MCQs - Lens and Vitreous Flashcards
Which one of these ocular structures has the highest refractive index?
a. Vitreous humour
b. Aqueous humour
c. Air-cornea interface
d. Lens
Which one of these ocular structures has the highest refractive index?
c.Air-cornea interface
Well done. The air-cornea interface is the prime refractive interface
The supply of nutrients and oxygen to and waste removal from the adult lens is performed by
a. The lens capsule
b. The pupillary membrane
c. Aqueous and vitreous humour
d. The posterior hyaloid artery
The supply of nutrients and oxygen to and waste removal from the adult lens is performed by
c.Aqueous and vitreous humour
Well done. This role is fulfilled by the aqueous humour and, to a lesser extent, the vitreous humour
A lack of menace response may indicate a lesion
a. Along the optic nerve or in the visual cortex
b. Involving the facial nucleus or facial nerve
c. Within the eye, optic nerve or visual cortex
d. Within the eye, optic nerve, visual cortex, facial nucleus or facial nerve
A lack of menace response may indicate a lesion
d.Within the eye, optic nerve, visual cortex, facial nucleus or facial nerve
Which one of the following techniques will allow you to localise a lesion within the lens most accurately?
a. Slit lamp biomicroscopy
b. Distant direct ophthalmoscopy
c. Ultrasound
d. Direct ophthalmoscopy
Which one of the following techniques will allow you to localise a lesion within the lens most accurately?
a.Slit lamp biomicroscopy
Well done. The use of the obliquely directed slit beam allows localisation of the lens lesion with more accuracy than other techniques
Which one of the following statements about congenital cataract is most accurate?
a. Congenital cataracts in the Miniature Schnauzer are usually symmetrical and primarily involve the lens cortex
b. Congenital cataracts are inherited
c. Congenital cataracts may occur as part of the suspected hereditary MOD (multiple ocular defects) complex
d. Congenital cataract associated with PPM (persistent pupillary membrane) primarily involves the lens nucleus
Which one of the following statements about congenital cataract is most accurate?
c.Congenital cataracts may occur as part of the suspected hereditary MOD (multiple ocular defects) complex
This is true. Breeds such as the CKCS, English Cocker Spaniel, Golden Retriever, Old English Sheepdog and West Highland White terrier may be affected
Most metabolic cataracts in dogs are associated with diabetes mellitus. Which one of the following statements is most accurate?
a. The main pathway for glucose metabolism in the lens of the normal dog is catalysed by aldose reductase
b. Clefts within the lens tend to occur along the suture lines as these are the strongest part of the lens structure
c. Glucose metabolism in the lens of the diabetic dog produces sorbitol, which attracts water into the lens by osmosis
d. Lens volume decreases as water is attracted into the aqueous humour by osmosis
Most metabolic cataracts in dogs are associated with diabetes mellitus. Which one of the following statements is most accurate?
c.Glucose metabolism in the lens of the diabetic dog produces sorbitol, which attracts water into the lens by osmosis
Cataract progression and resorption may stimulate uveitis. This is attributable to
a. Reduced intraocular pressure
b. Increased tension on the zonules, which originate from the ciliary body and support the lens
c. Changes in glucose levels within the aqueous humour
d. Leakage of lens protein
Cataract progression and resorption may stimulate uveitis. This is attributable to
d.Leakage of lens protein
Which one of the following statements regarding lens instability is most accurate?
a. Anterior lens luxation can be difficult to identify with the naked eye unless secondary signs are present or the lens is cataractous
b. The preferred surgical treatment for anterior lens luxation is phacoemulsification
c. Medical management of posterior lens luxation is usually effective and carries minimal risk
d. Primary glaucoma with secondary lens luxation, and primary lens luxation with secondary glaucoma are managed in the same way
Which one of the following statements regarding lens instability is most accurate?
a.Anterior lens luxation can be difficult to identify with the naked eye unless secondary signs are present or the lens is cataractous
After surgical lens removal, which one of the following complications may be encountered in the immediate post-operative period?
a. Transient drop in intraocular pressure
b. Posterior synechiae between the iris and lens capsule
c. Uveitis
d. Glaucoma
After surgical lens removal, which one of the following complications may be encountered in the immediate post-operative period?
c.Uveitis
Well done. All intraocular surgery induces a degree of uveitis, and management is key to long term success
Focal deposits of lipid may be seen as particles scattered through the vitreous. These particles move with the vitreous but return to a normal position once the globe is still. This is termed
a. Vitreal membranes
b. Asteroid hyalosis
c. Ciliary body cysts
d. Synchisis scintillans
Focal deposits of lipid may be seen as particles scattered through the vitreous. These particles move with the vitreous but return to a normal position once the globe is still. This is termed
b.Asteroid hyalosis
