4. Tropia and Phoria Flashcards
What is altnerating cover test used for and how does it work?
Important for assessing phoria. It gives time to dissociate the eyes. So smaller phoria easier to see.
What does concomitant mean?
Size of phoria/tropia remains the same in all positions of gaze and for which ever eye fixates.
What does incomitant mean?
Size of phoria/tropia changes in different positions of gaze.
Devation increases when affected eye fixates.
Often pathological and of recent onset.
For which phoria or tropia should you mention which eye?
Phoria is in both eyes.
So tropia mention which eye it is in.
What is the distribution of adult heterophoria for distance viewing?
Most of population is near zero (orthophoria).
Graph is fairly symmetrical
What is the distribution of adult heterophoria for near viewing?
Peak at 8 Exo.
Slightly more on the exo side.
Fairly symmetrical, with greater spread (meaning higher sized esophoria and exophoria)
What is the relationship between heterophoria and age at distance viewing?
Stays pretty much the same.
What is the relationship between heterophoria and age at near viewing? What could be the reasons for this?
Exophoria increase with age.
Could be due to proximal convergence, and accommodative convergence.
What is compensated heterophoria?
When the phoria is well controlled.
Most phorias are well controlled, so do not cause symptoms or break down to strabismus.
What is decompensated phoria?
A phoria that is difficult to control.
What symptoms can adults get from decompensated phoria?
Effort to maintina BSV:
Frontal headache
Eye strain
Excessive blinking
Asthenopia (Tired eyes)
Failure to maintain BSV:
Transient diplopia
Blurred vision (from manipulating accommodation)
Jumbling of letters
What are the symptoms in children from decompensated phoria?
Children can get suppression, the child’s visual system is adapting by ignoring input from one eye to avoid diplopia.
