|Year : 1989 | Volume
| Issue : 1 | Page : 24-26
Myopic strabismus fixus convergens
Prem Prakash, Naresh K Gupta, Vimala Menon, Mahesh Chandra
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, A.I.I.M.S., Ansari Nagar, New Delhi - 110 029, India
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, A.I.I.M.S., Ansari Nagar, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
A case report of myopic myositis, a rare entity, leading to strabismus fixus convergens, occurring in a high myope at the age of 46 years is presented. The possible differential diagnosis along with the aetiopathogenesis is discussed.
Keywords: Myopic myositis, strabismus fixus convergens
|How to cite this article:|
Prakash P, Gupta NK, Menon V, Chandra M. Myopic strabismus fixus convergens. Indian J Ophthalmol 1989;37:24-6
Strabismus fixus has been described as a condition in which both eyes are fixed either in convergence or divergence, hence the term strabismus fixus convergens and strabismus fixus divergens respectively. The condition has been described in both congenital and acquired form. In the acquired type, various cases ,, have been ascribed but none proven as yet.
A case of acquired strabismus fixus convergens occurring in a high myope, at 46 years of age is being presented as a rare case of possible myopic myositis which led to the present state of the eyes.
| Case report|| |
A 56 year old male presented with complaints of inward deviation and gradual diminution of vision of both eyes of 10 years duration. He had perfectly straight eyes till the age of 45 years when he was using myopic glasses of -17 Dsph. O.U. A diagnosis of bilateral immature senile cataract with right convergent squint with high myopia in both eyes was made at the age of 46 years. At the time his best corrected vision was counting fingers at 6 inches O.D. and 5/60 O.S. A few years later, the left eye also started deviating inwards with further diminution of vision. After being diagnosed as a case of convergent squint in both eyes at the age of 53 years, the patient underwent squint surgery on both the eyes in two stages, a bilateral lateral rectus resection of 7 mm, followed four months later by a 6 mm recession of the right medial rectus. He felt a slight improvement in his visual field following surgery. One year later he underwent cataract extraction in the left eye. The left eye pupil remained dilated post- operatively and regained a best corrected V.A. of 6/60. Acuity of vision was only perception of light in the right eye.
When the patient presented at our centre, ocular examination, revealed a marked bilateral convergent strabismus fixus. The strabismus was estimated at about 70 degrees for his right eye and 60 degree for his left eye. The right eye was immobile while the left eye showed some motility in down and upgaze.
The best corrected visual acuity in the right eye was only perception of light and in the left eye 6/60. The patient fixated with the left eye by means of a face turn to the left and he had a very small field of vision due to the mechanical restriction. He had advanced immature cataract in the right eye and aphakia in the left eye. The fundus revealed marked myopic chorioretinal degenerative changes. Systemic examination was within normal limits and no neurological deficit was elicited.
The forced duction test, revealed marked restriction of abduction in both eyes and a diagnosis of strabismus fixus convergens of the acquired type with high myopia was made.
Further step-wise surgical procedures were undertaken in both eyes under general anaesthesia, consisting of bilateral medial rectus recession of 7 min (the right medial rectus was already recessed by 6mm), with liberal recession of conjunctiva and lateral rotation of the eyeballs by scleral stay sutures. Muscle biopsy taken from both medial recti revealed no abnormalities on light microscopy.
Post-operatively the eyes started deviating inwards again and the stay sutures gave way on the 4th post operative day. Again lateral rectus resection of 14 mm in the right eye and 12, mm in the left eye along with stay sutures was undertaken. During the surgery the. lateral recd were found to be very lax. Post operatively, the patient was kept on oral and local steroids to prevent adhesions. Immediately after the second stage surgery there was almost full correction of deviation in the left eye and 40 degrees correction in the right eye. The operated eye remained in position for 2 weeks and then again began to converge gradually.
Eight weeks after the 2nd operation, the patient had residual convergent squint of about 45 degrees in the right eye and an almost straight. left eye when looking straight ahead [Figure - 3].
| Discussion|| |
Strabismus fix us convergens was first documented as a type of retraction syndrome ,,, and was thought to be a congenital structural anomaly ,, (fibrosis of the medial rectus). It was Villascca who first described this condition as different from retraction syndrome and documented it in one of his cases which acquired it at a later age. Others , later confirmed this acquired variety.
The condition when first seen should be differentiated from two other conditions namely, congenital cross fixation and acquired bilateral sixth nerve palsy. The congenital bilateral sixth nerve palsy resembles cross fixation and sometimes it may become impossible to decide whether the origin is myogenic or neurogenic.
Acquired bilateral sixth nerve palsy is commonly seen in middle aged individuals with history of diabetes, head injury or increased intracranial pressure symptoms. At a later stage, when secondary changes have set in, it may be difficult to differentiate it from strabismus fixus.
In our patient gradual deviation of the right eye started first with immature cataract in both the eyes at 46 years of age. The left eye started deviating five years later. The patient was using a correction of -17 Dsph. in the right eye pre-operatively which led us to believe in the occurrence of imbalance of ocular movements in high myopia .Hugonnier and Magnard  in a retrosepective study, highlighted the imbalance of ocular movement in 66 cases in high myopia with specific clinical pictures. In most of these cases the problem of binocular vision became obvious after using contact lenses or after extraction of the lens which diminishes the degree of myopia considerably.
The various clinical types described ,, (1) myositis in high myopia in adults (2) esotropia of congenital high myopia, and (3) the vertical imbalance which is very frequent but generally symptomless, are extremely unusual. The type that is best known is that of high degree of convergent strabismus in high myopes of which two types have been described .The type which supervenes during midlife is usually due to prolonged near work, using the remote point at the cost of distant blurred vision. The second type occurs in the fifth decade and beyond and is marked by development of an esotropia that may reach very high levels. This has been found in these individuals not infrequently following cataract surgery. The temporary loss of binocular vision with continuation of extensive near work, often done at the far point of the unoperated eye, may precipitate this problem.
The exact pathogenesis of this type of motility derangement is unknown. Although external recti weakness is generally thought to by the cause of adult onset esotropia, fibrosis of the medial rectus remains a distinct possibility ,. Even adult onset hyperphoria-tropia that is associated with myopia has been described. This motility disorder is also ascribed to myopic myositis sub . Recently, Zolog  in a histologic study found disappearance of myofibrils in the external recti of highly myopic eyes, with added tissue changes of homogenization, acidophilia pyknosis and karyolysis. These findings suggest involvement of the external recti in some myopathic process in pathological myopia as hypothesised earlier. But it is still controversial as to which muscle is primarily affected in pathological myopia resulting in such ocular imbalances.
In our patient, the clinical presentation rules out the possibility of bilateral sixth nerve paralysis and the fibrosis of the medial rectus and associated high myopia goes more in favour of the diagnosis of a possible myopic myositis.
| References|| |
Hugonnier R and Hugonnier S : (1969) Strabismus Heterophoria, Ocular motor paralysis, clinical imbalance, Translated and edited by S. Veronneau Troutman, The C V Mosby C., St. Louis.
Leurent P : (1961) A case of post traumatic strabismus fixus in an adult, Bull See Ophthal
Villaseca A : (1959) Strabismus fixus, Am J Ophthalmol 48:761-762.
Aebli R : (1933) Retraction syndrome, Arch Ophthalmol 10:602=610.
Bielschowsky.A : (1939) Lectures on motor anomalies, Am J. Ophthalmol 22:357-367
Brown H W : (1958) Strabismus Ophthalmic Symposium II pp 402 Mosby, St. Louis.
Duke-Elder S : (1949) Text Book of Ophthalmology Vol IV, Kimpton, London.
Huggonnier R and Magnard P : (1960) Desequilibres oculomoteurs verticauz au tours de la myopic forte, Bull Soc Ophthal Fr. 7:414-416.
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[Figure - 1], [Figure - 2], [Figure - 3]
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