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EYE ADVICE: Professional Papers


A. Ciliary Muscle Action and Innervation

Most advocators of MA are of the view that it is achieved by an asymmetric contraction of the ciliary muscle. Even though this has been disputed, evidence from work carried out by several workers including Henson and Volckers (1878) and Barany (1966) demonstrates that asymmetric contraction is possible.

The ciliary body's antero-posterior length is always greatest on the temporal side. (Straatsma et al 1968). This would fit in with Tscherning's finding of a physiological lens tilt of between 3 - 7 degrees about a vertical axis, with the temporal lens border lying behind the nasal (Duke-Elder 1970).

Hallden and Henriesson (1974) showed that by soaking a cotton pledget with 10% pilocarpine, and placing it temporally to the conjunctiva overlying the ciliary muscle, a change in astigmatism of 1D could be elicited.

It is probable that the muscle fibres responsible for MA are specific for this alone and are located temporally in the ciliary muscle. This would explain the increased muscle mass temporally, as there would be no necessity for this if all the fibres of the ciliary muscle were subserving spherical accommodation. The hypothesis that the MA fibres have their own, separate innervation, explains the ability of the ciliary muscle to contract asymmetrically.

Grossman (1904), who is quoted by Morgan (1944), found that physostigmine caused "against-the-rule" (ATR) refractive astigmatism in the cat. Morgan (1943) found ATR refractive astigmatism upon stimulation of the oculomotor nerve. This would support the existence of parasympathetic meridional accommodation (PMA). This is the predominant form of meridional accommodation, just as parasympathetic spherical accommodation (PSA) predominates over sympathetic spherical accommodation.

Morgan invariably found "with-the-rule" (WTR) astigmatism in the cat, upon sympathetic stimulation. By extrapolation to humans, this would give some support for the existence (however imperceptible) of an opposing sympathetic meridional accommodation (SMA).






Paper 1 - Meridional (Astigmatic) Accommodation  Abstract

Physiology of Meridional Accommodation (A) Ciliary Muscle Action and Innervations
(B) Corneal Changes due to Ciliary Muscle Action
(C) Theory of Initiation of Meridional Accommodation

Clinical Implications of Meridional Accommodation


(A) Astigmatic Changes Related to WTR Corneal Toricity (i) Latent Astigmatism
(ii) Primary Accommodative Astigmatism (PAA)       (B) Reflex or 2°PMA and Induced ATR Astigmatic Changes
(C) Eye Preference and Meridional Accommodation (i) 1° PMA and Eye Preference
(ii) 2° PMA and Eye Preference (D) Proactive Prescribing for Presbyopia (i) Phakic Presbyopes
(ii) Pseudophakes and ATR Corneal Changes (E) Refractive Techniques and MA (i) Balancing Meridional Accommodation
(ii) Binocular Test of Cylinder Power (F) Further Clinical Subject Areas and Meridional Accommodation (i) Preventing Induced Oblique Astigmatism in Children
(ii) Low Vision
(iii) Keratoconus
(iv) Hard Contact Lenses
(v) PRK and PARK (Photorefractive Astigmatic Keratectomy)



Paper 2 - Common Chronic (Infective) Conjunctivitis and Nasal Rinsing

Paper 3 - Primary Open-Angle Glaucoma

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