|Year : 1973 | Volume
| Issue : 2 | Page : 66-67
Microstrabismus with bilateral eccentric fixation. A case report
SD Gupta, SC Sood
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
S D Gupta
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gupta S D, Sood S C. Microstrabismus with bilateral eccentric fixation. A case report. Indian J Ophthalmol 1973;21:66-7
|How to cite this URL:|
Gupta S D, Sood S C. Microstrabismus with bilateral eccentric fixation. A case report. Indian J Ophthalmol [serial online] 1973 [cited 2020 May 31];21:66-7. Available from: http://www.ijo.in/text.asp?1973/21/2/66/31408
Only the unilateral eccentric fixation has been described in Microstrabismus in the literature (Helveston et al  ) and (Lang  ). No case of microstrabismus with bilateral eccentric fixation has been described to the best of our knowledge. The following case, therefore, is worth reporting.
| Case Report|| |
A twenty three years old female using the glasses for the last 6 years came to the Eye Out-Patient Department for the check-up of her eyes as she was not satisfied with the old glasses.
Her eyes were straight and the cover test did not reveal any tropia or phoria shift. Refraction under homatropine revealed a refractive error of
+ 8.50 DS with + 2.00 DC x 95 in RE. and
+ 8.50 DS with + 2.00 DC x 115 in LE.
The best corrected vision was RE 6/36 with + 4.00 DS and + 2.00 D cyl. x 95 and LE 6/18 with + 4.00 DS and + 2.00 D Cyl x 115.
Media were clear. Fundus examination did not reveal any abnormality, except that the discs were small in size. Examination with the visuoscope revealed bilateral eccentric fixation - para macular nasal on the right and parafoveal nasal on the left side.
The patient had grade II binocular vision. Amplitude of fusion was from + 6 to - 4' prism diopters. Supression at the fixation points could be demonstrated with 4 prism base out test in both eyes.
Bagolini's lenses and after image test showed perfect cross indicating harmonious abnormal retinal correspondence. Bifoveal correspondence test showed that the macula in each eye did not correspond to the fixation point of the other eye and the two eccentric fixation points corresponded to each other. So a harmonious abnormal retinal correspondence was demonstrated on all the tests.
| Discussion|| |
A long continued controversy exists over the definition of microstrabismus. It is an ultrasmall angle squint which is not detectable by cover-test and in which the angle the squint, angle of anomaly and a degree of eccentricity are equal (Helveston et al  ). But Lang  defined microstrabismus as a condition with a small angle squint (less than 5°) and the tropia shift may be present or absent, fixation may be central or eccentric but abnormal retinal correspondence and amblyopia of varying degree are present.
Lang's  definition of microstrabismus is rather a confusing one, as it will not only include the cases of HELVESTON et al  but also the cases of small angle squint with abnormal retinal correspondence and the cases of fixation disparity defined by Bullock.  We, therefore, feel that the term microstrabismus should be restricted to the cases showing amblyopia in straight eyes with eccentric fixation which is fully adapted to the angle of anomaly so that the various types of cases are not mixed under the same heading.
The present case is a unique one in the sense that it had a bilateral eccentric fixation with harmonious abnormal retinal correspondence in the absence of any tropia shift or any such history in the past. Bilateral eccentric fixation could be due to bifoveal instability which is an inherited defect (Hermann et al  ) or small undetectable macular haemorrhage in both eyes at birth. Finally, it may also be the result of refractive blurring because of the high refractive errors (HILL AND IKEDA  ). The two eccentric points later on started corresponding with each other and developed abnormal retinal correspondence.
We agree with Lang  that anisometropia is not the only cause of microstrabismus as shown by the absence of anisometropia in the present case. Other factors may also be responsible for the condition.
A case of microstrabismus with bilateral eccentric fixation has been described, and the possible factors responsible for the bilateral eccentric fixation have been compendiously discussed.
| References|| |
Bullock, K. Fixation disparity, Brit. Orth. J. 23: 41 (1966).
Helveston, E. M. and Gunter. K. Von Noorrden, Microtropia. Arch. Ophth. 67:
Hermann, S. J. and Priestley B. S. Bifoveal instability. Amer. J. Ophth. 60:
Hill, R. M. and Ikeda, H. Refracting a single retinal ganglion cell. Arch. Ophth. 85:
Lang, J. Microstrabismus. Brit. Ortho. J. 26: