Discrepancy between fluorescein angiography and optical coherence tomography in detection of macular disease.

Macular edema (ME) is a common denominator for the decrease of central vision in many diseases affecting the posterior segment of the eye. Intraretinal fluid in the macula can result from subretinal disease such as choroidal neovascularization as well as from diseases causing breakdown of the blood-retina barrier at the level of retinal vessels causing leakage of intraretinal fluid from perifoveal abnormal capillary vessels or microaneurysms, such as aphakic or pseudophakic ME, uveitis, or vascular occlusion.1-6 Most recently, great emphasis has been placed upon detection and changes in intramacular fluid seen in patients with choroidal neovascularization to monitor and guide treatment of that disease with anti-vascular endothelial growth factor agents such as bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA) and ranibizumab (Lucentis; Genentech, Inc.).7,8 ME is clinically defined as an increase in the retinal tissue resulting in an increase in foveal thickness. In its cystoid variant, cystoid macular edema (CME), cystoid changes have a predilection to the outer plexiform layer and the inner nuclear layer.9-11 ME can be diagnosed using noncontact stereoscopic biomicroscopy/contact lens biomicroscopy, fluorescein angiography (FA), and optical coherence tomography (OCT). Although FA can assess ME qualitatively, OCT provides quantitative measurement of foveal thickness.12 Therefore, the pathophysiologic aspect of ME can be determined by FA, and its anatomical features such as the extent of retinal thickening and the retinal layer involved can be assessed best using OCT. Previous studies have shown that both FA and OCT are highly sensitive in detection of ME of various etiologies, with OCT superior to FA according to certain parameters.13-15 The noninvasive character of OCT compared with FA makes it a much more popular option among patients and among some clinicians. With the extensive use of OCT for the diagnosis of ME, there is a tendency toward the less frequent use and even abandoning of FA, especially during frequent follow-up visits. Some indirect observations have also mentioned occasional cases of discrepancy between OCT and FA findings.16-18 Previous studies have carefully compared OCT with clinical examination for detection of ME,19 and small studies have evaluated OCT in comparison with FA. The latter studies either analyzed one cause of ME13 or used OCT2 technology.15,16 We conducted the current study to assess the ability of both techniques to detect ME of various etiologies in cases in which ME has been confirmed by either one of them. We determined the frequency of discrepancy between the two techniques and possible explanations for such discrepancy.