Eye Health

Some eye diseases affect the eyes only e.g. cataract, macular degeneration (AMD) and others are associated with more general systemic conditions e.g. (diabetic eye disease, hypertensive retinopathy, arthritis related conditions).

Some conditions gradually affect the eye and others can have a sudden and severe impact on vision Unfortunately there are not always obvious signs or symptoms where a sight threatening disease exists and this is where the importance of regular eye checks with your optometrist becomes important.

Common eye conditions: click on the links below

Strabismus / Squint
Cataracts
Diabetic Eye Disease
Age-Related Macular Degeneration (AMD)
Glaucoma

Strabismus or squint is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the eye muscles so that the direction of gaze of the two eyes is different i.e. there is a "turn" in the eye. The condition may be caused by be either a disorder of the brain coordinating the eyes or a disorder of one or more of the eye muscles. The "turn" in a persons' eye may not be present all of the time and may only be noticeable when they look at certain distances. It is important that children who appear to have a deviated eye or who have family members with the condition, have their eyes checked at a young age. After about the age 7 years, it is difficult to get both eyes working together and achieving a standard level of vision when strabismus is present. From birth to approximately 6 years of age is known as the "critical period" in terms of ocular development. If refractive corrections are not prescribed where needed or "turns" not treated during this time, it is very likely that a child may have sub-standard vision in one or both eyes for their lifetime. Treatment: Often young children with a "turn" will be encouraged to wear a patch over one eye in an effort resolve their problem. In other cases glasses may be prescribed and in certain situations surgery may be indicated. For older people, often treatment will be for cosmetic reasons only and surgery may be undertaken to align the two eyes.

A cataract is a very common condition, affecting mostly older people. It is said "everyone will eventually develop a cataract if they live long enough". What is a cataract? Basically there is a lens in the eye that controls focusing. As a person ages this lens can become cloudy which dims the vision, like looking out of a dirty window. There are many different types of cataract depending on which part of the lens is affected and the underlying cause (i.e. age, injury or health problems such as diabetes). Not all types of cataract are the same and not all will develop in a similar manner. Indeed some cataracts, congenital cataracts are present from birth and others may arise due to trauma or because of a person being on certain medication. However, the majority of cataracts are seen in older people.

A person with an age related cataract might find that they can't see as well as they used to or that their vision in general is "dimmer" than before. They may also suffer from glare. Their prescription may have changes suddenly after a long period of stability. The change is often gradual and is painless and in many cases a person may not have any symptoms in the early stages of cataract development.

Cataracts can be treated by means of a very simple procedure, which is usually carried out under local anaesthetic as an out patient procedure in a hospital. When to treat a cataract is a decision for the eye specialist (ophthalmologist) but your optometrist will advise you if / when you will need to consult an ophthalmologist. Many ophthalmologists would not consider treating a cataract until it begins to sufficiently bother the patient. UV exposure has been linked to cataract development, so wearing well fitting sunglasses with full UV protection and good coverage can help reduce your risk of cataract development.

Diabetes related eye disease is the leading cause of vision loss in adults of working age (20-65) in industrialised countries. 5.4% of females and 4% of males in the Repubic of Ireland have been diagnosed as having diabetes. 74% of those who have diabetes for over 10 years will develop diabetic eye disease.

There are two main types of Diabetes, early onset (Type I) and late onset (Type II). Both forms of Diabetes can cause damage inside the eye. The damage caused by Diabetes inside the eye may be seen by your optometrist before you ever notice any symptoms yourself. Early intervention is essential to avoid visual loss. Diabetes sometimes causes vision to fluctuate from day to day or throughout the day. This symptom can often be the first indicator for an optometrist that a patient could have diabetes. If diabetes is diagnosed, good blood sugar control should stabilise vision. Over time, particularly in poorly controlled diabetes, serious retinal damage can occur.

After diabetes has been present for some years, changes may occur at the back of the eye in the retina. These changes are known as diabetic retinopathy. There are two main types of this condition: non-proliferative (sometimes called background) retinopathy and proliferative retinopathy. The risk of developing retinopathy increases with the length of time you have had diabetes. The risk is also increased when there is poor control of blood sugar levels. As diabetic retinopathy develops, blood vessels at the back of the eye leak and if left untreated a person could lose their sight altogether. Whilst not all those with Diabetes will develop Diabetic Eye Disease, it is essential to have regular eye tests to examine behind your eye even if you feel your eyesight is "fine and clear". Often your optometrist or ophthalmologist will put some drops in your eyes to "dilate" them, which makes the pupil larger and allows a more detailed examination of the back of your eye.

The best way to attempt to avoid developing diabetic eye disease is to maintain blood sugar levels at advised by your doctor and attend for regular check ups. It is also recommended that you see your optometrist at least annually for a dilated eye examination.

Diabetic retinopathy will often be treated with a laser, which helps to stop leakage from the blood vessels at the back of the eye. Regular eye examinations and good control of blood sugar levels should help reduce the likelihood of this treatment being necessary. For more information- Diabetes Association of Ireland

This is a progressive condition that can affect people as they get older. It tends run in families. There are different forms which have different outcomes for vision. AMD accounts for 45% of people over 70 years of age who are registered as legally blind. With macular degeneration central vision does become severely affected but sufferers will retain a certain level of peripheral vision.

The following figures relate to the percentage of the population suffering from diabetes. 4% of over 40s 9% of over 50s 23% of over 60s 30% of over 80s

AMD is the result of ageing processes in the eye. The part of the retina (the tissue on the inside of the eye) responsible for seeing fine detail and colours and for making out facial features and shapes, is the macula. The macula is affected in age-related macular degeneration. This part of the eye suffers "wear and tear" over time and it is believed that a build up of waste material at and around the macula is the reason for the reduction in vision that occurs in this condition.

There are two types of AMD, Dry and Wet. Dry AMD is the most common form of the condition and usually causes gradual changes in vision, often little changes over many years. Wet AMD affects a much smaller percentage of sufferers and is usually of sudden onset with significant and obvious reduction in vision. In Wet AMD, abnormal blood vessels develop beneath the macula and begin to leak. This leakage of fluid results in straight lines looking wavy or distorted. In some cases of Wet AMD treatment is possible, but it is vital that referral to a retinal specialist occurs as soon as possible.

Glaucoma is a condition in which the nerves which transmit information from the eye to the brain become damaged. It is often associated with a build-up of pressure in the eye. The eye is filled with fluid which is constantly being replaced. If too much fluid is produced, or if it cannot drain away properly, the pressure inside the eye can increase. In some forms of glaucoma, the pressure inside the eye can become extremely high, but in other forms the pressure may remain normal. If untreated, glaucoma can cause blindness. Initially peripheral vision is affected but the damage extends if not treated. The damage to the nerve cells cannot be reversed although it is often possible to prevent further damage. The longer the disease is left untreated, the greater the likelihood of damage.

People over the age of 40 years are far more likely to have glaucoma than younger people. Also, glaucoma tends to run in families so anyone over 40 with a blood relative who has the disease should have their eyes checked on a regular basis, at least every two years

The exact causes of glaucoma are not known. In some cases the drainage network of the eye may not be formed properly, or may become blocked by natural materials or due to injury; in other cases there is no clear cause.

In most cases a person would not be aware that they had glaucoma. It normally develops over a period of time without any pain or blurring of vision. Glaucoma affects peripheral or side vision first, allowing perfect central vision to be maintained for a long time. Central vision allows us to read and see faces clearly and when this remains normal we may not notice other changes in peripheral vision.

To diagnose glaucoma the optometrist looks at the nerve fibres at the back of the eye, measures the pressure in the eye with a special instrument called a tonometer and tests the field of vision. These tests are simple and painless. For more information see : eye examination. It was once believed that the eye pressure was the single cause of the condition, we now know that people with normal eye pressure may also develop the condition.

Eye drops are usually used to treat glaucoma. Surgery may be necessary if there is a blockage in the drainage system and the pressure cannot be reduced. Glaucoma can be very hard to diagnose initially and if your optometrist feels you may be at risk of developing the condition they will often repeat the eye pressure and visual field tests a number of times before deciding whether to refer you or not.