NEW IOL DESIGNS

NEW IOL DESIGNS   

Still no perfect IOL but the latest developments are bringing notable improvements  by Priscilla Lynch in Dublin 

IOL designs are continuing to improve  with exciting developments in  improving accommodation but there  is still no ‘perfect’ lens available to  surgeons, Rajesh Aggarwal MD, FRCOphth  told the joint Irish and UKISCRS refractive  surgery meeting.  Dr Aggarwal, consultant ophthalmic  surgeon, Southend University Hospital, UK  discussed the latest developments in the IOL  market. “Ideally as we all know the ideal  lens is the crystalline lens of a 21-year-old.  At present we have nothing that can come  anywhere near it.â€Â  However, he acknowledged there  is a lot of innovation going on in IOL  designs. The crystalline lens is now much  better understood, as are the theories  of accommodation, which Dr Aggarwal  said is helping with new designs. Surgical  techniques are also continuing to improve.  “In future for example with femtolaser,  things are going to get even more  predictable and that’s allowing for new  development and better IOL designs.â€Â  The four key issues new IOLs are trying  to address are astigmatism, presbyopia,  capsular bag transparency and higher order  aberrations  Dr Aggarwal said if there is rotational  instability of the IOL, then a surgeon can  almost forget trying to correct astigmatism  with IOLs. Thankfully the newer toric IOLs  are very stable and do not show the rotation  that the previous IOLs used to, he noted.  To tackle astigmatism Dr Aggarwal  said most would agree that it is possible  to reduce surgically induced astigmatism  by keeping the incision below 2.0mm for  implantable IOLs.  Another interesting development  is the attempt to manipulate higher  order aberrations to actually mimic  accommodation he said.  Presbyopia is one of the biggest drivers  of IOL design improvement, and the  current premium multifocal IOLs give very  good near and distance vision, but poor  intermediate vision, he reported. This is now  being addressed by trifocal IOLs. There are  also issues with dysphotopsia, especially night  vision, and reduced contrast sensitivity.  The accommodative IOLs do not have  issues with dysphotopsia at night or contrast,  but near vision and the accommodative  range is poor, according to Dr Aggarwal.  Multifocals Dr Aggarwal said that the  four most commonly used multifocal IOLs  all have particular positive attributes, but  indicated a preference overall for the MPlus  (Topcon) lens, partly due to its better night  vision results. “The other intriguing advance  has been the tri-focal lens. When first this  was mentioned to me I thought here we go,  we are going to get more problems and I  was a bit reluctant… but to my surprise it  (Fine Vision Trifocal IOL) has become my  standard of multifocal lens now.â€Â  He said this lens gives very good distance,  reading and intermediate vision.  Summarising, Dr Aggarwal said the  newer multifocal IOLs have a better range  of focus, reduced light loss, better contrast  sensitivity profile, reduced dysphotopsia and  better patient acceptance  “But they are still not perfect and they  never will be perfect in my opinion because  you are introducing abnormalities by  having more than one focus within that  lens, so I think the way forward has to be  accommodative lenses – if we can get them  to accommodate.â€Â  Accommodative lenses There  remains a question as to whether the  current accommodative lenses are  truly accommodative or if it is pseudo  accommodation, Dr Aggarwal remarked,  saying that in his opinion single  accommodative lenses do not accommodate  well. He said dual optic accommodative  IOLs give good results but have issues with  delivering emmetropia.  Research has shown that high  accommodative amplitudes can be achieved  by lens curvature changes and experiments  with new lenses using that approach are  yielding good results.  He also briefly discussed LiquiLens and  Fluid Vision lens, which he said show some  progress, while he expressed excitement at  the development of light adjustable lenses  and the SmartIOL.  Concluding, Dr Aggarwal said patient  needs are key to choosing the right lens  but the newer lenses coming on stream will  mean more flexibility, and better results  and choice.