Final Flashcards
What does normal visual acuity imply?
- ocular media are relatively clear 2. fovea centralis is intact. 3. CN II and visual pways are intact. 4. visual centers are intact
T or F: Normal visual acuity indicates that the eye is free of disease.
False - does NOT indicate lack of dz
What is the hardest letter to recognize?
B
What is the easiest letter to recognize?
L
What are the minimums for legal blindness?
< 20/200 in better eye OR a visual field that subtends an angle of <20 degrees
What chart do you use to indicate acuity for near vision?
Rosenbaum chart
What is known as “old vision”?
Presbyopia
What is presbyopia?
age-related loss of elasticity in lens => far-sightedness for near vision
Which msls are relaxed for far vision?
ciliary msls
When ciliary msls contract, what are they accomodating for?
near vision
What is known as the bending of light rays?
refraction (80% cornea, 20% lens)
What is emmetropia?
normal acuity (refraction of cornea and lens match the eye’s length)
What is it called when parallel light rays come to focus in front of the retina?
refractive myopia and near-sightedness. (refractive power of cornea/lens is too great)
What is it called when parallel light rays come to focus way in front of the retina?
axial myopia/high myopia and extreme near-sightedness (eyeball is too long for refractive power of eye)
What condition would have an increased chance of retinal detachment?
axial myopia/high myopia/extreme near-sightedness
What is it called when parallel light rays come to focus behind the retina?
refractive hyperopia and far-sightedness (refractive power of cornea/lens is too little)
What is it called when parallel light rays come to focus way behind the retina?
axial hyperopia and extreme far-sightedness (eyeball too short for refractive power of eye)
What has an increased chance of acute glaucoma?
axial hyperopia and extreme far-sightedness
What is defined as “unequal refraction in different meridians of the eyeball”?
astigmatism
What does an astigmatism cause difficulties in seeing?
fine detail
What is a “regular” astigmatism?
different degrees of refraction in vertical and horizontal planes => two focal points (right angle)
What is an “irregular” astigmatism?
different degrees of refraction in 2 or more meridians (NOT at right angle)
What are objective blind spots when assessing peripheral vision called?
negative defects
What are perceived blind spots called when assessing visual fields?
positive defects