Ophthalmology Flashcards
Visual functions
Spatial resolution
Temporal resolution
Wavelength discrimination
Depth perception
What is spatial resolution reliant on
Optical properties of cornea and lens
Cone density at fovea
Neural processing
Distance and up close
Contrast and reduced contrast as well
Temporal resolution relays involves?
Motion perception
Peripheral field
Function on peripheral retina
Wavelength discrimination
Colour vision
Depth perception
Binocular Stereopsis
The factors in aviation that can affect vision function
Extreme environment - hypoxia - high G - low humidity - glare sources - very low light Heads up displays/visor display NVG
How do we test for spatial resolution
VA - Snellen chart - LogMAR Temporal resolution - peripheral vision Wavelength discrimination - ishihara plates - congenital red-green deficiencies - Farnsworth lantern —- Binocular test —- Mesopic condition —- distinguish white-red-green Accommodation - Foster’s rule Convergence - foster’s rule - tested using Maddox Rod test —- measure the angle of deviation Strabismus - cover test Visual fields - testing to determine anterior vs posterior Depth perception
When testing visual fields what pathways with present with which defects
Anterior visual pathways
- altitudinal defect
- retina or macular pathology
- optic neuropathy
Posterior visual pathways
- vertically delineated defect
- chasm pathology
- occipital lobe pathology
Anomalies of the visual system
Refractive errors
Fields
Colour disorders
Diseases
Types of refraction errors
Myopia - Near-sightedness. Close is clear and fas is not. Eye too long
Hypermetropia - close is blurry. Common in adults. Also known as far-sightedness. Eye too short.
Astigmatism - abnormal curve of eye or lens.
Presbyopia - aging disorder. Failure to change from far to near
Effect of spectacles in the aviation environment
Good central vision Frame scotoma Peripheral aberrations Reflections Fogging of lenses No complication
Effections of aviation on contact lenses
Good quality vision Good field Movement on eye Affected by hydration and altitude Allergy to lens and solutions Hygiene
Discuss difference between PRK and LASIK
PRK
- laser eye
- weeks to months to recovery
LASIK
- Flap with laser underneath
- rapid recovery
- return to flying quicker
Used to treat myopia, hyperopia or astigmatism
Explained significant of monovision
Occurs for treatment of presbyopia
Gives one eye close vision and one eye as far vision
Leads to issues with depth perception
Contraindicated for aviations
Monochromats
Monochromats - very rare
- only see in black and white
- can see through camophage
- Cone = good VA but Rod = poor VA