Eyes Flashcards
Eye development in children
- macula develops 4-8 months- 80% NB farsighted (decreases 7-8yrs)- eyeball adult size age 8
Eye Developments in Older Adults
- drooping (loss of skin elasticity)- lipids gather at iris/limbus- lens cannot change shape (presbyopia), discolors/thickens (cataract)- floaters in vitreous humor- glaucoma (increased pressure)
distance vision acuity test
Snellen Chart- patient at 20 ft- 20/20 (distance/where normal eye could read same line)- 20/200 = legally blind
myopia
nearsighted
hyperopia
farsighted
presbyopia
> 40; trouble reading due to loss of ability of lens to accommodate (not shape of eye)
approximate completely
when upper lid and bottom lid close completely
Pupil size
3-5mm 5 mydriasis (increase intraocular pressure - glaucoma, increase intracranial pressure)
strabismus
weakness or paralysis of 1+ extraocular muscles, due to congenital defect, orbital fracture, trauma, or CVA-related palsy
nystagmus
when eyes will oscillate in place, only normal in far lateral view
visual pathways: optic nerve cut
blind in that eye, CN2 does not cross over
visual pathways: chiasm cut
bitemporal hemianopsia: blind in temporal vision field; only the fiber on the nasal side crosses over chiasm (nasal views temporal)
visual pathways: optic tract
will lose nasal field in side that was affected and temporal field of opposite side
optic disc
fibers converge to form CN2; on nasal side, should have distinct edges; creamy yellow/pink in color
physiologic cup
small circle area inside disc - where blood vessels exit and enter
retinal vessels
4 - paired artery and vein; arteries are brighter red and narrower
general background
varies in color based on skin color
macula
temporal side, darker pigmented; surrounds fovea centralis (sharpest vision)
A-V nicking
artery crosses vein and vein disappears (common in HTN)
papilledema
- inflammation of optic disc due to intracranial pressure- cloudy around disc and no pulsations
Conjunctiva
transparent, thin mucous membrane protective layers- palpebral: lines lids, many blood vessels (clear/pink)- bulbar: overlays eyeball (clear/white sclera shows)
limbus
where 2 conjunctiva merge with cornea
lacrimal apparatus
(upper outer area of eye) - provides constant irrigation to keep cornea/conjunctiva moist/lubricated- secretes tears
3 coats/layers of the eye
sclera, choriod, retina
sclera
outer fibrous layer; bends light rays to be focused on retina; touch stimulates blinking
choroid
middle vascular - supplies blood to retina
ciliary body
muscles controls thickness of lens
lens
biconvex dish, transparent; keeps objects focused on retina; thickness controlled by ciliary body
anterior chamber
posterior to cornea, anterior to iris/lens, contains aqueous humor - continuous flow for nutrients and drain of metabolic waste(amt determined intraocular pressure)
retina
inner nervous/visual receptive layer; light waves converted to nerve impulses
fixation
reflex direction of eye towards object attracting attention; “smooth pursuits”
accommodation
adaptation of the eye for near vision - increases curvature of lens by mvmt of ciliary muscles - seen by:- convergence and constriction