As mentioned in the original summary above, Jackson Coleman postulates that the zonules have little to do with accommodation with the exception of the anterior zonules, which help to form a “catenary” like shape with the anterior surface of the lens capsule.   According to Coleman, the primary result of the upward and inward movement of the ciliary muscle is to create a hydraulic affect, or change in pressure gradient between the anterior and posterior chambers.   As the ciliary muscles move in, the ciliary diameter decreases and the change in pressure from the vitreous pushes the lens into the anterior catenary formed by the anterior capsule surface and the anterior zonules (Much like a reverse hammock – see balloon diagram below from one of Coleman’s abstracts.  Note: assume the balloons are upside down to best understand Coleman’s analogy since it is the anterior zonules, not the posterior zonules, that are forming the catenary).   The primary drawback to this approach is that at its best, it probably confuses cause and effect.   While there may be a slight change in pressure gradient between the anterior and posterior chambers during accommodation, the change in pressure is much more likely to be the result of other forces that are changing the shape of the crystalline lens, rather than the cause.   Moreover, critical to the success of this theory is the taughtness of the anterior zonules to form part of the catenary for the front surface of the lens.   However, it has been well established with virtually no dispute in the industry that the anterior zonules become slack during accommodation.

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Coleman – Catenary Theory of Accommodation

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