Prof. Brézin, what were the most important innovations in cataract surgery in the last few years?
The most important innovation of the last 25 years was phacoemulsification. With this technique, an incision is made in the cornea and the lens capsule is opened before the lens is broken up (emulsified) into tiny pieces with an ultrasonic probe and then suctioned off. The back of the capsule is preserved and the prosthetic intraocular lens is implanted into it. As eye incisions only have to be a few millimetres in size with this technique, phacoemulsification has improved the safety of this operation and substantially reduced rehabilitation time. It is the standard method used today all over the world, except in some developing countries.
20 years ago, the first foldable intraocular lenses appeared on the market. As long as the prosthetic lenses were rigid, the corneal incision had to be as large as the size of the prosthetic lens, i.e. at least six millimetres. With the advent of new foldable materials such as acrylic and silicone, the incision only had to be as large as necessary for phacoemulsification, i.e. 3 mm or less.
Since then, there has been fierce competition in the industry to minimise the incision size required for phacoemulsification and to produce lenses that can be implanted through smaller and smaller openings. The necessary incision length has thus been reduced to 2.3 to 2.4 mm. Today there are even phaco probes that work through a 1.8 mm opening. At the moment, there is a lot of discussion on whether quality is being sacrificed with these extremely folded lenses. But there is an unmistakable trend towards procedures through mini incisions, also called MICS (MicroIncision Cataract Surgery).
What progress is being made in the development of new lenses?
We used to only have monofocal lenses, with which the patient could either see close up or long-distance and additionally needed glasses to correct his vision. Then, industry developed multifocal lenses, although they cannot really make up for the missing accommodation. They sharply focus both a close-up and a distant image on the retina, and the eye then chooses the right image. However, this may be at the expense of contrast sensitivity, and this type of lens is not suitable for every patient.
A totally new approach is accommodating lenses. New materials and designs are developed to enable the lens in the eye to actively focus . These lenses could take advantage of the fact that the ciliary muscle responsible for accommodation often still functions in very elderly patients. With lenses such as these we could fully restore patients’ eyesight. A great deal of research is being done in this direction, but the products have not achieved sufficiently satisfying results yet.
How many cataract operations do you perform and how long does the operation take?
I did twelve operations yesterday. In a year, I do about 500 – which is not a particularly large number in comparison with colleagues doing surgery full time, who do up to a thousand. I also work in a university hospital, where part of my job is to train doctors in cataract surgery.
I work in two operating rooms in parallel. While I am operating in one room, the next patient is prepared in another. Altogether, all the preparatory measures even take longer than the operation itself, which usually takes 12 to 15 minutes. The duration of the operation also depends on how hard the lens is, as this influences the ultrasonic destruction.
In general, it can also be said that the number of operations is continuing to rise all over the world. One reason is that people are living longer and longer. Also, cataract surgery is so safe and stressless for patients that they are less afraid of the operation and go to see the ophthalmologist in good time. Apart from this, cataracts are still the most common cause worldwide for treatable and therefore reversible blindness. India, for instance, finances large-scale programmes for low-cost cataract surgery.
Figure left: Modern intraocular lenses, such as the multifocal, asphericalAcrySof® IQ ReSTOR® IOL from Alcon, have a special optic design that makes spectacles unnecessary in most cases. Courtesy of Alcon, Inc.
What role does the microscope play in cataract surgery?
This operation is not possible without an excellent microscope. Another equally important factor is good organisation of the whole procedure – not least because the effect of the normally used local anaesthetic starts to wear off after 15 minutes. Therefore, the microscope has to be immediately ready for use at the beginning of every operation. I have no time to focus my eyes on anything else but the eye of the patient through the microscope. The microscope must provide the assistant with an excellent image as well. Working as a trainer of medical students, I often sit in the assistant’s place, so I know how important this function is.
Prof. Brézin works in two operating rooms in parallel. While he is operating in one room, the next patient is prepared in another.
What do you expect of future surgical microscopes?
It would be a great help, for example, if I could see data and settings of other instruments directly in the microscope – like a virtual overlay in a corner of the image. This would be particularly useful during phacoemulsification, when I am looking through the microscope and adjusting the ultrasound on the basis of different sounds from the instrument. After all, I can’t look at the screen of the instrument.
Another point, which doesn’t apply to the microscope alone, is the full integration of all surgical and patient data. The microscope of the future should be able to communicate with all computer and software systems of the hospital. However, this would require standardisation of data formats – even including video formats to allow a video of the operation to be directly added to the patient’s virtual file.
René Descartes Université Paris V, Cochin Hospital