mock 1 - concepts Flashcards
what is fixation disparity?
small alignment of visual axis is measured under associated conditions
what is associated conditions?
images from each eye are fused by the pt
- ex fixation disparity
what are the adverse effects of tetracyclines?
bone growth retardation
discoloring of teeth
IIH/ pseudotumor cerebri
what is dissociated conditions?
each eye views a different object and the images from the two eyes are not fused.
ex - Maddox rod, cover test, von graefe
the tectospinal tract is thought to be involved in …..?
reflexive head movements in response to visual stimuli
what is contained in the middle ear?
- tympanic cavity
- auditory ossicles (malleus, incus, stapes small ear bones)
- stapedius
- tensor tympani
what is contained in the inner ear?
semicircular canals
what is sensitivity?
ability of a test to accurately detect the pt has the disease
what is specificity?
ability of a test to accurately detect a pt does NOT have a given disease
what is spositive predictive value?
probabitlity the pt has the disease given the test is positive
what is negative predictive value?
probability the pt does not have the disease given the test is negative
what are the retinal signs of non-exudative (dry) AMD?
drusen
RPE mottling or granularity
RPE atrophy
offical RPE hyperpigmentation
what are signs of choroidal neovascularization in exudative (wet) AMD?
subretinal fluid
sub-RPE fluid
subretinal hemorrhage
sub-RPE hemorrhage
CL power will have less ___ (more ___) power compared to spectacle lens
less minus (more plus)
ex. Spec rx = -6.50D
CL rx = -6.0D
a keratometer measures the radius of curvature of the cornea by treating the cornea as what type of surface?
Convex mirror - the cornea forms a reflected image of the keratometer mires. The size of the reflected image is used to determine the radius of curvature of the cornea
corneal epithelium is derived from _____?
surface ectoderm
the lens vesicles develops from ___?
develops in response to the formation of the optic cups
the neural crest cells form the ____ and _____?
corneal stroma and corneal endothelium
what is holocrine secretion?
entire cell that contains the product is shed into the lumen of the duct
ex. meibomian glands
what is apocrine secretion?
the products of the cell are secreted into a membrane-bound vesicle into the lumen.
Ex.
goblet cells
glands of Moll
what is merocrine secretion?
cell products are simply exocytosed into the lumen
ex. main lacrimal gland
the parvocellular pw is responsible for
detection of detail
color
perception of size, shape, detail
receives infor from neurons in central retina that are sensitive to high spatial frequencies
what is the magnocellular pw responsible for?
detection of motion
-receive infor from peripheral retinal neurons that are sensitive to low spatial frequencies
what is the MOST common causes of prespetal cellulitis?
Hordeolum **
- ocular infection (hordeolum, dacryocystitis)
- systemic infection (upper respiratory tract, middle ear infections, skin trauma (wound, insect bite
What is the most common cause of orbital cellulitis?
- sinus infection (ethmoiditis)
orbital fracture, dental infection
color vision is determined by ….?
the relative responses of photoreceptors based on the number of photons absorbed
-wavelength determines the probability the photon is absorbed by photopigment w/in photoreceptor
- color vision is based on the relative responses of different photoreceptors based on the number of photons each absorbed
what is the principle of univariance?
once photon is absorbed, all info regarding the wavelength of the photon is lost.
therefore, a single photoreceptor cannot discriminate btw colors as it cannot distinguish btw the intensity of different photons.
what is the MOST common benign orbital tumor in children ?
Capillary hemangioma
- cause proptosis
- deprivation amblyopia
what is the most common benign orbital tumor in adults?
cavernous hemangioma
what is the most common secondary orbital malignancy in children?
neuroblastoma
what is the most common primary pediatric orbital malignancy?
rhabdomyosarcoma
