Theory- Actuating mechanisms of accommodation and development of | 56989
Journal of Clinical and Experimental Ophthalmology

Journal of Clinical and Experimental Ophthalmology
Open Access

ISSN: 2155-9570

Theory- Actuating mechanisms of accommodation and development of the theory of accommodation by Helmholtz

3rd Global Pediatric Ophthalmology Congress

March 22-23, 2018 | London, UK

Olga Svetlova, Ivan Koshits

Department Ophthalmology of North-Western State Medical University named after I.I. Mechnikov;
Petercom-Network / Management Systems Consulting Grope Cl. Corp; Saint-Petersburg, Russia

Scientific Tracks Abstracts: J Clin Exp Ophthalmol

Abstract :

Basic Helmholtz of lens accommodation theory (HLAT) has stood the test of time [1]. However, the truth of accommodation was disclosed only in part, and on the basis of HLAT could not be attributed to a number of physiological and clinical facts. In particular, HLAT cannot explain facts partial ability to accommodation in the eyes with the artyphacia and aphacia. In addition, actuators in HLAT were not fully developed. Traditional views on the functioning of the single lens mechanism of accommodation on HLAT violate the laws of mechanics. It is believed that when you look "completely near" zonula fiber relaxed, but then in the eye do not have structures that hold the lens in position (fig. 1). However, Helmholtz considered that when looking "totally near" the Zonula fiber did not relax but only weaken [8]. I.e. in all phases of accommodation the Zonula fiber is tight, and when vision nears the minimum, while vision distance maximum [9]. Our research has made it possible to develop basic HLAT, which for now is consistent with the laws of mechanics in all phases of accommodation [7-11]. Also we have been able to find many other additional mechanisms of accommodation [12]. 2. The basic and additional mechanisms of accommodation. The tension of the zonula depends on the size of stretching "biological spring" - choroid. Muscle ciliary (MC) stretches or weakens the elastic structure of choroid. It should be noted that MC is behind in choroid in the area dentate line and corneal stroma in front [8]. Front and rear portions of the zonula fiber fastened between the lens capsule and choroid in the field of jagged lines, and are not directly related to muscle ciliary [8,10,12]. Such structure of zonula fiber allows you to press the lens to the Vitreous Chamber in all phases of accommodation. Vitreous Chamber and zonule fiber provide hold lens on the center of the optical axis. In addition, the Vitreous Chamber is constantly damps vibrations of the lens. Our scheme HLAT is shown in Figure 2 [8]. The evolution of mechanisms of accommodation in birds, reptiles and many animals has led to the creation of the human eye with generalized mechanism accommodation (fig. 4). This generalized Executive accommodation mechanism in humans consists of intraocular and extraocular links. Extraocular mechanisms can be clearly divided into scleral and corneal, as well as corneal-scleral (for example, the Eyelid compression mechanism). Intraocular mechanisms consist of the lens accommodation - the primary Helmholtz mechanism and many other additional mechanisms of accommodation.Only our classification today is present the basic mechanism of Helmholtz lens accommodation and 13 additional executive mechanisms of accommodation. Note that we found also detected a new executive mechanism of accommodation, which is present in the lens. A mechanism for changing the refractive power of the lens by using the front and rear mini-lenses. These mini-lenses are part of lens capsule and allow you to focus the beams going around the optical axis of the eye, even with a narrow pupil (Fig. 5) [13]. Change the radius of the rounding and mini lens refractive power is associated with a change in pressure inside the lens at different phases of accommodation. For example, when pressure inside the lens near vision as much as possible, and with vision away - minimal [8]. Therefore, both mini-lens have a maximum capacity for focusing the work of near. Diagram of the mini-lens attend as an additional executive machinery accommodation provided in Figure 6 [13]. On the diagram, notice that the cornea itself is weakly dispersive lens. It is worth noting that this new mini-lens accommodation mechanism could change our ideas about the theory of accommodation as a whole, but it can also serve as a natural analogue for the development of accommodative intraocular lens for the new generation. Conclusion. The our common classification [8,10] there are intraocular and extraocular actuating mechanisms of accommodation. They allow you to explain the volume of accommodation in 2.5 diopters even in the eye with artiphacia. Extraocular additional mechanisms of accommodation are as follows. Corneal: Mechanism of narrowing eye lids for increasing depth sharpness and mechanism of the changes radius and astigmatism of the cornea when the ciliary muscle tone at the maximum. Scleral mechanism: changing the length of the optical axis of the eye sclera is compacted outer muscles. Cornea-scleral mechanism: the combined change in corneal astigmatism and the length of the optical axis of the eye convergence-divergence. Extra capsulated mechanisms: mechanism of narrowing of the pupil, the mechanism of curvature of the surfaces of the lens capsule, mechanism of displacement along the optical axis of lens capsule, change mechanism of astigmatism lens - uneven accommodation in different meridians, change mechanism of elasticity horoidei structures, fixed installation mechanism of the retina, local retinal displacement mechanism. Intra capsular mechanisms: possible change in the mechanism of the optical power of the lens nucleus, mechanism of refractive power change mini-lens lenses. All these mechanisms operate in relationship with one other. The fastest accommodative mechanisms is the narrowing eye lids with the help of striated muscles, as well as the work of the extraocular eye muscles striated. Ciliary muscle is a slow reflex muscle, therefore, all accommodative mechanisms that are associated with it, cannot be attributed to fast. Recent Publications 1. Helmholtz H. ??ber die Akkomodation des Auges.- Albrecht von Graefe`s Arch.Ophthalmol.,1855.- Vol. 1.- 2: 1â??74. 2. Kotliar K.E., Svetlova O.V., Skoblikov A.S., Smolnikov B.A. Biomechanical modeling of the accommodative system based on some contemporary conceptions of lens supporting apparatus functioning. Vision Science and Its Applications,1999.- Santa Fe, Optical Society of America.- P. 156-164. 3. Kotliar K.E., Svetlova O.V., Koshitz I.N. Some peculiarities in functioning of the biomechanical model of interactions between the drainage and accommodation regulatory systems of the eye.- Third World Congress of Biomechanics.- Sapporo, 1999.- P.297. 4. Schachar R.A. Original article "Is Helmholtz's Theory of accommodation Correct?" Annals of Ophthalmology, 1999. - Vol 31, 2: 10-17. 5. Schachar R.A., Siganos D.S., Knorz M., et al. In: The Mechanism of accommodation.- Manual of Refractive Surgery,2000.- ECRS, P.39-41. 6. Shapovalov S.l. Clinico-physiological characteristics of absolute human eye accommodation and its research methods.- Thesis of doctor of medical sciences.- Moscow,1997.- 29 ??. [in Russian] 7. Svetlova O.V., Kotliar K.E., Smolnikov B.A. Contemporary biomechanical conceptions about zonula and choroidea functioning. Experimental eye research, 1998, Vol.67, Suppl.1.- P.26. 8. Svetlova O.V., Koshitz I.N. Modern of biomechanical view on the theory accommodation Helmholtz.- ?« Biomechanics of the eye 2001?»: Сollections of scientific papers.- Helmholtz Institute of eye illnesses.-Moscow,2001: 142-178. [in Russian] 9. Svetlova O.V., Koshitz I.N., Krylova I.S., Kotliar K.E., Smolnikov B.А. Further elaboration of the Helmholtz conception of the accommodation on the base of biomechanical analysis of the contemporary clinical observation.- Acta of Bioengineering and Biomechanics (Wroclaw), 2002.- â?? Vol. 4, Suppl. 1. â?? Р. 719. 10. Svetlova O.V., Koshitz I.N. Evolution, classification and execution of the primary and secondary accommodation mechanisms in human eye.- Ophthalmic Research,2003. â??Vol.35, S.1 â?? Р. 44. 11. Svetlova O., Koshits I., Smolnikov B., Gorban A., Kotliar K. Biomechanical analysis of the hypotesis on ?«rest of accommodation?» // Ophthalmic Research, 2006. - Vol. 38, S. 1. â?? Р. 57. 12. Svetlova O., Koshits I., Kotliar K., Smolnikov B., Makarov F. Classification and physiological principles of accommodation mechanisms in the human eye.- Abstracts of Conference on Visual Perception. â?? St. Petersburg, 2006. â?? Р. 5. 13. Koshits I.N., Svetlova O.V., Guseva M.G., Pevko D.V., Egemberdiev M.B. Optical features of the passage of light through the refractive structures of the eye.- Ophthalmic journal,2017.- 4 (477): 60-83. [in Russian, in English]. 14. Rohen J.W., Rentch F.J. Architecture and function of the zonula apparatus in the human eye.- Graefes Arch. Clin. and Exp. Ophthalmol., 1969, v.176, N 4, p.1-19.

Biography :

Olga Svetlova, Med.Sc.D., professor of Department Ophthalmology of  North-Western State Medical University named after I.I. Mechnikov. Author of 211 scientific works, 2 monographs (2016). More than 25 years, conducts research on Biomechanics and physiology of the eye at the intersection of academic disciplines. The co-author generalized classification of executive mechanisms of accommodation and proposals for development of the theory of accommodation of lens by Helmholtz, including the joint work of the front mini-lens and posterior mini-lens in the capsule of the lens to create a sharp image. Co-author and developer of the theory of functions of fibrous sheath eyes, the theory of open angle glaucoma and metabolic adaptation theory of acquired myopia. As well as the co-author of new dynamic diagnostic methods to determine the in vivo new physiological and biomechanical characteristics of the eye
Ivan N. Koshits, mechanical engineer, a member of the St. Petersburg Sechenov Society of physiologists, biochemists, pharmacologists. Author of 59 scientific works in biomechanics, normal and pathological physiology of the eye and its elements, 2 monographs (2016). Organizer and co-head of the first scientific conferences in Russia on the Biomechanics of the eye in 1998-2011. Co-author and developer of the theory of functions of fibrous sheath eyes, the theory of open angle glaucoma and metabolic adaptation theory of acquired myopia. As well as the co-author of dynamic diagnostic methods to determine the in vivo new physiological and biomechanical characteristics of the eye. General Director of Petercom-Network / Management Systems Consulting Grope Cl. Corp