This article is more than 5 years old. Information may no longer be current.
Third-generation OCT aids in PDT re-treatment decisions
Imaging device overcomes limitations of fluorescein angiography.
Click Here to Manage Email Alerts
NEW YORK – Optical coherence tomography, now in its third generation, can help guide decisions about re-treatments with photodynamic therapy when fluorescein angiography results are inconclusive, according to a surgeon speaking here.
Although the original PDT protocols called only for the use of fluorescein angiography (FA), OCT findings can detect subretinal or intraretinal fluid that might have been otherwise missed with that diagnostic tool, said Michel Eid Farah, MD, who spoke at the meeting of the American Society of Retina Specialists.
Dr. Farah presented the results of 156 eyes that underwent PDT for either subfoveal choroidal neovascularization secondary to age-related macular degener-ation (147 eyes) or pathologic myopia (nine eyes).
After the first round of PDT, investigators employed FA to assess the procedure’s effect.
Re-treatment decisions
Eyes underwent re-treatments at 3-month intervals when investigators detected evidence of leakage beyond the limits of the lesion. Surgeons did not re-treat for cases of subretinal fibrosis or retinal atrophic changes.
When FA findings were inconclusive, surgeons utilized OCT to make a final decision.
Of the 156 eyes, 16 had questionable leakage with suspicious subretinal fluid or intraretinal edema on FA. These eyes then underwent OCT for a follow-up evaluation; 10 were OCT positive and were submitted to re-treatment.
OCT revealed that eight eyes had subretinal fluid, and eight eyes had intraretinal fluid. Six eyes had both types of fluid.
Results
Of the 10 eyes that were re-treated, eight experienced fluid resolution after one re-treatment with PDT; two eyes required two re-treatments.
None of the eyes experienced vision loss after PDT treatments. Five of the eyes that underwent one re-treatment experienced visual acuity improvements, and the other three eyes had no change in vision.
The two eyes that required a second re-treatment also had unchanged vision after the final procedure. (The median visual acuity among all 156 patients was 20/200 at entry.)
Of the two eyes that required two re-treatments, one had intraretinal fluid only, and one had both types of fluid.
Case 1. Preop | Three months postop |
| Case 2. Preop | Three months postop |
| Occult CNV in age-related macular degeneration. (All images courtesy of Michel Eid Farah, MD.) | |
OCT benefits
“The decision-making process of PDT re-treatments may be very complex,” Dr. Farah told Ocular Surgery News. “It depends on visual acuity, metamorphopsy, fluorescein leakage and even, as we believe, on OCT findings.”
OCT is particularly useful in cases of discrete leakage, in which patients may have stable or even modest improvements in visual acuity without subretinal or intraretinal fluid displacement, according to Dr. Farah.
He noted that in the absence of OCT, surgeons have tended to undertreat eyes with questionable or undetectable leakage.
In addition, some patients have been lost to follow-up while their condition was silently deteriorating, he noted.
“Fortunately, OCT is becoming more popular,” Dr. Farah said. “Biomicroscopy with a good slit lamp and stereo fundus photography may reveal sub- or intraretinal fluid in questionable cases. But even so, some cases may be very difficult to detect, and OCT may help in this situation.”
Applications
At the Federal University of São Paulo, Brazil, Dr. Farah has utilized OCT since 1996. The imaging device is now in its third generation (the Stratus OCT 3, Carl Zeiss Meditec) and has applications for both retina and glaucoma practices.
Dr. Farah noted that while questionable leakage on FA is generally seen in about 10% of patients, OCT findings are also beneficial in making a differential diagnosis and during the follow-up of other types of treatment.
OCT, for instance, can help surgeons distinguish AMD from other diseases that cause similar symptoms of intraretinal or subretinal fluid and retinal hemorrhage, according to Dr. Farah. These diseases include retinal angiomatous proliferation, polypoidal choroidal vasculopathy, chorioretinal anastomosis and cystoid macula edema.
The technology might also increase understanding of the progression of AMD, he said.
“OCT may help … in the comprehension of the mechanism involved during the process of AMD and to demonstrate or document the morphological characteristics of the disease,” he said.
He added that there are now convincing results from a number of studies that show OCT is a valuable investment for retina specialists.
“The clinical [PDT] trials took into consideration the leakage on the fluorescein angiogram as the only parameter for the indication of re-treatments,” Dr. Farah said. “It seems that now that we have more knowledge available and other examination techniques … we should plan to use, when necessary, all data to help the decision in questionable cases. Clinical trials with OCT deserve further evaluation,” he said.
For Your Information:
- Michel Eid Farah, MD, can be reached at Centro Oftalmologico São Paulo, Au Ibijau, 331 4o. Andar Moema, São Paulo SP 04524-020 Brazil; 55-11-5055-1177.