·
Kesten-Baum index refers to ratio of large blood
vessels versus small blood vessels on the disc. Normal ratio is 4:16. This
ratio is decreased in patients with optic atrophy.
·
Cup-disc ratio.
Normal cup disc ratio is 0.3. (i) Large cup may be
physiological or glaucomatous. (ii) Cup becomes full in papilloedema
and papillitis.
·
Results of EOG are interpreted by finding out
the Arden ratio as follows:
Arden ratio = (Maximum height of
light peak/ Minimum height of dark trough) × 100
Normal curve values are 185 or
above.
Subnormal curve values are less
than 150.
Flat curve values are less than
125.
·
Normal arterioles
are bright red in colour and veins are purplish with
a caliber ratio of 2: 3.
Following abnormalities may be detected:
Narrowing of arterioles is seen in
hypertensive retinopathy, arteriosclerosis, and central retinal artery
occlusion.
Tortuosity
of veins occurs in diabetes mellitus, central retinal vein occlusion and blood dyscrasias.
Sheathing of vessels may be seen
in periphlebitis retinae,
and hypertensive retinopathy.
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