Convergence Vocab Flashcards
Convergence provides pt with
Binocular, single vision
Superior rectus major action and innervation
Elevation of the eye. Front of the eye moves up and the back of the eye moves down. Innervated by CN 3
Inferior rectus major action and innervation
Depression of the eye. Front of the eye moves down and the back of the eye moves up. Innervated by CN 3
Medial rectus
Adduction. Inward motion. CN III
Lateral rectus
Abduction. Outward motion. CN VI
Superior oblique
Depression, but not along the midline. CN IV
Inferior oblique
Elevation, but not along the midline. CN III
Which two muscles are not innervated by CN III
LR6SO4
Convergence
The function, whereby the eyes turn in to maintain single vision. Easier to do than divergence
Fusion-meter angles dioptric stimulus
Total amount of turning in of two eyes to fixate at a distance
Prism diopters
1 cm deviation of light at 1 meter
Pupillary distance
Distance between the two eyes
To determine the prism dipper stimulus to converge (amplitude of accommodation), multiply the ___ x ____
Reciprocal of distance (D) by PD in cm = prism dipper stimulus to converge at that moment
Purpose of prism
Deviates path of light
“Ductions” are
monocular eye movements
Adduction
Movement of the line of sight of one eye towards the body’s midline
Abduction
Movement of the line of sight from one eye away from the body’s midline
Supraduction
Movement of the line of sight of one eye above the straight ahead position. Above primary gaze. Technically 1 eye only.
Infraduction
Movement of the line of sight of one eye below the straight ahead position- below primary gaze. Technically 1 eye only.
“Versions” are
Parallel movement of both eyes
Dextroversion
parallel movement to the right
Levoversion
Parallel movement to the left
Supraversion
Parallel movement up (implying both eyes)
Infraversion
Parallel movement down (implying both eyes)
Divergence
Movement of lines of sight away from the body midline or away from each other. Hard to do, based on muscle insertion.
Fusional vergence
Convergence moment with no associated change in accommodation.
Phorias
The lines of sight meet at the same point, after any tendency has been overcome.
Eyes have the tendency to not align properly for target. Eyes tweak convergence to fix this, but they have to work for it.
Equivalent to a hyperope and emmetrope looking at a distance- they can both see clearly but a hyperope has to work for it.
Phorias must be uncovered by testing.
Orthophoria
The two eyes converge directly on the target, with no tendency to turn in or out, up or down.
Convergence equivalent to emmetrope.
Exophoria
Eyes converge at a point beyond the object. They don’t converge enough. This tendency is overcome by positive fusional vergence. (PFV)
The eyes naturally want to align outside of the target. Most converge more/PFV.
Pt is unaware that this is occurring. Might have fatigue.
Esophoria
Eyes converge at a point in front of the object. They converge too much. This tendency is overcome by negative fusional vergence (NFV).
The eyes naturally want to align closer than the target. Eyes must diverge/NFV. If not overcome, would see clearly but the object would be doubled.
Hyperphoria
Relative misalignment of the line of sight of one eye to the other. One eye has a line of sight with the tendency to be displaced upward relative to the other eye. This person will see double all over the place- distance and near unless they overcome it by vertical fusion vergence.
Independent of accommodation.
Hypophoria
The tendency of one eye to have a line of sight that is below the other. This tendency is overcome by vertical fusional convergence.
Independent of accommodation
How to describe when pt has hyperphoria or hypophoria
Only talk in terms of hyperphorias to keep things simple.
Strabismus
A deviation of one eye relative to the other- also called tropia/squint/strab/lazy.
Deviation of the eye cannot be overcome. Cannot use fusional vergence to the degree needed to get the eye aligned.
This person is not binocular. Binocular means 2 eyes working at the same time and seeing the same thing.
They can be biocular- Both eyes are seeing something, but what they are seeing is not the same = double vision.
They could also see clearly, but have one eye suppressed.
Exotropia
The deviation of one eye out
Esotropia
The deviation of one eye in.
Hypertropia
The deviation of one eye up
Hypotropia
The deviation of one eye down
Binocular vs biocular
Binocular- both eyes working at the same time and seeing the same thing. Single vision.
Biocular- both eyes are seeing something, but what they are seeing is not the same. Double vision.
Strabismus and ___ are synonyms
Tropia
The difference between exotropia and exophoria
Exophoria- eyes tend to converge at a point beyond the object. The patient is able to use positive fusional vergence to adjust accommodation and get eyes to focus on the correct object. Vision is clear, but work is done to see clearly. Pt is unaware of this extra work, but they might have fatigue.
Exotropia- One eye turned out, and pt is not able to overcome the deviation with negative fusional vergence. Pt is either biocular (has double vision) or one eye is suppressed.
Little person with esotropia. This pt has what refractive error?
Uncorrected hyperope, and likely at a high magnitude. Pt is trying to accommodate so much that the eye turns in due to the near point triad.
Pt needs to see doctor, preferably before the age of 7-11 so that the esotropic eye can be corrected, so it is not suppressed and the neural pathway isn’t diminished.
Fusion
The images seen by two eyes being coordinated into one image cortically, in the brain.
Suppression
Cutting off vision in one eye cortically, because fusion is not possible.
Monocular
Only one functional eye, or only one of the two eyes is seeing. Lost due to disease/infection or suppression.
Tonic position
Where eyes want to go to. Their happy place. The position of the two eyes at far point with NO STIMULUS TO ACCOMMODATION OR CONVERGENCE, the physiological position of rest; measured at far point.
Proximal/psychic convergence
Vergence brought about due to the awareness of the nearness of an object. Ex: pt may become more esophoric. Do all binocular testing outside phoropter.
Fusional vergence
Vergence movement with no associated change in accommodation. No change in accommodation. Purely muscle movement.
Anatomical position of rest
When all innervation to the extra muscles has been removed, in deep anesthesia or death, the eyes are usually up and out.
Minus lenses look like a series of prism __ to __
Apex to apex
Plus lenses look like a series of prism __ to __
Base to base
Prism: Light deviates towards the ___
Image appears to be shifted towards the ___
Base
Apex
If light enters through the optical center of the prism, light will travel in which direction?
Undeviated. If light enters in any other location, it will travel towards the base.
An orthophore is made artificially esophoric by the addition of
BI prism
Negative fusional vergence
An orthophore is made artificially exophoric by the addition of ___. They would then need to use ___ fusional mergence to maintain fusion.
BO prism
Positive fusional vergence
Exophores are corrected, or neutralized by ___. Now the pt can use less ___
BI prism
Pt uses less PFV
Exophores are made worse by the addition of ___. Now they have to use more ___ fusional vergence.
BO prism. They must use even more PVF vergence
Esophores are corrected, or neutralized with __ prism
BO prism. This allows them to use less NFV
Esophores are made worse by the addition of __ prism. They now have to use more ___ fusional vergence.
BI
NFV
Punctum remotum of convergence
The position of the lines of sight when fusion is removed during far point fixation with accommodation relaxed.
Position of tonic convergence
Where is the PR for an
- Orthophore
- Exophore
- Esophore
- Infinity
- Beyond (express as a negative value. Although stimulus is zero, pt still has work to do)
- Infront. (Less work to do inside infinity. They don’t start converging until you pass their esophoria)
Punctum proximum
The closest point at which the patient can maintain single binocular vision, determined by performing the near point of convergence.
Measured in cm, at the lateral canthus.
Amp of convergence
The prism dioptric difference between the PR and the PP
When we add prism to a pt’s glasses, what are we doing?
We are NOT correcting their muscle alignment. We have simply moved the image plane to their eye’s happy place. Now pt does not have to use fusional vergence to see singly and binocularly.