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ORIGINAL ARTICLE
Year : 1983  |  Volume : 31  |  Issue : 4  |  Page : 363-365

Cam vision stimulator in the treatment of strabismic and anisometropic amblyopia


Sarojini Devi Eye Hospital & Institute of Ophthalmology, Hyderabad, India

Correspondence Address:
R Hanumanth Reddy
Sarojini Devi Eye Hospital & Institute of Ophthalmology, Hyderabad
India
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Source of Support: None, Conflict of Interest: None


PMID: 6677590

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How to cite this article:
Reddy R H, Vidyavati. Cam vision stimulator in the treatment of strabismic and anisometropic amblyopia. Indian J Ophthalmol 1983;31:363-5

How to cite this URL:
Reddy R H, Vidyavati. Cam vision stimulator in the treatment of strabismic and anisometropic amblyopia. Indian J Ophthalmol [serial online] 1983 [cited 2020 Oct 20];31:363-5. Available from: https://www.ijo.in/text.asp?1983/31/4/363/27555

Treatment of amblyopia has remained static for the past century. Pleoptics have been popular but not successful and lasting in many cases, Recent neurophysiological findings suggest that visual neurons in the visual cortex can be activated by different spatial frequency gratings, using a repetitive grating pattern with sharp luminance edges, slowly rotating through 180° the visual system being exposed to this gamut of motion. Basing on this, Campbell has devised an apparatus coining the name "CAM VISION STIMULATOR"


  Material and methods Top


CAM Vision Stimulator contains a motor which slowly drives a turntable at a speed of 1 cycle per minute, on which can be fixed a series of discs bearing patterns of spatial fre­quency gratings, as also a slot for inserting transparent perspex plates with coloured patterns.

24 patients were assessed fully prior to treatment. Visual acuity assessed for 6M dis­tance and at 1/3M for near. Cycloplegic refra­ction done and glasses prescribed. Cases with gross eccentric fixation were omitted from the series. Binocular functions assessment (on Clement Clarke synoptophore) was done. Con­trast sensitivity was roughly assessed by ask­ing the child to indicate the directions of the lines by placing all gratings.

Patients were divided into group A, consisting of 12 patients which included five heterotropic cases and seven heterophoric cases, who had no previous treatment for amblyopia except for correcting refractive error and, Group B, also consisting of 12 patients who had occlusion and correction of refractive error for amblyopia. This group also consisted of 7 heterophorics. and 5 heterotropes.


  Method of use Top


The patient's normal eye is covered and the other set at about 28 cm from the appara­tus. After assessing contrast sensitivity, the largest square wave grating disc and a pers­pex plate are fitted to the spindle of CAM. By switching on the instrument, the disc is rotated for one or two miutes and the next finer grating is placed on the spindle and the game recommenced. Meanwhile, the child is either asked to draw with the coloured pencils provided on the colour etchings on the pers­pex plate or can play with another child or the orthoptist some games on the same. The whole treatment lasts about 7 minutes when all seven gratings are used. This will require visual concentration while the amblyopic eye is exposed to rotating high contrast square wave gratings.

The treatment was repeated at intervals which varied from daily to weekly and some­times as long as a month but basically, weekly treatment was preferred. The visual acuity for distance and near was assessed every week during treatment. Treatment was stopped when three consecutive treatment sessions failed to improve the visual acuity further.


  Observations Top


Graph A depicts results before and after treatment in group A patients. Of the 12 cases, two failed to improve (cases 8, 9). A perusal of the results shows that heterophoric ones (cases 1. 3, 4, 5, 6, 7, 8 & 12) had more visual improvement than heterotropic ones cases (2, 8, 9, 10 & 11). The higher age groups cases 3 & 8 did not benefit much by this treatment.

Graph B depicts results in 12 cases which were previously treated with occlusion and then subjected to CAM vision stimulation. The results showed superiority of CAM stimulation over occlusion. Here also the heterophoric cases (1, 4, 6, 7, 8, 10 & 11)

showed more improvement in visual acuity as compared to the heterotropic cases (2, 3, 5. 9 & 12).

Near vision improved more than vision foi distance. It was observed that distance vision for opto type exceeded at least by one line compared to linear type. The results before and after treatment are displayed in the slides.

In our series the number of treatment sessions varied from 4 to 14. We did not inc­lude cases who had been undergoing pleoptic treatment.


  Summary Top


This method of treatment being simple and exercises being interesting, even the very young children co-operate better than for the rigid and monotonous exercises in the pleop­tic treatment. It also does away with the need for occluding the normal eye which is long drawn and psychologically disturbing to the school going child. Thus it scores over the pleoptic treatment. The only precaution requi­red in its use is in the treatment of a child above the age of 8 years, who has developed squint recently. Since the rapidity of develop­ment of vision is quick, intractable diplopia may be precipitated while the child is still awaiting medical or surgical treatment for the condition.


    Figures

  [Figure - 1], [Figure - 2]



 

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Material and methods
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Observations
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