Fluorescein angiography and OCT reveal different findings in mild uveitic macular edema

This retrospective study of patients with uveitis macular edema (ME) found discrepancies between fluorescein angiography (FA) and optical coherence tomography (OCT) findings in 46 percent of cases. This is a greater discrepancy than has been previously reported and occurred predominantly in mild ME. The authors conclude that FA and OCT imaging are complementary investigations, with each revealing different aspects of the pathophysiology of uveitic ME.

We may have to consider the results of investigations conducted with both FA and OCT in patients with mild ME. The findings of mild uveitic ME may not be evident by biomicroscopy and clinical examination.

The study included 78 patients (112 eyes) with uveitic ME on FA, OCT or both. Positive results of both imaging methods were observed in 61 eyes (54 percent) and discrepant results in 51 eyes (46 percent). Discrepant results with FA+/OCT- occurred in 34 eyes (30 percent) and FA-/OCT+ in 17 eyes (15 percent), with both typically occurring with mild degrees of ME.

FA+/OCT- occurred in 50 percent of eyes with birdshot chorioretinopathy (7/14). It occurred more often in intermediate uveitis than in other anatomic locations. Those with active disease frequently showed consistency between FA and OCT (FA+/OCT+), while 44 percent of those with inactive uveitis showed the FA-/OCT+ discrepancy.

In patients with severe ME, a median central retinal thickness of 318 µm showed no discrepancy between FA and OCT, but a median central retinal thickness of 274 µm did. Patients with severe leakage on FA were positive on OCT. Reasons for the discrepancy between FA and OCT include the presence of retinal atrophy. The discrepancy may also be due to the imprecise definition of ME by FA and OCT. By FA, the optic disc diameter for defining ME Grade 2 is larger than the area of the central 1 mm defined for OCT. And the grading of ME on FA may not be accurate.