Because of the widespread use of OCT, the use of FA has dropped to second place in routine consultations, but it is still an essential examination for studying CNV in patients with AMD, and FA and ICGA are especially important for identifying occult disease. When comparing both techniques, because OCT is gaining definition with new versions and devices, the non-invasive nature of FA and ICGA takes precedence over conventional angiographic techniques, to the extent that some studies have reported similar results for both examinations. Krebs and colleagues and Saddu and colleagues proposed that OCT can detect signs of activity similar to FA in a study in which two independent observers analyzed the agreement. The authors reported that even OCT was slightly more sensitive than FA for determining the activity of the membranes, while other authors stated that it was necessary to manually adjust the segmentation analysis of images to achieve similar results. ^22,38 More recently, Malamos and colleagues used high-definition OCT to analyze patients diagnosed by FA with different types of AMD (early, neovascular classic, minimally classic, and occult). They reported a significant correlation between different angiographic patterns and various parameters with OCT. The authors could discriminate different types of damage using OCT to the extent that they could identify their precise anatomic retinal maps.³⁹ In cases with hidden membranes and some cases of RAP, the relevance of FA is undoubtedly even greater because of the difficulty of localizing the pathology in the tomography images (Figure 14). However, some authors have described changes associated with OCT membranes, such as exudation signs and the almost constant presence of RPE detachments, and changes within the polymorphic features of these lesions.³

 

Until the development of new techniques to visualize the choroid with OCT such as that proposed by Spaide and colleagues, the most informative method to explore these cases is FA.^0-42 However, OCT seems to override FA in the identification of signs of activity in patients previously treated with PDT, in which interobserver agreement is much higher for OCT than for FA.^43-44 Finally, the sequential use of both techniques for screening of wet AMD in patients with impaired visual acuity (VA) has been proposed. The screening was first performed with OCT and then based on the results, fluorescein and indocyanine FA, which obtained adequate sensitivity and specificity for the early detection of AMD in these patients.⁴⁵

Autofluorescence allows gathering of information about the metabolic status of the retina. This technique based on the ability of tissues to emit more or less fluorescence depending on the amount of accumulated lipofuscin to be excited by light at specific wavelengths and provides the opportunity to evaluate the retinal functional status. Since OCT obtains a detailed picture of the retinal anatomy, several studies have evaluated the structure/function in patients with AMD and correlated the two techniques. Bearelly and colleagues⁴⁶ reported that there was a significant association between OCT and autofluorescence findings and that marked hyperfluorescence at the edges of the plaques of GA correlated with hyperreflective changes in the outer retinal layers identified by OCT that did not occur in healthy retinas with normal autofluorescence and OCT (Figure 15). These findings used a combination of both techniques to determine the patterns of progression of GA plaques in patients with AMD, which had been targeted previously by other authors as discussed below.⁴⁷

 

Autofluorescence currently is the most frequently used test to assess disease progression in dry AMD; however, OCT provides additional information, so its role has not been ruled out in the study of these patients to the extent that some authors have proposed methods based on OCT to evaluate progression of atrophic plaques, as described in the following section.¹⁷