Week 2 Flashcards
Routine eye examination includes
History and symptoms
Visual function and refraction
External eye examination
Internal eye examination
Investigations
Visual acuity
Contrast sensitivity
Colour vision
Pupil reaction
Distance vision
- Distance vision is measured at the start of the exam gives us the current level of vision of px
- Measured with the refractive correction on
- No refractive correction vision should be measured unaided
- To distinguish between ocular disease and refractive error use pinhole test
- Indication for pinhole test is when there is sudden, unilateral and recent onset of reduced vision
Near visual acuity
- Near VA is recorded using reading chart and N notation
- Good NA is N5
- Poor NA is N24
- Macular disease or posterior subcapsular cataract can disproportionally impair near VA
Contract sensitivity
- Used to find out how good is the patient as detecting contrast
- Polli robison chart used to measure contrast sensitivity
Measure monocularly and binocularly
Test distance of 1m
Keep reading until cant read any faint lines
Always encourage the patient to keep reading
Younger adults>1.80 Older adults >1.65 - Indication for contrast sensitivity is when px complaints of poor vision despite good va
- Troubled by sun glare
- Difficulty seeing at night
Contract sensitivity can be impaired after refractive surgery
Colour vision
- Acquired colour vision deficiency is caused by ocular diseases which effects one eye more than the other. It is important to test for this monocularly
- Age related cataract can cause yellowing of lens
- Red desaturation test indication for when symptoms of change on colour vision an when symptom of neurological disease
Control of pupil size
- Pupil size are controlled by the iris sphincter muscle and the iris dilator muscle based on the changes detected in light level
- Constriction (meiosis) and dilation (mydriasis) are controlled by the efferent and afferent neural pathway
Purpose of assessing pupils
Pupil assessment are carried out in order to investigate the integrity of neural pathway related to vision and eye function
Pupil size
- Pupil size are controlled by the iris sphincter muscle and iris dilator muscles based on the change in level of light detected
- Constriction (meiosis) and dilation (mydriasis) and both controlled by the efferent and afferent nerve pathway
Afferent Pathway
- Information from the eyes is transferred to the brain, detecting changes in light level
- Signals travel via the optic nerve to the brain where processed change the size of the pupil
Efferent Pathway
- Efferent signals from the brain change the size of the pupil based on the change in level of light
- Iris sphincter muscle makes the pupil constrict in increased light and iris dilator muscle make it dilate in the decreased light
Clinical assessment of pupils
- Pupil assessment in clinic is done under dim light to allow proper observation of pupil reactions
- Check for anisocoria
-Test direct and consensual response to test the integrity of the efferent and afferent nerve pathway
RAPD
Relative afferent pupillary defect acesses the strength of the afferent signal to the eye and to test the weakness in the pupil response tot the light that may not be apparent in direct assessment
Swinging flashlight test
- Swinging flashlight is used to test for RAPD
- Torch is quickly moved between the two eyes and the pupils are assessed
Normal vs healthy rapd
- In healthy individuals the pupil size show limited variation during swinging test
- In RAPD one eye is weaker than the other showing signs of ocular and neurological disease
