Understanding spiral optics designed Rayner Galaxy Intra Ocular Lens
- Subhabrata Bhattacharya
- Mar 1, 2025
- 8 min read
Updated: Mar 6
Since the launch of the RayOne Galaxy lens, there has been a significant amount of attention focused on spiral optics and how such design provides multiple focal points to provide depth of vision to patients. The adoption of spiral optics to provide such multifocality in IOLs or contact lenses is new, and not many literature is available that would help a layman like myself, to comprehend. So here I set out to reflect what I have understood whatever reading material is available, and by talking to some of the experts in the subject.
Have you ever seen water in the kitchen sink slowly draining out but also creating a vortices of water (Image 1). What exactly is a vortex? Vortex is a fluid particle rotating about a center creating a hollow section in the center. This rotation of fluid particle is always present even if the drain pipe is clogged and water flows out slowly. If you have tiny food particles in the sink, you will find them rotating as water slowly drains out of the sink. When the drain is unplugged and their is no major obstruction on the drain pipe, gravity causes the water to wash down and the rotation is intensified and we see the formation of vortex. The same vortex is also seen in tornado, which is created by warm ocean water. Such phenomenon can be seen in your coffee mug, as you stimulate with the spoon for the sugar to absorb.
Vortices are not just seen in the kitchen sink, coffee mug, or the hurricanes. It is seen in whirlpools in the ocean, wind direction created by the flying aircraft, etc. However, all of these have something in common, angular momentum. Momentum is a product of mass of the object and its velocity. By momentum, we generally mean its movement in a linear direction. By angular momentum we refer to its momentum when it moves in circles or rotation. The earth's movement on its axis is an example of angular momentum. Angular momentum can be derived by speed multiplied by the radius of the circle it is moving in and the mass of the object. If the ball in image 2 starts moving towards the center while still maintaining its rotation, the angular momentum will increase and it will start spinning faster. Thus the velocity of fluid in the kitchen sink is inversely proportional to the distance from the vortex . This is exactly what happens with the water in the kitchen sink or in a tornado. As the water spins and come closer to the kitchen outlet, it spins faster (generates greater angular momentum) creating a vortex of water. Thus water surrounding the vortex will be shaped in a tubular form.
Let us now come to light which is our subject of interest. In a previous article in this website, I had described how two wavefronts of light passing through two slits or openings, can be made to interfere so that it creates constructive (and destructive) interference of light. This property of light has been exploited by IOL scientists to help provide multifocality and depth of focus. Another exciting aspect that can be created of light property is vortices of light, like image of light forming as donuts. Thus light has both linear and angular momentum like a top spinning. A laser light moving on an angular momentum, will create a dark spot in the center (vortex), surrounded by light. This dark spot will be similar to the vortex of water created in the kitchen sink, or the eye of the tornado.
In a toric IOL, there are two meridians of power to correct the astigmatism of the cornea. The two meridians of power are 90 degree away, and helps converge the light to a single focal point. Thus a toric lens surface, consisting of two different refractive powers are designed to bring focus all rays of light to a image point. This may be called a stigmatic lens.
The spiral optics is designed to help elongate this focal point. To do this, a lens based on spiral optics would have different refractive powers in different meridians of the lens. Thus, unlike the toric IOL, it is designed to elongate the focal point as a zone of focus by the help of angular momentum (vortex in kitchen sink) such that a tubular zone (vortex) is created which stretches the focal points by exploiting the angular momentum of light.
