252
Ahlers and colleagues the Medical University of
Vienna led by Ursula Schmidt-Erfurth, MD, pointed
to a new parameter as a prognosis factor in patients
with AMD, i.e., the optical density ratio of the sub-
retinal fluid detected by OCT.
69
The authors sug-
gested that this ratio may be an indirect way to meas-
ure the integrity of the barrier and therefore be useful
for differential diagnosis between different exudative
macular diseases such as central serous chorioretin-
opathy and to assess the response to antiangiogenic
drugs (Table 4).
OCT andWet AMD in Clinical Practice
To reach a consensus on the criteria of treatment and
frequency of revisions, daily management of these
patients is individualized, and the decisions are based
on clinical examination and qualitative analysis of
OCT images.
2
The main signs of activity of the neo-
vascular membranes in the OCT are the presence of
intraretinal or subretinal fluid and RPE detachments
and tears. These OCT findings should be evaluated
biomicroscopically for the presence of fibrosis in dis-
ciform scars, which are final and irreversible stages
of the disease that sometimes can have show of these
signs on OCT. The presence of any of these tomo-
graphic signs, the patient’s VA, and the ophthalmo-
scopic and angiographic appearance of the lesions
should be evaluated by ophthalmologists to reach
Table 4.
Prognosis Factors According to OCT as Identified by Various Authors.
Parameter
Total retinal thickness
Subretinal tissue volume
Neurosensory retina thickening
RPE status
Integrity of the union of outer and
inner segments of photoreceptors
Posterior vitreomacular adhesion
Optical density ratio
Author and year
Kiss 2009
Sayanagi 2009, Kaluzny 2009, Chen 2009,
Witkins 2009
Lee 2009, Mojana 2008
Ahlers 2009
Keane 2008
Singh 2009
treatment decisions and revisions in each case until
the current prospective multicenter studies shed light
on results based on conclusive evidence.
17. New Techniques and Prototypes in AMD
OCT and Confocal Scanning Laser Ophthalmoscopy
Some new SD-OCT instruments (Spectralis HRA-
OCT, Heidelberg Engineering, Inc., Heidelberg,
Germany; Spectral OCT/SLO, Opko/OTI, Inc.,
Miami, FL) are equipped with this method, which
simultaneously captures digital funduscopic images
(infrared, red free autofluorescence, FA and ICGA)
and OCT images from the same light source. This
enables clinicians to correlate the two images pixel
by pixel and allows a detailed topographic survey
and tomographic retinal structures.
70
In AMD, these
devices are used especially in studies attempting to
correlating OCT and autofluorescence in GA.
71-72
Displaying the Choroid with Depth-Enhanced Optical
Imaging OCT
The principle of OCT requires penetration of the emit-
ted beam through the structures observed before being
received for analysis. Thus, with the standard technique,
images of the full-thickness retina to the RPE, Bruch’s
