Week1- Approach to the investigation and Diagnosis of eye disease Flashcards
What is the function of mydriatic drops?
Dilates the pupil
What is the function of nasalocrimal cannulae?
Used for flushing
Name 5 bits of equipment that could be used in an opthamology exam
Direct opthalmoscope
Finhoff transilluminator
Converging lens
Tonovet/ Tonopen
Name 5 consumables you might use in an opthalmic exam
- Schirmer tear test
- Mydriatics
- Nasolacrimal duct cannula
- Topical anaesthetic
- Opthalmic dyes
What is a goniolens?
Used to view drainage areas (iridocorneal angle)
any abnormalities that lead to glaucoma
What is a binocular opthalmoscope used for?
Allows you to look at both eyes
What is the palpebral fissure?
The space between the upper and lower eyelids
What might you do during an external eye assesment
Gentle palpation of periorbital strcutures and bony orbit
* assess eyelids, conjunctiva and third eyelid
* note ocular discharge
assess the cornea and tear film
What is the purkinjie reflex?
Refers to the light that is usually reflected off the eyes optical structures
What is the schirmer tear test 1?
- Place the tear test strip in the fornix for 60 seconds
measures reflex production of the aqueous component of the tear film
What are the indications of the schirmer tear test 1 in dogs?
- Less than 5 = KCS
5-10= suspicious if combined with clinical signs
What are the indications of the schirmer tear test 1 in cats?
Variable, low readings must be interpreted with clinical signs
What is Schirmer tear test 2 measured with?
usually measured with local anaesthesia applied- goes on to measure the basal tear production
animal cant feel so there is no additional tear production
What eye disease are cats usually prone to?
Melanoma
What is the function of tonometry?
Measures the intraocular pressure of the eye
What is the function of a tonopen?
- local anaesthetic is needed
applanation tonometry measures the force required to flatten an area of the cornea
What is a tonovet?
Rebound tonometry measures the time for a small probe to propel and contact the cornea before rebounding to the instrument
What is a schiotz tonometer?
Indentation tonometry measures the amount of corneal indentation produced by a given weight
Why should you not put mydriatics in if the animal has glaucoma?
Pupil dilation decreases the drainage angle
How much pupil dilation is required to complete an opthalmic examination?
Tropicamide 1%
(wait 20 minutes)
What is lens luxation?
When the lens becomes dislocated from its original position
What is the difference between indirect and direct opthalmoscopy?
Direct Ophthalmoscopy is best for detailed central retina examination, especially in clinics where quick checks are needed.
Indirect Ophthalmoscopy is superior for viewing the peripheral retina, detecting retinal detachments, hemorrhages, or tumors.
Indirect ophthalmoscopy is commonly performed with a head-mounted binocular device or a handheld lens.
How would you do a corneoconjunctival culture?
- Roll a sterile swab on the corneal lesion or lower conjunctival sac
- place in the correct transport medium
How would you do a corneoconjunctival cytology?
- Remove excess mucus before sampling
- Gently scrape conjunctiva with the blunt end of the scalpel blade or cytobrush
- If concerns over a corneal lesion, use a mini-tip swab
What is fluorescein dye most commonly used for?
- Used to detect corneal ulceration
- attaches to the exposed stroma as it is hydrophillic
- Lipophobic so will not adhere to the corneal or conjunctival epithelium
- Fluoresces more clearly using cobalt blue filter on direct opthalmoscope
Name 4 **other ** uses of fluorescein
- Detect conjunctival epithelial defects
- To detect aqueous fluid leakage
- Qualitatively test the tear film
- assess nasalocrimal drainage
What is rose bengal usually used for?
- Used to diagnose tear film disorders
Useful for certain types of ulceration that dont stain as clearly with fluorescein - hepatic keratitis
- Punctate keratitis
- Preocular tear film disorders
How would you perform a nasalocrimal flush?
- Cannulate the upper punctum and slowly irrigate with 3-5ml sterile saline
- confirm patency of puncta and caniculi with fluid exiting from the lower punctum
- Occlude the lower puncta and confirm patency of the nasalocrimal duct with fluid exiting from the ipsilateral nostril
cats may need sedation due to having small puncta
What are the indications for ocular imaging?
- eyelid or periocular swelling
opacity of cornea, anterior chamber, lens or vitreous
suspected trauma or foreign body
What are the indications for orbital imaging?
- Exopthalmos
- Strabismus
- Suspected trauma or foreign body
Periorbital disease
Facial swelling or distortion
