Opthalmology

Question 1

Schirmer’s test is indicated when?

What are normal ranges?

Answer 1

Schirmer’s test indicates lacrimal gland function and tear production.

Evaluates conjunctivitis + tear deficiencies
Normal range is 15-20mm/min
<10mm/min = keratoconjunctivitis sicca

Question 2

What surrounds the anterior chamber of the eye?

Answer 2

pupil and iris behind it,

cornea in front of it

Question 3

What produces aqueous humour?

Answer 3

Made by the ciliary body in the posterior chamber

Question 4

What happens to the pupil in glaucoma?

a) Mydriasis
b) myosis

Answer 4

Mydriasis

Question 5

Name main reflexes when doing eye examination (4)

Answer 5

Palpebral reflex
Pupillary light reflexes
Corneal reflex
Menace reflex

Question 6

What does atropine do to the pupil?

a) Mydriasis
b) Myosis

Answer 6

Mydriasis

Question 7

Where is aqueous humour reabsorbed?

Answer 7

Anterior chamber (specifically into venous circulation via the sinus venosum in the irido-corneal angle)

Question 8

Structures of cornea (4 layers)

Answer 8

Endothelium
Descemet's membrane 
(Stroma)
Bowman's layer 
Epithelium

Question 9

Non-direct ophthalmoscopy is method that produces….

a) a true/non-inverted image
b) a reversed/inverted image

Answer 9

Reversed/inverted image

Question 10

When is the fluorescein test positive?

Answer 10

In case of corneal ulceration or damage, fluorescein will adhere to these areas

Question 11

What is tonometry?

What are physiological ranges of IOP in dogs?

2 pathologies associated with IOP and their ranges?

Answer 11

Tonometry is testing of intraoccqular pressure

10-25mmHg is physiological

> 25mmHg - Glaucoma
<10mmHg - Uveitis

Question 12

When and why is corticosteroids contraindicated in ophthalmology

Answer 12

When there is already infection or inflammation of the eye

CS’s cause increased IOP, decreased immunity, retardation of post-op healing

Question 13

What is the effect of gentamycin on (inner structures of the eye)?

Answer 13

Used as an ATB, especially against pseudomonas infections.

Careful: Gentamycin can be irritating and toxic to a perforated eye

Question 14

What are the most common disorders of the eyelashes and what kind of surgical interventions do they require?

Answer 14

Distichiasis - extra eyelashes
Trichiasis - abnormal contact of hair (usually in entropion)
Ectopic cillia - cillia grow from meibomian glands not eyelid follicles

Cryo or laser destruction of follicles
electroepilation
surgical resection of eyelids

Question 15

Describe eyeball prolapse, treatment and management

Answer 15

Eye is trapped in front of eye lids.

replacement of globe or enucleation followed by tarsorrhaphy

Question 16

Characterise follicular conjunctivitis, aetiology, clinical symptoms and therapy

Answer 16

“Chronic inflammation of the conjunctiva followed by lymphoid hyperplasia of follicles of conjunctiva/third eyelid”

Cats: infectious (FIV, Chlamydiosis, mycoplasma)
Dog: non-infectious (dry eyes, allergic, entropion + trichiasis)

Question 17

Function of the iris?

Answer 17

Control the diameter of the pupil (thus how much light enters the eye)

Question 18

How many layers has tear film got? Name them. (inner to outer)

Answer 18

3 layers
Mucin layer
Aqueous layer
Lipid (oil) layer

Question 19

Clinical signs of uveitis

Answer 19

photophobia, 
excessive tear production, 
blepharospasm, 
miosis, 
deep scleral injection, 
corneal oedema, 
aqueous flare, 
blood in anterior chamber of eye, 
hypopyon, 
synechiae, 
reduced IOP

Question 20

Dislocation of lens what are the types and diagnosis

Answer 20

Anterior or posterior dislocation
Primary (inherited), secondary (trauma, tumours, uveitis)

Dx: Iris vibration + lens movement

Question 21

What is glaucoma, aetiology, clinical signs and therapy

Answer 21

Increased IOP (>25mmHg)
Obstruction of flow of tears from anterior to posterior chamber for reabsorption. 

Cx: Globe enlargement, pain, redness, mydriatic non-responsive pupil, blindness

T:
Medical: increase drainage (latanoprost) , decrease production of aqueous humour (dorzolamide) and reduction of IOP (timolol)

Surgical: shunt implantation
enucleation
Partial destruction of the ciliary body

Question 22

Tarsorrhaphy – characteristics and indications

Answer 22

Joining the upper and lower eyelid to a partially or complete closure of the eye.
It is used to help the cornea heal or to protect the cornea for a short period

Question 23

What is a corneal flap and when do we use it?

Answer 23

A flap of the conjunctiva is sutured over an ulcer to aid healing and after 2-3 weeks it is removed

Question 24

What is “Cataract”?

Answer 24

opacity of the ens capsule. Lens fibres are disrupted.