(i) Regular eye examinations
are particularly important form middle age onwards.
Some relatively common serious eye diseases are
not symptomatic in their early stages. In
order to prevent the progression of these eye diseases, it is essential
to have regular eye examinations. Examples of such diseases are
glaucoma and diabetic eye disease in which an affected person may
lose most of his/her sight before becoming aware of having an eye
problem. It is especially important to have regular eye examinations
if you have a family history of a certain eye condition. A good
example again is glaucoma. As familial glaucoma can appear from
an earlier age than usual, regular eye examinations should begin
from the teenage years if there is a family history of glaucoma.
It is also important to realise that several
important and commonly occurring systemic diseases, such as high
blood pressure and diabetes, are not uncommonly associated with
subtle or pronounced eye changes. The author has encountered numerous
cases of undiagnosed systemic disease in the course
of providing routine eye examinations. For these reasons, one should
have regular eye examinations even if one does not need to change
their glasses or if one decides to wear ready-made spectacles that
are sold at department stores etc.
occurs almost universally with age, to varying degrees. Many people
remark that they become more reliant on glasses after wearing a
correction for their presbyopia. This is because the eyes are less
stressed when wearing glasses and they are allowed to become more
long-sighted. On the other hand, deliberately avoiding a correction
for presbyopia necessitates greater muscular tension within the
eye. This can lead to either the appearance of astigmatism (of the
against- the-rule type, see Part IIA)
I have found that many people prefer to have
the full correction, which gives them the most clear and comfortable
vision and do not mind a greater reliance on glasses. Other people
prefer to avoid using glasses and make greater efforts in focusing.
These people will be less reliant on glasses, however, they experience
more eyestrain symptoms (tired eyes etc). They also have more difficulties
in adjusting to spectacles, especially when they are used for distance.
Excessive straining of the eyes may be associated with more permanent
eye health problems.
When the best possible vision and comfort
is required, the full recommended near correction is the best option.
It is preferable to make the spectacles in such a way as to allow
for regular shifting of the focus into the distance. This need only
be for a couple of seconds and is effective in preventing eyestrain.
Bifocals or single vision lenses in a look-over frame are ideal
for this purpose.
Practicing good vision habits will help prevent
eyestrain and consequent effects on the eyes. Refer to Appendix
I for details. VDU users may refer to Part II (C):
hints on eye usage with computers
for detailed discussion and appropriate recommendations
related to VDU use.
(a)Glaucoma related to increased pressure.
If upon examining the eyes, the health professional
finds a mildly increased pressure in the eyes which does not
require medical treatment, it is wise to consider the possible causes
of the increased eye pressure. This may help to prevent a possible
further increase in eye pressure leading to glaucoma. If there are
no obvious general health problems that need to be attended to,
and the eye care professional cannot find any causes within the
eye for the increased eye pressure, there are several factors that
need to be considered.
As nervous stress is considered
to be a major contributing factor, a concerted effort in finding
ways to reduce emotional stress would be strongly recommended. Exercise
is an important life style factor that needs to be considered. Treadmill
walking has been found to reduce eye pressure by as much as 30%.
Daily outdoor walking can only be of even greater
benefit as this would also help to reduce stress. Caffeine
intake can increase the eye pressures and thus it is important
to try to limit or eliminate coffee drinking if possible. If an
excessive amount of continuous close work is carried out, it would
be important to ensure that it is performed with regular
shifting of the focus say every five to ten minutes. Further
details on appropriate eye use are given in Appendix
I. Obesity, excessive salt or fluid intake and high blood pressure
may also lead to raised eye pressure and need to be controlled.
The life-style changes suggested above can
also be implemented when your eyecare practitioner prescribes anti-glaucoma
medication. This is usually in the form of eye drops. If drops are
prescribed, they should be used as directed to
obtain maximum benefit and prevent loss of sight.
Ask your practitioner to show you an appropriate method of instilling
the eye drops to ensure they get into the eye. After instilling
the drops, close your eyes for a few minutes and
press the inner corner of your eye with your index
finger to prevent escape of medication into the nostril. Wait at
least ten minutes between instilling different drops to ensure adequate
penetration of the drops. Care must be taken to prevent
contamination of the bottle by contact with eyelashes,
lids, skin or the tears in the eye.
(b) Normal Tension
The primary cause of nerve damage in normal
tension glaucoma is thought to be poor blood flow at the
optic disc. The factors that are involved in reducing blood flow
are not clearly understood. Thus there are not any widely accepted
medications or other treatments for normal tension glaucoma. However,
it has been shown that in these patients, it is particularly important
to bring the eye pressures down to the perfectly optimal reading
of 15mmHg or less. This is because there is already a problem with
blood flow, and even a slightly raised pressure may further decrease
the blood flow in some patients.
As smoking is known to affect
the health of blood vessels and thus blood circulation, it is advisable
that smoking be limited or stopped. Exercise
improves blood flow and should be encouraged. The blood
pressure should be regularly checked to ensure that it
does not fall significantly below the normal levels. This applies
especially to those who are on anti-hypertensive (blood pressure
lowering) drugs. Betaxolol (Betoptic) is a drug that appears to
be of particular use in normal tension glaucoma as it helps to increase
blood flow at the optic disc. This is done by the dilating effect
that Betoptic has on the small blood vessels and by the drug's other
action of reducing the eye pressure.
It is suspected that vasospasm (abnormal muscle
contraction leading to narrowing of tiny blood vessels) may be an
important cause of reduced blood flow at the optic disc and thus
of normal tension glaucoma. It may thus be of benefit to try to
reduce nervous stress as it is often implicated
in other cases of vasospasm such as migraine. It has been shown
that migraine sufferers have an increased risk of glaucoma compared
to the normal population. Finally, it has been suggested that certain
foods are beneficial to blood flow and health of nervous tissue
in the eye. These foods include blueberry and cod liver oil.
The most important factor to consider in trying
to prevent progression of diabetic eye disease is the general health
and strict control of blood sugar levels. Stress reduction the appropriate
diet and adequate exercise are the key factors to consider in controlling
diabetes. All those factors that affect blood flow such as smoking
should be optimised. Regular eye examinations as recommended for
each particular individual by their eye care practitioner, are essential
in order to detect serious damage to the retina. If this damage
is detected early enough, laser treatment can be successfully applied
in most cases to prevent more serious loss of vision.