Ophthalmology Terms and Refractive Errors Flashcards
Pathology of Amblyopia?
Dullness or obscurity of sight for no apparent organic reason, therefore, not correctable with glasses or surgery.
How can someone see with amblyopia?
One eye becomes dependent on the other eye to focus, usually develops in early childhood.
What is Anisometropia?
Condition of the eyes in which the eyes have unequal refractive power.
Whats Aphakia?
Absence of the lens of the eye
Whats Asthenopia?
eye strain
Whats Binocular vision?
Simultaneous use of the two eyes.
Allows for a wider field of vision.
What is convergence?
Turning both eyes inwards so that they are both “aimed” towards a near object. (people with poor convergence will get double vision)
What is cycloplegia?
Paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation or……… a dilated pupil (cant focus on near by objects)
What secondary issues come out of exophthalmos?
cant close their eyes while they are sleeping. dries their eye out and can damage the cornea
Whats hemianopia?
What are common causes of this?
a blindness or reduction in vision in one half of the visual field due to damage of the optic pathways in the brain.
Stroke or brain tumor
What is hyphema?
What are some common causes of this? 3
collection of blood in the anterior chamber
intraocular surgical procedures or blunt trauma to the eye. could occur spontaneously but pretty rare
What is the pathology of hypopyon?
What are some common causes? 3
leukocytes in the anterior chamber=pus
TB, herpes simplex, herpes zoster
Definition of legal blindness
means central visual acuity of 20/200 or less in the better eye with the best possible correction
What is chemoses?
the swelling (or edema) of the conjunctiva --sign of eye irritation. allergies/rubbing or scratching the eye
What is papilledema?
Swelling of the optic disc caused by increased Intracranial Pressure
- biateral usually
- disc is raised
What is pterygium?
A painless non-cancerous growth of the conjunctiva that lays over the sclera and extends onto the cornea
What is Pinguecula?
Non cancerous yellowish-brown subconjunctival elevation composed of degenerated elastic tissue; may occur on either side of the cornea.
(most along the nasal side)
What cranial nerve is affected in ptosis and what could it be caused by? 5
CNIII
- damage to nerves that control muscle responsible for raising eyelid or
- looseness of the skin of the eyelid
- tumor
- diabetes
- stye
What is miosis?
constriction of the pupil
What is mydriasis?
dilation of the pupil
What can cause nystagmus?
3
stroke
MS
blow to the head
What is synechia?
an eye condition where the iris adheres to either the cornea (i.e. anterior synechia) or lens (i.e. posterior synechia).
What is scotoma?
What can this be caused by? 3
Area or island of loss or impairment of vision surrounded by a field of normal vision
MS, toxic substance that gets in the eye, nutritional deficiencies, rarely bilateral
What is a scintillating scotoma?
When are these often seen?
usually begins as a spot of flickering light near or in the center of the visual fields, which prevents vision within the scotoma. The scotoma then expands into one or more shimmering arcs of white or colored flashing lights.
migraines/aura
What does diopter tell us?
basically the thickness of your glasses-how much correction you need
What are tiny yellow or white accumulations of extracellular material build up between Bruch’s membrane and the retinal pigment epithelium of the eye?
What can we get these from?
drusen
macular degeneration
What is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a conical shape than a normal gradual curve?
keratocnus
What is retinitis pigmentosa?
(what is it caused by,
What does it cause,
pathology)
- An inherited degenerative eye disease
- that causes severe vision impairment
- due to progressive degeneration of rod photoreceptor cells in the retina
What symptoms are associated with retinitis pigmentosa?
night bindness or tunnel vision
What does OD stand for?
Oculus dexter (right)
What does OS stand for?
Oculus sinister (left)
What does OU stand for?
Oculus uterque (both)
What is emmetropia?
3
What can be seen clearly when the ciliary muscle is relaxed?
When
- parallel light rays from distant objects
- are in sharp focus on the retina
- when the ciliary muscle is completely relaxed
distant objects
What risk factors is farsightedness associated with?
3
Maternal smoking during pregnancy
Prematurity
Low birth weight
What are the signs and symptoms of hyperopia?
5
Aching eyes Blurred vision of close objects Strabismus Eye strain Headache while reading
What are the causes of hyperopia?
2
- by the eyeball being too small or
- the focusing power being too weak.
Many children outgrow hyperopia as the eyeball lengthens with normal growth
HOw do we diagnose hyperopia?
2
Visual acuity (snellen chart)
Objective refraction using retinoscopy
-uses rays to measure what distance an object is focused on the retina
What can farsightedness be a risk factor for?
2
glaucoma
cross eye
How can farsightedness be corrected?
3
with glasses or contact lenses
refractive surgery
Whats the most common refractive error of the eye?
Why is this increasing?
myopia
from eye fatigue from computers and near vision tasks (also a genetic predisposition)
Signs and symptoms of myopia?
2
- Often have headaches or eye strain and might squint or feel fatigued when driving or playing sports
- Blurred vision or squinting when trying to see distant objects (children often cannot read the blackboard, but can easily read a book)
What causes myopia?
When the eyeball is longer than usual from front to back
Treatment of myopia?
3
May be corrected with glasses contact lenses or eye surgery
What surgeries could we do to fix myopia?
3
- Photorefractive keratectomy (PRK) -predecessor to LASIK
- LASIK
- Orthokeratology (contact lens that you wear at night and shapes your cornea and during the day it will change to that shape. put them back in at night)
What is a condition which the eye does not focus light evenly onto the retina?
astigmatism
light is bent differently dependiing on where it strikes the cornea(irregularly shaped)
Is astigmatism associated with farsightedness or nearsightedness?
both
What is irregularly shaped in astigmatism?
The cornea but sometimes it can be the lens too
Signs and symptoms of astigmatism?
4
Blurred or distorted vision at all distance
Photophobia
HA
Excessive squinting (close their eyes constantly tryinig to focus)
Explain the pathology of astigmatism?
3
- Astigmatism occurs when the cornea is oblong instead of spherical
- In most astigmatic eyes, the oblong or oval shape causes light rays to focus on two points in the back of the eye, rather than on just one.
- This is because, like a football, an astigmatic cornea has a steeper curve and a flatter one.
How do we diagnose astigmatism?
3
- Keratometer or corneal topography machine (asses shape of anterior cornea)
- Astigmatic dial
- Visual acuity test
Treatment of astigmatism?
3types
eyeglasses or contact lenses
3 kinds:
Rigid
Gas permeable
Soft
Which surgery techniques can be used for astigmatism?
2
Photorefractive keratectomy (PRK) LASEK or LASIK
What happens to the lens as a person grows older?
4
- Lens grows larger and thicker
- Lens becomes far less elastic
- Ability of the lens to change shape decreases
- Power of accommodation decreases to almost 0 diopters by the age of 70
What do people notice when they first start getting presbyopia?
blurred near vision
Signs of symptoms of presbyopia?
3
- Decreased focusing ability for near objects.
- When people develop presbyopia they need to hold things at a arms length to read it
- When they perform near work, such as embroidery or handwriting, they may develop headaches, eye strain or feel fatigued.
What specially changes in the lens that makes it harder, firmer and less elastic?
- proteins in the lens
2. and muscle fibers surrounding the lens
With less elasticity the eye has a harder time focusing where?
up close
Treatment for presbyopia?
eyeglasses with bifocal or progressive additional lenses (PALS) are the most common corrective lenses for presbyopia
What do the upper and lower parts of bifocals help see?
the main part of the lens is a prescription for distance vision and the lower part is a stronger prescription for close up work
Surgeries to correct Prebyopia?
3
Keratoplasty
LASIK
Cataract surgery
