For some time we were baffled by the fact that patients who had had cataract surgery and could read the smallest print still could not see as well a 20 year old healthy eye. While the cataract patient could see the fine detail, the younger eye could see better when tested in situations of reduced contrast or when the edges of colours were important. Then it was discovered that the young healthy lens was not spherical in shape as we had thought but has a shape called aspheric. Spherical lenses cannot bend light evenly so that light entering the lens at the centre is bent differently to light entering at the periphery. Aspheric lenses bend the light rays so that all the light going through them come to one focus, this greatly improves the quality of the image. Research has shown that aspheric intraocular lenses give better vision than standard lenses. Patients with the new aspheric lenses generally have a visual performance similar to a twenty year old. The Problem: Spherical Aberration with a Spherical IOL The Solution: Correction with an Aspheric Optic The pictures above show the effect of the new lens. With the standard lens the light passing through the centre of the lens is focused on the retina but the light passing through the periphery of the lens is bent too much and comes to a focus in front of the retina. This degrades the quality of the image. In the aspheric lens all the light passing through the lens comes to one focus on the retina, just like when we were younger. Spherical aberration of an actual patient implanted with a standard UV - only spherical IOL Reduction of spherical aberration in the same patient, contralaterally implanted with an Acrosoft IQ LOL The “Mexican Hat” is a examination of light focusing on the retina in a patient who has a standard lens in one eye and the IQ lens in the other. The flatter the hat the better the vision.