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Y4 SA - Ophthalmology > The ophthalmic exam > Flashcards

The ophthalmic exam Flashcards

(45 cards)

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1
Q

Signalment clues

A

Breed
- e.g. Westies get KCS
- e.g. terriers get lens laxation

Age e.g. animal printing with hyphaema
- puppy = congenital abnormality (e.g. malformed blood vessels)
- 12y/o cat = systemic hypertension
- 12y/o dog = intraocular neoplasia

Gender
- not usually important
- entire female with pyo can present with uveitis

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2
Q

Hx - general

A
  • vaccination, worming, diet
  • other pets in house? esp relevant for cats
  • indoor vs outdoor cat
  • travel hx: exotic dz becoming more common/relevant
  • general health: other medical conditions, appetite, thirst, urination/defecation, demeanour
  • current meds
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3
Q

Hx - ophthalmic

A
  • previous ocular problems?
  • unilateral or bilateral?
  • duration and progression of signs

Presenting complaint
- ocular pain: blepharospasm, increased tearing
- change in appearance: e.g. redness, discharge, swelling
- decreased vision: day vs night, any changes in unfamiliar surroundings, 1 or both eyes?

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4
Q

Normal variations

A
  • coat, iris and fundus colour are related
  • heterochromia = different coloured eyes
  • brown eye = yellow/green fundus
  • blue eye = red fundus
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5
Q

Suggested ophthalmic exam/routine

A
  1. hands off
  2. hands on
  3. STT
  4. CN tests
  5. examine anterior segment with pen torch in dark
  6. ophthalmoscopy: distant direct, close direct, indirect
  7. further testing if required:
    - fluorescein staining
    - swabs or scrapes
    - tonometry
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6
Q

Hands-off exam - from a distance

A
  • behaviour: does the pt seem visual?
  • are the eyes painful? (eye(s) open or closed, discharge)
  • symmetry: of face and between eyes, looking from above is very useful to identify exophthalmos
  • eyelid conformation
  • size of palpebral fissure: narrowed can indicate ocular discomfort, macropalpebral fissure in the brachycephalic
  • position of 3rd eyelid
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7
Q

Hands-on exam

A
  • restraint: hand under chin, hand back of head
  • external anatomy
  • palpation
  • look under upper eyelid
  • examine anterior surface of 3rd eyelid
  • retropulsion
  • retropulse eye through upper lips and pull lower eyelid down to protrude 3rd eyelid
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8
Q

STT - when to do

A
  • any eye with discharge, conjunctivitis or lacklustre cornea
  • at start of exam (before drops applied)
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9
Q

STT - when not to do

A
  • deep ulcer/risk of perforation
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10
Q

STT - what does it do?

A
  • measure aqueous part of tear film
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11
Q

STT - how to do

A
  • position in middle to lateral 3rd of eye
  • contacting cornea not 3rd eyelid (measures basal and reflex tear production)
  • eyelids open or closed
  • 1 minute: take out and record reading
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12
Q

STT - reference ranges

A

Dogs
15-25mm/min = normal
10-15mm/min = borderline (diagnostic of KCS if CS support)
<10mm/min = underproduction = KCS
>25mm/min = suggests overproduction i.e. ocular irritation

Cats
- readings variable (normal range 0-30, stress may lower

Both eyes should be similar

Beware pain can falsely elevate e.g. pain from corneal ulcer

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13
Q

Ocular reflexes

A
  • palpebral reflex
  • menace response (most reliable test of vision)
  • dazzle reflex
  • pupillary light reflexes
  • vestibule-ocular reflex
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14
Q

What is the vestibule-ocular reflex?

A
  • moving head from side to side to check for normal nystagmus
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15
Q

At what age will pups/kittens get a menace response?

A
  • 12-14w
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16
Q

Problems with PLR

A

False negatives common
- weak light source in daylight, not strong enough to elicit PLR
- scared/stressed animal -> high level sympathetic tone -> eyes stay glazed / pupil stays open
- iris atrophy (age-related iris constrictor muscle atrophy)

Positive result not always consistent with vision

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17
Q

Cranial nerve testing i.e. what test tests which CNs?

A

Palpebral
- afferent pathway = trigeminal nerve V
- efferent pathway = facial nerve VII
- perform before menace to check eye can blink

Menace
- afferent pathway = optic nerve II
- efferent pathway = facial nerve VII
- learned response (12-14w in puppies)
- involves visual cortex

Dazzle
- afferent pathway = optic nerve II
- efferent pathway = facial nerve VII
- subcortical reflex

PLR
- afferent pathway = optic nerve II
- efferent pathway = oculomotor nerve III (parasympathetic)
- false negative common
- positive result ≠ vision

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18
Q

Afferent vs efferent

A

Afferent = carry SENSORY information from the body to the CNS

Efferent = carry MOTOR commands from the CNS to muscles & glands

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19
Q

Additional tests for vision

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A

Tracking
- following cotton wool ball
- something light that won’t make a sound and doesn’t smell

Maze test
- navigating obstacles

Visual placing
- approach table with pt
- should put feet out to stop bumping into it

20
Q

Additional test of corneal sensation

Study These Flashcards
A

Corneal reflex
- use if suspect disorder or blinking/trigeminal dysfunction
- STT will assess corneal sensation to some extent
- stimulus: wisp of cotton wool or cotton bud gently touched to lateral cornea, outside line of vision (sensation: V)
- normal response: globe retraction (VI) & blink (VII)

21
Q

How to examine the anterior segment

Study These Flashcards
A

Focal light source (e.g. pen torch) in the dark ± magnification if available
Be systematic e.g. examine from outside to inside and superficial to deep
- eyelashes, nasolacrimal puncta
- 3rd eyelid
- conjunctiva, sclera, limbus
- cornea
- anterior chamber
- iris & pupil

22
Q

Conjunctival vs episcleral vessel congestion

Study These Flashcards
A

Conjunctival
- lots of small vessels
- generalised redness

Episcleral vessels
- bigger vessels
- deeper red colour
- don’t quite reach the edge of eye
- don’t branch as much as conjunctival

23
Q

What does the Purkinje image tell you?

Study These Flashcards
A
  • information on tear film and surface contour
  • if distorted indicates non-smooth cornea
24
Q

Types of ophthalmoscopy

Study These Flashcards
A
  • distant direct
  • close direct
  • indirect
25
Ophthalmoscopy: distant direct - settings, use
- 0 diopter setting, arm's length - uses tapetal reflex to highlight visual axis - compare pupil size - opacities in visual axis - nucelar sclerosis vs cataract -- cataracts block the tapetal reflex, nuclear sclerosis doesn't
26
Ophthalmoscopy: close direct - settings, use
- 0 diptres, lower the rheostat, use brow rest, get close to pt (2-3cm) - dilate pupil with tropicamide if needed - key-hole effect: -- small, highly magnified field of view -- hard to examine whole fundus - 0D for retina - +10D for lens - +20D for eyelids & cornea
27
Indirect ophthalmoscopy - options
- monocular indirect ophthalmoscopy - binocular indirect ophthalmoscopy
28
Monocular indirect ophthalmoscopy - equipment
- 20-30dioptre or 2.2 panretinal condensing lens - pen torch or Finhoff transilluminator
29
Indirect ophthalmoscopy - method
- aim: line up eye, light source, condensing lens and animals eye - hold pen torch at side of temple in line with eye - move to pick up tapetal reflex - place the condensing lens with most curved side towards you, 2-4cm in front of the eye - dilate pupil to make it easier
30
Indirect vs direct ophthalmoscopy
Indirect - upside-down, back-to-front, wider field of view - perform 1st for general overview Direct - narrow 'key-hole' field of view - perform 2nd to look at any lesions in more detail
31
Fluorescein staining - what is it? use?
- orange dye that turns green in alkaline conditions - stains corneal stroma green - no uptake by intact corneal epithelium or by Descemet's membrane - indicated for majority of ophthalmic presentations - do towards end of exam - ulcer assessment and Jones test for nasolacrimal potency - touch onto bulbar conjunctiva (white of eye) - always flush: water, saline or false tears
32
Johnes test
- fluorescein should appear at both nostrils within 3-5mins of fluorescein application to the eyes - indicates functional nasolacrimal ducts
33
Swabs and scrapes - use
Corneal cytology/bacteriology - suspected infected/melting ulcers - suspected neoplasia Conjunctival microbiology: sterile swabs - cats with ocular surface dz -- chlamyophila felis -- feine herpes virus -> PCR tests -> swab in dry, sterile tube - suspected bacterial infection -> place swab in charcoal medium
34
Tonometry - use
- measurement of intraocular pressure (IOP)
35
Tonometry - when to do
- at end of exam but before dilating pupil - essential if: reduced vision, red eye, blue eye (corneal oedema), dilated pupil, buphthalmic globe, exophthalmos, suspected lens luxation
36
Tonometry - normal IOP values
10-25mmHg in the dog and cat 15-20mmHg in the rabbit
37
Tonometry - changes in IOP and what they indicate
Raised IOP -> suspect glaucoma Lowered IOP -> suspect uveitis Difference of >8mmHg between eyes is abnormal
38
Tonometry - pt restraint
- care when prising eyelids open - care with pressure around neck
39
Indentation tonometry: Schiotz
- inexpensive (£140 approx) - cumbersome to use, needs practice, but better than not measuring IOP - LA drops applied 1st - requires conversion table to work out IOP
40
Applanation tonometry: TonoPen
- v accurate - expensive (£2500 approx) - LA drops applied 1st - disposable latex tip - instrument can be used at any angle - tap surface of eye with it
41
Rebound tonometry: Tonovet
- v accurate - expensive (similar to TonoPen) - probs easier to use than TonoPen - LA drops not required - disposable metal probe with plastic tip - must be held in horizontal position
42
Specialist ophthalmic diagnostic tests
- slit lamp - ERG - gonioscopy - advanced imaging
43
Slit lamp biomicrosopy
- v good illumination and magnification - slit beam of light helps to e.g. judge depth and localise lesions - great at looking at anterior segment
44
Goniosopy
- assessment of iridocorneal drainage angle (angle between iris and cornea -> used to diagnose goniodysgenesis (primary glaucoma) - requires slit lamp, specialised goniolens and expertise Goniodysgenesis = reduced angle, reduced draining within the eye
45
Electroretinography (ERG)
- to assess retinal function - eye equivalent of ECG - corneal electrode = contact lens - skin electrodes, light source

Y4 SA - Ophthalmology (7 decks)

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