We live in a visual world. So much of our lives depends on sight. Our eyes are incredible sensory organs that we should value highly and take good care of. This short article will consider a few important aspects of eyes, eyesight, vision, and how best to preserve this most-valuable of senses.
A quick overview of how vision works: Our eyes gather light through the cornea and lens and then onto the retina at the back of the eye. The retina converts this light into nerve impulses and passes these onto the brain. The brain understands these as the images we appreciate as “sight”. This all works similarly in most mammals, albeit that there are small differences in some cases.
There is some variability in visual acuity – some people see better than others. This is largely genetic/inherited and although there are some ways to train/improve vision the reality is that these make only small differences. Fighter pilots, racing car drivers, crack shots, etc. are mainly born with excellent vision – they can and do train this somewhat but for the most part, they are born with a vision advantage.
The most common type of vision problem is refractive error, where the shape of the eye and the working of the lens are such that people are not able to see close-up and or at distance very well. This can be something that starts in childhood but the most common and typical type of refractive error is the presbyopia or long-sightedness (see well at distance but struggle close-up) that affects the majority of older people (typically starts around age 45-50). Most refractive errors can be managed quite effectively with spectacles or contact lenses. Surgery can be used in some cases.
Another very common vision problem is the development of cataracts. Cataracts are cloudy deposits within the lens of the eye. Cataracts develop with age and are most commonly seen in those over 60. These can be treated very effectively with cataract surgery where the cloudy lens is replaced with a new plastic lens. Cataract surgery is now a routine and safe procedure, which is one of the most effective medical interventions today.
There are various types of eye infection that can threaten vision. Mercifully these are increasingly uncommon in the developed modern world, provided people have and make use of early access to quality healthcare. In the underdeveloped world, serious eye infections continue to be an important cause of visual impairment and blindness.
Disease of lifestyle such as diabetes and high blood pressure can and do cause changes to the eye (mainly the retina) and while these changes can be managed to a degree, the main opportunity is prevention: healthy living (weight control, exercise, etc.) reduces the risks substantially.
Eye injuries are important. Scenarios like welding, grinding, wood-working, fights, and falls, can lead to vision-threatening eye injury. Once again, modern healthcare can usually salvage eyesight in these cases provided the patient presents early enough. Any eye injury is a good reason to see your doctor urgently (same day or immediately).
Some 2 billion people worldwide have impaired vision. We all know people who need spectacles or have other vision problems. Much can be done through general healthy living, regular eye checks, and seeking medical care promptly when needed.
Written by Dr Colin Burns