The ophthalmic examination

• Hands-off examination - from a distance

  Behaviour - does the patient seem visual

  Are the eyes painful? Blephorospasm, discharge

  Symmetry - of face and between eyes.

  Eyelid conformation

  Size f palpebral fissure

  Position of third eyelid.
• Hands on examination

  External anatomy

  Palpation

  Look under upper eyelid.

  Examine anterior surface of the third eyelid.

  Retropulsion (when the globe sinks back into the socket).
• What are the indications to do a Schirmer tear test?

  Any eye with discharge.

  Conjunctivitis.

  Lacklustre cornea.
• When do you not do a Schirmer tear test?

  Deep ulcer with a risk of perforation.
• How do you do a Schirmer tear test?

  Measure aqueous part of the tear film.

  Position in middle to lateral throw of the eye.

  • Contacting cornea not throw eyelid - measure basal and reflex tear production.

  Eyelids open or closed.
• What are the references ranges for a Schirmer tear test?

  15-25mm/min - normal

  10-15mm/min - Borderline (diagnostic of KCS if clinical signs support)

  <10mm/min - underproduction: KCS

  >25mm/min - suggests overproduction i.e. ocular irritation.
• What are the ocular reflexes?

  Palpebral reflex.

  Menace response - most responsible test of vision.

  Dazzle reflex - need a bright light.

  Pupillary light reflexes - need a bright light source.

  Vestibulo-ocular reflex - when moving the head side to side to see if it has a normal nystagmus.
• What are the problems with PLR?

  False negatives common:

  • Weak light source in daylight
  • Not strong enough to elicit PLR.
  • Scared/stressed animal
  • High level sympathetic tone
  • Iris atrophy:
  • Age-related iris constrictor muscle atrophy.

  Positive result is not always consistent with vision.
• Examine the anterior segment with focal light source in the dark

  Pen torch or similar in dark room +/- magnification if available.

  Be systemic - e.g. examine from outside to inside and superficial to deep.

  • Eyelids - eyelashes, nasolacrimal
  • Third eyelid
  • Conjunctiva, sclera, limbus.
  • Cornea
  • Anterior chamber
  • Iris and pupil.
• How do you tell the difference between conjunctiva and episclera vessels?

  Conjunctival vessels are thinner, epislcera vessels are thicker and indicate high pressure in the eye, very important clinical sign.

  
• Ophthalmoscopy - distant direct

  Essential one of the most useful parts of the exam.

  0 dioptre setting, arm’s length.

  Uses tapetal reflex to highlight visual axis.

  Compare pupil size.

  Opacities in visual axis - nuclear sclerosis vs cataracts.
• What does this picture show?

  Mature cataract in right eye, no cataract in left eye.

  
• What does this picture show?

  Immature cataracts in both eyes.

  
• What does this image show?

  Anisocoria due to reflex uveitis in right eye.

  
• What does this image show?

  Dyscoric pupil due to suspected neoplasia in the right eye.

  
• Close direct ophthalmoscopy

  0 diopters, lower the rheostat, use brow rest, get close to the patient.

  Dilate pupil with tropicamide if needed.

  Key hole field:

  • Small, highly magnified field of view
  • Hard to examine whole fundus.
• Fluorescein staining

  Orange die that turns green in alkaline conditions.

  Stains the corneal stroma green, but does not stain the corneal epithelium or by Descemet’s membrane.

  Always flush after (with saline or water) - to wash out the excess dye otherwise can give false positives.
• Fluorescein has been applied to both eyes five minutes earlier, how would you interpret this Jones test?

  1 Both nasolacrimal ducts are functioning.

  2 Neither nasolacrimal duct is functioning.

  3 The right nasolacrimal duct is functioning ok but the left is not.

  4 The left nasolacrimal duct is functioning ok but the right is not.

  3

  
• Swabs and scrapes from the eye

  Corneal cytology/bacteriology:

  • Suspected infected/ melting ulcers.
  • Suspected neoplasia.

  Conjunctival microbiology: sterile swabs

  • Cats with ocular surface disease
  • Chlamydophila felis
  • Feline herpesvirus-1
  • PCR tests -> swab in dry, sterile tube.
  • Suspected bacterial infection -> place swab in charcoal medium.
• Tonometry

  Measurement of intraocular pressure (IOP)

  Normal IOP values:

  • 10-25mmHg in the dog and cat
  • 15-20mmHg in the rabbit.

  Raised IOP -> suspected glaucoma

  Lowered IOP -> suspect uveitis
• A dog is presented with a painful left eye. The IOPs are 20mmHg in the right eye and 45mmHg in the left eye, what is the most likely diagnosis?

  1 Glaucoma

  2 Optic neuritis

  3 Reflex uveitis

  4 Systemic hypertension

  1
• Electroretinography (ERG)


  To assess retinal function.

  Eye equivalent of an ECG.

  Corneal electrode = contact lens.

  Skin electrodes, light source.
• What is SRMA?

  Sternum responsive meningitis.

  Build up of CSF and expansion of the central canal, associated with pain, unlikely to present with pain and paraesis
• What is wobbler syndrome?

  Cervical lesion that makes animals ataxic in the fore and hind limbs, characteristic gait, front legs are a short choppy gait, back legs are long striding gait. Caudal cervical spondilomyelopathy, could be a ventral, lateral, medial or dorsal compression. Will present with a chronic progressive problem. WIll only get an acute presentation with an extrusion.