpupillary thermotherapy was performed
using a slit-lamp delivered 810-nm diode laser (model SLx, IRIDEX, Mountain
View, Calif). A 3.0-mm laser spot size setting was used delivered through a 1.05-magnification
laser contact lens. A power setting of 780 mW and treatment duration of 60 seconds
was used. The patient reported only a mild warmth sensation during treatment and
there was no visible color change in the retina observed during the therapy. The
patient returned for routine follow-up visits during the next several weeks.
At the 3-month post-TTT visit, the vision in the patient's left
eye had improved to 20/60. There was a significant reduction in subretinal blood
and retinal edema (Figure 4). Fluorescein angiogram showed resolution of subretinal
blood with mild subretinal late staining only (Figure 5). OCT showed significant
reduction in subretinal fluid and retinal edema (Figure 6).
Figure 3. OCT at initial presentation.
This case study describes effective treatment
of an occult subretinal membrane due to exudative AMD. The patient was treated using
standard laser parameters for the specific lesion and patient characteristics. Minor
changes in laser treatment parameters are sometimes required for lesions of different
size and for variations in retinal pigmentation due to racial variations. It should
be noted that this patient presented prior to the availability of any anti-VEGF
therapies such as pegaptanib sodium (Macugen, OSI), bevacizumab (Avastin, Genentech),
and ranibizumab (Lucentis, Genentech). As well, PDT with verteporfin was an uninsured
and expensive therapy for this lesion type.
The clinical safety and efficacy of TTT has been demonstrated
in a large number of non-randomized clinical papers. As well, subgroup and per-protocol
analysis of the recent TTT4CNV randomized clinical trial demonstrates possible clinical
benefit in certain subgroups of patients. At the present time, only pegaptanib sodium
and ranibizumab have been rigorously proven in randomized clinical trials to show
clear benefit for patients with occult membranes. However, these therapies are expensive,
require multiple treatments and frequent follow-up, and present risks to the patient
resulting from intraocular injections.
Transpupillary thermotherapy may be an alternative therapy for
certain cases of exudative AMD, especially in patients unwilling to have intraocular
injections or where treatment cost is an issue.
Ali, MD, FRCS(C), is director of clinical research at the Canadian Centre for Advanced
Eye Therapeutics in Toronto, Canada. He has no financial interest in any of the
products or therapies mentioned in this article.
Figure 4. Red-free photo 3 months post-TTT.
Figure 5. Late-phase fluorescein angiogram 3 months post-TTT.
Figure 6. OCT 3 months post-TTT.
Retinal Physician, Issue: September 2006