Stanley Chang: "Some retina problems change your life"

Stanley Chang is one of the most important ophthalmologists since the second half of the 20th century.

You described the appearance of vitrectomy-associated glaucoma in 2006. Why does this complication arise?
Because of the change in oxygenation in the vitreous space during a vitrectomy. This metabolic change also causes cataracts, which affect a much higher percentage of patients. While glaucoma appears in 10% of those operated on, cataracts are present in 80% or 90% of all cases.

At the Conference, you advised your colleagues to monitor patients who have undergone a vitrectomy for several years. Why is this?
Because secondary glaucoma associated with a vitrectomy does not appear until five years after the operation. Furthermore, it is one of the more serious forms of glaucoma and is more difficult to treat than primary glaucoma. It is, therefore, extremely important not to lose track of patients and to monitor them annually.

Could this complication be avoided in the future?
I hope so. At present, we are working on locating the patients at risk, so that they can be treated to lower the intraocular pressure after the vitrectomy as a preventive measure to avoid glaucoma. 30% of the patients we operate on show signs of an increase in intraocular pressure immediately after surgery, but it is not advisable to give treatment to those who will not develop glaucoma, as this could be harmful.

Is it worth doing vitrectomies when you know that 10% of patients will suffer glaucoma and almost 90% will develop cataracts?
There are much fewer complications associated with the vitrectomy than there are benefits. Millions of people have benefitted from the great advances we have made over recent decades in this type of retinal surgery. A great many good ophthalmologists perform vitrectomies all over the world using the best technology, which means that many patients who would have inevitably lost their sight decades ago can keep it or even recover it to very satisfactory levels.

And what are the current challenges?
I think the key to future treatment lies in gene therapy, which is already extremely advanced in some illnesses, such as Stargardt disease, caused by a mutation of the ABCR gene that gives rise to the degeneration of the photoreceptors in the retina, leading to a loss of sight. Another important line of work is neuroscience, in which technology is being developed for a greater connection between the eye and the brain. We are currently in the final stage in the application of the chip in the retina, which will enable the blind to see certain things.

Can retinal problems be detected?
Visual distortion is a typical symptom of problems in the retina. If you see twisted lines, then you have a macular problem (in the centre of the retina).

And can they be prevented?
You can look after what you eat, making sure it is rich in vitamin A or retinol (as this produces pigment in the retina). You can avoid alcohol and tobacco and, in general, lead a healthy life, which will help prevent, delay or improve the prognosis of systemic and retinal diseases.

But, if it is genetic, nothing can be done…
I think retinal disorders arise from a combination of genetic and environmental factors. We have located two genes that cause over half of all retinal diseases. Then, tobacco, food, exposure to sunlight and certain systemic illnesses such as diabetes, which can be devastating for the sight, also play their part. At Columbia University, I have visited diabetic patients with few resources and a low cultural level who only make the appointment when the illness has totally destroyed their sight in one eye and is now affecting the other one.

Are the most serious ocular illnesses those that affect the retina?
Yes, many retinal problems change your life, because they seriously affect your sight, which is an extremely important sense. Sight is vital for a good quality of life. Without it, you cannot read, go to the cinema or visit museums…

Although there are still cases in which lost sight cannot be recovered, these are increasingly few and far between… Could you highlight a particularly difficult case to give hope to patients with serious retinal disorders?
Around 20 years ago I was visited in New York by a young woman from Hong Kong. She was desperate, because she had been told that her problem could not be treated. However, we treated her, and she recovered her sight. Six years later, she came to study at Columbia University and graduated. It was an incredible experience! I also remember the case of a diabetic student who went blind. We were able to treat him, and he was able to finish his studies.

Finally, how is your visit to Barcelona coming along?
I am really happy to be in Barcelona with my friend and colleague Borja Corcóstegui.

What do you think of the new IMO?
I think it is the best ophthalmology centre in the world… And I have been in a lot.

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