THE ageing process begins soon after reaching sexual maturity. The biological systems gradually accumulate damage, degenerate and lose function. The biological ageing clock measures how our cells grow old. Scientists can track this through DNA methylation (chemical ‘tags’ on our genes), oxidative stress and telomere shortening, protective caps at the ends of DNA strands that act like the plastic tips on shoelaces. Age-damaged cells lose their capacity to repair.
The reversal of ageing might have remained a fantasy if not for a fortuitous incident in a marine biology lab in 1988. Christian Sommer, a German student, kept jellyfish in a glass jar for study, and accidentally left the fish unattended. The adult jellyfish, instead of dying, miraculously reverted to juvenile polyps. Till then, backward ageing was considered impossible.The ‘immortal jellyfish’ became a pioneering model showing that ‘transdifferentiation’, the ability of cells to reprogramme themselves, was possible in multicellular organisms, prompting scientists to investigate molecular mechanisms for reversing senescence.
Unlike humans, simple animals like jellyfish maintain a vast pool of stem cells that continually repair damaged cells and tissues. In humans, though, the complex biology designed to prevent cancer formation limits the cells’ potential to proliferate and transdifferentiate.
To reverse ageing, many people opt for botox, fillers, etc, to prevent/remove wrinkles and/or thinning hair. Some biohacking methods such as calorie restriction and ice-cold baths can slow down the cellular ageing process. However, calorie restriction can lead to muscle and bone loss, while ice-cold baths are best avoided by those with heart or lung conditions.
Have you ever wondered how you could focus on a distant object and the next moment clearly read the book in your hands? The crystalline lens in eyes is a marvel of nature’s engineering. It is a bag filled with layers of highly elastic transparent fibres. The lens hangs behind the iris diaphragm, supported by a multitude of fine zonular fibres connected to a circumferential muscle (ciliary) lining the inside of the eyeball. A blurred image of a near object prompts the muscle to contract, relaxing the zonular fibres and allowing the lens to change shape, becoming more powerful and bringing the near object into sharp focus on the retina.
While a young child can increase its power by almost 15 diopters (D), this ability continues to decline as we grow older. You need at least 3D to read at a distance of 30cm from your eyes. For a while, pushing the book/object farther away may help, but soon enough, the words remain a blur.
The senescence of the crystalline lens gradually occurs around the age of 40, with the lens fibres losing their elasticity, leading to presbyopia, from the Greek meaning ‘old man’s eye’. The lens can no longer change shape when needed. This change is unavoidable with age. People living near the equator tend to develop presbyopia nearly a decade earlier than those living at higher latitudes.
Presbyopia is the gradual loss of the eyes’ ability to focus on nearby objects, caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age. It is the most common cause of vision impairment worldwide. Because it is an ageing phenomenon, until recently the WHO did not include near vision impairment in its global blindness data.
The most economical solution is to acquire a pair of reading glasses. The estimated prevalence of uncorrected presbyopia has ranged from 510 million (Lancet Global Health, 2021) to 846 million (Frick and colleagues, 2018) and is projected to reach nearly a billion by 2050. Over 90 per cent of affected individuals live in low-income countries in Sub-Saharan Africa, South Asia, and Southeast Asia. Surprisingly, more than 12 per cent of the population in India and China lacks access to reading glasses.
Providing near glasses to tea garden workers in Assam increased productivity by over 20 per cent, according to a report led by Dr Reddy from Pondicherry and many others worldwide. Conservative estimates of the global productivity loss due to uncorrected presbyopia amount to nearly 1 lakh crore, and if the productive age is extended to 65 years, the loss doubles.
Humans might never achieve reverse ageing, but we can fix the ‘old man’s eye’. It remains a public health challenge to deliver the ‘miracle’ of glasses to those in need, not only to restore near-sightedness but also to regain productivity and dignity.
— The writer is Emeritus Professor, PGI, Chandigarh
Factcheck: Presbyopia prevalence in India is high, with estimates suggesting nearly one-third (around 33%) of adults aged 30 and above have uncorrected presbyopia, making it a significant public health issue impacting productivity and quality of life, especially as it affects many daily basic tasks like reading. Studies show rates can reach over 40% in specific age groups (35 or above), with factors like older age, lower literacy, and in women often correlating with higher prevalence, while spectacles coverage remains low.
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