Elsevier

Medical Hypotheses

Volume 81, Issue 1, July 2013, Pages 36-40
Medical Hypotheses

Correcting lenticular astigmatism by reinstating the correct neuromuscular message

https://doi.org/10.1016/j.mehy.2013.03.041Get rights and content

Abstract

The Problem

The spasm of the oblique muscles can contribute to lenticular astigmatism. The visual cortex interprets the tension of the oblique muscles as an eye that is in near focus mode. It overrides the response to the information generated by depth perception to bring a distant image into focus. Any excessive effort to bring it into focus will not be successful and continuing to make that effort can cause a misalignment in the tension of the rectus muscles. This in turn can directly induce corneal astigmatism and indirectly induce lenticular astigmatism. The astigmatic eye can still bring a near image into focus, but a distant image remains aberrant.

Methodology

The design of a special contact lens to treat lenticular astigmatism is similar to the design of a contact lens to treat corneal astigmatism by means of orthoculogy (or ortho C) as outlined in the paper Correcting Corneal Astigmatism by Reinstating the Correct Neuromuscular Message. The ortho C lens is worn for about two minutes to attend to the blur and distorted aspects of “simple myopic astigmatism”. Both of these refractive errors are corrected simultaneously.

Results

Once the oblique muscles become “loose” due to a “contact lens draw”, it triggers the visual cortex to reinstate the proper neuromotor message to stimulate the ciliary muscle (the muscle that controls the shape of the crystalline lens) to relax along a certain meridian—which in turn “flattens” the crystalline lens along that meridian to bring a blur and distorted image in the distance into focus. The correction only takes a few minutes because the ciliary muscle of an astigmatic eye was not compromised.

Conclusion

The correction is not strictly due to an ortho C lens. Its design is the same for corneal astigmatism or lenticular astigmatism. The purpose of the design is to “loosen” the oblique muscles in a certain manner depending on the degree of astigmatism instead of a specific type of astigmatism. The visual cortex can discriminate whether to correct for corneal astigmatism or lenticular astigmatism after the “draw” from the lens relaxes the oblique muscles.

Section snippets

The hypothesis

The neuromuscular message for distant focusing in response to depth perception can be interrupted if the oblique muscles become excessively tight. The visual cortex interprets this tension as a revised neurosensory message, and it sends a revised neuromotor message. The incorrect message produces an increase in “effort to see” when images in the distance remain blur. This excessive effort can contribute to lenticular astigmatism.

The degree of refractive error depends on how much the original

The problem

The visual cortex regards the astigmatic eye to be permanently in near focus mode. This interpretation is based on the tension of the oblique muscles. The response to this neurosensory message can override the response to a blur distant image brought about by depth perception.

As a result, the visual cortex sends a revised neuromotor message to relax the rectus muscles (to allow the eyeball to elongate if necessary) and to tighten the ciliary muscle (to allow the crystalline lens to adopt a

Why the sclera needs to elongate

When the eye is stuck in near focus mode, the amount of effort expended to bring a distant image into focus even when it does not come into focus simulates a condition that is comparable to maintaining the focus of a very close image. It implies that the ciliary muscle needs to become tense to entice the crystalline lens to assume a maximum “bulged” shape. To maintain the focus of an object in that proximity, it also implies that there is the tendency for the sclera to elongate as well as the

Treatment plan

Unlike treating corneal astigmatism, the intention is not to enhance the natural tendency to compensate for astigmatism. The crystalline lens cannot naturally compensate for the distortion of the cornea if it is due to an excessive steepness along the horizontal axis. Instead, the lens would aggravate the refractive error produced by the distortion of the cornea by becoming steeper along the horizontal axis. Thus the treatment plan should be about “correcting” the crystalline lens instead of

Implication of relieving the spasm of the oblique muscles

Due to the spasm of the oblique muscles, the visual cortex interprets the eye to be in near focus mode when it regards an object that is near or far away. Once ortho C produces the tendency to “loosen” the oblique muscles, the visual cortex reinterprets the reception of this new neurosensory message as an eye that is in distant focus mode instead of near focus mode when it regards an object far away. By re-establishing the eye in distant focus mode, it can deal with a specific type of simple

Conflict of interest

None.

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