Lecture 5 Anomalies of convergence and Accommodation Flashcards
What convergence anomalies can you get?
convergence insufficiency
convergence fatigue
convergence paralysis
covergence/accommodative spasm
What is convergence insufficiency?
what is normal amount?
Inability to obtain binocular convergence without undue effort
primary and secondary
common abnormality
6-10cm
What are the precipitating factors of primary convergence insufficiency?
illness
fatigue
drugs (antidepressants)
pregnancy
students with exam stress
change of jobs (using one eye)
computers
constant distance vision
What are the causes of secondary convergence insufficiency?
Heterphoria-converge weakness phoria
uncorrected refractive errors-not wearing glasses
Accommodative insufficiency
latrogenic weakened medial recti-surgeon can cause CI
parkinsons
thyroid eye disease
internuclear ophthalmoplegia
What are the causes of secondary convergence insufficiency?
Heterphoria-converge weakness phoria
uncorrected refractive errors-not wearing glasses
Accommodative insufficiency
latrogenic weakened medial recti-surgeon can cause CI
parkinsons- refer to GP
thyroid eye disease- refer to GP and HES
internuclear ophthalmoplegia- refer HES
What are the symptoms of convergence insufficiency?
headaches
eyestrain
difficulty changing focus
asthenopia
blurred vision (XOP decompensating)
Diplopia (XOT)
What cover test results will you get in the distance for someone who has convergence insufficiency?
Don’t need to converge in the distance a
px will be orthophoric in distant
What cover test results will you get at near for someone who has convergence insufficiency?
failure to converge at near
exophoria
exotropia if severe CI and more constant
CR will be nasally displaced
What is convergence fatigue?
*Initially able to converge properly
*Over prolonged period, convergence decreases
*Symptoms occur after prolonged near work
What cover test results are you likely to get in a px with convergence fatigue?
*Initially cover test will be normal for distance and near
*After prolonged dissociation with occluder, it may start to reveal exophoria or exotropia at NEAR.
What differences can you expect between convergence insufficiency and convergence fatigue when measuring them using an RAF rule?
CI-reduced or poorly mantained near point
CF-first attempt normal, 2/3rd attempt near point reduces
How do you measure NPC?
Test subjectively- when px reports diplopia
Test objectively- note which eye diverges first
Make sure they are wearing glasses (presbyopes SVN, hyperopes, and high myopes).
What is Jump covergence?
*Ask them to look at a distance object and then the near object
*Px looks at the green distance star and then the near red star. Each time we come back to the near object, move the red star closer to the eyes.
*Each time they look to the near object, they will be converging more and more.
What else should you measure if convergence is impaired?
accommodation
PCT
VA
stereo acuity
ocular motility
fundus exam
cycloplegic refraction
PFR- BO at near is reduced
What is the management of convergence insufficiency?
treat underlying pathology
full refractive error corrected
exercises
What exercises can you have for convergence issues?
DOT CARD- place card at the end of nose and try to keep furthest dot single.
Binocular convergence exercise with pen
Jump convergence exercises
Lend prism bar for BO
Stereogram- done at 33cm, 2 targets with some different characteristics. px stares at near object in front (pen) and moves the target until 3 figures seen.
What are the rules about giving convergence exercises?
watch px carry out exercises
symptoms may initially worsen
give a lot of encouragement
specify how long they should do them for (1-2 mins x3 daily)
MUST relax eyes afterwards by looking at objects far away to reduce risk of convergence spasm
regular monitor these px due to risk of convergence spasm
give px written instructions for exercises
tell px if you carry out exercise regularly, they will work
What is convergence paralysis?
*The ability to converge closer than infinity is entirely lost
What is the etiology of convergence paralysis?
primary or secondary
secondary: closed head injury, viral illness, occlusive vascular disease, encephalitis feature of Parinauds
What are the symptoms and signs of convergence paralysis?
-XOT with crossed diplopia
*No response to pupil constriction when eyes converge. Pupils will converge when light shone in them.
*Blurred near vision as accommodation effected
*Normal ocular movements (unless associated with neurological condition)
*Nil BO fusional reserves
*Good BI fusional reserves
What is the Management of convergence paralysis?
URGENT referral
occlusion
Botulinum toxin
BI prisms to correct XOT
if they also have accommodative insufficiency, give near ADD
What is convergence/accommodative spasm?
*We don’t know if convergence spasmed first or accommodation spasmed first
*If you get convergence and spasm accommodation spasm, you will also get pupil miosis.
*Convergence spasm: MR may become contracted
*Accommodative spasm: ciliary muscles become contracted
What is the Aetiology of convergence/accommodative spasm?
*Overzealous treatment of CI (exercising too much)
*Uncorrected hyperopia: accommodation resulting in convergence
*Intermittent distance XOT: trying to accommodate and pulling your eyes in to converge
*Organic: drugs, inflammation, alcohol. Problems with brain.
*Non organic: psychological
What are the signs and symptoms of convergence/accommodative spasm?
*Could result in esotropia (uncrossed double vision)
*Esotropia greatest in distance (as you need to relax convergence the most)
*MR are getting tighter due to convergence spasm. So, if you look to the side, esotropia will increase as MR can’t relax
*Blurred vision in the distance
*Macropsia
*Constricted pupil
*Pseudo myopia (accommodating so hard so rays fall Infront of retina)
*Headache
*Lead on dynamic ret (accommodated too much)
