– Ed

For the past thirty years the improvements in hygiene conditions and medical progress have led to an impressive reduction in morbidity amongst elderly people, many of whom now live without any major incapacity to over 80 years and beyond. Why do we age? The important question that we all ask ourselves still remains. As we age, our past abilities are substituted by new and increasing inabilities that mark every stage on our final journey. Our various organs age in their own specific ways: blood vessels lose their suppleness, the heart is invaded by fibrosis, the brain by neurofibrillar degeneration and the appearance of a senile plate, the kidney function declines, immune defences are down and the frequency of cancer increases with age.

The eye itself evolves in its own way. The first obvious sign of its ageing is the difficultly in reading close up, which is known as presbyopia. In reality this is merely the revelation of a long process that affects the accommodative power of the crystalline lens. If one compares this power, at the age of twenty, with that of a four year-old child, it is already clear that a large part of the accommodative power has already been considerably reduced. But at that time it is still of no consequence. It is only around the age of forty-five that someone with no refractive error (emmetropia), begins to experience some difficulties with reading, which will only increase with age. The causes of presbyopia are due to structural changes in the crystalline lens and the ciliary muscles, which are responsible for modifying the curves of the lens. Up until the thirteenth century this was a major handicap for intellectuals and was resolved only by the introduction of magnifying lenses. Today we can consider that presbyopia has found its remedy in the remarkable solutions provided by designers of corrective spectacle lenses.

Everyone knows that cataract occurs with age. It is the main cause of changes to vision after the age of sixty-five. This gradual change in the crystalline lens leads to modifications in its transparency, which results in a range of visual defects, such as reduced acuity, glare or an alteration in contrast. Thanks to remarkable technical developments, cataract surgery,
is now a precise, short, out-patient procedure which restores normal vision.

It is in the retina where ageing is the most harmful to vision and the origin of major visual handicaps. Age-related macular degeneration (AMD) is the most common of these handicaps, and is understandably feared amongst the ageing population. With age the retina regularly loses photo-receptor cells (cone and rods) but without affecting vision, since 30% of them are enough to maintain what we consider to be normal vision. AMD affects around 25% to 30% of men and women aged over 80. It is the consequence of a degenerative alteration of the retina, which affects central vision, which is used for reading and seeing colours. It can occur from the age of around sixty, but only in a very low percentage of cases. This percentage increases regularly with age. AMD is expressed in two ways: the most common is a slow-progression, dry form, characterised by the presence of lipid deposits or “drusen” on the macula and, to a lesser extent, a fast-progressing exudative or “wet” form, characterised by major vascular proliferation. It has been clearly established that high-risk factors encourage the appearance of AMD (age, tobacco, oxidative), but also that major genetic factors are involved and these are beginning to be identified with precision.

Although AMD is the major retinal complication during the ageing process, added to it are slow degenerative modifications to the retinal periphery. Degeneration of the vitreous humour, may be the cause of retinal tears, which are themselves responsible for retinal detachment. There is a particularly large incidence of these cases in very short-sighted people over the age of fifty.

It is often during an examination by an Eye Care Professional that a patient is found to have glaucoma. Patients are usually unaware that they are suffering from this terrible disease, since at the outset it is entirely without symptoms. If diagnosed early, glaucoma can be treated successfully. Without treatment we know that it leads to optic atrophy and irreversible loss of vision.

Although expressions of ageing on the eye mainly affect the clinical forms previously mentioned, there are many other signs. We have all noticed the changes that affect the eyes with age. Those eyes that were so fascinating, lose their sparkle and those previously highly colourful irises have now become dull. De-pigmentation of the iris is the cause of this, the pupil that was previously so black turns greyish in colour and the cornea that was so transparent often bears at its periphery a white ring, known as arcus senilis. The conjunctiva itself can become dull and yellowish because of growths called pingueculas. What to think about the “bags” that hang over or underline the eyelids and which are linked to the failing of an orbital septum, itself the victim of tissue degeneration? Why do old people so often have watery eyes? A condition caused by eyelid distortion and, above all, late onset obliteration of the tear ducts. This is an extremely common and unpleasant handicap, but to a lesser extent than the reverse, the constitution of ocular dryness, which is responsible for chronic keratitis and the need to humidify the eye several times a day.

Will we be able to write another story one day? The story of humans who could live up to the limits estimated by science, at least thirty years longer than our current averages without any expression of ageing.

Share this on Facebook: