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