Chronic Vision Loss Flashcards
What is the most important way to detect glaucoma?
Examining the optic nerve
(the optic nerve can be damaged in glaucoma despite a normal intraocular pressure)
A. normal optic nerve
B. glaucomatous optic nerve (note: enlarged “bean pot cup” excavation)
open angle glaucoma
Superior arcuate scotoma (area of reduced or absent vision) as shown by automated visual field testing
(black is the visual field loss - nasal step)
Why is pressure created in the eye?
There is some resistance of flow of the aqueous through the trabecular meshwork and Canal schlemm → IOP of 10-20 mmHg
Signs and symptoms of acute angle closure glaucoma (ocular emergency) that do NOT appear w/open-angel glaucoma.
- Pain
- Nausea
- Colored halos
- Rainbows around light
Chronic angle closure glaucoma signs and symptoms (3)
- Intermittent headache & blurred vision (especially when pupils dilate
- decreased pupillary rxn (Marcuss-Gunn pupil)
- Increased IOP ( scarring of the drainage angle)
Congenital or infantile glaucoma signs and symptoms
- Tearing
- Sensitivity to light secondary to corneal edema (result of elevated IOP)
- If untreated → “cow eye” (buphthalmos)
At its point of origin, the optic nerve is called the _____.
optic disc
(has a small depression called the optic cup)
Relationship of the IOP and optic nerve
IOP exerts pressure on all surfaces of the internal eye, including the optic nerve and blood vessels
Define glaucoma
A general term used to describe the progressive optic neuropathy that can lead to blindness
The optic nerve is supplied with blood via branches from the _____ (2)
Internal carotid artery → ophthalmic artery
(important because vascular disease can lead to glaucoma)
Diagnosing and monitoring glaucoma (3)
- Measurement of IOP (tonometry)
- Evaluation of optic nerve appearance (stereo disc photography)
- Visual field testing (perimetry)
(may also use oiptical coherence tomography to measure nerve fiber layer)
Which patient population is at the greatest risk for developing glaucoma?
African-Americans and Hispanics
(screen every 2-4 years, also increases in age and family hx)
Three major causes of slowly progressive visual loss in adults
- Glaucoma
- Macular degeneration
- Cataract
IOP is measured with ______.
tonometry connected to slit lamp (“gold standard”)
Why is the color of the optic nerve important in determining atrophy?
Temporal pallor of the optic nerve can occur because of damaged nerve fibers
(ex: brain tumors, optic nerve inflammation)
Temporal pallor of the optic nerve
(indication of optic nerve atrophy; note the normal color in the nasal aspect of the disc)
Define glaucomatous cupping
- Increase in the size of the optic cup relative to the optic disc that occurs in glaucoma
- Due to loss of nerve fibers bundled in the optic nerve
(vertical cupping is more commonly seen)
glaucomatous cupping
(also note the asymmetry of cup-disc ratios - another glaucoma indicator, anything above .5 = glaucoma; 0.3 = normal)
disc hemorrhage
(indicates glaucomatous damage, flame shaped hemorrhage across margin of disc is a sign of primary open-angle glaucoma)
glaucomatous optic atrophy
(cupping apparent at the point where the vessels disappear over the edge of the attenuated rim)
Which glaucomatous indicators warrant a referral to an ophthalmologist?
- symptoms of glaucoma
- optice cup diameter 1/2 or more the disc diameter
- cup-disc asymmetry
What happens to our lenses as we age?
they continue to grow and thicken and protein is deposited in them → increase in insoluble protein (up to 35% by mass) → cataract
define cataract
- opacity or discoloration of the lens, local or complete loss of transparency
- yellow or amber color to lens
(clinically, we care about the ones that affect visual acuity)
mature cataract (lens is totally opacified & no red reflex)
Risk factors of cataract (other than family Hx; 6)
(different than the pathological causes; see basic eye disorders)
- chronic corticosteroid use
- trauma
- nutritional deficiency
- inflammation
- DM
- sun exposure smoking
Posterior subcapsular cataract symptoms (4)
(note the dark shadow on the red reflex)
- Blurred vision (as lens clouds)
- Glare (unique to post. subcapsular)
- Loss of near vision
- Rapid decrease in vision
Nuclear cataract symptoms (5)
(note the distortion of the red reflex & the yellow color of the cataract)
- Posterior subcapsular effects near vision
- Nuclear sclerosis have a second sight
- See multiple images
- Starbursts
- Difficulty driving at night
Types of cataracts
- Mature or immature
- Congenital
- Developmental
- Nuclear
- Posterior subcapsular
Where is the aqueous humor produced?
the body of the ciliary body
Flame shaped hemorrhage across margin of disc is a sign of_____.
primary open-angle glaucoma
Fluorescein angiography
(note the macula does not have a lot of vessels (black area))
Drusen: hyaline nodules (or colloid bodies) deposited in Bruch’s membrane, which separates the retinal pigment epithelium (the outermost layer of the retina) from the inner choroidal vessels
(this is a sign of dry form of macular degeneration)
Geographic atrophy - dry macular degeneration
What can decrease the rate of macular degeneration (dry form)?
AREDS: vitamins: zinc, Vit E, C, A, Betacarotene
(no evidence that it will prevent the development of dry macular degeneration if you don’t have it already)
If you find Hemorrhage in the macula what is the diagnosis until proven otherwise?
Wet macular degeneration
How do you use the Amsler grid
Have the patient cover one eye at a time→ look at the dot in the center → ask them if any of the lines around the dot appear wavy or are missing→ if yes → Wet macular degeneration
