Talk:Accommodation reflex

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Introductory paragraph

Regarding: "The Accommodation Reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object (and vice versa)." "Focusing on a near object" is called "accommodation", therefore, the essence of the statement is "the accommodation reflex is a reflex in response to accommodation". The sentence would be more accurate if that part read "viewing a near object". The last phrase (i.e. "then looking at distant object (and vice versa)" should be removed because viewing a distance object is not actually part of the reflex.

Regarding: "It is dependent on cranial nerve II (afferent limb of reflex), higher centres and cranial nerves III, IV and VI (efferent limb of reflex)." Unless there is some new theory, I don't believe IV and VI are involved in the reflex. Edwardian 06:35, 21 July 2005 (UTC)[reply]

You raise good points. Technically it is true that IV is not involved... but only if you're in the the horizontal (transverse) plane of the eye. Generally, that exception aside I do believe IV is important 'cause you can't look up and down without it relaxing or contracting. It might be a question of definition... not sure. VI controls the lateral rectus and that muscle has to relax... tone has to decrease ('cause it is opposes the medial rectus). A reference would be a good thing... Nephron 07:13, 21 July 2005 (UTC)[reply]

Regarding "you can't look up and down without it relaxing or contracting": I'm not sure what you mean by "it" - the superior oblique muscle (innervated by IV) or the ciliary muscle? I don't think the accommodation reflex is dependent on IV and VI because you CAN look up or down or to the side and not accommodate. Edwardian 18:05, 21 July 2005 (UTC)[reply]

Conditions that affect accommodation and cause vision problems

The main article describes correct operation but not conditions that cause vision problems with example images. Can someone add a list of conditions that affect accommodation and resulting vision changes? Deformation while accommodating. Can changing focus deform an uneven lens resulting in multiple focal points (multiple images or blur in each eye separately)? The optometrist performs the standard tests and supplies a prescription that works (myopia & astigmatism) for a very narrow range of accommodation. If I defocus while using a single vision lens and single eye at a time, I see the image separate into multiple copies of different sizes/shapes/locations (of the order of 0.1 degree per 2 diopter change). I read with only a window of 2 characters in focus with the adjacent characters loosing legibility by 50% per character from centre (ie. the c of centre I can guess correctly 25% of the time when eyes are focused between the "n" and "t"). My peripheral vision test as normal, my central vision correctable with glasses but obviously more complicated. — Preceding unsigned comment added by Tygrus (talk • contribs) 03:19, 10 October 2019 (UTC)[reply]