20. 4bones form the Medial orbital wall
Remember: The lamina papyracea, which forms part of the medial wall, is
paper-thin and perforated by numerous foramina for nerves and blood
vessels. Orbital cellulitis is therefore frequently secondary to ethmoidal
sinusitis.
50. Levator function (upper lid
excursion) is measured by
placing a thumb firmly
against the patient’s brow
to negate the action of the
frontalis muscle, with the
eyes in downgaze. The
patient then looks up as far
as possible and the amount
of excursion is measured
with a rule. Levator
function is graded as normal
(15 mm or more(
61. In proptosis assessment, readings greater than 20
mm are indicative of proptosis and a difference of 2–3
mm or more between the two eyes is suspicious
regardless of the absolute values