WO2020167258A2

WO2020167258A2 - Intraocular lens with intentionally changeable power

Info

Publication number: WO2020167258A2
Application number: PCT/SY2019/000003
Authority: WO
Inventors: Samer HAJJO
Original assignee: Hajjo Samer
Priority date: 2019-02-17
Filing date: 2019-10-07
Publication date: 2020-08-20
Also published as: WO2020167258A3

Abstract

This is an invention of a special intraocular lens that has intentionally changeable power. The lens has an external gas-filled reservoir located anteriorly and laterally outside the field of sight and has also a central posterior concave liquid-filled cavity; the reservoir and the concave cavity are connected from above by a tunnel. While bending the head forward and turning the eyes downward there will be gas-liquid exchange inside the lens and this will add a certain positive power that permits near vision, the power addition will persist constantly after head lifting and turning back to the original power situation will not occur until opposite head and eye movement.

Description

Title of the invention: Intraocular lens with intentionally changeable power Background of the invention:

Cataract surgery is one of the most common surgeries around the world, and maybe the commonest in elderlies, the main principal of this surgery is replacing the partially or totally opaque crystalline lens in the human eye by artificial intraocular lens (IOL).

All lOLs had two main parts "optics" which is the real iens, and "haptic" which supports the lens to be steady inside the eye.

Ideal IOL must allow accurate and automatic focus for all distances of view, unfortunately this lens doesn^'t exist yet, and many attempts had done in this field of invention.

Regarding the focus distance, lOLs can be classified into three main categories, traditional monofocal IOL, multifocal IOL, and accommodative IOL.

Monofocal lOLs are the simplest and in the same time the most popular, they offer best vision for certain distance (usually far distance), subjects have these lOLs in their eyes will usually need reading glasses and sometimes additional glasses for intermediate distance (50 - 150cm).

Multifocal lOLs had modified surface, in the way that more than one dioptric power will be included in the same time. This idea allows good visual acuity for distance and near, and moreover - in newer models - for intermediate distance, but unfortunately significant percentage of subjects will not be satisfied with these lenses because of glare and halos. Accommodative lOLs change their power automatically when subject change his viewing distance (like normal human crystalline iens), the lens may change its power by changing its surface curvature, making slight front- back movement, making fluid exchange inside the lens, or by overlapping of two lenses, the trigger of power change may be the cilliary muscle efficacy or head bending. Changing the IOL power in response to cilliary muscle contracture is the exact way that normal biological crystalline lens changes its power, this seems superior, but unfortunately being accurate and applicable, this seems unreachable in near future. Changing IOL power in response to head bending is a previously invented idea, although this maybe applicable and can facilitate reading without gla^se^, it may confuse the subject markedly. Brief description of the drawing:

Fig.1 : is a front view of the lens optics

Fig.2: is a cross sectional view of the lens optics

Fig.3: illustrates the simultaneous movement of the head and eye that makes the lens in the horizontal plane and the front surface becomes downward.

Fig.4: illustrates the simultaneous movement of the head and eye that makes the lens in the horizontal plane and the front surface becomes upward.

Fig.5: Illustrates the way of changing lens power.

A: illustrates the basic state (far viewing state) B: illustrates the simultaneous movement of the head and eye in order to change the lens power toward 'near state'.

C: illustrates 'near state'

D: illustrates the simultaneous movement of the head and eye in order to change the lens power toward 'basic state'. Detailed Description of the Invention:

This is an invention of new intraocular lens (IOL); its novelty is derived from the way that its power shifts between far and near position. Changing the lens power is intentional and will occur as one wants it, by a special conjugate eye and head movement. Ail lOLs had two main parts, the optically efficient part, which is called "optic", and the legs, or the holder that supports the lens to be steady inside the eye and is called "haptic". Regarding to this invention, any type of lens haptic will be convenient, and there is no concern to lens haptic in the following description and in the drawings.

The components of the lens are shown in fig.1 (which is front view), and fig.2 (which is sectional view). The front surface of the lens (1 ) is normal surface as any monofocal IOL but it offers most of the far viewing power. The back surface (6) will be even or has very mild curvature and will add zero or minimum power to the lens. Posteriorly inside the lens optic there is a concave cavity (2), this cavity may share ^its^posterior wall with posterior surface of the lens (6), but its anterior wall (7) is necessarijy concave. The diameter of the concave cavity is equal or slightly smaller than the diameter of the optically efficient zone of the lens. Adjacent and at the side of the anterior surface there is a reservoir (3), this reservoir has an internal volume equal to that of the concave cavity, and the two volumes are connected from above by a tunnel (4). The reservoir is fixed to the anterior surface of the lens by a band (5) but also can be fixed by any other way.

Thus there is a continuous volume consists of two equal in size and connected parts, the concave cavity which is located posteriorly and centrally inside the lens optic, and the reservoir which is located laterally and anteriorly outside the lens optic and outside the field of vision. This dual volume will be filled half by a translucent liquid and half by a gas. Any biocompatible translucent liquid and gas may be used (e.g. air and water).

In this way, the lens will change its power according to what is filling the concave cavity, the liquid or the gas. While the liquid fills the concave cavity, the power of the lens will be suitable for far gaze, and this dynamic state of the lens will called "Basic state", whereas if the gas fills the concave cavity the power will be suitable for near gaze, and this state will called "Near state ".

When implanting the lens inside the posterior chamber of the eye, it^'s obligatory to be in the correct position, this means when the head is erect and the eye is looking forward the lens must be in a vertical plane, the front surface is anterior, the reservoir is lateral, and the tunnel is superior.

Shifting between basic state and near state requires the liquid and the gas to exchange their containers (i.e.: the reservoir and the concave cavity), and this will not take place until the liquid container becomes in a superior level regarding to the gas container.

Shifting from basic state to near state requires the lens to become in a horizontal plane in the way that the front surface is looking downward; this will put the concave cavity in a superior level and the reservoir in an inferior level, thus the liquid will leave the concave cavity toward the reservoir across the tunnel, and simultaneously the gas will leave the reservoir toward the concave cavity. Fig.3 illustrates how.one can change the power of the lens to "Near state" just by looking downward and in the same time bending the head foreword. This

simultaneous movement of the eye and the head will make the reservoir in an inferior level regarding to the concave cavity, and consequently the liquid will fill the reservoir and the gas will fill the concave cavity (since the liquid is heavier than the gas). The expected time for this exchange is just few seconds, thereafter one can turn his head and eyes back to normal position and enjoys reading or any near activity without any glare, halos, or blurring.

T urning back from near state to basic state needs opposite eye and head movement, as shown in Fig.4, one should look upward and turn his head back in order to set the lens at horizontal position ant the concave cavity in an inferior level regarding to the reservoir. This transitional position will allow the liquid to turn back to the concave cavity and the gas to turn back to the reservoir, and consequently turning the lens back to the basic state (i.e.: far vision state). Fig.5 shows how to shift position from basic state (A) to near state (C) through the transitional position (B), and how to turn back to the basic state through the opposite transitional position (D).

Head tilting laterally is another optional transitional position may also cause gas- liquid exchange and changing the power of the iens. Since the reservoir is located laterally and the concave cavity is located centrally, this means that tilting the head laterally to the same side of the reservoir will make the reservoir in an inferior level regarding to the concave cavity, and consequently will change lens power from basic state to near state. In the opposite way, tilting the head opposite to the side of the reservoir will make the concave cavity in an inferior level regarding to the reservoir and consequently will change lens power from near state to basic state. Thus, head tilting laterally is an alternate way to change the power of the lens intentionally, and a combination of head bending, eye vertical movement, and head tilting laterally may be done to facilitate lens power changing.

The effect of head tilting may be enhanced by making the reservoir more lateral, and may be canceled by making the junction between the concave cavity and the tunnel at opposite direction to the side of the reservoir.

The reservoir location may be to left side or to right side, but when there is a lens in each eye, the two reservoirs may be at the same side (i.e.: both are at the right or at the left), or may, be at opposite sides (i.e.: one to the right and the other to the left). If the two implanted lenses have their reservoirs at opposite direction, changing lens power by pure lateral head tilting (toward the shoulder) will change the power of one lens only. This will lead to state called "Monovision state", which means using one eye for far vision and the other for near vision, and this is an additional feature of this invention.

However, the more interesting possible addition to this IOL is manufacturing the anterior surface as bifocal surface with just +0.75D power addition, this will achieve intermediate distance coverage in basic state and in the same time will extend the field of near vision in near state. One would expect no or minimal halos and glare in such bifocal surface because of very small addition of +0.75

This IOL can be made from any material used for manufacturing lOLs, and there is no restricts that prevent it from being foldable IOL (i.e.: can be inserted from small incision), being aspheric IOL (i.e.: has a decreased bending in the periphery in order to enhance clarity), or being toric IOL to correct astigmatism.

The reservoir can be made from the same material of the lens, but it is preferable to manufacturing it from a thin and elastic biocompatible material, this will aid lens folding during implanting it without the risk of damaging the reservoir. In the same time, being made of thin and elastic material, this allows - in certain circumstances - the possibility of converting the lens to normal monofocal IOL by making a puncture in the reservoir either by Nd. YAG laser or surgically by a needle, when puncturing the reservoir the gas will leave the lens and will be replaced by aqueous hummer.

For basic calculations, we suppose that:

"P" is the required power of the lens inside the eye for far vision.

"R1 " is the radius of curvature of the anterior surface of the lens in meters.

"RG is the power of the anterior surface of the lens inside the eye.

"R2" is the radius of curvature of the anterior surface of the concave cavity in meters.

"P2" is the power of the anterior surface of the concave cavity when filled by liquid. is the power of the anterior surface of the concave cavity when filled by gas.

"R3" is the radius of curvature of the posterior surface of the lens (which is also the posterior surface of the concave cavity)

"P4" is the power of the posterior surface of the lens when the concave filled by liquid.

"P5^M is the power of the posterior surface of the lens when the concave filled by gas. "A" is the required power addition for near vision (usually +2.75 or +3.00 diopter)

"n1" is the refractive index of lens material.

"n2" is the refractive index of the liquid inside the lens.

Then:

P = P1 + P2 +P4 (by neglecting lens thickness)

P2 = (n1 -n2)\R2 (positive power surface)

P3 = (n1-1 )\R2 (refractive index of the gas is 1 )

It is somewhat very recommended that the posterior surface of the lens is even and has zero dioptric power, this will facilitate power calculations and lens manufacturing but it^'s not obligatory. By supposing (R3 = ¥), and then consequently (P4 = 0) and (P5 = 0), this will lead to:

A = P3 - P2 = [(n1-1)\R2] - [(n1 - n2)\R2] = (n2-1 )\R2

Thus: R2 = A\ (n2-1 ) (This illustrates that R2 is not related to lens material and power)

When using water inside the lens this will mean that (n2 = 1.333), and if the required addition for near vision is +3.00 (i.e.: A = 3) then:

R2 = 0.333\3 = 0.1 1 1 m this is the radius of curvature of the anterior surface of the concave cavity whatever was the required power of the lens but supposing that the liquid inside the lens is the water, the posterior surface of the lens has zero power, and the required power addition for near vision as +3.00D.

Claims

What is claimed is:

1. An intraocular lens for human eye that subject can change its power

intentionally by certain movements of the head and the eye. It has an optic body comprised of:

a) Anterior surface offers most of the power required for far vision.

b) Posterior surface has zero or minimum optical power because of his even or minimally bending curvature.

c) Concave cavity located centrally and posteriorly inside the optic body.

Its diameter is equal or slightly smaller than the diameter of the optically efficient zone of the lens.

d) A reservoir located outside the optic body of the lens and outside the field of vision and attached to the anterior surface of the lens laterally (at left or right direction). This reservoir must be equal in its internal volume to the internal volume of the concave cavity.

e) A tunnel connecting the concave cavity with the reservoir superiorly (i.e. starting posteriorly from the top of the concave cavity and then passes anteriorly and laterally toward the reservoir and then pierces the anterior surface of the lens to finally enters the reservoir from its top).

f) A translucent biocompatible liquid fills the concave cavity while the lens in far vision state, and fills the reservoir while the lens in near vision state.

g) A biocompatible gas fills the reservoir while the lens in far vision state, and fills the concave cavity while the lens in near vision state. The lens has two power states, the basic state (or far vision state), and the near state. Shifting from basic state to near state requires looking downward and bending the head foreword, while turning back from near state to far state requires opposite eye and head movement (i.e. looking upward and bending the head backward). Alternate method for shifting lens power is lateral head tilting, when tilting the head to the same direction of the reservoir the lens will shift to near state, while tilting the head to the opposite direction will shift the lens state to basic state.

2. An intraocular lens as described in claim 1 , that the change in lens power state by head tilting laterally can be canceled by making the tunnel enters the top of the concave cavity from a side opposite to the location of the reservoir.

3. An intraocular lens as described in claim 1 , that its anterior surface has bifocal curvature with a small additional power, as a useful and optional addition for enhancing lens function and making it suitable for all distances of vision.