Accommodative IOLs: experimental and clinical measurements

Speaking at the Clinical Research Symposium on the opening day of the ESCRS Congress in Paris, Dr Gerhard Auffarth, acting chairman of the Dept. of Ophthalmology at the University of Heidelberg in Germany reminded delegates that whilst accommodative lenses have been with us for the past 30 years, “Surgical techniques and materials were not then really ready for them but nowadays a lot has changed.

“We have really been through three phases of accommodation,” explained Auffarth. “Firstly, there was the single optic lens, such as the Crystalens but studies have shown these lenses cannot move as much as they need to in order to be able to achieve 3 to 4 dioptres of accommodation. The Vienna Group has even had some evidence that they have even moved backwards in some instances.”Auffarth's results have shown that the reality is somewhere in the region of 0.25 to 0.75 D.

Auffarth confirmed that the second phase, namely the dual optic systems, are able to move to produce 2 to 3 dioptres of accommodation. The dual optic system ensures that the two optics that move away from one another for near vision and come closer for distance vision can cover a distance that could not be achieved by a single moving lens. The Synchrony dual optic lens has a dioptre of +30 dioptres anterior lens and a minus lens of variable power, depending on emmetropisation. Accommodative values around 1 to 4 dioptres have been measured.

“The ultimate goal,” said Auffarth, “is to change curvature. By changing curvature we can enter a completely different league going up to 8 to 10 dioptres.” The ultimate goal of cataract and refractive surgery is still emmetropia and full accommodation and it would appear that the opportunities offered by products such as the NuLens and FluidVision will point the way forward.

Dr Auffarth presented a study of the NuLens, which imitates the accommodative mechanism of the avian eye. Its design uses changes in the refractive power of the lens to increase the accommodative effect. The flexible material is displaced through an opening in a diaphragm, creating a bulge. The curvature of the latter then determines the power of the lens.

The FluidVision fluid-controlled accommodating IOL uses natural, muscular, accommodating forces in the eye to transport fluids in the lens. This results in a change of the lens’ shape, similar to what occurs in the natural lens, which changes from thin to thick upon accommodative effort to create a large accommodative range. Dr Auffurth presented a study demonstrating clinically that the FluidVision accommodating IOL has the potential to achieve more than a 5.00 D change in power.

Details of Professor Auffarth's results will appear in a future issue of Ophthalmology Times Europe.