ABSTRACT

Purpose: To test the hypothesis that the action of the extraocular muscles, particularly the superior obliques,  can elongate the globe.

Method:   A viewing device was constructed consisting of two identical photographic transparencies depicting a visually rich pattern. When the subject (a high myope) looked through the device, each eye viewed one of the transparencies. The transparencies were then incyclorotated, i.e. as seen by the subject, the right-side image was rotated counterclockwise and the left-side image was rotated clockwise. To maintain fusion of the two images,  each eye must then rotate in the same direction as the image it is viewing, i.e. the upper end of the vertical meridian of each eye leans nasalwards.

The movement of incyclorotation is opposed by the check ligaments and other fascial structures of the orbit. If an effort is made to maintain fusion, the traction of the superior obliques, which wrap part way around the globe, will exert pressure in the general area
of the equatorial meridian and, presumably, elongate the globe.

   Results: The existing myopia increased by some 5 D. An unexpected result was that the uncorrected acuity became nearly emmetropic (20/25). The subjective vision consisted of a nearly sharp image superimposed on a highly blurred image. This dual mode of vision could be interpreted as a combination of high myopia and near emmetropia in each eye.

  Conclusion:  The probable cause was pressure from the superior obliques transmitted through the sclera to the vitreous, forcing it forward against the posterior surface of the lens and flattening its peripheral area. This may have been merely an extreme case of the normal spherical aberration that occurs when the eye accommodates.

The dual vision persisted for several years, which suggests that a highly deformed lens is extremely slow to revert to its original state, and the same may be  true of a lens distorted by long periods of accommodation.

[For complete paper, click on tab above]

--R. McCollim