I want to understand how accommodation of my eyes functions. Per wiki now Helmholtz theory is challenged: Hermann_von_Helmholtz Wiki
His theory of accommodation went unchallenged until the final decade of the 20th century.
- can somebody explain Helmholtz idea (as explanation in wiki seems "strange" to me) and why it is now challenged (and what proofs we have that it is nonetheless correct)?
- when talking about Helmholtz idea wiki have link to some 2008 publication in German. I could not find original text. Where can I read what Helmholtz wrote (in German ok, I expect to be able to translate)?
Changing the curvature of the lens is carried out by the ciliary muscles surrounding the lens; this process is known as "accommodation". Accommodation narrows the inner diameter of the ciliary body, which actually relaxes the fibers of the suspensory ligament attached to the periphery of the lens, and also allows the lens to relax into a more convex, or globular, shape. A more convex lens refracts light more strongly and focuses divergent light rays from near objects onto the retina, allowing closer objects to be brought into better focus.
As ciliary body is where I see fibers are, it IMO means fibers are relaxed by putting pressure on them.
Helmholtz—The most widely held theory of accommodation is that proposed by Hermann von Helmholtz in 1855. When viewing a far object, the circularly arranged ciliary muscle relaxes allowing the lens zonules and suspensory ligaments to pull on the lens, flattening it. The source of the tension is the pressure that the vitreous and aqueous humours exert outwards onto the sclera. When viewing a near object, the ciliary muscles contract (resisting the outward pressure on the sclera) causing the lens zonules to slacken which allows the lens to spring back into a thicker, more convex, form.
Rather complex for me explanation.