Refractive Errors, Glaucoma and Cataracts Flashcards
Refractive errors include
Myopia
Hyperopia
Astigmatism
Presbyopia
Myopia is
near sightedness
Hyperopia is
Farsightedness
Astigmatism is
distorted vision at all distances
Presbyopia is
loss of ability to focus up close (reading), usually 40-50 yo
Point of focus is in front of retina: cornea too steeply curved, axial length of the eye too long or both
distant objects are blurred but near objects are seen clearly =
Myopia
to correct myopia you need
a concave (minus) lens
Point of focus is behind retina, cornea too flatly curved, axial length too short or both
in adults both near and distant objects are blurred
Hyperopia
To correct hyperopia you will need
a convex (plus) lens
non-spherical (variable) curvature of cornea or lens causes light rays of different orientations to focus at different points
astigmatism
To correct astigmatism you need
a cylindrical lens
Loss of the lens’ ability to change shape to focus on near objects due to aging
typically becomes noticeable upon reaching early-mid 40s
Presbyopia
To correct Presbyopia you need
a convex (plus) lens used for correction when viewing near objects, lenses may be supplied as separate glasses or built into a lens as bifocals or variable focus lenses
Treatment of refractive errors
eyeglasses
contact lenses
refractive surgery
primary sx of refractive errors is
blurred vision for distant/ near or both objects
HA
excessive staring - eye irritation, itching, visual fatigue, FB sensation, redness
Perceived imbalance, dizziness, stumbling
Amblyopia means
lazy eye
functional reduction in visual acuity of an eye caused by disuse during visual development - development takes place in first 3yrs of life but not complete until 8 yo
severe loss of vision can occur in affected eye if not detected and treated before 8 yo
amblyopia
Treatment of amblyopia
eyeglasses or contact lenses
cataract removal
patching
atropine drops
treatment of strabismus if present
Strabismus is
misalignment of eyes resulting in different retinal images being sent to visual cortex
most common cause of irreversible central vision loss in older pts
AMD - age-related macular degeneration
Two different forms of AMD
dry (all AMD starts as dry form) - nonexudative or atrophic
wet - exudative or neovascular
Treatment of AMD
dietary supplements, intravitreal injection of antivascular endothelial growth factor drugs, laser photocoagulation, photodynamic, low-vision devices
causes changes of retinal pigment epithelium, typically visible as dark pinpoint areas
accumulation of waste products from rods and cones results in drusen, which appear as yellow spots
no elevated macular scar, edema, hemorrhage or exudation
Dry AMD
new abnormal blood vessels develop under the reina, choroidal neovascularization
localized macular edema or hemorrhage may elevate an area of the macula or cause a localized retinal pigment epithelial detachment
Wet AMD
Wet AMD - Untreated neovascularization will cause
a disciform scar under the macula
________ usually occurs late and can become severe in Dry AMD
central blind spots (scotomas)
Dry AMD sxs are usually
bilateral
Wet AMD sxs are usually
unilateral - affects one eye at a time usually
Exams for wet AMD
color fundus photography = wet AMD
fluorescein angiography = wet AMD
Fundoscopic exam will dx both
wet and dry AMD
Treatment of dry AMD
no way to reverse damage
reduce risk of wet AMD taking supplements, reduce CV risk factors (eat foods high in Omega 3 fatty acids and dark green leafy vegetables)
Treatment of wet AMD
daily nutritional supplements as recommended for dry AMD
intravitreal injection of anti-vascular endothelial growth factor
thermal laser photocoagulation
photodynamic therapy
corticosteroids
clouding of the lens (looking through a steamed window) - leading cause of blindness worldwide, leading cause of vision loss in US
Cataracts
Main sx of Cataracts
gradual, painless vision blurring
Treatment of Cataracts
surgical removal and placement of an intraocular lens
_____ use by women after menopause may be protective but should not be used solely for this purpose
estrogen
early sx of cataracts
loss of contrast, glare (halos and starburst around lights), needing more light to see well, problems distinguishing dark blue from black
Treatment of Cataracts
frequent refractions and corrective lens prescription changes may help maintain useful vision during cataract development
surgical removal of the cataract
placement of intraocular lens - if lens is not implanted, contact lenses or thick glasses are needed to correct
Cataracts - indications for surgery include
best vision with glasses is worse than 20-40
pt reports that vision is limiting (preventing ADLs)
there is no advantage to removing a cataract early
Cataracts - Post-op treatment
tapering schedule of topical abx and topical steroids for up to 4 wks
abx may instead be injected into eye at end of surgery
pts wear eye shield while sleeping and should avoid valsalva maneuver, heavy lifting, excessive forward bending, eye rubbing for several wks
2nd most common cause of blindness worldwide and 2nd most common cause of blindness in US
Glaucoma
Most common type of glaucoma in the US is
primary, open-angle glaucoma
an acquired loss of retinal ganglion cells and axons within the optic nerve (optic neuropathy), that results in a characteristic optic nerve head appearance and corresponding progressive loss of vision
increase in IOP
Glaucoma
associated with physically obstructed anterior chamber angle, chronic or acute
sx - severe ocular pain and redness, decreased vision, colored halos around lights, HA, nausea, vomiting
IOP is elevated
angle - closure glaucoma
Angle - closure glaucoma pathophysiology
pressure from continued secretion of aqueous into posterior chamber by ciliary body pushes peripheral iris anteriorly
closure blocks aqueous outflow, resulting in rapid and severe elevation of intraocular pressure
What are the 5 supplements recommended for AMD treatment
Zinc
Copper
Vit C
Vit E
Lutein/zeaxanthin (or beta carotene or vit a)
acute angle - closure glaucoma treatment
homatropine or systemic meds with potential to dilate pupils
if episode of pupillary block resolves spontaneously after several hours, usually after sleeping supine
intermittent angle - closure glaucoma
if angle narrows slowly, allowing scarring between peripheral iris and trabecular meshwork, IOP elevation is slow
chronic angle-closure glaucoma
mechanical obstruction due to coexisting condition, contraction of neovascular membrane or inflammatory scarring can pull iris into angle
secondary angle - closure
Severe ocular pain and redness, decreased vision, colored halos around lights, HA, nausea, vomiting
systemic complaints may be so severe that misdiagnosed as neurologic or gastrointestinal problem
acute angle - closure glaucoma
acute angle - closure treatment
laser peripheral iridotomy (LPI)
opens another path to pass fluid from posterior to anterior chamber
chronic angle - closure treatment
LPI
syndrome of optic nerve damage associated with open anterior chamber angle and elevated or sometimes average IOP
primary open-angle glaucoma
Treatment for primary open-angle glaucoma
topical drugs (prostaglandin analogs, beta blockers) open requires laser or incisional surgery to increase aqueous drainage
Sx of open-angle glaucoma
result of visual field loss, both eyes usually affected but not usually equally
Open-angle glaucoma pathophysiology
aqueous humor drainage in inadequate but production by ciliary body is normal
Open-angle treatment
drug therapy, then laser therapy, then incisional surgery if target IOP is not/ cannot be met
