Dr. Jensen's lecture Flashcards
What is the definition of AC/A
The change in the near lateral phoria measurement that is produced by a specific change in the stimulus to accommodation, usually 1 D. AKA change in accommodative convergence/change in accommodation
How do you determine gradient AC/A
- measure near lateral phoria at 40 cm
- Add +1.00 sphere to change the stimulus of accommodation by 1 D.
- Measure the near lateral phobia through the +1.00 sphere.
- Take the difference between the two (taking the signs into consideration) and put 1 as the denominator.
- Take the absolute value
Change in convergence includes both accommodative convergence and ____ convergence
proximal
what is the equation for convergence demand?
PD x MA = PD (cm)/ TD (m)
MA = 1/TD (m)
- 64 mm = 6.4 cm
- 40 cm = .4 m
What are normal findings for gradient AC/A
4/1 +/- 2
So: 2/1 through 6/1
What is the definition of accommodative insufficiency and what are patient characteristics?
Symptoms such as blurry vision at near, discomfort or strain with near tasks, fatigue associated with near tasks, and difficulty with attention and concentration at near. Often associated with ESOPHORIA at near.
What are characteristics of accommodative insufficiency
- Low accommodative amplitudes
- Low PRA
- Typically will accept plus at near regardless of age
What is Panum’s area?
Within certain limits, fusion is possible when the two retinal images of an object are not formed on corresponding retinal points. Panama’s area is the area around a corresponding retinal point in one eye within which stimulation still produces sensory fusion. AKA fudge factor
_____ convergence is Convergence made by extraocular tonus (fixation = infinity)
Tonic
_______convergence is Convergence due to awareness of a near object (phoropter may generate this)
proximal
_____ vergence is Typically autonomic but can be voluntary. When your brain notices that you need to put two images together. (Image falls outside Panum’s Fusional area) 3 Types (all disjunctive movement):
Fusional
