Difference between revisions of "Convergence ability"

From EyeWiki
m
 
(14 intermediate revisions by 4 users not shown)
Line 2: Line 2:
 
|Authors=Liene;Muceniece
 
|Authors=Liene;Muceniece
 
|Category=Pediatric Ophthalmology/Strabismus
 
|Category=Pediatric Ophthalmology/Strabismus
|Reviewer=Liene;Muceniece
+
|Assigned editor=Donny.Suh
|Date reviewed=May 31, 2017
+
|Reviewer=Donny.Suh
|Article status=Not reviewed
+
|Date reviewed=September 9, 2019
|Local Videos=
+
|Article status=Up to Date
 
}}
 
}}
 +
{{Infobox disease
 +
| Name = {{PAGENAME}}
 +
| DiseasesDB =
 +
| ICD9 =
 +
| ICD10 =
 +
| OMIM =
 +
| MeshID = D003290
 +
| MedlinePlus =
 +
}}
 +
 +
= Diagnostic Intervention  =
 +
== Description/Overview ==
 
Convergence ability can be tested with 2 different methods:
 
Convergence ability can be tested with 2 different methods:
1. Near point of convergence (NPC)  - is the point where the visual axes intersect under the maximum effort of convergence. It is a measure of pursuit convergence.
 
2. Jump convergence - convergence level increased by rapid jump to closer point. A qualitative assessment of the quality of convergences fixation jumps from distant to mid-distant target at near point.
 
  
Convergence ability should be a part of routine examination. Patients with a poor convergence  can be suffering from headache and diplopia while they read. As well people can complain of blurry words after some time of reading. Child can be shy and not complain about this symptoms. Still, need to be reminded that patients with convergence weakness can be asymptomatic. If a child is noticed by convergence weakness  it should be re-tested and obtaining a history of patients complains. Asymptomatic convergence weakness don't need any specific treatment.
+
# Near point of convergence (NPC)  - is the point where the visual axes intersect under the maximum effort of the convergence. It is a measure of pursuit convergence.
 +
# Jump convergence - the convergence level being increased by rapid jump to a closer point. A qualitative assessment of the convergence quality of fixation jumps from distant to  the near target point.
 +
 
 +
 
 +
The convergence ability should be a part of routine examinations. Patients with a poor convergence  while reading something can suffer  from headache and diplopia. People also can complain of blurred words after reading. Sometimes children are shy and do not complain about this symptoms. Surprisingly patients with poor convergence can also be asymptomatic. If a child is diagnosed  with convergence weakness  he should be re-tested and it is useful to obtaining a full history of complains. In general  asymptomatic convergence weakness don't need any specific treatment.
 +
 
 
It is not appropriate to test convergence ability for heterotropia patients
 
It is not appropriate to test convergence ability for heterotropia patients
  
 
= Near point of convergence  =
 
= Near point of convergence  =
This is a standard test for convergence ability. It is easy to make and does not require special equipment.
+
This is a standard test for convergence ability. It is easy to perform and does not require special equipment.
Equipment: fixation target and ruler.
+
As a fixation target can be used a pencil or pen. To get child attention it is better to use some small toy with common character. It should be with small details that are clearly to see. It is available to use some specific ruler for convergence and accommodation ability testing.
+
If there is a high level myopia or hypermetropia test should be done with needed correction.
+
  
== Test performing  ==
+
Equipment: A fixation target and a ruler.
  
1. Patient should sit straight and look directly to fixation object what is placed at nose level approximately 50 cm from it.
+
The fixation target is a pen or pencil. To get the child's attention a small toy with common character can be used. It should be with small details that are clear to see. Also there is special ruler for convergence and accommodation test.
2. Room should be illuminate well so there could be option to see any changes at eye movements
+
3. Slowly and smoothly move fixation object closer to patient, speed should be proximately 10s to move it from 40 cm till nose.
+
4. Ask for the patient to say when there is 2 objects. It should be explained for patient that object can become blurry, but still need to fixate to it.
+
5. While performing test should examine patients eyes because some patients are not feeling diplopia. When one of eyes is not fixating to object anymore then is found near point of convergence.
+
6. Move fixation object more far from patient till both eyes start to fixate on subject - there is a recovery near point of convergence.
+
  
Test should be performed more than one time to be sure that patient understood and concentrate to test. For patients with convergence insufficiency repeated tests will give more far near point of convergence.
+
If there is a high level myopia or hypermetropia test should be done with needed correction in advance.
  
[http://eyewiki.org/File%3ANear_point_of_convergence.jpg]
+
== Test performing  ==
 +
 
 +
# Patient should sit down in a comfortable chair with looking directly at the fixation object that is placed at the nose level approximately 50 cm from it.
 +
# Room should be well illuminated so the examiner could notice minimal changes in eye movements.
 +
# Examiner will move the fixation object slowly and smoothly close to the patient's nose. Moving speed should be proximately 40 cm in 10 seconds.
 +
# Ask the patient to note when he sees the fixation object in double. We should explain to the patient that object can become blurry, but still need to continue to fixate on it.
 +
# While performing the test, the examiner should observe the patient's both eyes because some patients do not notice diplopia - when one of the eyes is not fixating to the object.  As a result this point is the near point of the convergence .
 +
# Move the fixation object far front from both eyes of the patient until they start to fixate on the object. Keep in mind that there is a recovery point when we are moving from the diplopia point to the point where the convergence will act again.
 +
 
 +
 +
The test should be performed more than once to be sure that the patient understood and will follow the test. For the patients with convergence insufficiency repeated tests will move the near convergence point far from the previous ones.
 +
<gallery widths="200px" heights="240px">
 +
image: Near point of convergence.jpg
 +
</gallery>
  
 
=== Results  ===
 
=== Results  ===
  
Normal near point of convergence is about 6-10 cm. but convergence renewing point till 15 cm. If NPC is more than 10 cm it is a sign of poor convergence. Meanwhile recovery near point of convergence that is more than 15 cm can be a cause of astenopic complains if there is an intense reading.
+
Normal near point of convergence is about 6-10 centimetre for normal eyes but the convergence recovery point (CRP) is until 15 centimetre. If the near point of convergence (NPC) is more than 10 centimetre there is sign of poor convergence.  
  
Result of test should be noted for example, NPC 7cm, CRP 12 cm
+
In addition, long hours and intense reading in people with convergence problem can cause asthenopia (diplopia and headaches). In this situation the recovery near point is more than 15 centimetre.
 +
 
 +
The results of the test should be noted for example, NPC 7cm, CRP 12 cm
  
 
= Jump convergence  =
 
= Jump convergence  =
Test is more realistic to typical near viewing situation. Test can be used additionally for patients that are showing some signs of convergence insufficiency.
+
This test is more realistic to typical near viewing situation. As additional test it can be used for the patients with signs of the convergence insufficiency.
Equipment: dot card or Brock string. Length of card can be variating but not smaller than 20 cm. At the middle of card is well seen points that are placed 1-2 cm from each other
+
 
If patients is high myopic or hypermetropic then test should be performed with needed correction.
+
Equipment: The Dot Card or Brock String. The length of the card can be vary  but must not be shorter than 20 centimetre. There are some black points at the midline of the card that are placed 1-2 centimetre from each other.
 +
 
 +
If the patient is high myopic or hypermetropic then the test should be performed with needed correction.
  
 
== Test performing  ==
 
== Test performing  ==
  
1. Patient should sit straight. At the end of nose add a dot card.
+
# Patient should sit down in a comfortable chair and the card is placed at the patient's nose level.
2. Room should be well illuminated, so it would be easily to notice any changes at eye movements.
+
# Room should be well illuminated, so any changes in eye movements can be noticed easily.
3. Patient is asked to fixate at forest point on the card and should ask:
+
# Patient will be asked to fixate at the farthest point at  the card and should be asked:
- how many lines are there
+
#*<code>How many lines are there?</code>
- are they crossing at this fixation point
+
#*<code>Are these lines crossing at the fixation point?</code>
4. If patient can fixate to this point then move to closer point till patient see 2 parallel lines or just one eye (other eye is suppressed)
+
# If the patient can fixate to this point then move it to the closer point until the patient sees two parallel lines or just one line (in this case the other eye is suppressed)
5. Last point where patient can see 2 lines that are crossed at the fixation point is near point of convergence.
+
# The closest point where the patient can see these two lines crossing at the fixation point is the near point of convergence (NPC).
 +
  
Test should be performed more than one time to be sure that patient understood and concentrate to test. For patients with convergence insufficiency repeated tests will give more far near point of convergence.
+
The test should be performed more than once to be get sure that the patient understood and will follow the procedure. For patient who has convergence insufficiency repeated tests will move the near convergence point far from the previous ones.
 +
 
 +
<gallery widths="200px" heights="240px">
 +
Image: Jump_convergence.jpg
 +
Image: Jump_convergence_(close).jpg
 +
</gallery>
  
 
===Results  ===
 
===Results  ===
  
Test results should be written down for example convergence 8 cm (Brock string)
+
Test results should be written down for example convergence 8 centimetre  (Brock String)  
Person with a good convergence ability both test should show similar results.  
+
 
 +
In an individual with a good convergence ability both tests should show the similar results.  
  
 
=Most commune errors=
 
=Most commune errors=
1. Relying upon subjective NPC measures. Objective observation should be done to notice converge
+
# Relying on subjective near point convergence (NPC) measures and not objective observation of the eye fixation.
2. Carrying test only once.
+
# Doing the test only once.
3. Moving the target too rapidly that can over estimate convergence ability. Moving target too slowly so child is loosing interest of it.
+
# Moving the target too fast that can over estimate the convergence ability or moving the target too slow so the child can lose the interest of doing the test.
4. Not encouraging patient enough to keep the NPC target - use different targets for children each time.
+
# Not complying patient or where the examiner is not encouraging the patient (most of the time a child) to follow the NPC target. Using different objects at each time.
5. Not testing at slight downward gaze
+
# Not testing the patient in non standard gaze for convergence studies which is slight downward gaze for example testing in upward gaze.
  
  
 
= References  =
 
= References  =
  
1. David B. Elliott PhD, Clinical procedures in Primary eye care Fourth edition. Elsevier limited, 2014
+
# David B. Elliott PhD, Clinical procedures in Primary eye care Fourth edition. Elsevier limited, 2014
2. Brad Bowling Kanski's Clinical ophthalmology Eight edition. Elsevier limited, 2016
+
# Brad Bowling Kanski's Clinical ophthalmology Eight edition. Elsevier limited, 2016
3. Frank Eperjesi PhD, Hannah Bartlett PhD, Mark Dunne PhD Ophthalmic Clinical Procedures Elsevier limited, 2007
+
# Frank Eperjesi PhD, Hannah Bartlett PhD, Mark Dunne PhD Ophthalmic Clinical Procedures Elsevier limited, 2007
4. Darcy A.Umphred PhD, Gordon U.Burton PhD, Rolando T. Lazaro PhD, Margaret L. Roller Umphred's neurological rehabilitation Six edition. Mosby, 2013.
+
# Darcy A.Umphred PhD, Gordon U.Burton PhD, Rolando T. Lazaro PhD, Margaret L. Roller Umphred's neurological rehabilitation Six edition. Mosby, 2013.

Latest revision as of 08:30, September 10, 2019

Assigned editor:
Review:
Assigned status Update Pending
 by Donny W. Suh, MD,FAAP on September 9, 2019.


Convergence ability


Diagnostic Intervention

Description/Overview

Convergence ability can be tested with 2 different methods:

  1. Near point of convergence (NPC) - is the point where the visual axes intersect under the maximum effort of the convergence. It is a measure of pursuit convergence.
  2. Jump convergence - the convergence level being increased by rapid jump to a closer point. A qualitative assessment of the convergence quality of fixation jumps from distant to the near target point.


The convergence ability should be a part of routine examinations. Patients with a poor convergence while reading something can suffer from headache and diplopia. People also can complain of blurred words after reading. Sometimes children are shy and do not complain about this symptoms. Surprisingly patients with poor convergence can also be asymptomatic. If a child is diagnosed with convergence weakness he should be re-tested and it is useful to obtaining a full history of complains. In general asymptomatic convergence weakness don't need any specific treatment.

It is not appropriate to test convergence ability for heterotropia patients

Near point of convergence

This is a standard test for convergence ability. It is easy to perform and does not require special equipment.

Equipment: A fixation target and a ruler.

The fixation target is a pen or pencil. To get the child's attention a small toy with common character can be used. It should be with small details that are clear to see. Also there is special ruler for convergence and accommodation test.

If there is a high level myopia or hypermetropia test should be done with needed correction in advance.

Test performing

  1. Patient should sit down in a comfortable chair with looking directly at the fixation object that is placed at the nose level approximately 50 cm from it.
  2. Room should be well illuminated so the examiner could notice minimal changes in eye movements.
  3. Examiner will move the fixation object slowly and smoothly close to the patient's nose. Moving speed should be proximately 40 cm in 10 seconds.
  4. Ask the patient to note when he sees the fixation object in double. We should explain to the patient that object can become blurry, but still need to continue to fixate on it.
  5. While performing the test, the examiner should observe the patient's both eyes because some patients do not notice diplopia - when one of the eyes is not fixating to the object. As a result this point is the near point of the convergence .
  6. Move the fixation object far front from both eyes of the patient until they start to fixate on the object. Keep in mind that there is a recovery point when we are moving from the diplopia point to the point where the convergence will act again.


The test should be performed more than once to be sure that the patient understood and will follow the test. For the patients with convergence insufficiency repeated tests will move the near convergence point far from the previous ones.

Results

Normal near point of convergence is about 6-10 centimetre for normal eyes but the convergence recovery point (CRP) is until 15 centimetre. If the near point of convergence (NPC) is more than 10 centimetre there is sign of poor convergence.

In addition, long hours and intense reading in people with convergence problem can cause asthenopia (diplopia and headaches). In this situation the recovery near point is more than 15 centimetre.

The results of the test should be noted for example, NPC 7cm, CRP 12 cm

Jump convergence

This test is more realistic to typical near viewing situation. As additional test it can be used for the patients with signs of the convergence insufficiency.

Equipment: The Dot Card or Brock String. The length of the card can be vary but must not be shorter than 20 centimetre. There are some black points at the midline of the card that are placed 1-2 centimetre from each other.

If the patient is high myopic or hypermetropic then the test should be performed with needed correction.

Test performing

  1. Patient should sit down in a comfortable chair and the card is placed at the patient's nose level.
  2. Room should be well illuminated, so any changes in eye movements can be noticed easily.
  3. Patient will be asked to fixate at the farthest point at the card and should be asked:
    • How many lines are there?
    • Are these lines crossing at the fixation point?
  4. If the patient can fixate to this point then move it to the closer point until the patient sees two parallel lines or just one line (in this case the other eye is suppressed)
  5. The closest point where the patient can see these two lines crossing at the fixation point is the near point of convergence (NPC).


The test should be performed more than once to be get sure that the patient understood and will follow the procedure. For patient who has convergence insufficiency repeated tests will move the near convergence point far from the previous ones.

Results

Test results should be written down for example convergence 8 centimetre (Brock String)

In an individual with a good convergence ability both tests should show the similar results.

Most commune errors

  1. Relying on subjective near point convergence (NPC) measures and not objective observation of the eye fixation.
  2. Doing the test only once.
  3. Moving the target too fast that can over estimate the convergence ability or moving the target too slow so the child can lose the interest of doing the test.
  4. Not complying patient or where the examiner is not encouraging the patient (most of the time a child) to follow the NPC target. Using different objects at each time.
  5. Not testing the patient in non standard gaze for convergence studies which is slight downward gaze for example testing in upward gaze.


References

  1. David B. Elliott PhD, Clinical procedures in Primary eye care Fourth edition. Elsevier limited, 2014
  2. Brad Bowling Kanski's Clinical ophthalmology Eight edition. Elsevier limited, 2016
  3. Frank Eperjesi PhD, Hannah Bartlett PhD, Mark Dunne PhD Ophthalmic Clinical Procedures Elsevier limited, 2007
  4. Darcy A.Umphred PhD, Gordon U.Burton PhD, Rolando T. Lazaro PhD, Margaret L. Roller Umphred's neurological rehabilitation Six edition. Mosby, 2013.