The ultimate priority

In his shortlisted essay for the 2018 John Henahan Prize, Dr David Chen says cataract surgery needs compassionate cataract surgeons

David Chen

Posted: Friday, July 6, 2018

For years, the randomised controlled clinical trial has been considered the gold standard in clinical experimental research. A well-conducted trial could eliminate bias, control for confounders and definitively help clinicians with decision-making. Publication of major prospective trials such as the SPRINT trial (1) helped establish target blood pressures for patients at risk of cardiovascular events, and the CHANCE trial (2) proved the benefits of dual antiplatelet agents for patients with high-risk transient ischaemic attacks. However, major randomised controlled clinical trials are time-consuming and resource-intensive – do they still have a role in cataract surgery, where surgical outcomes are already close to excellent?

To answer this question, let us first look at the evolution of cataract surgery over the past centuries. Ancient techniques of cataract removal were brutal and had abysmal visual outcomes, and though there was slow refinement of techniques from intracapsular cataract extraction to extracapsular cataract extraction, cataract surgery always involved significant morbidity and prolonged visual rehabilitation. This all changed with the first phacoemulsification surgery by Dr Charles Kelman, who revolutionised the way cataract surgery was performed and drastically improved surgical outcomes. Since then, further improvement in intraocular lens designs, phacoemulsification machine mechanics and surgical techniques have progressively propelled cataract surgery to the standard we know today.

Research has been an integral process of this evolution. It has helped to prove the superiority – and sometimes non-inferiority – of one surgical option over another. Different randomised controlled trials showed that even though phacoemulsification was a more expensive surgery, it provided more cost-savings in the long run when compared to extracapsular cataract extraction in a developed country (3); that manual small-incision cataract surgery was a preferred option for patients with white cataracts in developing countries (4); and that femtosecond laser-assisted cataract surgery was not superior to standard phacoemulsification surgery in terms of visual outcomes. (5)

So, do we need a randomised controlled clinical trial in cataract surgery? Yes, we do – not one, but many. There are yet many clinical questions unanswered in the world of cataract surgery, and despite the major advancements in surgical outcomes, there are still areas for improvement that current technology does not allow. These include, briefly, accommodative intraocular lenses that allow presbyopic correction without compromises, optimum phacoemulsification settings that do not damage the endothelium without prolonging operative time, real-time anterior segment optical coherence tomography that predicts anterior chamber instability and prevents posterior capsular rupture, just to name a few. We have come a long way, but there is still a great distance to go before the cataract surgery could truly restore the function of the clear crystalline lens. As life expectancy continues to increase, the importance of performing the ideal cataract surgery becomes ever more pressing.

However, randomised controlled clinical trials are time-consuming and expensive endeavours. They are well-suited for answering focused clinical questions, but the results of each trial may not be easily extrapolated to demographically dissimilar populations. The clinically controlled settings also do not always accurately reflect real-world outcomes. To answer all the questions about cataract surgeries would require many different trials, on many different populations, involving many different centres and surgeons – this may not be economically feasible.

Therefore, research for cataract surgery should include more than just a randomised controlled clinical trial. It should include cross-sectional studies, longitudinal cohort studies, case-control studies and a combination of these, depending on the clinical question to answer. The consolidation of these findings could be assimilated in meta-analyses. In addition, the information technology explosion in recent years has also opened the possibility of Big Data, while the recent revolution in Blockchain technology enables potentially secure and decentralised information storage. Altogether, this information could eventually be fed into a predictive decision-making tree where neural networks could help personalise the surgical option for the ideal cataract surgery for each unique patient.

Cataract surgery needs research to get better. It needs randomised controlled trials, it needs basic science experiments, it needs meta-analyses, it needs evolution through artificial intelligence. More than just research, cataract surgery also needs years of dedication to the perfection of this delicate surgical skill. Most importantly, however, cataract surgery needs the compassionate cataract surgeon, who will never stop placing the patient’s best interest as the ultimate priority.

1. Anon. A Randomized Trial of Intensive versus Standard Blood-Pressure Control.
N Engl J Med 2015;373:2103–2116.
2. Wang Y, Wang Y, Zhao X, et al. Clopidogrel with Aspirin in Acute Minor Stroke or Transient Ischemic Attack. N Engl J Med 2013;369:11–19.
3. Minassian D, Rosen P, Dart J, et al. Extracapsular cataract extraction compared with small incision surgery by phacoemulsification: a randomised trial.
Br J Ophthalmol 2001;85:822–829.
4. Venkatesh R, Tan CSH, Sengupta S, et al. Phacoemulsification versus manual small-incision cataract surgery for white cataract.
J Cataract Refract Surg 36:1849–1854.
5. Manning S, Barry P, Henry Y, et al. Femtosecond laser–assisted cataract surgery versus standard phacoemulsification cataract surgery: Study from the European Registry of Quality Outcomes for Cataract and Refractive Surgery. J Cataract Refract Surg 42:1779–1790.

Dr David Chen is a resident in the Department of Ophthalmology, National University Health System, Singapore

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