What makes up the eye?
• Adnexa (lids), Precorneal Tear Film, Cornea, Anterior chamber, Iris, Lens, Vitreous, Fundus
• Protect the eye
• Provide part of and spreads the tear film
• Regulate the amount of light that enters the eye
• Clear foreign material
• Protects the cornea by removing foreign material
• Contains the gland of the third eyelid
• Helps to spread the tear film
• Only moves passively in the dog
• Can move actively in the cat
• Outer lipid layer created by the meibomian glands
• Middle aqueous layer created by the lacrimal gland (65%) and gland of third eyelid (35%)
• Inner mucin layer created by the coblet cells of conjunctiva
• Palpebral
• Bulbar
• Third eyelid
• More than just a windshield!
• Accounts for 70% of the focusing power of the dog and cat
• Only 0.5 mm thick
• Layers: Epithelium, Stroma, Endothelium and Descetmet's membrane
• Fluid filled space between the cornea and iris
• Can fill with pus, blood, fat, protein, cells, or tumor
• Produced by glands in the ciliary body
• Provides nutrition and oxygen to the lens and cornea
• Provides the fluid support for the eye (IOP)
• "color" of the eye
• The color in dogs is simply different amounts of pigment cells-not different pigments
• Empty space in the center of iris
• Can be different shapes
• Controls amount of light entering the eye
• Shape: Dog – circle, Cat - vertical oval, Horse - horizontal oval
• Behind the iris
• 30% of focus power in the eye
• Lens is where cataracts occur
• The lens is anchored by the zonules that extend to the lens from the ciliary body
• Zonules pull on lens to change its shape in accomodation
• Jello-like material that fills the back of the eye
• Holds the retina in place against the back of the eye
• The "film" in the eye
• 10 cell layers that transmit images to the optic nerve and then to the brain
• Dogs and cats have a tapetum
• No tapetum: Human and pigs
• Tapetum Fibrosum: Horses and cows
• Tapetum Cellulosum: Dogs and cats
• What does your doctor need to know?
• Signalment, Age, Breed, Sex, Weight, Indoor/outdoor, Other health issues, Known trauma, Other meds
• Glaucoma in Cockers, Bassets
• KCS in Cockers, Bulldogs, Pugs, Lhasas, Shih Tzu
• Retinal degeneration in Poodles, Labs
• Indolent corneal ulcerations in Boxers, Retrievers
• What did you notice first? How long has the problem been going on? What treatment have you been giving if any? When did the treatment start?
• Color? Character? Constant?
• Squinting, Rubbing, Lethargic
• Color of the eye: Red, Green/orange, Cloudy/white
• How well can they see? Is the vision different in dark vs. light? Are they bumping into things? If loss: sudden or gradual? Any other systemic problems?
• Quiet dark room, Comfortable exam space, Stool or chair, You the technician!
• Gather equipment and proceed to a low lit area
• Bright light source
• Schirmer tear strips
• Fluorescein stain
• Proparacaine
• Tono-Pen/Tono-Vet
• Head loops
• Direct ophthalmoscope or lens
3 Rules in Order of Testing
• Schirmer tear test is ALWAYS first!!!!!!
• Don't do ANY other tests before STT!!
• Don't forget the STT at the beginning!!!!
• 1 minute
• Insert notch between the lower eyelid and cornea
• Performing: Do not touch the notched end with your fingers. If you like to fold them, do it PRIOR to removing from the plastic package. Always perform test on BOTH eyes.
Dog
• 15-25 mm = normal
• 10-15 mm = suspect
• <10 mm = too dry
• Ask your doctor if culture is a possibility, Acquire prior to putting any drops in the eye
• Can culture: Cornea, Discharge, Lower conjunctival fornix
• Stains exposed stroma
• Will not stain the intact corneal epithelium
• Stains "sick" epithelial cells, Shows unhealthy tear film, Pathognomonic staining of Herpes virus "dendritic ulcers"
• Wash eye well first, Sample the site affected
• Tonopen: Applanation tonometry
• TonoVet: Rebound Tonometer
• Schiotz: Indentation tonometry
• Normal IOP: 15-25mmHg
• Low= uveitis
• High= glaucoma
• Large field of view
• 3D picture with head loops
• How to : Transilluminator and lens, Hold lens close to the patient's eye, Hold transilluminator next to your eye
• Small view but very magnified
• Dogs and cats have more rods than cones. Their tapetum reflects light
• Minimum threshold for light: Cats- 6 times lower than humans, Dogs – somewhere in between
Surveys find a lack of support for midlevel practitioners in the veterinary industry
July 18th 2024Surveys conducted separately by Veterinary Management Groups and American Association of Veterinary State Boards support better utilization of credentialed technicians as the solution to workforce issues
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