ANATOMY

Question 1

• Interpalpebral fissure

Answer 1

Vertical: 8-11mm
Horizontal: 30-32mm

Question 2

Angle between the upper and lower eyelids medially and laterally

Answer 2

60 degrees

Question 3

The lateral canthal angle usually lies

Answer 3

2-3mm higher than the medial canthal

Question 4

The eyelid can be divided into 5 structural planes:

Answer 4

1. The eyelid skin and TCSC.
2. The orbicularis oculi.
3. The orbital septum.
4. The eyelid retractor muscles.
5. The tarsal plates and conjunctiva.

Question 5

UPPER EYELID SKIN CREASE

Answer 5

• The skin crease varies in height and tends to lie:
  o 5 to 6 mm above the eyelid margin centrally in men
  o 7 to 8 mm above the eyelid margin centrally in women
• Medially the crease extends to within 3 to 4 mm of the eyelid margin
• Laterally it lies approximately 5 to 6mm above the eyelid margin

Question 6

The orbicularis oculi muscle is divided anatomically into 3 parts:

Answer 6

1. Orbital
2. Preseptal
3. Pretarsal

Question 7

A deep plane of fat lies posterior to the orbital part of the orbicularis M superiorly and inferiorly.

Answer 7

• The suborbicularis oculi fat (SOOF) lies over the inferior orbital margin.
• The retroorbicularis oculi fat (ROOF) lies over the superior orbital margin