Clinical signs in ophthalmology Flashcards
Most eye diseases are in what area of the eye?
the “front”: conjunctiva, cornea, anterior chamber
FIP and ocular signs
The signs of feline infectious peritonitis vary depending on which organs are involved. Many organs, including the liver, kidneys, pancreas, CNS, and eyes, can be affected.
The initial clinical manifestation is unilateral or bilateral anterior uveitis manifested by change in iris color, cloudiness, and flocculant debris in the anterior chamber, keratic precipitates on the back side of the cornea, and anisocoria.
What disease causes pink eye in cattle?
keratoconjuntivitis, bo rhinotracheitis caused by bovine herpes virus
Equine pupil shape?
horizontal oval
Squinting/holding the eye shut/blinking excessively is called…?
Its due to…?
blepharospasm
Acute pain, irritation (inflammation)
How would you describe these eyes?
Red, irritated eyes so conjunctival hyperemia; severe edema/swelling is chemosis. Erythema can affect the eyelids.
* Causes: irritation, inflammation
Chemosis is the swelling (or edema) of the conjunctiva.
When horses “pull their eyes into the orbita” it is…
the equine version of blepharospasm.
Cats and dogs don’t pull their eyes back and in, but horses do.
Grey, brown, green/yellow ocular discharge can indicate
Inflammation, irritation
lacrimation, runny eyes aka epiphora
The causes of epiphora can be divided into groups: (4)
- Increased tear production e.g. reflex lacrimation indicating inflammation, mechanical irritation of eye (e.g. entropion, distichiasis etc.).
- Tear drainage disorder
- Anatomical imperfection of tear drainage pathways
- A combination of several factors can be present.
3 things a cloudy, grey cornea can be
Not diseases.
corneal edema
corneal scar
corneal dystrophy (benign)
corneal edema
corneal scar
Benign corneal dystrophy
– accumulation of calcium/cholesterol crystals in the corneal stroma (middle layer).
Can be due to genetic predisposition in certain breeds.
Cloudiness of the pupil area which can indicate cataracts.
Cataracts must be distinguished from normal age-related lens sclerosis aka nuclear sclerosis.
How to tell corneal edema from cataracts/sclerosis?
In cataracts/sclerosis, you can always see the border of the iris/pupil.
If its obscured then its more likely corneal edema.
Looking at the eye from various angles will help you too.
Top is cataract, bottom is corneal edema, note that the iris/pupillary margin is properly visible.
How to tell cataracts from nuclear sclerosis?
Ophthalmoscopy helps:
* In case of nuclear sclerosis (1), nothing interferes with observing the fundus, there are no spots on the lens.
- In case of cataract (2) – the fundus is not well visible, there are opaque areas in the lens.
If the lacrimal gland doesn’t produce sufficient tears…
the conjunctiva will try to compensate by producing too much mucus.
E.g. in KCS
Brown/black spots on the cornea can indicate? (3)
Most common in dogs, rare in horses and cats.
- Corneal pigmentation, melanoSIS of the cornea (NOT the same as melanoMA)
- Chronic irritation
- Chronic inflammation
In cats, it can be corneal sequestrum/necrosis.
Define limbus.
The limbus forms the border between the transparent cornea and opaque sclera, contains the pathways of aqueous humour outflow, and is the site of surgical incisions for cataract and glaucoma.
Melanocytes can migrate from limbus to near by sclera due to chronic inflammation (see pictures, brown pigment on sclera).
Causes of feline corneal sequestrum/necrosis. (4)
- Corneal irritation, usually chronic (like entropion)
- Feline Herpes Virus infection
- Iatrogenic drying of the cornea during general anesthesia
- Idiopathic
Often Persian and British short haired cats.
Often bilat, but at different times.
Which chamber has aqueous humor and which, virteous?
Anterior - aqueous
Posterior - vitreous
Cornea is cloudy + red = edema +
vascularisation and granulation
- Irritation
- Inflammation
- Part of healing process
What’s this and what can cause it? (8)
Protrusion of third eyelid.
Can be due to:
* Pain/light hypersensitivity
* Irritation, 1
* Inflammation, 1
- Third eyelid lacrimal gland prolapse (cherry eye) or eyelid eversion, 2
- Neurological problem (like Horner’s syndrome), 3
- Small eye (congenital), big orbita and large eyelid
fissure (macroblepharon), 4 - Neoplasia
- Idiopathic, Haw’s syndrome in cats (both protrude)
What is Haw’s syndrome?
Haw’s syndrome is a relatively common problem in cats. It is a condition where both third eyelids protrude (or prolapse). Protrusion of the third eyelids can occur for many reasons in cats.
When it has a sudden onset, and is associated with diarrhea or other gut conditions, it is called Haw’s syndrome.
Usually occurs in cats around a year old but older cats can also be affected.
3 main differentials for iris changes/spots
inflammation/uveitis
neoplasia (iris melanoma)
normal iris pigmentation (nevus)
Neoplasia – malignant diffuse iris melanoma
Neoplasia –malignant focal iris melanoma
Normal iris pigmentation
(nevus,freckle)
inflammation/uveitis
Bleeding/hemorrhage in anterior chamber is called?
Can be due to? (6)
hyphema
- trauma
- systemic hypertension
- blood clotting problem
- paraneoplastic syndrome
- uveitis
- glaucoma
Persistent pupillary membranes.
The one eye bigger than the other can indicate… (3)
- High intraocular presssure (glaucoma)
- Neoplasia
- +/-inflammation
Diagnosing eye problems should include: (6)
- Describe changes (swelling, what color spots, blood vessels, hyphema, blepharospasm etc.)
- Localize where exactly the changes are (conjunctiva, cornea, iris, etc.)
- What the changes mean (inflammation, irritation, pain etc.)
- Diagnosis at eye level (conjunctivitis, keratitis, corneal ulcer, uveitis, etc.)
- Think about animal species!
- Diagnosis at the causal level (viral conjunctivitis due to systemic herpesvirus, corneal ulcer due to foreign body or trauma, uveitis due to infectious feline peritonitis etc.)
define corneal and iris melanosis
Abnormal accumulation of pigmented (i.e. often brown) cells in the eye and can eventually block the drains that are responsible for removing fluid from the eye.
Ocular Melanosis is inherited.
inflammatory cells in the anterior chamber of the eye is termed…
hypopyon
vascular layer of the eye
uvea
uvea may be divded into (3)
iris, ciliary body, choroid
aqueous humor is produced in
the ciliary body (posterior chamber)
drainage of aqueous is through the
iridocorneal angle
The outer opening of the iridocorneal angle is spanned with the pectinate ligament.
Disturbed development of the ligament may narrow the angle, predisposing for glaucoma..
What keeps the lens in
its proper position
The zonula-zinni fibres extend from the ciliary body to the lens and keep the lens in its proper position.
The fibres are able to retract and relax, thus altering the shape of the lens (accommodation).
A severe blunt trauma against the eye, or in glaucoma
with enlargement of the globe may cause the fibres to rupture, resulting in displacement (subluxation or luxation) of the lens.
A primary defect in the fibres may also be present; this condition is inherited in some dog breeds (the terrier breeds, Tibetan terrier and border collie). (Primary Lens Luxation (PLL).)
Contraction and relaxation of the pupil are dependent on?
the M.sphincter pupillae which is innervated
by the III cranial nerve (N.oculomotorius)
and M.dilator pupillae innervated by the sympathetic nerve.
The retinal pigment epithelium (RPE) is the outer layer of the retina. The RPE cells lack pigment in the tapetal area.
Animals with an albinotic fundus (back of the eye), for instance blue merle-colored dogs, often lack pigment in the whole RPE. The RPE may also be poorly pigmented in color-diluted dogs, making the choroid vessels visible.
The RPE is necessary for
normal photoreceptor function.
Vitamin A is stored here.
eye disease PRA
In the disease Progressive Retinal Atrophy (PRA) the rods initially undergo degeneration. Reduced vision in dim light together with diminished side vision (tunnel
vision) is therefore the initial clinical signs of the disease. Rods are mostly situated in the
periphery of the retina.
most common in middle aged to older dogs.
FIP can cause what eye disease?
severe otitis can affect the eyes, how?
what can lymphoma do to the eyes?
uveitis
can cause Horner’s
also uveitis
