229
OPTICAL COHERENCE
TOMOGRAPHY IN AGE-RELATED
MACULAR DEGENERATION
21
Optical coherence tomography (OCT) acquires cross-
sectional images with semihistologic resolution. The
technology precisely defines the location and nature of
the changes in the retina and adjacent structures and
objectively evaluates the thickness of the retina and
surrounding structures. These capabilities allow detec-
tion of newly emerging fluid and/or intraretinal or
subretinal tissue and tissue below the retinal pigment
epithelium (RPE). OCT provides important informa-
tion on serous retinal detachments, hemorrhages, and
subretinal neovascular membranes that are components
of exudative macular degeneration and more precise
analysis of anatomic structures and subtypes of neo-
vascular membrane lesions. These capabilities facilitate
an understanding of the differences among the classic
membranes, hidden membranes, retinal angiomatous
proliferation (RAP), and disciform scars in the natural
course of the disease and assess the treatment response.
The images are presented in a scale of colors (or gray),
such that tissues that reflect more light or disperse more
light are shown in red and white, respectively, while the
ones that reflect or disperse the least light are shown in
blue and black. Tissues that moderately reflect light are
shown as green or yellow. The color represents the opti-
cal properties of the tissues and not the tissues them-
selves. Therefore, the image is not real but represents
the true dimensions of the measured structures.
1-10
The vitreous transmits light without reflecting it and is
depicted in black in OCT images (Figure 1). The poste-
rior hyaloid usually is indistinguishable from the retinal
surface except when the posterior vitreous detaches and
appears as a weakly reflective band. The choriocapillaris
and choroid are highly reflective layers, because they are
vascular and limit light penetration into the deeper lay-
ers. Blood vessels are identified by their high reflectiv-
ity and the screening effect generated on adjacent tissues
(Table 1).
7,8,11
1. Introduction
Authors:
1
Ophthalmology Department. Clínica Universidad de Navarra.
Pamplona. Spain
2
Ophthalmology Department. Complejo Hospitalario de Navarra.
Pamplona. Spain.
