terminology and guidelines for glaucoma ii - Kwaliteitskoepel

Fig. 3
Optic disc hemorrhage.
Beta Zone
Alpha Zone
Fig. 4
ONH with parapapillary atrophy: Alpha dystrophy is located
peripheral to beta dystrophy, characterized by irregular
hypopigmentation and hyperpigmentation; Beta dystrophy
is adjacent to the optic disc edge, outer to the Elshnig rim,
with visible sclera and visible large choroidal vessels.
1.3.1.b - Optic disc hemorrhages
The prevalence of small hemorrhages related to the
optic disc has been estimated at 0 to 0.21% in the
normal population and 2.2 to 4.1% in glaucomatous
patients; they may be more common in normal-tension
glaucoma (up to 40%). Since the prevalence of
disc hemorrhage is low in the normal population,
their presence is very likely to be pathological, especially
if recurring. It is a sign of local vascular damage
8,9 (Fig. 3).
1.3.1.c - Parapapillary atrophy 10-12
A temporal crescent of parapapillary atrophy is common
(80% in the normal population). However, the
frequency and area covered increases in glaucoma.
Parapapillary atrophy is least frequent in normal
eyes in the nasal disc sector. The site of the largest
area of atrophy tends to correspond with the part of
the disc with most neuroretinal rim loss. The extent
of atrophy may be greater in NPG. Because some
degree of atrophy is present in many normal eyes, a
large area of atrophy should be regarded as an extra
clue, rather than as a definite sign of local vascular
damage associated with glaucoma (Fig. 4).
1.3.1.d - Acquired baring of circumlinear vessels
An early sign of acquired rim thinning is a circumlinear
vessel becoming bared. A circumlinear vessel is
a small arteriole or vein that lies superficially on the
neuroretinal rim, at its inner edge, and leaves the
disc towards the macula; at least one is present in
about 50% of eyes. As the rim narrows the loss of
tissue leaves this vessel isolated, or ‘bared’. It may
then remain superficial or come to lie on the inner
slope of the rim or on the cup floor (Fig. 5).
1.3.1.e - Appearance of the retinal nerve fibre layer
The nerve fibre layer (NFL) is best seen with a 78D
or 90D lens or a contact lens at the slit lamp with a
bright, rectangular, green light. The fibre bundles
are seen as silver striations. From about two discs
diameters from the disc the NFL thins and feathersout.
Slit-like, groove-like, or spindle-shaped apparent
defects, narrower than the retinal vessels, are seen in
the normal fundus. The NFL becomes less visible
with age, and is more difficult to see in lightly pigmented
fundi.
Defects are best seen within two disc diameters of
the disc. Wedge and slit defects (wider than retinal
vessels) are more apparent in early disease, when
there is little generalized thinning of the NFL, and
are seen as dark bands extending from the optic
disc. Generalized thinning of the NFL, with a loss of
brightness and density of striations, is a difficult sign
to objectively confirm. When the NFL is thinned
the blood vessel walls are sharp and the vessels
appear to stand out in relief against a matt back-
Ch. 1 - 18 EGS