Refractive errors, Glaucoma and Cataracts - waldron Flashcards
what is the leading cause of blindness and low vision in the US
primarily age related:
Age-related macular degeneration (AMD)
Cataract
Diabetic retinopathy
Glaucoma
what are refractive errors
most frequent eye problems in the US
myopia, hyperopia, astigmatism, presbyopia
most can be corrected by classes, contacts, or surgery
what is Myopia
near sightedness
point of focus is in front of retina: cornea too steeply curved, axial length of eye too long, or both
distant objects are blurred
what is hyperopia
far - sightedness
point of focus is behind the retina: cornea too flatly curved, axial length too short or both
adults: both near and distant objects blurred
what is astigmatism
distorted vision at all distances
non-spherical (variable) curvature of cornea or lens causes light rays of different orientations to focus at different points
what is presbyopia
loss of ability to focus up close i.e. reading
loss of lens’ ability to change shape to focus on near objects due to aging
typically becomes noticeable upon reaching early-mid 40s
how do you correct myopia
concave (minus) lens
how do you correct hyperopia
a convex (plus) lens
how do you correct astigmatism
cylindrical lens (a segment cut from a cylinder)
how do you correct Presbyopia
a convex (plus) lens is 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
What is anisometropia
significant different between refractive errors of the 2 eyes (usually > 3 diopters)
when corrected with glasses, a different in image size is produced
what is aniseikonia
difference in image size
what are the symptoms of refractive errors
primary is blurred vision for distant objects, near objects or both
headaches: excessive ciliary muscle done, prolonged squinting and frowing with ocular use
eye irritation, itching, visual fatigue, FB sensation, rendess
percieved imabalance, dizziness, stumbling
what is difference in image size
aniseikonia
how do you diagnose and work up refractive errors
visual acuity
refraction: should be done every 1-2 years. screening children visual acuity helps detect refractive errors before interfering with learning
comprehensive eye exam: ophthalmologist/optometrist
what are the treatment for refractive errors in the eye
glasses, contacts, refractive surgery
what are the numbers of corrective lens prescriptions
first number: power (magnitude) of spherical correction required (- for myopia; + for hyperopia)
second number: power of cylindrical correction required (+ or -)
third: axis of cylinder
What is amblyopia
lazy eye
what is a functional reduction in visual acuity of an eye caused by disuse during visual development
amblyopia
What is strabismus
misalignment of eyes resulting in different retinal images being sent to visual cortex
-childs brain can pay attention to only one eye at a time, input from other eyes is suppressed - results in diplopia rather than suppression of one image
what is anisometropia
different focus of retinal images. with image from eye with greater refractive error being less well focused
what is obstruction of the visual axis
at some point between the surface of eye and retina something interferes with or completely prevents formation of retinal image affected eye
what is the clinical presenation of amblyopia
often asymptomatic, commonly discovered on routine vision screening
child rarely complains of unilateral vision loss, but may squint or cover one eye
if strabismus is cause, deviation of gaze may be noticeable to others
cataracts causing occlusion of visual axis may go unnoticed
how can stabismus be confirmed
with alternate cover test or cover-uncover test
how do opthamoloists confirm anisometriopia
doing a refraction on each eye
what is the treatment of amblylopia
eyeglasses or contact lenses
cataract removal
patching atropine drops
treatment of strabismus if present
what is the most common cause of irreversible central vision loss in older patients
age-related macular degeneration (AMD)
what is the diagnostic test for AMD
dilated fundoscopic findings
what is the treatment of AMD
dietary supplements, intravitreal injection of anti-vascular endothelial growth factor drugs, laser photocoagulation, photodynamic therapy, low-vision devices
what are risk factors for AMD
age
genetic variants
family hx
smoking
CVD/HTN
obesity
sun exposure
diet low in omega-3 fatty acids and dark green leafy vegetables
what are the forms of AMD
dry (non-exudative or atrophic) - all starts here
wet (exudative or neovascular)
What is dry AMD
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
What is Wet AMD
new abnormal blood vessels develop under the retina: choroidal neovascularization
localized macular edema or hemorrhage may elevate an area of the macula or cause a localized retinal pigment epithelial detachment
what can untreated neovascularization cause
disciform scar under the macula
what is the clinical presentation of Dry AMD
loss of central vision occurs over years and is painless
central blind spots (scotomas) usually occur late and can become severe
symptoms are usually bilateral
what is seen on fundoscopic exam with dry AMD
changes in retinal pigment epithelium
Drusen
Areas of chorio-retinal atrophy
What is the clinical presentation of Wet AMD
rapid vision loss, usually over days to weeks
first sx usually visual distortion (i.e. central blind spots (scotoma) or curving sraight lines (metamorphopsia))
peripheral vision and color vision generally unaffected - may become legally blind if not treated
often unilateral
what is the criteria for legally blind
< 20/200 vision
What are the fundoscopic changes with Wet AMD
subretinal fluid, appearing as localized retinal elevation
retinal edema
gray-green discoloration under the macula
exudates in or around macula
detachment of retinal pigment epithelium
subretinal hemorrhages in or around the macula
Define scotomas
centrally blind spots
how is AMD diagnosed/worked up
fundoscopic exam: will dx both forms
color fundus photography: suspect wet AMD
fluorescein angiography: suspect wet AMD
optical coherence tomography (OCT)
visual changes can be detected with Amsler grid
What is the treatment of dry AMD
no way to reverse damage
can reduce risk of wet AMD by taking zinc, copper, vitamin C, vitamin E, Lutein
reduce CV risk factors, eating flood high in omega-3 fatty acids and dark green leafy vegetables
what is the treatment of wet AMD
unilat: daily nutritional supplements as recommended for dry AMD (reduce risk of AMD-induced vision loss in other eye)
choice of tx depends on size, location and type of neovascularization
intravitreal injection of anti-vascular endothelial growth factor drugs
what are the supportive measures for AMD
low vision devices: magnifiers, high-power reading glasses, large computer monitors, telescopic lenses
software can display computer data in large print or read information aloud
low-vision counseling is advised
what are Cataracts
clouding of the lens
“looking through a steamed-up window”
congenital or degenerative opacity of the lens; several possible locations
what is the leading cause of blindness worldwide, leading cause of vision loss in the US
cataracts
what are the possible locations of cataracts
central lens nucleus (nuclear cataract)
beneath posterior lens capsule (posterior subcapsular cataract)
on side of the lens (cortical cataract)
what are the main symptoms of cataracts
gradual, painless vision blurring
how do you diagnose cataracts
opthalmoscopy and slit-lamp examination
what is the treatment of cataracts
surgical removal and replacement of an intraocular lens
what are risk factors of cataracts
trauma (may present years later)
smoking
alcohol use
exposure to x-ray
heat from infrared exposure
systemic disease
uveitis
systemic drugs
undernutrition
chronic UV light exposure
what are the clinical presentations of cataracts
usually develop slowly over years
early symptoms: loss of contrast, glare, need more light to see well, problems distinguishing dark blue from black
painless blurring
what are the clinical presentation of nuclear cataracts
distance vision worsens; near vision may improve in early stages temporarily; presbyopic patients may be temporarily able to read without classes (second sight)
what is the clinical presentation of posterior subcapsular cataract
reduced visual acuity when pupil constrics; more likely to cause loss of contrast and glare, esp. from bright lights or from car headlights at night
how are cataracts diagnosed/worked up
opthalmoscopy followed by slit-lamp examination
dx best made with pupil dilated
appear as gray, white or yellow-brown opacities in lens
what are the treatment options for cataracts
frequent refractions and corrective lens prescription changes may help maintain useful vision during cataract development
indirect lighting while reading minimizes pupillary constriction and may optimize vision for close tasks
sx removal or cataract - placement of intraocular lens
phacoemulsification (extracapular cataract extraction)
what is phacoemulsification
type of extracapuslar cataract extraction
hard central nucleus is dissolved by ultrasound and then soft cortex is removed in multiple small pieces
preferred procedure
what is the second most common cause of blindness worldwide and 2nd most common cause of blindness in the US and leading casue of blidness for AA and hispanics
glaucoma
what is POAG
primary, open-angle glaucoma
what is glaucoma
group of eye disorders characterized by progressive optic nerve damage; key component is a relative increase in IOP
acquired loss of retinal ganglion cells and axons within the optic nerve, that results in a characteristic optic nerve head appearance and corresponding progressive loss of vision
what is “angle”
angle formed by junction of iris and cornea at periphery of anterior chamber
where >98% of aqueous humor exits eye via either trabecular meshwork and schlemm canal (major pathway, particularly in elderly) or ciliary body face and choroidal vasculature
what is primary glaucoma
cause of outflow resistance or angle closure is unknown
what is secondary glaucoma
outflow resistance result from a known disorder
what is angle-closure glaucoma
associated with physically obstructed anterior chamber angle, chronic or acute
acute: sever ocular pain and redness, decreased vision, colored halos around lights, headache, N/V
IOP elevated
what is the treatment of angle-closure glaucoma
immediate tx of acute condition with multiple topical and systemic drugs is required to prevent permanent vision loss, followed by definitive treatment - iridotomy
what causes angle-closure glaucoma
factors that either pull or push iris up to angle physically blocking drainage of aqueous and raising IOP
elevated IOP damages optic nerve
may be primary or secondary to another condition (acute, subacute or chronic)
what is primary angle-closure glaucoma
as age, lens continues growth; growth can push iris forward, narrowing angle
risk factors for narrowing angles: Fhx, advanced age, ethnicity
pressure from continued secretion of aqueous into posterior chamber pushes peripheral iris anteriorly, closing angle
ophthalmic emergency requiring an immediate treatment
what is the presentation of Acute primary angle closure
pupillary dilation (mydriasis) can push iris into angle and precipitate angle-closure glaucoma in any person with narrow angles
severe ocular pain and redness, decreased vision, colored halos around lights, headache, N/V
systemic complaints may be so severe that misdiagnosed as neurologic or GI problem
what are the types of primary angle-closure
intermittent angle-closure glaucoma: if episode of pupillary block resolves spontaneously after several hours, usually after sleeping supine
chronic angle-closure glaucoma: if angle narrows slowly, allowing scarring btwn peripheral iris and trabecular meshwork; IOP elevation is slow
what is secondary angle-closure
mechanical obstruction due to coexisting condition
-proliferative diabetic retinopathy (PDR)
-ischemic central vein occlusion
-uveitis epithelial down-growth
contraction of neovascular membrane or inflammatory scarring can pull iris into angle
what is seen on examination of acute angle closure
conjunctival hypermia, “hazy” cornea, fixed mid-dialted pupil, anterior chamber inflammation
vision is decreased
IOP usually 40-80mmHg
optic nerve difficult to visualize due to corneal edema ; visual field testing not done because of discomfort
what is seen on clinical exam with chronic angle closure
manifests like open-angle
may have ocular redness, discomfort, blurred vision, headache that lessens with sleep
angle is narrow and periopheral anterior synechiae (PAS)
IOP may be normal but usu higher in affected eye
how are angle closure glaucomas diagnosed/worked up
acute: measurement of IOP and clinical findings
chronic: Gonioscopy showing periopheral anterior synechiae and characterisitic optiv nerve and visual fild abnormaliteis
what is the treatment of Acute angle-closure glacucoma
tx immediately
multi-drug regimen: timolol, pilocarpine, brimonidine, acetazolamide, osmotic agent
response is evaluated by measuring IOP
what is the definitive treatment of acute angle-closure glaucoma
laser peripheral iridotomy (LPI)
opens another path to pass fluid from posterior to anterior chamber
what is the treatment of chronic angle-closure glaucoma
chronic, subacute or intermittent: LPI
what is primary open-angle glaucoma
syndrome of optic nerve damage associated with open anterior chamber angle and elevated or sometimes avg IOP
how do you diagnose POAG
opthalmoscopy, gonioscopy, visual field examiation, measurement of central corneal thickness, IOP
what is the treatment of POAG
topical drugs (prostaglandin analogs, beta blockers); often requires laser or incisional surgery to increase aqueous drainage
what are risk factors of POAG
older age
Fhx
African ethnicity
thinner central corneal thickness
HTN
DB
myopia
what is normal pressure glaucoma or low-pressure glaucoma
IOP within average range, but optic nerve damage and visual field loss typical of glaucoma are present
higher incidence of vasospastic disease
average-range IOP more common among asians
what is the clinical presentation of Open angle glaucoma
early primary symtpoms are uncommon
usu. aware of visual field loss only when optic nerve atrophy is significant; typically, asymmetric deficits contribute to dleay in recognition
unobstructed open angle on gonioscopy and characteristic optic nerve appearance and visual field defects
what is seen on fundoscopic with open angle
increased cup to disk ration (increasing ration over time)
thinning of neurosensory rim
pitting or notching of rim
nerve fiber layer hemorrhage that crosses disk margin (splinter hemorrhages)
vertical elongation of cup
quick angulations in course of exiting blood vessels (bayoneting)
how is open angle diagnosed/worked up
visual field testing
ophthalmoscopy
measurement of central corneal thickness and IOP
exclusion of other optic neuropathies
diagnosis of POAG is suggested by examination)
what is the treatment of open angle
goal to prevent further optic nerve and visual field damage by lowering IOP
topicals are preferred (prostaglandin analogs - latanoprost, tafluprost) then beta- blockers (timolol))
surgery: selective laser trabeculoplasty (SLT), Argon laser trabeculoplasty (ALT)
guarded filtration procedure, partial-thickness procedures
