|Year : 1971 | Volume
| Issue : 2 | Page : 55-60
Lack of retinal correspondence
DK Sen, GC Sood
Department of Ophthalmology Maulana Azad Medical College and Associated Hospitals, New Delhi, India
D K Sen
Department of Ophthalmology Maulana Azad Medical College and Associated Hospitals, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sen D K, Sood G C. Lack of retinal correspondence. Indian J Ophthalmol 1971;19:55-60
Lack of retinal correspondence (L.R.C.) is a distinct entity which should not be confused with Lack of normal retinal correspondence. In the latter event the patients while being tested on the major amblyoscope attempt to "put the lion into the cage" but are unable to do on account of suppression; they, however, can see the pictures crossing.
Lack of retinal correspondence (L.R.C.) is fairly common but surprisingly no detailed studies are available. As late as in 1954 Levinge and in 1957 Lyle and Foley studied the various anomalies of retinal correspondence in some details but did not also pay any attention to this condition. Lyle  briefly mentioned that a person should be diagnosed as having L.R.C. when he on the major amblyoscope cannot see the pictures crossing at any angle. While investigating the nature of retinal correspondence in our cases of squint with central fixation this criterion of Lyle  for diagnosing L.R.C. appeared insufficient to us as some of the cases with amblyopia diagnosed on major amblyoscope as having L. R.C. were found to be actually having normal or abnormal retinal correspondence by the afterimage test.
We, therefore, undertook a systematic study of this condition.
The preliminary observations have been reported earlier Sood, Sen and Jain. The present report analyses all available data in detail in a series of 102 cases.
| Methods and Materials|| |
Three hundred and fifty cases of various types of horizontal comitant squint [Table - 1] with normal fundi and central fixation (as determined by projectoscopy using the Linksz star graticule) were thoroughly studied and fully investigated in our Orthoptic and Pleoptic Clinic. Visual acuity was recorded with the correcting glasses by means of Snellen's test types using the full line. Retinal correspondence was determined in all the cases by the Synoptophore method (Lyle  ) and after image method as described in our preliminary report (Sood, et al  ). In the latter method all the patients who failed to perceive both the horizontal and vertical afterimages at the same time were put under the category of L.R.C. All the cases of L.R.C. were given Orthoptic exercises for atleast a period of six weeks to note the response.
| Observations|| |
Of the 350 cases studied 120 were found to have L.R.C. by the Synoptophore method and 102 cases by the after-image method, which make an over-all incidence of 34.3% and 29.1% respectively. As the cases diagnosed by the preliminary observations by after-image method are the true cases of L.R.C. only they are considered in this study in detail.
Of the 102 cases diagnosed by the after-image method the maximum number (45 constituting 44.1%) were in the age group of 10 to 20 years. There were only 12 patients below the age of 10 years and 3 patients over the age of 40 years. The condition occured in exotropia in 22.8% cases and in esotropia in 38.5% cases. Of the unilateral exotropias the condition was present in 31.7 cases and of the alternating exotropias the condition was present in 19.0% cases. Again, of the unilateral esotropias the condition was present in 41.7% cases and of the alternating esotropias the condition was present in 24.0% cases. The over all incidence in unilateral squint was 38.2% and in alternating squint was 19.7% [Table - 2]. In 54 cases (52.9%) the onset of squint was before 3 years of age and in 91 cases (89.2%) the onset of squint was before 6 years of age. There was only 1 case where the onset of squint was after 10 years of age [Table - 3]. In the majority of the cases (75, 73.5%) the degree of squint was between 10° and 25° [Table - 4]. Visual acuity in the affected eye in unilateral cases was 6/60 or less. In alternating squints the visual acuity was 6/9 or more in the majority of the cases (28 out of 34) [Table - 5].
Response to orthoptic exercises was very poor in all the cases.
None of them showed any improvement.
| Comments|| |
The term "Non Retinal Correspondence" introduced by us (Sood, Sen and Jain  ). should be preferred to "Lack of Retinal Correspondence" as the latter term may be easily confused with the term "Lack of Normal Retinal Correspondence" which is not necessarily a serious condition from the point of view of restoration of binocular function. The incidence of "Lack of Retinal Correspondence" is fairly high in this country (29.1%). That is because a large number of patients suffering from squint in this country report very late for treatment by which time dense amblyopia has usually set in. The condition is present in almost all types of squint, though its incidence varies with the type of squint. The condition is commoner in esotropia especially in unilateral cases. That is because dense amblyopia is more common in these types of squint. Incidence also varies with the age of onset of squint and the age at which treatment is started. The earlier the onset of a constant squint and the longer the treatment is delayed, the greater the likelyhood of the development of dense amblyopia with consequent loss of retinal correspondence in some cases. In the present series in 89.2% cases the onset of squint was before 6 years of age. Incidence is dependent also on the type of test employed for diagnosing the condition. Synoptophore test as advocated by Lyle records more number of cases as some cases of marked amblyopia with normal or abnormal retinal correspondence are misdiagnosed as being cases of Non-Retinal Correspondence. However, the incidence is not dependent on the degree of ocular deviation. That the degree of squint in the majority of the cases was between 10° and 25° is because most of the patients attending the clinic had squint between 10° and 25° .
There are probably two groups of cases of Non-Retinal Correspondence. In one, it is suggested, retinal correspondence never had a chance to develop. Binocular vision, in its development, depends upon certain physiological processes - the binocular reflexes. According to the theory put forward by Chavasse, the binocular reflexes will develop normally in a child under normal conditions, and will only fail to develop normally if prevented from doing so by some obstacle. Onset of squint at a very early age is one such obstacle which may not permit the development of binocular vision. That is the reason why L.R.C. is a constant finding in essential alternators.
In the other group the condition follows intense suppression. When a squint is constant, suppression occurs, either uniocularly or alternating, and normal retinal correspondence may after a short period be lost. The patients when being tested on the Synoptophore fail "to put the lion into the cage" but can see the pictures crossing indicating that simultaneous perception is still present ("Lack of Normal Retinal Correspondence"). From that stage onwards one of two things may happen (Lyle and Bridgeman). Either simultaneous perception is lost (Non Retinal Correspondence) or else the patient develops a method whereby the two eyes may be used together inspite of the incorrect alignment (Abnormal Retinal Correspondence).
Chances of restoring binocular function in both the categories of cases of L.R.C. are practically nil as orthopitc exercises proved valueless in all the cases. Therefore, it is imperative to recognise this condition early so that a child having the condition is spared the regime of unnecessary orthoptic treatment.
| Summary|| |
Non Retinal Correspondence was found to be present in 29.1% of cases of concomitant horizontal squint with normal fundi and central fixation by the after-image method which was found to be more reliable than the Synoptophore method for diagnosing the condition. A person having the condition sees only one afterimage at a time in the after-image method.
The condition was commoner in esotropia and in unilateral cases. Incidence was dependant more on the age of onset of squint and the age at which treatment was started than on the degree of squint. Prognosis for binocular vision was found to be poor in all such cases. Orthoptic treatment was of no value.
It is stressed that the term "Non Retinal Correspondence" should be preferred to "Lack of Retinal Correspondence as the latter may be easily confused with the term "Lack of Normal Retinal Correspondence" which is altogether a different entity.
| Acknowledgement|| |
We acknowledge our thanks to the Director, Indian Council of Medical Research for the grant sanctioned for carrying out the study.
| References|| |
CHAVASSE, F. B.: Cited in 4, P.1.
LEVINGE, M.: Value of abnormal retinal correspondence in binocular vision. Brit. J. Ophth. 38, 332 (1954).
LYLE, T. K. and FOLEY, J.: Prognosis in cases of strabismus with special reference to Orthoptic treatment. Brit. J. Oph. 41, 139 (1957).
LYLE T. K. and BRIDGEMAN, G, J. O.: Worth and Chavasee's squint, ed. 9th, Bailliere, Tindall & Cox, London (1959).
LYLE, T. K. and WALKER, M. P.: Lyle and Jackson's Practical Orthoptics, ed. 4th, p. 54. Lewis, London (1953).
SOOD, G. C.: SEN, D. K. and JAIN, D. K.: Non Retinal Correspondence. Orient. Arch. Ophth. 7, 340 (1969).
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]