Week 7 Lesson 50: Eye Examination

What are the 4 tests of an ophthalmic examination?

1. Hands off

2. Hands on, lights on

3. Hands on, lights off

4. Additional tests

What does the first step of the ophthalmic examination, hands off, mean?

LOOKing for conformation, discharge, discomfort/pain, blink rate, blepharospasms, photophobia

What does the second step of the ophthalmic examination, hands on, light on, mean?

Maze test

Detailed “Look” at palpation, retropulsion, corneal reflectivity and several reflexes

What does the third step of a ophthalmic examination, hands on, lights off mean?

Darness and light source to test ref

What are some tests that are used for vision testing?

• Menace responce

• Visual tracking (Cotten wool drop, laster pointer)

• Visual placing (maze test/obstacle course)

What test is a rudimentary assessment of vision manifested by blinking? If it’s absent, it may reflect an intra-ocular lesion, damage to visual neural pathways, facial nerve dysfunction, reduced mentation, or immaturity.

Menace response

At what does the menace response fully develop?

2-3 weeks

What test results in retraction of the globe and blinking on response to a bright light. The response of subcortical and may help to differentiate cortical blindness form disease of the eye, optic nerve or optic tract.

Dazzle reflex

What test assesses the integrity of the trigeminal nerve (Sensory), the facial nerve (motor), and neural connections in the brainstem? Assessed before sedation or regional anaesthesia.

Palpebral and corneal reflexes

What test assesses the integrity of the retina, subcortical visual pathways, efferent parasympathetic function of the oculomotor nerve and the iris constrictor muscle. Both the direct and consensual portion of this test should be assessed before sedation or use of mydriatics.

PLR

In what species is the consensial reflex is weak?

Horses

T/F: An intact PLR does not indicate vision because the reflex is subcortical.

True

What are the three basic ophthalmic test?

1. Schirmer tear test

2. Fluorescein

3. Tonometry

What are the four different types of ancillary diagnostic tests?

1. Mydriasis

2. Gonioscopy

3. Swabs, Scrapes, biopsy

4. ERG, Ultrasound, Scans

What test is performed to ensure that the eyes are producing enough tears to keep them moist?

Schirmer tear test

T/F: The STT should always be performed after any drops are placed on the eye or the eye is cleaned?

False

What test is touched to the upper fornix with a strip into each eye, which allows defects in the cornea to be spotted?

Fluorescein stain

What test is uses a tonometer to detect the pressure within the eye?

Intraocular pressure

What can be flushed to evaluate the external parts of the eye?

Nasolacrimal tear duct

What test is used for eye perforations?

Seidel test

What test is used for a naso-lacrymal flush to test the external parts of the eye?

Jones test

What are the two types of tonometers are used to estimate the IOP?

Applanation or rebound

Depending on the type fo tonometer used, prior instillation of what may be required?

Topical anesthetic

T/F: Tonometry should be performed before dilation of the pupil.

True

A swab may also be used to obtain a sample of bacteria or fungi for what?

Culture

What does the direct and indirect ophthalmoscopic examination evaluate?

lens, vitreous, and ocular fundus

When shoudl direct and indirect ophthalmoscopic examination be performed?

After inducing mydrisis with tropicamide because without dilation they cannot be fully evaulated

What is the drug that used to dilate eyes for direct and indirect ophthalmoscopy?

Tropicamide

What type of ophthalmoscopy is this?

Direct

What type of ophthalmoscopy is this?

Indirect

What structure is indicated by the yellow and blue arrows?

Tapetal fundus

What structure is indicated by the white arrows?

Non-tapetal fundus

What is a special methods of examination, may require sedation or local, regional or general anesthesia depending on the species?

SLB

Ultrasound

ECG

What test evaluates the retinal ganglion cells and their axons? it is used to assess night blindness in horses when all other signs are normal.

Electroretinography

What test is used for measurement and visualization of the iridocorneal angle and drainage angle?

Gonoioscopy

T/F: Examinations should start from inward to outward and from anterior to posterior.

False

What are the reasons for an eye exam in a horse?

Routine neonatal

PPE

Trauma

Ocular discharge

Change in shape/size

How do you perform a thorough ophthalmic exam on a horse?

In the dark by turning the horse to the darkest corner of the stable for direct opthalmoscopy

What two nerve blocks are used to faciliate an ophthalmogogic exam?

Auriculopalpebral and supraorbital

What are the topical anesthesia that is used in horses to facilitate an opthalmologic exam?

Proparacaine drops

What condition is common issue in horses and should be checked using fluorscein?

Blocked tear ducts

What stain is used in mostly in large animals?

Rose bengal staining

In equine patients all red or painful eyes much be stained with what stains?

Fluorescien and rose bengal dyes

What may rapidly progress to an eye rupture in horses?

Corneal ulcers

What are bad when the cornea retains fluorescein stain?

Topical corticosteroids

What can be caused by a corneal ulcer or stromal abscess may be very difficult to control?

Uveitis

What are things to look for in a far off exam of livestock?

• Is it uni or bi lateral

• Discharge

• Related to rest of body systems