Which score on a Snellen chart is classified as blind?
3/60 or worse
What is the most common cause of blindness in the elederly population within the developed world?
Age related macular degeneration
What is the most common cause of blindness in the working population within the developed world?
What is the most common cause of blindness in the young within the developed world?
Inherited retinal disorders
What is the secondary biggest cause of blindness in the developing world?
(due to chlamydia trachomatis infection)
What is Onchocerciasis?
An infectious cause of blindness in the developing world
A parasitic fly injects larvae into the eyes causign inflammation and corneal scarring
Which complication involving the eyelashes contributes to the blindness associate with trachoma?
(recirrent abraision to cornea, due to inwardly pointing eyelashes leading to blindness)
What is Xerophthalmia?
Abnormal dryness of the conjunctiva and cornea of the eye, with inflammation and ridge formation
Xerophthalmia is typically associated with a deficiency in what?
Someone with emmetropia has what type of vision?
What is myopia?
Why does myopia occur?
The light focusses too soon (often in vitreaous and not on retina)
Why is a negative lens required for myopia?
It diverges light and causes it to focus later (on the retina)
What is hyperopia?
What can hyperopia lead to in children?
- Lazy eye
What is stigmatism?
Rays of light from a single point do not focus upon on a single point on the retina
This is due to the cornea being abnormally shaped
What is keratoconus and why does it cause distorted vision?
Progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape
This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision.
What are the treatment options for keratoconus?
- Rigid contact lenses
- Corneal transplant
What is the normal intra-ocular pressure?
Which type of vision is lost when diabetic retinopathy is treated with laser treatment?
- Night/dim vision (rod cells destroyed)
How is cataracts treated?
- Intra-ocular lens implant
What is presbyopia?
Long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age
Whcih features should be commented on when examining an optic disc?
- Cup/disc ratio
Temporal crescent pigmentation is a normal finding with which condition?
Argon scarring in the fundus is indicative of which condition?
What is the swinging light reflex?
Pupillary light reflex causes constriction in both eyes when only one eye is exposed to light
Affected eye will constrict weakly in light and fully when other eye is in light
This is a relative afferent pupillary defect
What is photophobia?
Pain in light
What induces closed angle glaucoma?
Long sighted individuals are affected
Pupil dilates in dark and causes iris to bunch up closing the iridocorneal angle
How can closed angle glaucoma be treated?
- Laser to reduce pressure
How do steroids affect the trabecular meshwork?