In the above text, I have outlined the fundamental factors involved in eye health that pertain to a developed city environment. These factors can affect the eye indirectly by first affecting the general health or nearby tissues, and they can also directly affect the eye.
The fundamental factors that affect the general health include genetic makeup, stress, diet, exercise, cleanliness (infections etc.) and physical agents (mechanical, physical, and chemical).
An optimal level of stress allows for the smooth functioning of nervous and muscular tissues, and prevents unnecessary depletion of essential vitamins and minerals. Stress can play an important role in disease (including AMD), diabetes (and consequent retinopathy), and has also been implicated in myopia development, infections and disorders of the immune system affecting the eye.
A healthy diet can help to prevent refractive errors and sub-normal retinal development in infants. It can also help to prevent cataracts, diabetic retinopathy (through good control of diabetes), and AMD in older people. Visual fatigue and even night blindness and severe disease of the cornea can also develop when the diet is inadequate.
A healthy diet implies a well-balanced intake of nutrients that are also free from impurities such as preservatives etc. Good long-term eye health should be added to the list of important benefits of a good diet and healthy lifestyle i.e. lower blood pressure, better cholesterol and sugar levels, lower levels of heart disease and cancer etc.
The way in which the eyes are used is important in preventing
eyestrain and refractive (sight) problems. Inadequate visual
experience in infants can prevent optimal visual development.
However, the more important cause of sight problems nowadays is
poor visual hygiene in children and adults, leading to myopia
and other vision changes. Increasing children's awareness of these
problems through government funded eye education programs is one
way of preventing vision problems in children of school age. Another
way is to encourage children in primary school to make their
own bookstands in their arts and crafts classes.
Today we enjoy high standards of cleanliness and personal hygiene
as many of the important infectious diseases have been eradicated
due mainly to our highly developed sewerage systems. However, despite
this, eye infections continue to be of some concern today.
The reason for this disparity lies principally in our failure to
recognise the adverse effects of polluted air environments
(both outdoor and indoor) on the hygiene of our nasal
passages and sinuses. Build-up of contaminants and infection
in these areas, acts as a source of infection to other parts of
the body as well, including ears, throat etc. If we wish to improve
nasal hygiene and prevent spread of infection, nasal
rinsing becomes a necessity especially in city environments.
If one had to single out the most important fundamental cause
of eye disease/permanent vision loss throughout the world, one would
have to point to sun radiation. Unfortunately, the importance
of sun protection from a
very young age is still not well understood, leading to cumulative
damage of the eye tissues with age. Diseases that are associated
with radiation damage vary from growths in the front-most part of
the eye (including pterygia and malignant tumors) to cataracts and
retinal damage (including age-related macular degeneration).
Other sources of radiation that can have cumulative adverse effects on the eyes include UV radiation from arc welding, etc., and infrared radiation e.g. from molten steel, etc.
Eye trauma resulting from failure to take appropriate safety precautions
(mainly the wearing of goggles) is currently at unnecessarily high
levels. The home handyman accounts for almost half of the eye injuries
according to a Tasmanian survey. Foreign bodies lodged in the eye,
especially from grinding and welding, chemical injuries (lime and
acid), gardening accidents (especially from tree branches), and
sporting accidents (particularly from squash), are relatively common
causes of eye injuries.