Ocular Exam Tech/DX

Question 1

General concepts for exams

Answer 1

Examine at room lighting - palpate, retropulse globes
Examine under focal lighting - dim/darker conditions

Question 2

Anterior segment exam tools

Answer 2

Trans Illuminator
Magnification
- head loupe
- direct ophthalmoscope - setting depends on goal
- otoscope w/out cone: 2-3x mag

Question 3

Transilluminator use

Answer 3

Oblique illumination - apply at various angles NOT directly into the eye
Can highlight subtle corneal opacities, depth, contours of ocular structures

Question 4

Coaxial illumination

Answer 4

Light aligned w observers line of sight, can highlight obstructing opacities in eye - set at 0 diopters
Work at arms length from patient

Question 5

Difference between coaxial and oblique illumination

Answer 5

Co axial - light and line of sight are on the same axis
Oblique - any angle that’s not oblique, are on separate axis

Question 6

Nuclear sclerosis vs cataract

Answer 6

Cataracts obstruct light - depends on degree
Nuclear sclerosis does not

Question 7

Magnified ocular surface exam

Answer 7

Set diopter setting at 15 – 20D
• Move in towards area, like hand until lesion comes into focus
• Limitation is small surface area that can be visualized in
this manner - not great screening tool

Question 8

Fundus exam

Answer 8

Determining cause of vision loss
- retinal degeneration
- retinal detachment
- optic nerve disease

Question 9

Fundus exam - systemic disease

Answer 9

Can see affects on retina
- hypertension
- infectious disease
- neoplasia

Question 10

Challenges of ocular exam

Answer 10

Takes time for developed technique
Wide variation within species and individuals
Requirement for pupillary dilation in learning stages
Tools and knowing how to use them

Question 11

Direct vs indirect techniques

Answer 11

Direct - easy exam
Indirect - difficult exam but best screening field, image is upside down

Question 12

Direct ophthalmoscope fundic exam

Answer 12

Set lens to 0, set focus on retina, adjust diopter focus as needed. Stay 2-3cm away from cornea
Use same side eye to examine the same eye - R/R, L/L
Easiest to perform with dilated eye

Question 13

Image from direct ophthalmoscope

Answer 13

Highly magnified - Best opportunity for fine detail
– Significant magnification is usually unnecessary
• Difficult to evaluate entirety of fundus
– Especially the peripheral fundus
• Hard to isolate/localize lesions due to eye movements
Real image
• Image is in anatomical orientation
• Example: Direct gaze downwards to find lesion in lower retina

Question 14

Indirect ophthalmoscope tools

Answer 14

Monocular indirect ophthalmoscopy
Employs handheld light source
Finoff transilluminator held adjacent to observers eye
Direct ophthalmoscope (look through at 0 Diopters)

Question 15

Binocular indirect ophthalmoscope

Answer 15

Employs specialized headset
– Allows for stereoscopic image (better depth perception and evaluation of raised or depressed lesions)
– Frees both hands for manipulating lens and patient

Question 16

Basic indirect technique

Answer 16

Use low level of illumination
1. Obtain tapetal reflection
2. Position indirect lens into path of light in front of patient’s eye to obtain fundic image
Lens distance from cornea depends on lens strength
- move towards /away form eye until fundus imagine fills entire lens. If iris or eyelids enters view = incorrect distance

Question 17

Indirect image

Answer 17

Wide field of view - virtual imagine = upside down & reverse
Tapetum is dorsal but appears ventral in image
To track lesion that appears dorsal lateral in image, adjust to look ventral/medial = opposite direction

Question 18

Rules for indirect ophthalmoscope

Answer 18

Always work at arms distance from patient
• Direct light beam in line (coaxial) with your eye - With monocular technique, hold light source beside your eye
• Hold lens perpendicular to light beam - Must maintain this when looking at different areas of retina
• Hold lens at proper distance from patient’s eye - Distance varies by lens diopter strength. Maintain hand contact with patient for stability of lens position

Question 19

Indirect lens alignement

Answer 19

Lens should be help perpendicular to light beam - maintain this alignment when looking at different areas of retina

Question 20

Indirect lens power

Answer 20

Field of view and magnification are inversely correlated
As mag goes up the field of view gets smaller
As mag goes down the field of view gets bigger

Question 21

Tips for all forms of ophthalmoscopy

Answer 21

Retina is best viewed in a dark room
• Use lowest practical light intensity
• Appropriate restraint is very helpful
• Pharmacologic dilation whenever possible
– Use short acting agents such as 1% tropicamide
– Dilation is contraindicated if concerned about glaucoma /lens instability

Question 22

Ophthalmic diagnostics

Answer 22

Schirmer tear test
Tonometry
Fluorescein stain

Question 23

Schirmer tear test

Answer 23

Measures tear production • Insert in lower eyelid up to notch on strip (can pre-bend if desired)
• Leave in place 1 minute • Read immediately following
removal
- Measurements in mm/min
• Normal values vary by species

Question 24

Topical fluorescein stain

Answer 24

By directly touching pre-moistened fluorescein strip to
conjunctiva
– create fluorescein solution in syringe and apply drop to ocular surface
• Useful if applying frequently during course of day

Question 25

Use for topical fluorescein stain

Answer 25

Corneal ulcer detection** ulcer will highlight w stain
Evaluation nasolacrimal duct patency - dropper

Question 26

Fluorescein stain light

Answer 26

Fluoresces under cobalt blue light - increases sensitivity to detect stain uptake

Question 27

Tonometry

Answer 27

Measures Intraocular pressure
Measures in mmHg
Acceptable methods
- rebound (Tonovet)
- applanation (tonopet)
- indentation (schiotz)

Question 28

Practice tips for Tonometry

Answer 28

Topical anesthetic for TonoPen and Schiotz, not for TonoVet – Minimize animal stress
– NO PRESSURE ON GLOBE
– Minimize jugular pressure
– Always measure both eyes