OPTH Lec03 Flashcards
What are the characteristics of glaucoma?
Characterized by arcuate visual field defects that correspond to optic nerve damage. Involves elevated IOP (but IOP CAN be normal)
What is normal IOP?
8-21 mmHg
What is the normal course of aqueous in the eye?
Aqueous is produced by the ciliary body percolates through the conules over the lens, across the pupil into the AC and exits through the trabecular meshwork into the canal of Schlemm into episcleral veins
What causes glaucoma?
When the flow of aqueous is altered
What is the most common form of glaucoma?
open angle
What does Acute narrow angle glaucoma do?
Causes sudden elevated IOP by mechanical blockage of flow. Medical emergency
What is angle closure glaucoma?
When the canal of schlemm is occluded and the aqueous cannot flow out.
What are characteristics of optic nerve problems?
PAIN, colored halos around lights, red eye with tearing and steam cornea, mid fixed and ciliated pupil, nausea, vomiting, chest pain, firm eye to palpation
What is the path of the optic nerve?
Nerve fibers will begin as retinal ganglion cells and become a nerve fiber layer gathering at the optic nerve. They will travel retro orbitally to and through the sphenoid optic canal, cross in the optic chiasm and end in the lateral geniculate body
What can cause damage to the optic nerve?
interruption of blood flow to nerve fibers at the optic nerve head or mechanical pressure pushing the nerve fibers against the lamina cribrosa which will interrupt axoplasmic flow
What are risk factors of glaucoma?
over 40 years of age, black race, family history, chronic steroid us, cup to disc ratio of 0.5 or more, asymmetry
What do you examine when assessing for glaucoma?
optic nerve but unless there is extreme visual loss will not be found on confrontation VF
What is this?
Enlarged chronic nerve due to glaucoma
What is cataracts associated with?
age related, congenital, traumatic, nutritional, environmental or systemic
What causes cataracts?
changes in the crystalline lens
What are the symptoms of cataracts?
blurred vision, “second sight” can occur in nuclear sclerotic induces myopia, and diplopia and or glare from light scatter
Where can cataracts occur?
nuclear, cortical and posterior subscapular
What will determine the degree of visual disability?
the size and location of the opacity
What is cataracts?
An opacity (clouding) of the normally clear lens which may develop as a result of aging, metabolic disorders, trauma or heredity
What is this?
Cataracts
What should a PCP do when examining for cataracts?
check VA, pupils and red reflex to look at the lens and lastly ophthalmoscopy
What is the treatment for cataracts?
surgical treatment is considered if the patient’s best corrected vision is impairing quality of life. Treat by removing the nucleus of the lens and replace with an implanted artificial lens. Make sure to leave the capsule in the eye.
When is macular degeneration more prevalent?
Prevalence increases with age (25% at 70, 33% at 80, and 50% at 90
What is macular degeneration?
Vision loss of the macula
Where is the macula located?
An oval region 2 disc diameters temporal and slightly inferior to the disc. The rods and cones provide the detailed central vision. Fovea in the central macula I avascular without rods
How do you diagnose macular degeneration?
The foveal reflex will not be present in the macular degeneration
What are the symptoms or macular degeneration?
Painless loss of vision or metamorphopsia. Gray-green lesion visible in wet AMD. May have RPE tears or fold. Age related changes will include drusen (yellow or white extracellular accumulations between Bruch’s membrane and extracellular retinal pigment epithelium and choroid). Can be hard or soft and RPE may be hyperpigmented or atrophic (dry)
What is neovascular AMD?
Dry AMD can progress to the wet form (20%). Wet AMD is when the vessels extend from choroid capillaries through Bruch’s membrane into the subretinal space.
What is Dry AMD?
When there are spots accumulating
What is Wet AMD?
When the blood vessels infiltrate the rods and cones, RPE and nuclear layer of the macula
What is this?
Dry Macular Degeneration
What is this?
Wet AMD
How do you diagnose Macular Degeneration?
Flourescein angiography will help diagnose, examine using VA, Amsler Grid(will present with metamorphosia or distortion of central vision) and Central scotoma (will report a spot in the center where cannot see). Use ophthalmoscope or slit lamp biomicroscopy
What is the treatment for AMD?
Refer to ophthalmologist. Laser treatment
What are the long term complications of AMD?
Central vision will be lost but peripheral vision will be preserved = low vision (can be referred for low vision rehabilitation
