Facts on Eye Care
Daily news questions
- 1. How does diet affect eye health
Diet plays an extremely important part in the health, as well as in certain pathological conditions (diseases) in the eye. As the saying goes, “a healthy body sustains a healthy mind” so it is also true for the eyes. Taking into account, the most common causes of blindness in South Africa (and globally), it is easy to understand why diet plays such an important role. These causes include cataracts, age related macular degeneration (AMD), diabetic eye disease and glaucoma.
- Cataracts and AMD
Even though these two conditions are completely different, they share quite a few similarities. A cataract forms when the normal human crystalline lens inside the eye becomes opaque, and normal light cannot be focussed onto the retina (light sensitive nerve lining in the back of the eye). Treatment includes surgery, but research has also shown that taking supplements like Lutein and Zeaxanthin, as well as Vitamins C and E, can protect against the development and progression of cataract formation.
Some of these supplements, however has also been linked to protection against and delay in the progression of AMD. Several studies have shown that there is a reduction in the rate of progression of AMD, if certain formulations of supplements are added to the diet. These studies include the ARED and ARED2 studies.
Good food sources for Lutien and Zeaxanthin are green leafy vegetables, but other lifestyle modifications that can protect against both these conditions include wearing protective eyewear with a good UV filter and quitting smoking. Unfortunately advanced age and genetic factors also play a very important role, but these however are not modifiable.
- Diabetic eye disease
Diabetes mellitus (especially if uncontrolled) can have detrimental overall effects on the body. The eyes are no exception. People with type1 and especially type 2 diabetes are much more likely to develop cataracts as well as diabetic retinopathy. Diabetic retinopathy is a blinding condition in which new (abnormal) blood vessels can form in the retina, and can cause bleeding as well as local areas of retinal ischemia (oxygen deprivation) and swelling (diabetic macular oedema). Therefore it has been shown that diabetics should follow a strict diet (low in carbohydrates and sugar), to prevent the development of these conditions. This in addition to keeping your blood pressure under control can drastically decrease the risk of developing diabetic retinopathy. Also, limit your salt intake, maintain an overall healthy lifestyle and perform regular exercises – these all can play a role in maintaining good eye health.
Glaucoma is a condition in which the optic nerve (nerve transmitting information from the eye to the brain) is damaged due to a raise in the intra ocular pressure (IOP). Even though some non-conclusive evidence exist that certain food intake increases your chances of developing glaucoma, no definite relationship has yet been found between glaucoma and diet. Caffeine intake has been linked to a temporary raise in the IOP but this effect usually lasts only a couple of hours. The most common risk factors for the development of glaucoma however remains a raised IOP, glaucoma in your family and race (genetic factors).
- 1. What if detected early on, can avoid poor vision or even blindness
- Young children
In young children the most common eye conditions causing poor vision or blindness are amblyopia, refractive errors, eye infections and the most serious condition which is retinoblastoma.
Amblyopia means that the vision in one eye is poor due to the abnormal development of the normal visual pathways to the brain. Causes can include cataracts, strabismus (skew deviation of the eye(s)) and unrecognised refractive errors in one or both eyes.
Refractive errors can be divided into hyperopia (far-sightedness), myopia (near-sightedness) and astigmatism (distorted image that forms mostly due to an abnormally shaped cornea / lens).
Eye infections in children are not always easy to recognise unless it is very severe and presents with a red eye with a purulent discharge. Children are not always forthcoming with what is wrong with the eye and a constant eye rubbing can sometimes be a clue if the infection is not severe. Constant eye rubbing is almost never normal and should always be investigated by a qualified eye specialist.
Retinoblastoma is the most common eye cancer in children younger than 15 years of age. This very complex disease has got a very high mortality rate and is usually diagnosed in very young children. The most common presentation is when a child presents with a white discoloration in the pupil area (centre part of the coloured part of the eye). This can easily be seen on photographs if one eye has a red reflex and the other eye does not. This is not the only reason for not having a red reflex in one eye, but can give a clue to look for help.
Eye screening in children begin when they are born (done by the paediatrician), and if any problems are detected, this should be further investigated by an eye specialist. Further screening for the most common eye conditions can begin as early as 3-4 years of age but most children should undergo at least one screening eye examination before going to school for the first time. Children with a family history of eye related problems should undergo examination by an eye specialist as soon as any abnormality is suspected.
- Young adults
Most healthy and fit young adults do not require regular eye examinations unless there is a positive family history, or poor vision and even eyestrain that affect their daily activities or school work.
In the technologically advanced area we live in today, there is a very real and sometimes overlooked eye conditions which are emerging, called computer vision syndrome (CVS). This happens when prolonged exposure to the computer screen, causes a reduced rate of blinking. This will lead to eye strain, dry eyes and even blurry vision. Ways to prevent this and improve the symptoms of eyestrain include the following:
i. Taking breaks from the computer screen;
ii. Sitting at the optimal distance of at least 60cm from the screen; and
i. Using anti-reflective computer screen or even special anti-reflective spectacles.
- Adults and the elderly
The following general guidelines exist for the detection of some of the most common conditions causing poor vision and blindness in this age group:
i. Cataracts: A cataract (lens opacity) that causes reduced vision, glare around lights and difficulty reading small print in poor light, must be investigated during a thorough eye examination done by an eye specialist. If these symptoms affects your activities of daily living, surgery is indicated.
ii. AMD: This usually affects the elderly and can be in the form of “dry” AMD or “wet” AMD. Typical symptoms include blurring or distortion of only the central part of the vision (you can see someone’s whole face except for their nose). Sizes of objects also differs between the two eyes (metamorphopsia). Unfortunately “dry” AMD cannot be treated or reversed, but as described above, certain lifestyle changes can be made and supplementation can be taken to prevent this form of AMD to progress into the aggressive “wet” form of AMD. This form however can actively be treated by injection of a drug inside the eye.
iii. Diabetic eye disease: People with any type of diabetes must have a dilated eye examination at least annually from the date of diagnosis. This baseline examination is important to detect if there is any early (non-proliferative) or advanced (proliferative) diabetic retinopathy. Early diabetic retinopathy can either be monitored 3-6 monthly to detect progression, or be treated with laser if indicated. Patients with advanced diabetic retinopathy must undergo early treatment to prevent permanent blindness. Treatment may include laser, injections inside the eye or even surgery.
iv. Glaucoma: People over the age of 40 with a positive family history of glaucoma should have annual dilated eye examinations done as well as intra-ocular pressure measurements, visual field testing and OCT screening examinations to detect early signs of this condition. For people at risk, this will act as a base test and the follow up test will assist in making the diagnosis early and possibly starting treatment before permanent blindness occurs. Unfortunately glaucoma does not cause any symptoms at first, until the peripheral visual fields are affected and in advanced cases cause “tunnel vision” and complete blindness.
Article By :
Intercare Ophthalmologist – Dr Niemandt