Opthalmic Examination 1

Question 1

What 3 aspects must be taken into account when recognising lesions?

Answer 1

1. tissue response to injury
2. interaction between tissues in the eye
3. possible stages of every disease process

Question 2

3 main owner concerns in ophthalmic Hx?

Answer 2

1. altered appearance of the eye
2. loss of vision
3. presence of pain

Question 3

3 main aspects to judge facial/ocular symmetry?

Answer 3

• draw line lateral-medial canthi, see how much of the globe lies above/below the line
• medial canthus - pupil distance
• 3rd eyelid surface area (NOT pigment!)

Question 4

How is the 3rd eyelid naturally extruded? When may this not be the case?

Answer 4

• pain/discomfort -> retropulsion of the globe -> displacement of retrobulbar fat pad rostrally -> protrusion of 3rd eyelid
• IF globe is pushed out/bulging [exopthalmus] AND 3rd eyelid is protruded suspect space occupying lesion (tumour/cysts etc.)

Question 5

When should STT be carried out? How is this carried out?

Answer 5

• before use of light or eye maniopulation
• place laterally (avoid TE) between eyelid and cornea (lower conjuctival fornix,) care not to poke cornea
• wait 1 min per eye
• test both eyes and compare

Question 6

Which species have most and least sensitive cornea

Answer 6

(most sense) Humans, Rabbits, Cats, Dogs, Brachycephalic Dogs, Brachy Cats (least sense)

Question 7

How does STT2 differ?

Answer 7

Local Anasthetic applied before test

Question 8

Simplified analysis and reference ranges of STT readings

Answer 8

15mm/min normal

- inbetween unclear, repeat

Question 9

When may a “normal” STT result be abnormal?

Answer 9

Ulcer present but STT 17mm - normal? NO, should be tearing up d/t pain from ulcer -> off the scale STT. So 17 is LOW and ulcer likely d/t dry eye.

Question 10

How does KCS present?

Answer 10

• Keratoconjuntivitis Sicca

- asymmetrical and progressive dry eye

Question 11

When should menace test be carried out?

Answer 11

preferably after STT test

Question 12

Is the menance response a reflex? What does it test?

Answer 12

• NO learnt response, cortical (not subcortical reflex)

- tests vision (cortex involved) but v. crude

Question 13

What cranial nerve provides touch innervation to the globe and ocular region?

Answer 13

Opthalmic branch of trigem

Question 14

What are the 3 light examination techniques?

Answer 14

1. Tranillumination/Slit examination
2. Direct ophthalmoscopy (distant and close)
3. Indirect Opthalmoscopy

Question 15

What can be assessed using transilulmination/slit examination?

Answer 15

1. Anterior structure of the eye
   - eyelids, conjunctiva and TE
   - cornea, iris and anterior lens (contour and lesion depth of cataracts and ulcers)
2. Reflexes
   - dazzle reflexes
   - PLRs (direct and indirect)
   > NB: blinding cataracts will not always stop these reflexes

Question 16

What colour light is used to visualise fluorescin dye?

Answer 16

Blue

Question 17

What other colours of light are available on an opthalmoscope?

Answer 17

Greeen - no red so blood/blood vessels appear black but pigment remains brown

Question 18

Why does indirect PLR occour?

Answer 18

Decussation of fibres at the optic chiasm

Question 19

How is the PLR test carried out?

Answer 19

• Test one eye, check for constriction of the other

- swinging torch test - switch between both eyes, both should remain constricted

Question 20

Damage where will affect PLR?

Answer 20

• retina

- optic nerve before the chiasm

Question 21

What limitation doe a standard general practice opthalmoscope have?

Answer 21

• cannot tell depth of ulcers without v. expesive refrerral slit lamp biomicroscope thingy.

Question 22

What can be seen using a slit lamp ion transilluminable structure?

Answer 22

• surface contour (cornea, iris, anterior chamber, anterior and posterior bellies of the lens)
• layers (cornea, lens cataract localisation possible)
• anterior chamber (quality of aqueous humour, transparent v. turbid “flare”)

Question 23

How thick is the cornea?

Answer 23

~0.5mm dogs

~0.8mm LA

Question 24

How can ulcer depth be defined in general practice?

Answer 24

Pothole? Deep

Question 25

What is necessary in order to see both anterior and posterior bellies of the lens?

Answer 25

Massively dilated pupil!