Comp 7.1.7 Flashcards
Name four types of severe visual defects
Tunnel vision
Wiped out field
By temporal hemianopia
Homonomous hemianopia
What are some common causes of tunnel vision?
Glaucoma
Retinitis pigmentosa
Diabetes related retinopathy
Retinal detachment
Optic neuritis
Retinal vein, occlusion
What can cause wiped out field vision?
Advance glaucoma
Advanced cataracts
Central retinal artery occlusion
Retinitis pigmentosa
What could cause a bitemporal hemianopia?
Tilted disc syndrome
Tumours causing compression on the chiasm
Aneurysms of the anterior artery
What can cause a homonomous hemianopia
Stroke
Tumours, lesions
Trauma
What are some possible adaptations before the eye test that you could do for somebody with a reduced visual field?
Remove any obstacles
Guide patient, cautiously and system in finding the chair
Use double slots for their appointment
Test slowly.
Large brackets for power of lenses.
Unappropriate field test.
Appropriate targets for cover test 
What are some adaptations for refraction of a visual field defect patient?
Use a trial frame because the upper size is larger
Allow them to hold eccentric eye and head positions to help them see better.
Use objective techniques like radical retinoscopy to get a reflex because a patient might not be able to see out very well, but will be able to see better.
spending more time on retinoscopy to get a more accurate result
What are some adaptations you could use when performing subjective refraction
You could use a target that can be seen or reduce the testing distance to 3, two, 1 m or use CF, HM, PL, NPL
When doing sphere refinement use larger brackets, especially if you did not get a result and reduce the bracket size as the prescription is refined, but not by too much.
When doing a cylinder refinement use around target of appropriate size, if the VA is worse than 6/12, you can’t use a verhoff ring , so you should use a bigger size, C or O
Use higher power cyls
What must you be aware of when using pinhole?
If the LV patient is a cataract patient, then pinhole will improve the VA by miles as a scattered light is limited.
If the patient is a glucoma patient and only uses their central vision, adding a pinhole with limit their vision.
If the patient is a macular degeneration patient who is using the purple vision, adding a pinhole will block the light out fully resulting in NLP
What are some test adaptations you could use for somebody with visual field loss discuss both types
Central visual field loss. You would use an Amsler chart as it best identifies the area of vision that is defected, and you could also use chart to identify a potential preferred retinal locus, and you would suggest suggested the patient that they use this PRL to achieve their best vision.
Peripheral field loss; you would use kinetic perimetry such as Goldman, which would quickly indicate the remaining field, or you could use confrontation 
How was your refractive patient with AMD?
I would use larger steps to make it easier for the patient to see the difference, but make changes in 0.25D steps
How would you adopt the test if the patient cannot get onto the slitlamp
I would use direct opthalmoscopy
How would you measure visions for patient with a bi-temporal hemianopia?
I would use the central lines of the chart meaning the central two lines 
Describe a bi temporal hemianopia
describes the ocular defect that leads to impaired peripheral vision in the outer temporal halves of the visual field of each eye
Describe a homonymous hemianopia
field loss deficit in the same halves of the visual field of each eye, often resulting from cerebrovascular injury or tumor
