HLTH 2501: the eye Flashcards
what is the eye protected by?
the body orbit of the skull
muscle of the upper eyelid
the levator palpebrae superioris
what is the levator palpebrae superior controlled by?
the oculomotor nerve (III)
cranial nerves controlling the extrinsic eye muscles
III, IV, and VI
outer layer of the eye
is a tough, fibrous layer consisting of the cornea and the sclera
middle layer of the eye
aka the uvea; is made up of the choroid, the ciliary body, and iris
the choroid
is a dark, vascular layer that absorbs the light, preventing reflection
what supplies blood to the retina?
the choroid
ciliary processes
secrete aqueous humor
two muscles in the iris
the circular (contracts) and the radial (dilates)
lens
is a biconvex structure made up an elastic capsule surrounding an orderly alignment of fibres
retina
the inner layer that consists of the pigmented layer and the neural layer
fovea centralis
is a depression within the macula lutea that contains many cones and provides the most acute vision
colour blindness
is common in males and results from a deficit of one type of cone owing to an abnormal gene on the X chromosome
posterior cavity
is the space between the lens and the retina and contains the vitreous humor
anterior cavity
is between the cornea and the lens and is filled with aqueous humor and is further divided into the anterior chamber (cornea to iris) and the posterior chamber (iris to lens); the chambers are connected through the pupil
where is aqueous humor secreted from and where is it drained into?
secreted from the ciliary processes into the posterior chamber and drained from the anterior chamber by the canal of Schlemm
what does the aqueous humor supply?
nutrients to the lens and cornea because they lack blood vessels
complications of conjunctivitis
meningitis, cellulitis, septicemia, otitis media, pneumonia, and keratitis
otitis media
ear infection
what provides depth perception?
the double image projected rom different angles by both eyes
what pass through the optic disc?
the central retinal artery and vein
diagnostic tests for eye function
the snellen chart, visual field tests, tonometry, ophthalmoscope, gonioscopy measures, and muscle function and coordination
the snellen chart
consists of line of progressively smaller letters and numbers, measuring visual acuity
what are visual field tests used for?
to check central and peripheral vision
tonometry assessment
assess intraocular pressure by checking the resistance of the cornea
ophthalmoscope
is used to examine the interior structures of the eyes
gonioscopy
measures the angle of the anterior chamber
myopia
is nearsightedness and occurs when the image is focused in front of the lens; corrected with concave lens
hyperopia
is farsightedness and occurs when the image focuses behind the retina; is corrected with convex lens
presbyopia
is farsightedness associated with aging when the loss of elasticity reduces accommodation
astignmatism
develops from an irregular curvature in the cornea or lens
strabismus
results from a deviation of one eye, resulting in double vision; this is cross-eye
diplopia
aka double vision
what may strabismus be caused by?
a weak or hypertonic muscle, a short muscle, or a neurological defect