Test 107   (Ocular anatomy)

1. Normal ageing changes in the cornea include: 

a. decreased translucent

b. increased thickness of the Bowman's membrane

c. increased thickness of the Descemet's membrane 

d. increased thickness of the corneal stroma

e. decreased endothelium density

Answera.T  b.T  c.T  d.F  e.T
Decreased corneal translucence is caused by condensation in the cornea. The thickness of Descemet's membrane and Bowman's membrane increases with age but the stroma remain unchanged. The endothelium count decreases with time.
 

2. The vitreous is strongly adherent to:

a. the optic disc

b. ora serrata

c. ciliary processes

d. fovea

e. the centre of lattice degeneration

Answera.T   b.T   c.F   d.F  e.F
Vitreous is strongly attached to the optic disc, ora serrata, par plana of the ciliary body and the edge of lattice degeneration.

 
3. The suspensory ligament:

a. is thickening fo the inferior part of the fascial sheath 
   of the eyeball

b. is synonymous with Whitnall ligament

c. receives fascial contribution from the inferior rectus 
    and the inferior oblique.

d. is attached medially to the ethmoid bone

e. is attached laterally to the zygomatic bone

Answera.T   b.F  c.T  d.F  e.T
The suspensory ligament is also called the ligament of Lockwood. It expands laterally and medially to form the check ligament. Medially it is attached to the lacrimal bone and laterally to the zygomatic bone.

 

4. The macula lutea:

a. measured about 1.5 mm in diameter

b. is about 3 mm lateral to the optic disc

c. contains no blood vessels

d. contains xanthophyll in the retinal pigment epithelium
    which gives it a yellowish colour

e. receives blood supply from the cilioretinal artery in
    80% of patients

Answera.F  b.T  c.F  d.F  e.F
The macula lutea measures about 4.5 mm in diameter (the fovea measures 1.5mm) and is located about 3 mm lateral to the optic disc. 
The yellow colour is due to the presence of xanthophyll within the retinal layers.
Cilioretinal artery is present in 15% of the population.

5. The optic nerve:

a. is surrounded by the three meninges of the brain

b. is bathed in cerebrospinal fluid

c. receives myelination from the astrocytes

d. on average measures 40 mm in length

e. is made up of 10 million axons

Answera.T  b.T  c.F  d.T  e.F
Myelination of the optic nerve is by oligodendrocytes.
Each optic nerve contains 1 million axons.

 
 

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