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The evolving vision of cataract surgery

Intraocular lens surgery and implants to treat cataracts due to ageing have seen major advances in treatments

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MANY years ago, during a clinical Observership in Cataracts and Anterior Segment Reconstruction with Drs Robert Osher and Michael E Snyder at the Cincinnati Eye Institute, one of the United States' largest private eye centres, I was invited to co-author a chapter in the Textbook of Intraocular Lens Surgery (an ophthalmology textbook eventually published in 2017 by Thieme, available on Amazon and Kindle).

As part of my research for writing this chapter, I acquired a vintage book titled Intraocular Lenses and Implants, widely regarded as the first ever textbook on the subject, written and hand-signed by Dr Peter Choyce.

For the uninitiated, cataracts are opacification of the lens in our eyes, arising from ageing and accelerated by certain diseases, medications and trauma.

Dr Choyce, along with his more famous mentor, Sir Harold Ridley, were pioneers of intraocular lens (IOL) for use in cataract extractions in the 1940s. They recognised the shortfalls of conservative management with thick spectacles and unwieldy contact lenses to "replace" the focusing power of the extracted lens after cataract surgeries.

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That their work - described as chasing windmills then - is today a staple in cataract surgeries, the commonest operation in the world, belies their struggle for acceptance, replete with dealing with disdain and discourteous actions from many colleagues that they had to endure back in those early days.

The first IOL implant

Inspired by pieces of perspex from shattered warplane canopies that lodged inertly in the eyes of World War II fighter pilots whom he treated as an army doctor, Sir Ridley, who died in 2001 at the age of 94, designed the first IOL and implanted the first case at St Thomas' Hospital, London, in 1949.

It wasn't until significant improvements in designs were made 20 years later, that the IOL became mainstream, and recognitions streamed in for the inventors in the 1970s, culminating in the Gonin medal, the highest award in Ophthalmology and knighthood for Sir Ridley. The rest, as they say, is history.

In my eyes, Dr Choyce's IOL designs illustrated in the musty book published in 1964 are remarkable. Some were for lens replacement in traumatised eyes, iris replacement and routine cataract operations. Now seeming "retro", these ideas fathered the current generations of IOLs, and may continue to do so. In fact, some novel creations in the current IOL market echo these first designs, such as the IC8 pinhole IOL which may have been inspired by the Choyce stenopaeic aperture IOL, and the telescopic IOL, with the difference being the IOL shape and locations within the eye had changed.

Fast forward to 2019, generations of IOL designs had come and gone, and millions implanted into human eyes, the vast majority to the recipients' benefit.

IOL materials improved, sometimes arising from mistakes in the past. Together with advances in lens extraction techniques using ultrasound (phacoemulsification) and nowadays with a touch of femtosecond laser, modern surgical incision sizes are much smaller, and safety and efficacy approaching near-perfection.

In fact, IOL surgeries have evolved to become highly refractive, often bettering the pre-operative eye power. From my experience as a cataract and refractive surgeon, this contributed to a significant shift in our mindset, even leading to refractive lens exchange without significant cataracts.

It seems de rigueur for many resourceful patients to expect no less than perfect eyesight and eye power from their IOL operations, thanks to the sophisticated IOL designs and variety, meticulous pre-operative measurement and surgical planning, which together can and often successfully meet these heightened expectations.

A version of the IOL, called the implantable collamer lens (ICL) can be implanted into eyes without lens extraction, a solely refractive operation, which I also perform as a premium alternative to laser in-situ keratomileusis surgery or Lasik.

New designs continue to pour into the IOL market almost every year. Suffice to say that currently, in general, the simpler IOLs correct basic eye powers, while more advanced IOLs, which cost more, can also manage additional errors such as astigmatism, sphericity and presbyopia (such as multifocal and extended range lenses). Competition among IOL companies produces some unique differentiating features, whose merits the companies work to substantiate, and ophthalmologists critically assess and responsibly peruse to benefit the visual outcome of their patients' IOL surgery.

As a result of the plethora of IOL designs, it behoves any potential cataract surgery candidate to take a moment to understand his or her choices, as the surgery should ideally be done just once in a lifetime.

Apart from IOL, vision and visual quality results, technique of surgery such as with or without laser should be discussed, as these choices may affect short- or long-term outcome. The final option depends on the activities and lifestyle of the individual, and other aspects of the eye and health.

Even further refinement

While cost is a factor in the choice of implant and technique, there are alternative strategies that fall not far behind and sometimes arguably better, including glasses or the popular Lasik, for instance, for even further refinement after cataract and IOL operations.

I find that calculating an accurate IOL power for my patients is a rewarding part of my clinic's services. I currently employ a "ray tracing" software based on a Swiss-made eye scanner, and regularly audit the results, which I find excellent, and which I've recently shared at the Asia Pacific Academy of Ophthalmologists congress.

As such, with the increased IOL choices, increased "chair time" is expected, and a clear and thorough conversation should be sought between doctor and patient, since these surgeries are rarely emergencies.

For me, all individuals are unique and so are their eyes, hence a customised approach to the IOL choice is called for. Occasionally, true suitability for some of the more complex IOL designs, such as multifocals (bi- or trifocals) can only be fully ascertained after a period of post-surgical adaptation, making clear and open communication even more important.

As for my two precious textbooks of Intraocular Lens Implants (the first and the latest published to date, to my knowledge), I may just read them side by side, for my fascination, perspective and gratitude.

Indeed, we see further when standing on the shoulders of giants!

This series is produced on alternate Saturdays in collaboration with Singapore Medical Specialists Centre.