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| |  ARVO: Researchers Investigate Better Diagnosis for Macular Edema By Mike Fillon FORT LAUDERDALE, FL -- May 3, 2004 -- Since it is understood that different pathologies may lead to macular edema with different patterns, researchers recently surmised that if they could better recognize these patterns, they would be in a better position to prescribe the appropriate treatment. Using optical coherence tomography (OCT), researchers led by Mauro Goldbaum, MD, department of ophthalmology, Instituto Suel Abujamra, Sao Paulo, Brazil, compared the tomographic findings at the posterior pole of eyes with macular edema. Dr. Goldbaum presented the results of the study here on April 29th in a poster session at the Association for Research in Vision and Ophthalmology Annual Meeting. The study included all patients with macular edema secondary to nonproliferative diabetic retinopathy (NPDR) and retinal vein occlusion (RVO) referred for OCT evaluation to the Instituto Suel Abujamra from July 2001 to January 2003. All the patients underwent fundus examination and to the same exam protocol with OCT. The noninvasive imaging technique uses infrared light to visualize subsurface structure in biological tissues. Depths of a few millimeters can be imaged with about 20 mcm resolution. OCT is analogous to ultrasound imaging, but the magnitude of reflected light is measured instead of reflected sound waves. OCT achieves relatively high resolution and a large depth of imaging by combining characteristics of confocal microscopy and white light interferometry. In earlier studies, OCT had discovered diabetic macular edema in 3 different, nonexcluding categories–sponge like edema in 88%, cystic edema in 47%, and sub-retinal fluid in 15%. "The results of this study are quite similar," said Dr. Goldbaum. He explained that the protocol consisted of cross hair scans and linear scans (2.83 and 7.00 mm) in horizontal and vertical directions. Additionally, evidence of vitreous-retinal traction, represented by partial vitreous detachment or epiretinal membrane, was considered. In this study, 51 eyes of 33 patients were examined for NPDR. The researchers found 94.1% of eyes presented homogeneous edema (sponge-like), 45.1% presented cystic edema, and 19.6% presented sub-retinal fluid at the fovea. Suggestion of macular traction represented by partial posterior vitreous detachment and epiretinal membrane were noted in 25.5% and 13.7% of eyes, respectively. Among 21 eyes of 21 patients examined for RVO, 95.3% of eyes presented homogeneous edema (sponge-like), 90.5% presented cystic edema, and 52.4% presented subretinal fluid at the fovea, while 4.8% presented an epi-retinal membrane. Dr. Goldbaum said the researchers had theorized on the pathophysiology of serious retinal detachment in RVO with the main factors considered being increased intravascular pressure and vascular permeability. "Both factors are also participants in the formation of macular edema in NPDR," he said. "Possibly the different patterns of edema shown here reflect the way of installation of these 2 diseases; insidious in NPDR and abrupt in RVO. Increased signs of vitreous-retinal traction in NPDR may need a longer follow-up."
[Presentation title: Comparative Study of Macular Oedema Secondary to Diabetic Retinopathy and Retinal Vein Occlusion With Optical Coherence Tomography. Poster B-564]
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