Ophthalmology Flashcards
the eye exam
*visual acuity
*pupils
*intraocular pressure
*extraocular movements
*physical exam
measuring visual acuity
*20/20 is “perfect vision”
*first number = distance (in feet) away from the chart (20 ft in US)
*second number = how far a patient with perfect vision could stand and still read that letter (typically 20-400)
*near card is size adjusted
*check eyes individually
pupils (eye exam)
*pupils should be equal, round, and reactive to light
*light shone in one eye should cause BOTH pupils to react symmetrically
*unequal pupil size = anisocoria (can be caused by Horner’s syndrome, CN III palsy, trauma, tonic pupil, meds)
*irregular pupils usually secondary to trauma
*nonreactive pupils
causes of miotic (small) pupils
older age
opiates
clonidine
organophosphates
pilocarpine
causes of mydriatic (dilated) pupils
younger age
cocaine
nasal vasoconstrictors
scopolamine patches
red reflex
*red light reflection seen in ophthalmoscopic examination of the eye
*should be checked in infants and children
*abnormal red reflex warrants PROMPT REFERRAL to an ophthalmologist
*possible causes include cataract, strabismus, retinoblastoma
intraocular pressure
*normal = 8-22 mmHg
*high intraocular pressure can indicate glaucoma
emmetropia
*no refractive error (normal vision)
*distance light rays are focused perfectly on the retina
*for near vision, accommodative reflex causes lens to thicken and focus light on retina
refractive error
*light does not focus perfectly on retina
*due to the size (axial length) or shape (corneal curvature) of eye, and focusing power of lens
*important parts/measurements:
-length of eye
-curve of cornea
-flexibility, density, and shape of lens
presbyopia
*old eyes
*loss of accommodation associated with normal aging
*near vision becomes out of focus
*correctable with reading glasses or bifocal
accommodation
young lenses can change shape to focus near light rays on retina
myopia
*nearsightedness
*far away is blurry, close up is clear
*light rays from the distance focus IN FRONT of retina
*eye is too long
*typically gets worse with aging in children (eye continues to grow)
*corrected with a MINUS prescription (concave lens)
hyperopia
*farsightedness
*far away clearer than up close
*light rays from distance focus BEHIND the retina
*the eye is too short/small
*most kids are hyperopic but can still see clearly due to lens accomodation
*correct with PLUS prescription (convex lens)
astigmatism
*cornea is not spherical
*light rays do not create a single, sharp focus
*can occur with nearsightedness or farsightedness
*correctable with glasses/contacts
viral conjunctivitis
*most common cause of infectious conjunctivitis
*conjunctival infection, mucoid discharge, sometimes with URI
*starts unilateral and usually spreads to other eye
*HIGHLY contagious
management of infectious conjunctivitis
*strict handwashing, no sharing of linens, non contact lenses for 14 days
*artificial tears, cool compress
*antibiotics typically only required in hyperacute, severe bacterial conjuctivitis
corneal abrasion
*epithelial defect in the cornea
*usually heals without treatment in 24-48 hours
*look for associated foreign body (often metal which must be removed)
*associated conjunctival infection (dilated blood vessels on the white of the eye)
corneal ulcer
*corneal abrasion plus an underlying suppuration of corneal STROMA
*can be infectious or sterile (neurotrophic)
*usually occurs if a corneal abrasion gets infected
*almost always leads to permanent vision loss
cataract
*clear lens (made of crystalline protein) becomes cloudy
*blocks and scatters the light from getting to the retina
*can be congenital or traumatic
*TYPICALLY OCCURS WITH NORMAL AGING (most people will have cataracts at some point if they get old enough)
*tx = surgery
causes of cataracts
*normal aging
*UV exposure
*trauma
*diabetes
*corticosteroids
cataract surgery
*performed when poor vision is affecting activities of daily living (driving or reading)
*outpatient, fast (10-15 minutes), and typically performed under light sedation (very little recovery time)
glaucoma
*damage to the optic nerve, typically arising from HIGH INTRAOCULAR PRESSURE, resulting in permanent vision loss
*usually from INSUFFICIENT DRAINAGE of aqueous fluid
*results in loss of visual field (usually peripheral vision first)
*untreated, can lead to complete, irreversible blindness
open-angle glaucoma
*trabecular meshwork is clogged at microscopic level
*causes long-term increase in intraocular pressure
*usually asymptomatic
closed-angle glaucoma
*less common than open angle
*iris is pressed against cornea, blocking access to trabecular meshwork
*acute (pain, red eye, nausea, blurry vision)
*could be chronic
optic nerve cupping in glaucoma
*the cup gets bigger, the rim gets smaller, due to death of nerve fibers
*end result in open or closed angle glaucoma
treatment of glaucoma
*goal = lower the intraocular pressure
*medications - lower aqueous production or increase aqueous outflow
*laser - increase outflow through trabecular meshwork
*surgery - increase outflow; usually only if more conservative measures have failed
glaucoma medications that increase outflow of aqueous fluid
-prostaglandin analogues (latanoprost)
-cholinergic agonists (pilocarpine)
glaucoma medications that decrease production of aqueous fluid
-beta blocker (timolol)
-alpha agonist (brimonidine)
-carbonic anhydrase inhibitor (dorzolamide, acetazolamide)
-Rho Kinase inhibitors (netarsudil)
glaucoma surgery
*typically only if medications fail
*increase outflow by creating a guarded hole “trabeculectomy” from the anterior chamber beneath the conjunctiva
*increase outflow by placing a tube shunt from the anterior chamber to beneath the conjunctiva
*decrease aqueous production by destroying the ciliary body
common retinal disorders
*macular degeneration (dry and wet)
*diabetic retinopathy (nonproliferative and proliferative)
*retinal detachment
risk factors for macular degeneration
-age
-race (Caucasian and Scandinavian descent)
-family history
-UV exposure
-tobacco use
-HTN
dry macular degeneration
*retinal cells die and leave areas of missing, atrophic retina
*yellow clumps (drusen)
wet macular degeneration
*happens when there is a break in the RPE (retinal pigment epithelium) and blood vessels from choroid grow into the retina and bleed
*choroidal or subretinal neovascular membranes are abnormal blood vessels growing under the retina (from the choroid)
*driven by VEGF (vascular endothelial growth)
treatment for dry macular degeneration
-avoid UV exposure
-avoid tobacco
-AREDS antioxidant vitamins
treatment for wet macular degeneration
*anti-VEGF intraocular injections
nonproliferative diabetic retinopathy
*ischemia and blood vessel damage
*signs: microaneurysms, intraretinal hemorrhages, macular edema, exudates, and cotton-wool spots
*tx = control BG and BP, laser, intravitreal injections
proliferative diabetic retinopathy
*if vasculopathy is severe enough, retina becomes so ischemic that vascular endothelial growth factor (VEGF) is released and neovascularization occurs
*new, ABNORMAL blood vessels form
-grow on retina and from optic nerve
-fragile, so often bleed into vitreous
*usually causes blindness if untreated
treatment for proliferative diabetic retinopathy
*panretinal photocoagulation (PRP):
-kills peripheral retina to decrease release of VEGF
-sacrifices peripheral retina to preserve central retina
-permanent
*anti-VEGF injections (nondestructive by effect is short-lived)
retinal detachment
*“half of my vision is gone in my right eye”
*patient complains of flashing, floaters, or a “curtain coming across vision”
*usually, a small tear in peripheral retina that allows fluid into potential space and causes retina to detach
strabismus
*misalignment of the eyes
*causes:
-cranial nerve palsy
-congenital/developmental
-mechanical (trauma, thyroid eye disease, space occupying lesion in the orbit)
esotropia
*strabismus in which one eye is deviated inward (toward the nose)
*“crossed eyes”
exotropia
*strabismus in which one or both eyes look outward
complete CN III palsy
*presentation: affected eye down + out, ptosis, dilated pupil
causes: PCOM ANEURYSM**, ischemia, or trauma
abducens palsy
*presentation: affected eye turns inward + unable to abduct
*causes: elevated ICP (can be a sign of impending uncal herniation), ischemia, mass
strabismus in children
*eye misalignment
*brain suppresses the image from one eye to avoid diplopia
*treated with glasses and/or surgery
*untreated leads to amblyopia
amblyopia
*“lazy eye”
*insult to visual system during childhood leads to failure of normal cortical visual development
*causes: strabismus, anisometropia, high refractive error, deprivation (cataract, corneal scar, ptosis)
*treatment involves treating the underlying problem and patching the good eye to force cortical development of the weaker eye
thyroid eye disease
*autoantibodies against thyroid receptors (Grave’s disease) activate orbital fibroblasts
*enlargement of extraocular muscles, fatty and connective tissue within orbit
*eye retraction, proptosis, conjunctival infection, strabismus, and double vision
*compressive optic neuropathy
visual field defects are symmetric in both eyes if insult is where?
POSTERIOR to optic chiasm
visual field defects in one eye indicate a problem where?
with eye or optic nerve, ANTERIOR to optic chiasm
