I have just recently returned from the Australian Cataract and Refractive Surgery annual conference which this year was in Port Douglas. The focus of this meeting is as the name implies, on new developments in the area of cataract surgery and vision correction.
This year there were many new items which are worthy of discussing.
Implantable Collamer Lens (ICL)
I have written about this before and so it was timely that Visian should produce a new lens. This concept is not new but the current lens is new and improved.
One of the main changes is the incorporation of a small central hole in the lens. The reason for this is to minimise the risk of pupil block and subsequent angle closure glaucoma. Under normal circumstances, aqueous is formed by the ciliary body which is situated behind the iris. It then flows via the pupil to the trabecular meshwork. This normal physiology is interfered with by the presence of the ICL which sits just behind the pupil. Aqueous is still able to get past the lens as the seal between iris and lens is not watertight. Under certain circumstances it can become watertight and therefore lead to angle closure. In this scenario, fluid behind the lens cannot get past, increasing the pressure and causing the iris to be pushed forward. This is called iris bombe. The iris then in turn is pushed hard against the trabecular meshwork obstructing it.
The central hole in the new lens eliminates this risk as aqueous can flow through it making angle closure unlikely.
Finevision trifocal lens
This is another area which is developing and which in my opinion is now good enough to be worth considering. The holy grail in refractive and in cataract surgery is the problem of not being able to deliver vision at all distances. That is to say, we can deliver good distance vision but not simultaneously near vision. Or the exact opposite, in that we can deliver good near but at a cost of distance. This is because modern intraocular lenses cannot focus. Our own natural lens also loses its ability to focus at around age 45. This is why reading glasses become necessary. This is due to a stiffening of the lens preventing it from changing shape. Attempts to circumvent this problem using intraocular lenses have been around for some time but all suffer from numerous problems. Halos, glare and loss of contrast sensitivity are the main problems. These mulifocal intraocular lenses work by having a diffractive pattern on the lenses which result in two images, one for near and one for far. The problems stems from the diffractive pattern which lead to the glare and haloes. Further, as the slight is split for near and far, it means that only a small percentage of the available light is use at any time. Many patients are not bothered by this but those who are highly critical are. Also truck drivers, Taxi drivers and pilots in particularly are not good candidates due to the haloes and glare special at night time.
The FineVision lens which has just been released by Bausch and Lomb will hopefully address some of these problems. Instead of having a distance portion and a near portion, rather it has a near, intermediate and far portion. This will therefore translate into the ability to see to drive, use the computer and read. It still has the problems of other multifocal lenses but to a much lesser extent. This lens is probably still not for those whose lively hood depends on driving at night or flying but most everyone else. It is also not for those who are highly critical of their vision. Patients who have macular pathology such as macular degeneration or prior macula hole surgery are also best to avoid this lens.
My approach to this problem has been for a long time to implement monovision but this too has limitations.
This is another promising technology which addresses the problem of presbyopia. Little is known about this lens to date except that it is probably based on some form of multifocal platform. It is due to be announced at the forthcoming European Cataract and Refractive Conference in London in September.
A New Zealand based surgeon has implanted 20 of these lenses as part of a trial. He was not at liberty to discuss the lens in any detail but did present his own findings. Essentially he found that patients had excellent distance and intermediate vision and good near.
It is unknown when this lens will become available or wether it lives up to the hype. My guess is that it may be available sometime in 2015 in Australia, probably in the second half
SMILE is Small Incision Lenticule Extraction. It is an alternative to LASIK or PRK. In the SMILE procedure only a small opening is created in the cornea and a lenticule is formed by the laser in the stoma of the cornea. The lenticule is then removed. No flap is created. This has been referred to as “Bladeless Lasik”.
Lasik by contrast creates a large corneal flap and laser is applied to the exposed corneal surface and the flap is deposited.
The main advantage of SMILE is because only a small incision (2-4mm) is created, there is less severing of corneal nerves and therefore less corneal anaesthesia. This translates into less post procedure dry eye.
Our laser centre is at present evaluating this technology and we may be implementing it in the near future.