Week 7 Module 2 (SSI)

What is included in the visual inspection of an eye exam

Examine for symmetry, discharge, redness or swelling, cloudiness

What is included in palpation on an eye exam

Examine for pain or masses

What are the 2 responses you assess with PLR?

Direct response and consensual response (of opposite eye)

What does a schirmer tear test examine

Tests for keratoconjunctivitis sicca (dry eye)

What does a fluorescein staining test examine

Assess for areas of ulceration or abrasions on the cornea

What does tonometry measure

Intraocular pressure for glaucoma screening

What does the fundic examination of eyes measure (using ophthalmoscope)

Disease of the lens, vitrous and ocular fundus

After dilating the pupils with tropicamide what can be observed on the fundic eye exam

Retina, optic nerve, blood vessels

What is the correct sequence for preforming a standard eye examination in a dog?

Visual → PLR → Schirmer tear test → Fluorescein stain → tonometry → fundic exam

What can cause conjunctivitis? (pink eye)

infections, allergies, irritants, ocular disease

Symptoms of conjunctivitis?

Redness, swelling, discharge, squinting, tearing

What causes cataracts

Age, DM, genetics

What are symptoms to cataracts

Cloudy bluish white appearance of eye, difficulty seeing/blindness

How do you treat cataracts?

Surgical removal of the lens

What causes glaucoma

Increased intraocular pressure from fluid build up

What are symptoms of glaucoma 

Pain, dilated pupils, redness, vision impaired, bulging eyes

What causes corneal ulcers?

Trauma, infections, dry eye

What are symptoms of corneal ulcers

Squinting, tearing, pain, redness

What causes retinal disease

Inherited (progressive retinal atrophy, SARDS), high BP, trauma, retinal detachment or infection

What are some symptoms of retinal disease

Progressive vision loss, night blindness, or complete blindness 

What are the basic instruments you need to preform an eye exam

Light source, opthalmoscope, indirect funduscopic lens, magnifying loups, fluroscein test strips, schirmer tear test, tonometer, tropicamide, proparacain, sterile eye wash

What will you use instead of atropine to dilate the eye for SHORT PEROIDS of time

Proparacaine

What are the 4 main diagnostic steps when evaluating the eyes

1- LOOK (hands off)

2- Maze test + detailed look (hands on light on)

3- Darkness and light source (hands on lights off)

4- Additional tests

What nerve does the PLR test? What about the dazzle reflex?

PLR- CN III

Dazzle- CN VIIVII

Why is if difficult to evaluate PLR reflex in horses/cows?

Eyes are on opposite side of the head

Horses- corporal nigra and rectangular pupil make it hard to see

What does the palpebral reflex test?

CN V (sensory for cornea and eyelids)

What is another area of the body that can cause pain to the eye that you should examine when doing an eye exam?

Open the mouth (check zygomatic gland)

What can you use for visual tracking tests

Dropping a cotton ball or using a laser pointer

What is the visual placing test

Hold them by a table and move them and see if they put their paw up

Which reflex is characterized by the involuntary blinking of the eyelids when a sudden bright light is shone into the eyes?

Dazzle

Rudimentary assessment of vision manifested by blinking

Menace response

What could an absent menace response suggest

Intracellular-ocular lesion, damage visual neural pathway, CN VII dysfunction, reduced mentation

How long can it take the menace response to develop

2-3 weeks of age

What does the dazzle reflex help differentiate

Cortical blindness from disease of eye, optic nerve, optic tract

When should the palpebral and corneal responses be tested

Before sedation or regional anesthesia

What assesses the integrity of the retina, subcortical visual pathways, efferent parasympathetic function of CN III and the iris constrictor muscle?

PLR

When should the PLR be assessed?

Before sedation or use of mydriatics 

In which animal is the consensual PLR weak

Horses (eyes on opposite sides)

Does an intact PLR indicate vision?

NO (because the reflex is subcortical)

Which animal has the most variation in intraocular pressure using the tono device

Horses

What for the schirmer tear test are normal values for a dog and relaxed cat

15< each eye

What is assessed after pharmacologic mydriasis is preformed 

Ophthalmoscopy and slit lamp 

What can be flushed to evaluate external parts of the eye

Naso-lacrimal tear duct (Jones test)

What test is used for eye perforations and will use lots of fluorescein stain which will show a whorl pool in the vitreous humor if there is a deep perforation 

Seidel test

Which tonometers have replaced the older indentation tonometer

Applanation or rebound (topical anesthetic may be used depending on which device)

A swab may be used to obtain what

Sample for culture

What should be used with an ophthalmoscope to fully evaluate the eye

Dilation with tropicamide

What do you see with the direct opthalmoscope

Larger image but smaller field of vision (have to move it to see more)

What do you see with indirect ophthalmoscope

Smaller image with larger field of vision (the image will be inverted)

If you get more reflexion with the ophthalmoscope lens what does that mean

Retina is thinner from PRA (progressive retinal atrophy)

What evaluates retinal ganglion cells and their axons?

Electroretinography (ERG) and visual evoked potentials (eyes equivalent to ECG)

When is ERG used in horses

Assess night blindness when all other signs are normal 

Which test is preformed first to assess central vision in animals? Which is preformed secondary?

Menace response test (Primary)

Tracking response test (secondary)

What is used for measurement and visualization of iridocorneal angle (the drainage angle)

Gonioscopy

What will you see with gonioscopy on a patient with glaucoma?

Trabecular meshwork of aqueous humor is narrowed or absent 

How should you preform direct ophthalmoscopy of the horse

Take horse to darkest corner of the stable

What nerve blocks can be preformed to facilitate an ophthalmologist exam?

Auriculopalpebral (VII), supraorbital (V)

What is a type of stain used to assess superficial conjunctiva or corneal tissue change in horses and other large animals?

Rose bengal staining (and fluorescein)?

What word describes enlargement of the globe

Buphthalmos

What is a common eye issue in horses and how is it checked

Blocked tear duct (fluorescein at nares for patency)

What is recommended interval diagnostic approach for all cases of red or painful eyes in horses

Stain eyes with fluorescein (rose bengal in large animal after fluorescein)

What can corneal ulcers in horses rapidly progress to

Eye rupture (desometocele)

Do you use corticosteroid to treat corneal ulcers?

NO

What is true about uveitis caused by a corneal ulcer or stromal abscess in horses

Difficult to control

Condition where a corneal ulcer erodes down to the very last layer of the cornea (descemet’s membrane) creating risk of eye rupture and vision loss

Descemetocele

Normal sized eyes pushed out of the orbit by space occupying lesions

Exophthalmic

What is important to evaluate with an eye exam of production animals

Behavior alone vs with the herd

Which eye condition in animals is primarily caused by increased intraocular pressure leading to vision loss?

Glaucoma (caused by fluid buildup)

Inflammation of the cornea and anterior part of the eye which covers the pupil?

Keratitis

What are the grades of corneal ulcers

Superficial, stromal, descemet’s (deep)

Which diagnostic method is commonly used to confirmed a corneal ulcer

Fluorescein

An inherited or breed-predisposed condition in dogs, non-inflammatory, progressive deterioration in function and structure of the cornea leading to formation of white, opaque spots on cornea which are results of mineral deposits (triglycerides, cholesterol, and Ca2+).

Corneal dystrophy

What can continuous sloughing of the mineral deposits in the cornea lead to?

Ulcers, scarring, ocular infections, neo-vascularization

What are superficial nonhealing ulcers in dogs called

Indolent corneal ulcers or recurrent corneal ulcers

Corneal condition in older dogs which the corneal becomes water-logged and swollen. This may be bilateral/unilateral and have some vascularization. It can be painful if ulcers develop and is secondary to ocular disease or systemic conditions. Deposits of triglycerides, cholesterol, and Ca2+ may be present.

Corneal degeneration

What are the 2 pathways the aqueous humor can exit the eye

1- MOSTLY drain through trabecular meshwork and iridocorneal angle of anterior chamber (venous return)

2- SOME drain through uveoscleral outflow pathway (drain through ciliary body into sub-sclera space)

What can increased pressure in glaucoma cause

Destruction retina and optic disc

What types of glaucoma occurs in dogs

Primary (inherited) and secondary

What type of glaucoma occurs in cats

Secondary to anterior uveitis and neoplasia

Type of glaucoma which is a painless and gradual development of blind spots or loss of vision over a long period of time

Open-angle

Type of glaucoma which is a sudden increase in eye pressure with severe pain, redness, and loss of vision

Closed-angle

What is the normal values of IOP in dogs vs cats

Dogs- 15-25mmHg

Cats- 18-24mmHg

Detects iridocorneal and sclerociliary cleft opening outflow changes

Gonioscopy

What are some clinical signs of glaucoma

Increased IOP, pupils dilated or inactive, bulbar conjunctival venous congestion, episcleral injection, corneal edema

Is acute or chronic glaucoma more painful

Acute

What can be seen with chronic cases of glaucoma

Buphthalmus and corneal striae

What is the primary goal in glaucoma therapy

Preservation of vision and alleviate discomfort

What must you differentiate cataracts from

Nuclear sclerosis (light from slit lamp will go thru this but not cataracts eye)

Opacities of the lens or capsule

Cataracts

Normal increase in nuclear density in older animals

Nuclear sclerosis

Subluxated lenses are recognizable by what?

Aphakic crescent, iridodonesis (instability/trembling of iris), phacodonesis instability/trembling of the lens) 

How is lens opacity detected

Dilating pupil and examining the pupillary region against the retro illumination of the tapetal fundus

What is most cataracts caused by in cats and horses

Secondary to anterior uveal inflammation

In dogs what is usually the cause of cataracts

Inherited or acquired (DM)

What happens with DM and cataracts

DM → hyperglycemia → intralenticular sorbitol accumulation → increase osmotic forces of lens → fiber swelling, rupture and lens opacity 

Aqueous tear film deficiency usually bilateral and idiopathic and results in persistent conjunctivitis, mucopurulent discharge, superficial corneal vascularization, superficial corneal pigmentation, fibrosis and sometimes corneal ulcerization

Quantitative KCS

What is KCS associated with in dogs

Autoimmune dacryoadenitis and destruction of both the

What is KCS associated with in cats

feline herpesvirus (less common in cats than dogs) 

What is used to treat KCS

Lacrimogenic solutions (cyclosporin) or parotid ducts transplant

When the lipid or mucus layer of tear film is abnormal

Qualitative KCS