Optical coherence tomography aids in detection and analysis of occult CNV

Early identification of proliferating blood vessels is critical in the treatment of age-related macular degeneration, researcher says.

ByErin L. Boyle

Optical coherence tomography supplements angiography in the diagnosis of occult choroidal neovascularization in age-related macular degeneration, a study found.

Gabriel Coscas

In addition, optical coherence tomography (OCT) detected retinal fluid more easily than fluorescein angiography, the study authors said.

Gabriel Coscas, MD, Florence Coscas, MD, and colleagues published the results of the prospective, consecutive observational case series in the American Journal of Ophthalmology.

The researchers used OCT in conjunction with scanning laser ophthalmoscope fluorescein angiography and scanning laser ophthalmoscope indocyanine green angiography.

“From the beginning, using OCT, we were impressed by the ability to discover some subretinal fluids and some intraretinal fluids, even if, in these early images, it was not possible to analyze precisely the location of the new vessels,” Dr. Gabriel Coscas told Ocular Surgery News in a telephone interview.

“With the OCT III (Carl Zeiss Meditec), we … decided to have, on a regular basis, the OCT examination as preceded by the angiograms,” he said. “We used to have not only the fluorescein angiogram but also the [scanning laser ophthalmoscope indocyanine green] angiogram because occult choroidal vessels are by definition difficult to analyze on fluorescein and much more clearly detectable with the [indocyanine green], mainly with the [scanning laser ophthalmoscope].”

OCT is an effective tool for identifying and analyzing neovascularization, Dr. Coscas said.

Making a precise diagnosis

Neither OCT nor fluorescein angiography alone offers a precise diagnosis of occult CNV, Dr. Coscas said.

“If we use the OCT alone, it could be, in many instances, difficult to achieve a precise diagnosis,” he said. “And it is the same with fluorescein alone. We have, in many cases, some difficulties in getting a precise interpretation. But using them simultaneously and adding the information coming from the angiograms and from the OCT, we have now the conviction that this is the best way to achieve the best and most precise diagnosis.”

OCT provides additional insights about the proliferation of new vessels, Dr. Coscas said.

“OCT has brought us new information,” he said. “This new information is that occult choroidal new vessels are proliferating beneath the (retinal pigment) layer, inducing elevation or detachment of the RPE layer, easily detected with OCT.”

In some cases, new choroidal vessels may be largely exudative, and the pigment epithelium detachment will be large, serous, bullous and elevated. In other cases, choroidal vessels may proliferate more slowly with many fibrous tissues and less exudation, and the RPE detachment will appear fibrovascular, Dr. Coscas said.

“The last thing is that usually many doctors are considering only the sub- and intraretinal fluid accumulation,” he said. “With the OCT, we are able to see clearly and to be sure if the elevation of the pigment epithelium layer is a serous detachment or if it is a fibrovascular detachment and to know what happened to these changes during treatment and follow-up of treatment.”

Patients, methods and results

The study included 153 eyes of 130 patients with subfoveal occult CNV stemming from AMD. Mean patient age was 78 years ± 5 years. All patients presented with recently reduced visual acuity associated with metamorphopsia for about 3 months.

Researchers used the Heidelberg Retinal Analyzer scanning laser ophthalmoscope (Heidelberg Engineering) and the Stratus OCT III.

Diagnostic criteria for occult CNV on angiography included heterogeneous hyperfluorescence with late leakage in the macular region associated with pigment epithelial detachment, stippled hyperfluorescent dots and signs of deterioration such as recent changes in visual acuity, subretinal hemorrhages, or both, exudates and serous retinal detachment, the study authors reported.

Their essential finding was the presence of a marked elevation of the retinal pigment epithelium separated from the choroidal plane in 98% of cases.

OCT showed pigment epithelial detachment in 150 eyes (retinal pigment epithelium elevation in 54 eyes and complete detachment in 96 eyes). Limited elevation appeared as a small, discrete and barely prominent vaulting. Complete detachment was associated with altered and fragmented zones.

Scanning laser ophthalmoscope indocyanine green angiography detected pigment epithelial detachment in 137 eyes. The pigment epithelial detachment appeared as a hypofluorescent, high-contrast and homogeneous area with fairly regular borders, the study authors said.

Intraretinal fluid accumulation was detected in 122 eyes, subretinal fluid accumulation in 64 eyes and intraretinal and subretinal fluid accumulation in 53 eyes.

Early-stage disease responds well to treatment, Dr. Coscas said.

“The result of our studies and the follow-up of our patients have shown us that early stages are responding well to treatment quickly and without many injections,” he said. “And late stages with already developed fibrous tissue will have a response with this treatment but with more injections, more recurrences, more fibrous tissue [and] less visual acuity.”

For more information:

Gabriel Coscas,MD, can be reached at Eye University Clinic of Creteil, 40 Ave. de Verdun, 94010 Creteil, France; +33-1-45-175225; fax: +33-1-45-175227; e-mail: gabriel.coscas@libertysurf.fr. Dr. Coscas has no direct financial interest in the products discussed in this article. He is a consultant for Novartis and Pfizer.

Reference:

Coscas F, Coscas G, et al. Optical coherence tomography identification of occult choroidal neovascularization in age-related macular degeneration. Am J Ophthalmol. 2007;144:592-599.

Matt Hasson is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses on regulatory, legislative and practice management topics.