When people think about ageing, they usually picture greying hair, lines on the skin, or joints that feel stiffer than they used to. Few of us stop to consider that a delicate, paper-thin layer of tissue at the back of the eye, the retina, may in fact be ageing faster than almost any other part of the body.
In my years as a retina specialist, I have seen the effects of this accelerated ageing in the clinic on a near-daily basis, and I think it is something patients should genuinely understand, not just as a medical curiosity but as something that shapes how they should look after and nurture their eyes.
Retina is an unusually demanding tissue
The retina is made up of highly specialised neural tissue that converts light into the electrical signals that our brain reads as vision. It is one of the most metabolically active tissues we have in our body.
Photoreceptor cells burn oxygen and consume energy at a rate that rivals, and at times exceeds, that of the brain tissue. This constant activity produces a steady stream of oxidative by-products, and it is this very demand that leaves the retina prone to early & easy cellular wear & tear.
Why oxidative stress affects the retina
Skin cells renew themselves every few weeks, but retinal photoreceptors and the retinal pigment epithelium do not work this way. Once these cells mature, they largely stop dividing, so any damage they pick up over the years is never diluted or replaced. It simply builds up.
On top of this, the retina is exposed to light throughout our waking hours, including a good deal of high-energy blue light, so it is essentially under a low-grade, lifelong stress test that very few other tissues in the body ever face.
The vascular connection
The retina also carries one of the richest networks of tiny blood vessels found anywhere in the body, relative to its size. This makes it especially sensitive to the same vascular changes that come with diabetes, high blood pressure, and hardening of the arteries.
In many respects, the retina works like an early window into how the body's blood vessels are ageing & changing in these pathologic diseases. The retina is in fact the only tissue where the doctor can visualise the blood vessels of the patient without making an incision. Many of the pathologies affecting the brain are transmitted down the optic nerve, where they can be picked up by an ardent Retina specialist without expensive imaging like MRI.
The retina often reveals damage years before it becomes obvious anywhere else. Many AI models have been trained & designed to pick these up without the need for a doctor.
How modern lifestyle adds to the problem
Our present-day habits tend to speed this process up further. Long hours in front of screens, uncontrolled blood sugar, smoking, low intake of protective antioxidants, and not enough protection from ultraviolet light all add to the oxidative load on retinal cells. Conditions such as age-related macular degeneration, one of the leading causes of vision loss around the world, are really an expression of this same accelerated cellular ageing playing out in the macula.
What can be done
We cannot stop biological ageing altogether, but there is a good deal we can do to slow down how quickly the retina wears out. I generally advise patients to focus on the following:
1) Go for regular annual, comprehensive dilated eye examinations, even when there are no symptoms.
2) Eat a diet that includes plenty of lutein, zeaxanthin, and omega-3 fatty acids, like ‘green’ leafy vegetables, ‘yellow’ fruits like mango, papaya, fatty fish like salmon, sardines, mackerel, trout and tuna oil, egg yolk, and nuts like walnuts & almonds
3) Keep blood pressure, blood sugar, triglycerides & LDL under proper control
4) Wear eyewear that protects against ultraviolet light
5) Avoid smoking or tobacco
6) Use screens sensibly, with regular breaks for the eyes
7) Try to get atleast 8 hours of refreshing sleep where most of the damage gets repaired
The very metabolic activity that lets us see the world in such rich detail is also what makes the retina so vulnerable. Recognising that our eyes may, in a biological sense, be older than the rest of our body is a useful reminder that eye care needs to start well before any symptoms appear.
(The author is an ophthalmologist at Dr Agarwals Eye Hospital, Mumbai)
The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.
