Test 3
11.The corneal stroma:
a. has collagen fibres arranged in lamellae that are 4 microns thick 

b. consists mainly of  type I collagen 

c. is transparent due to its compact, regular arrangement of lamellae 
    and its positively charged Glycosaminoglycans matrix 

d. contains the occasional fibroblast, macrophage, lymphocyte and 
    poly-morphonuclear lymphocyte 

e. consists of the GAGs, Chondroitin4-sulphate, Keratan sulphate 
    and hyaluronic acid 

12. The corneal endothelium:
a. has a basement membrane 

b. despite being metabolically active does not reproduce by mitosis 

c. are all hexagonal in shape for maximal stability and interdigitation 
    of plasma membranes 

d. terminates at the trabecular meshwork 

e. is the layer most responsible for maintaining corneal dehydration 


13. The cornea is supplied:
a.  with oxygen at its centre from the tear film only 

b. with capillary blood from the anterior ciliary vessels of the 
    conjunctiva and sclera 

c. by the short ciliary nerves, branches of  the ophthalmic division of
    trigeminal nerve

d. by nerves that enter the orbit from the perichoroidal space and 
    divide to form the annular plexus also known as the perilimbal ring 

e. by nerves that are specific to pain 


14. With respect to the choroid:
a.  it extends from the iris anteriorly to the optic nerve posteriorly 

b. it is thickest at the posterior pole and thins as it passes anteriorly 

c. it has strong attachments to the sclera in the region where the 
    vortex veins leave the globe at the equator 

d. its pigment cells absorb light penetrating the retinal pigment 
    epithelium to prevent reflection 

e. changes in flow of the vasculature may be responsible for heat 
    exchange from the retina 


15.  The choroid:
a. consists of 3 layers, from superficial to deep: vessel, capillary, 
   Bruch’s membrane

b. is supplied by the long and short posterior ciliary arteries that 
    pierce the sclera to form the arterial circle of Zinn 

c. is innervated by the long ciliary nerves that are branches of the 
    lacrimal nerve of ophthalmic division of  trigeminal nerve. 

d. has as its innermost layer Bruch’s membrane that consists of 4 

e. is bounded externally by a potential space called the 
    suprachoroidal space 

To test 4
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