Ophthalmic Exam Flashcards
What are the components to an ocular exam?
- History
- Diagnostic tests
- Neuro-ophthalmic examination
- Dilation with mydriacyl
- Distant examination
- Orbital, adnexal, ocular and fundic examination
What is most important components of the ophthalmic history?
- Presenting complaint
- Duration
- Current/past eye medications: response to medication
- Ocular pain
- Vision loss: worse in day or night? Progressive?
What diagnostic tests should EVERY ophthalmic exam include?
- Schirmer tear test
- Tonometry
- Fluorescein stain
What are the 3 key points to every ophthalmic exam?
- Test and examine ALL animals on the table: need to behave and be still; held properly; you need to be eyelevel or lower
- Don’t skip a diagnostic test: dilate the eyes
- Always test and examine BOTH eyes!
What does the schirmer tear test measure?
- Measure tears: function of lacrimal and third eyelid gland
Describe the technique to use a schirmer tear test?
- Place in the conjunctival sac for 1 min
What are the normal values for dogs, cats and horses?
- Dogs: >10mm/min = normal; 10 mm/min = normal
What are the key points to the schirmer tear test?
- Do before any topical drops or irritation
- Don’t touch the body of the strips
- Read it right away
What does tonometry measure?
- Intraocular pressure
What are the 3 different devices used in tonometry?
- Tonovet: indentation - rebound
- Tonopen: applanation
- Schiotz: indentation
What are the normal values for tonometry in dogs, cats and horses?
- Dog and cat: 10-25 mmHg; 30 = glaucoma
- Horses: 15-35 mmHg; >35 = glaucoma
What are the key points to tonometry?
- Not holding the animal properly can falsely elevate pressures
o Keep the head up straight
o No pressure on the neck
o Avoid struggling with the animal
Why do we use fluorescein stain?
- To detect corneal epithelial defects
- Assess periocular tear film
- Test for nasolacrimal patency
Describe the technique of using fluorescein stain?
- Apply a drop to the conjunctiva and flush the excess with sterile saline
- Evaluate with a cobalt blue light
Why do ulcers fluoresce?
- The stain is absorbed by the corneal stroma if the epithelium is disrupted
How do you know if the nasolacrimal system is patent?
- If you see stain at the nares = patent
What are the key points when using fluorescein stain?
- Don’t store in a syringe with saline on the counter for repeated use: contamination
- Don’t touch the strip to the cornea: the cornea will absorb the stain
- Rinse well
- Do at the very end of the exam
What are the main reflexes tested for in the neuro-ophthalmic exam?
- Menace: CN II and CNVII (orbicularis oculi)
- Pupillary light reflex: CN II and CN III (iris constrictor muscle)
- Palpebral reflex: CN V and CNVII (orbicularis oculi)
- Occulocephalic reflex: CN II, VIII and III, IV and VI (extraocular muscles)
What are the key points to the menace response?
- Not reliable in young animals as it is a learned response
- Don’t be too close to the eye
- Make sure you are intimidating enough
What are the key points to the PLR?
- Use a transilliuminator
- Look for direct and consensual reflex
- Assess pupil symmetry
What are the key points for the palpebral reflex?
- Come from below the eyelid to prevent the animal from seeing your finger
What is the key point for occulocephalic reflex?
- Lift the forehead skin to see the sclera
Why do we need to dilate the eye? What do we use?
- Necessary for complete ophthalmic exam
- Lets you fully examine the lens and fundus
- Tropicamide: mydriasis in 20-30 mins and lasts for 4-6 hours
What are the contraindications to dilating the eye?
- Elevated Intraocular pressure
- For abnormal PLRs, anisocoria, and iridal lesions: make sure you examine the animal before the onset of dilation
