The fluorescein angiography may be given as a positive or negative transparency (see picture below). As most fluorescein angiographies encountered are on positive transparency, all the following interpretations are based on the apparance on positive tranparency.
 

Positive fluorescein angiography

Negative fluorescein angiography

The fluorescein angiography is best viewed by placing the transparency on a viewing box and examine the frames with a 20 D lens (those used for indirect ophthalmoscopy). The frame also contains the time lapsed from the moment of intravenous fluorescein sodium injection.

Fluorescein angiography can be analysed in the following ways (which complements each other):

• Sequential analysis -

it is examined frame by frames in the order that it was photographed. The major vascular phases of the angiogram is emphasized. This method is most useful in analysing vascular disorders of the retinal and choroidal.
a
• Anatomic analysis - 

observes each of the major layers of the posterior pose of the eye - the choroidal, 
RPE and neurosensory retina.
a
• Morphologic analysis - 

considers overall patterns. In an abnormal angiogram, some areas may be darker (hyperfluorescent) or lighter (hypofluorescent) than usually in a given location.

In the viva, the examiner would expect you to use the following term while describing the frames
(refer to principles of fluorescein angiography for pictures):

• red free: taken before the fluorescein injection
• choroidal phase
• arterial phase
• capillary phase
• venous phase
• late phase