3-D OCT may improve monitoring of CME progression, study suggests

Using three-dimensional optical coherence tomography may enable researchers to visualize the spatial extent of cystoid macular edema in each retinal layer and determine its relationship to the external limiting membrane, a study by researchers in Japan suggests.

"The use of 3-D OCT thus may improve the monitoring of CME progression and its response to treatment," the authors said.

Noritatsu Yamaike, MD, and colleagues at Kyoto University Graduate School of Medicine used a prototype 3-D OCT system based on Fourier-domain OCT technology to obtain 3-D images for 20 eyes of 20 patients with CME secondary to retinal vein occlusion. The investigators evaluated the pathomorphologic features of the CME in correlation with visual function.

The prototype 3-D OCT system was equipped with a superluminescent diode with an infrared wavelength of 830 nm and a bandwidth of 50 nm, resulting in a 4.3-µm axial resolution in tissue, according to the study.

"In 16 eyes, 3-D OCT showed large foveal cystoid spaces, most of which were accompanied by small cystoid spaces in the parafoveal region," the authors said.

While cystoid spaces were detected in all retinal layers, the researchers observed the majority of cystoid spaces in the inner nuclear and outer plexiform layers.

In 18 eyes, 3-D OCT clearly showed a thin back-reflecting line corresponding to the external limiting membrane (ELM).

Of these 18 eyes, seven eyes had cystoid spaces located on the inside of the ELM; nine eyes had cystoid spaces that appeared to be in direct contact with the ELM. In two eyes, the ELM line was not discernible beneath the large foveal cystoid spaces, the authors noted.

"Integrity of the ELM in the foveal region had a direct correlation with visual acuity," they added.

The study is published in the February issue of Ophthalmology.