Refractive Erros and Terms Flashcards
Amblyopia def
- lazy eye
- condition in which you lose vision d/t under use.
- dullness of obscurity of sight for no apparent reason, not correctable with glasses or surgery.
- one eye becomes dependent on the other to focus
- may lead to strabismus
Strabismus
- “Cross eyed” “eye turn” when one of the two eyes does not aim at the spot one eye is looking at.
- caused by imbalance in the muscles holding the eyeball.
Anisometropia def
-condition of the eyes in which the eyes have unequal refractive power. (one eye has much poorer vision than the other_
Aphakia
-absence of the lens of the eye
Asthenopia
eye strain
Binocular vision
simultaneous use of the two eyes, allows for wider field of vision
Convergence
- turning both eyes inwards so that they are both “aimed” towards a near object.
- poor convergence = dbl vision
Cycloplegia
-paralysis of the ciiary muscle of the eye, resulting in a loss of accommodation or…. a dilated pupil.
Diplopia
dbl vision
Exopthalmos
bulging of the eye, anteriorly out of the orbit
*may inhibit them from closing eyes while sleeping, dries out cornea leading to damage
Floaters
light spots or streaks and dark moving specks due to the vitreous traction (light flashes) on the retinal and solid vitreous material or blood (floaters)
Hemianopia
a blindness or reduction in vision in one half of the visual field due to damage of optic pathways in the brain.
Hyphema
collection of blood in the anterior chamber of the eye, can cover the entire anterior chamber.
usually caused by injury of most common is intraocular surgery. Rare fro them to occur spontaneously but it does happen.
Legal Blindness
means central visual acuity of 20/200 of less in the better eye with the best possible correction.
Limbus
the edge of the cornea where it joins the sclera
Chemosis
the swelling of the conjunctiva
- may be from allergies or excessive eye scratching
Papilledema
swelling of the optic disc caused by increased intracranial pressure.
- usually bilateral, may occur over hours to days from brain tumor hemorrhage glaucoma, etc.
Pterygium
painless non-cancerous growth of the conjuctiva that lays over the sclera and extends onto the cornea.
Pinguecula
non-cancerous yellowish-brown subconjunctival elevation composed of degenerated elastic tissue: may occur on either side of cornea.
Hypopyeon
leukocytes (pus) in the anterior chamber seen in TB herpes zoster herpes simplex virus.
Ptosis
“drooping eyelid” caused by weakness of the levator palpebrae. Damage to the nerves that control such muscles, CN III and VII
Miosis
constriction of the pupil
Mydriasis
dilation of the pupil
Nystagmus
vision condition in which the eyes make repetitive uncontrolled movements often resulting in reduced vision.
Synechia
eye condition where the iris adheres to either the cornea (anterior synechia) or lens (posterior synechia)
Scotoma
area of island of loss or impairment of vision surrounded by a field of normal vision
happens w/ MS nutritional sufficiency, rarely are these bilateral.
Scintillating scotoma
usually begins as a spot of flickering light near or in the center of the visual fields, preventing vision within the scotoma. The scotoma then expands into one or more shimmering arcs of white or colored flashing lights.
Diopter Definition
unite of measurement of the optical power of a lens, which is equal to the reciprocal of the focal length measured in meters.
*talks about the thickness of your lens (glasses)
Drusen definition
Tiny yellow or white accumulation of extracellular material build up between Bruch’s membrane and the retinal pigment epithelium of the eye.
What is the fovea?
small depression in the retina of the eye where visual acuity is the highest.
what is Keratoconus?
a degenerative disorder of the eye in which structural changes in the cornea cause it to thin and change to a conical shape rather than the normal gradual curve.
Peripheral vision
side vision, vision seen on the side when looking straight ahead
Reitinitis pigmentosa, what is this?
an inherited degenerative eye disease that causes severe vision impairment d/t progressive degeneration of rod photoreceptor cells in the retina. (Tunnel vision or night blindness)
What does OD, OS, and OU stand for?
OD- oculus dexter, right eye
OS- oculus sinister, left eye
OU- oculus uterque, both eyes
Signs and symptoms of hyperopia
aching eyes
blurred vision of close object
strabismus
eye strain
HA while reading
*some children may outgrow hyperopia as the eyeball lengthens w/ normal growth.
Diagnosis of Hyperopia
visual acuity- snellen chart
objection refraction-autorefraction machine or retinoscopy; uses rays to measure what distance an object is focused on the retina
Hyperopia
- complications
- tx
- farsightedness can be a risk factor for glaucoma and cross eye (strabismus)
- can be corrected with glasses/contacts or with refractive surgery
Myopia signs and symptoms
- often have HA or eye strain and might squint or feel fatigued when trying to see distant object
- eye strain
- difficulty reading road signs
Myopia Tx
-may be corrected with glasses/contacts or eye surgery
Surgeries include:
- Photorefractive keratectomy (PRK)
- LASIK
- Orthokeratology (re-shapes cornea while sleeping)
Signs and Symptoms of Astigmatism
- blurred/distorted vision at all distance
- photophobia
- HA
- excessive squinting
Astigmatism;
- Dx
- Tx
Dx-
- keratometer or corneal topography machine
- astigmatic dial
- visual acuity test
Tx-
- eyeglasses/contacts, unless its extreme
- Surgery= Photorefractive kerectomy (PRK) or LASIK or LASEK
At what age does presbyopia usually begin?
-40yo
Signs and Symptoms: Presbyopia
- decreased focusing ability for near objects
- need to hold things at arms length
- when performing NEAR work they may develop HA, eye strain, or fatigue
Tx of presbyopia
- bifocal or progressive addition lenses (PALS)
- reading glasses are another choice (for those who wear contact lenses you can get prescription reading glasses to wear while the contacts are in)
- surgery:
- keratoplasty
- LASIK
- Cataract Surgery
