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Year : 1961  |  Volume : 9  |  Issue : 2  |  Page : 33-35

Convergence insufficiency

Mahatma Gandhi Memorial Medical College, Indore, India

Date of Web Publication31-Mar-2008

Correspondence Address:
B K Dhir
Mahatma Gandhi Memorial Medical College, Indore
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Source of Support: None, Conflict of Interest: None

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How to cite this article:
Dhir B K. Convergence insufficiency. Indian J Ophthalmol 1961;9:33-5

How to cite this URL:
Dhir B K. Convergence insufficiency. Indian J Ophthalmol [serial online] 1961 [cited 2022 Jan 28];9:33-5. Available from: https://www.ijo.in/text.asp?1961/9/2/33/39681

Table 1

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Table 1

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This paper is based upon the find­ings of 158 cases of convergence in­sufficiency- dealt with in 5 years from 1955.

The advent of binocular vision in human beings has been an event of fundamental importance in the phy­logenetical order for the purpose of imparting clear vision. The presence of binocular vision presupposes the harmonious working of the two eves, not only in the performance of con­jugate movements, but also during the disjunctive movements e.g. Con­vergence.

We are all aware that several re­flexes in the body e.g. postural re­flexes, are unconditioned, i.e. they are predetermined. On the contrary, the binocular reflexes, being a later acqui­sition in phyiogeny, are conditioned i.e. they are developed post-natally. Out of these binocular reflexes also, the disjunctive fixation reflex, which is meant for carrying out the movement of convergence, is the last to be devel­oped. At birth, there is no conver­gence. It is developed by the age of six months. Convergence is thus very young phylogenetically, and, there­fore, very prone to anomalies, the commonest of which is Convergence Insufficiency.

We know that when an emmetropic person accommodates to see a near object, he also converges to a corres­ponding amount. To see an object at 25 cm, he uses 4 dioptres of accom­modation and 4 metre angles of con­vergence. Each metre angle is roughly equal to 2 degrees. This normal rela­tionship can often be disturbed. If a person concentrates at an object at 25 cm, adducting prisms (with base outwards) can be interposed without producing diplopia. The strongest prism, base out, that can be thus interposed without production of dip­lopia, can be a measure of the amount of convergence. This demonstrates the presence of Relative Convergence, which is of great importance in allow­ing the near work to be done with ease.

  Measurement of Convergence Top

Convergence can be readily mea­sured by drawing a fine line on a piece of paper and bringing it closer and closer to the eyes, till it appears double, at which point: the distance from the eyes is measured. 100 divided by this distance in centimetres gives a rough measure of convergence in metre angles. But to be accurate, this distance should be measured from the centre of rotation of the eves., which is 14 mm behind the apex of the cornea. This is readily done on the Livingstone's Binocular Gauge, which is calibrated for this purpose. Also the amplitude of convergence can be directly measured on the synoptophore.

  Incidence Top

In a survey of 660 cases which came for eye testing at the Ophthal­mic department of the Medical College Hospital, Indore extending over a period of nine months from 20th July, 1955, the following figures have been found:-­

Total number of refraction cases 660

Total number of cases who com­plained of headache and other symptoms ... 319

Total number of heterophoria cases with symptoms ... 34

Total number of cases of Conver­gence Insufficiency ... 22

This gives an incidence of 3.6%, among the cases who came for eye testing.

  Etiology Top

In a series of 158 cases of Conver­gence Insufficiency dealt with in the Orthoptic section of the Ophthalmic department of the Medical College Hospital, Indore, in 5 years from 1955, the following etiological factors were found:­[Table - 1]

This survey shows a marked pre­ponderence of cases, who were not suffering from any other ailment and who were thus primarily having Con­vergence Insufficiency. All the cases were of the 18 to 25 years age group. Females predominated, being go in number as compared to 68 males.

  Symptoms Top

Headache, especially on near work, was found to be the most marked symptom. Blurring of the print and difficulty of precision work along with ocular fatigue and watering from the eyes were amongst the other symptoms.

  Treatment Top

All cases were first diagnosed on the Synoptophore, Binocular gauge, Maddox rod and wing. Cases showing well marked Convergence Insufficiency only ,were picked up for treatment, e.g., a case having a poor fusional amplitude of about 10 on Synopto­phore, normal Maddox rod reading and normal or slightly exophoric wing reading, is a good case for treatment of this malady. A medical check up (including a blood examination in suitable cases) was done to find out any gross defect. If such a defect was detected, the case was sent for medical treatment and asked to return at least six weeks after discharge from the medical side.

Great difficulty arises in cases with neuroses. It was found that even after full treatment, they would return after a few weeks with the same symptoms.

Any error of refraction was correct­ed and such a patient was advised to return only after at least twelve weeks, use of glasses. The orthoptic treatment consists of increasing the fusional amplitude on the Synoptophore. Simple home exercises like bringing a thin rod nearer and nearer his eyes without causing diplopia were also prescribed.

The following assessment of the response to treatment is tabulated below:­

Uncorrected Myopia cases. Out of 22 cases, 8 became symptom free after application of suitable glasses. 14 were submitted to treatment. Res­ponse was excellent in all cases.

General Debility cases. Out of II cases treated after full medical treat­ment, only two became symptom free, as shown by a follow up for one year.

Neuroses cases. Out of 24 cases all returned with the same complaint. They were again submitted to treat­ment. 5 remained symptom free in a one year follow up period.

Others. Out of 101 cases, 49 became symptom free in six weeks, 27 became symptom free in 12 weeks. The rest 25 did not show any improvement.

  Summary Top

A survey of the response to treat­ment of 158 cases of Convergence In­sufficiency in a period of five years is given.

Thanks are due to the Superintend­ent of the M. Y. Hospital for allowing me to use the records, and to Miss Chanderwarker for helping me in dealing with the cases.

How much difference you find between the calculated intraocular (calculated by two weights schiotr tono meter readings and using 1955 Friendenwalds' monogram correcting ocular-rigidity slope to find out Po) and the I.O.P. reading by applana­tion tono meter, which you think (as you said) fails to diagnose low tension glaucomas (due to low ocular rigidity) ?


  [Table - 1]


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