Eye Conditions
In this section we have provided a brief description of various common eye conditions we are often asked questions about. We hope you will find it helpful but please feel free to ask more questions of our optometrists when you come in and see us.
Medical Terms in alphabetical order:-
Presbyopia – reading vision deteriorates
Myopia, also known as short sightedness, is when the eye is not able to focus on objects because it is too powerful. Generally this involves the lack of ability to focus on far away objects. Concave or minus powered lenses are used to correct this.
Hypermetropia, also known as long sightedness, is when the eye is unable to focus on objects because it is not powerful enough. Generally this involves the lack of ability to focus on near objects. Convex or plus powered lenses are used to correct this.
WHAT IS PRESBYOPIA & WHY DOES MY READING VISION DETERIORATE AS I GET OLDER?
As we get older the ability for the eye to focus on near objects deteriorates. The initial symptoms could start with the inability to read in lower levels of light. This can quickly progress into only being able to read if things are held further away and our arms seem as if they are not long enough. This is because the involuntary internal eye muscles that flex the lens inside the eye become weak. This usually starts to become apparent during our 40’s and continues to deteriorate until the mid to late 50’s. This condition is known as presbyopia and is easily corrected with spectacles.
Sometimes instead of the front of the eye being round like a football it is slightly squashed and misshapen like a rugby ball. This is called astigmatism. The consequence of this is that point objects are focussed inside the eye as a line. At lower levels of astigmatism this condition is not noticeable. However sometimes if higher levels of astigmatism are present then letters and numbers both far away and up close can get confused. A cylindrical lens set in a spectacle frame at the correct rotation can correct this.
DO YOU RECOMMEND LASER SURGERY?
We believe that laser corrective eye surgery is appropriate for some people. This may be due to the severity of their spectacle correction or their general lifestyle. Any form of eye surgery should not to be taken lightly and we are not experts in the laser correction field. We are happy to recommend a couple eye surgeons who regularly carry out this operation. From experience we know that they will be able to answer all your questions and be able to assess if your eyes are suitable to take the procedure.
Floaters are shadowy spots that can appear in your vision. They can vary in number and size. They are painless and are usually harmless but can be very annoying.
Floaters can seem as if they are in front of your eyes, but are actually inside your eyes. The back of the eyeball is filled with a jelly like fluid called the vitreous humour. Occasionally strands of a protein called collagen can appear within it. These strands can swirl when the eye moves casting shadows on the retina at the back of the eye.
Floaters are usually more common with age. The vitreous humour shrinks away from the retina at the back of the eye, and forms clumps. This is known as a posterior vitreous detachment (PVD). This is a very common condition and is present in about 50% of people by the age of 50. PVD’s do not normally cause any damage and can be asymptomatic, meaning that most people are not aware that it has occurred. In a very minor number of cases PVD’s can cause tiny splits or tears in the retina. This can cause a “shower” of floaters and occasionally, flashing lights. Retinal tears need to be treated urgently.
In all cases of floaters it is important to have a full eye examination to determine the exact cause.
A cataract is when the lens inside the eye becomes clouded and therefore makes things difficult to see. A cataract can cloud a small part of the lens or it may affect the whole of it. If the cataract becomes dense it can seriously affect your sight and you may need an operation to prevent blindness. The operation itself is fairly quick and painless and involves replacing the old lens with an artificial one.
There are many different types of cataracts. They generally tend to occur with age and can take a long time to form. When they do, the deterioration in vision can be gradual and go unnoticed. An optometrist can easily spot a cataract. It is therefore very important to have regular eye examinations.
The retina is the delicate tissue at the back of the eye where light is focussed. The central part of the retina is called the macula. This area gives us the sharpest and most detailed vision. Macular degeneration is a painless disorder that affects this region and can cause progressive loss of vision. Total blindness is extremely rare as the condition only affects the central retina making it difficult to read, recognise people’s faces or to drive, leaving peripheral vision clear.
Macular degeneration is the most common reason for people in the UK to be registered blind. Age-related macular degeneration (AMD) is the most common form. The incidence of AMD increases every decade over the age of 50 to almost 15% by the age of 75. It is more common in females. Other risk factors are family history and smoking. There are generally two types of AMD: Wet or Dry. The Dry type develops very slowly and causes a gradual loss of vision, whereas the Wet type is much more aggressive. Only about 10% of AMD sufferers have the Wet type.
A regular eye examination can reveal if macular degeneration is present.
HOW CAN DIABETES AFFECT MY EYES?
Over several years, a high blood glucose (sugar) level can weaken and damage the tiny blood vessels next to the retina at the back of the eye. This condition is called Diabetic Retinopathy and is the most common complication of diabetes. It can result in various problems, which include:
- Small ‘blow-out’ swellings of blood vessels (micro aneurysms).
- Small leaks of fluid from damaged blood vessels (exudates).
- Small bleeds from damaged blood vessels (haemorrhages).
- Blood vessels may just become blocked. This can cut off the blood and oxygen supply to small sections of the retina.
- New abnormal blood vessels may grow from damaged blood vessels. This is called proliferative retinopathy. These new vessels are delicate and can bleed easily.
- The leaks of fluid, bleeds and blocked blood vessels may damage the cells of the retina. In some severe cases, damaged blood vessels bleed into the vitreous humour (the jelly-like centre of the eye). This can also affect vision by blocking light rays going to the retina.
Diabetic Retinopathy usually develops gradually. The longer you have diabetes the more likely it is to develop. Almost all Type 1 diabetics will have some degree of retinopathy within 20 years of onset. Approximately 60% of Type 2 diabetics will also have signs of retinopathy over the same time period.
Regular eye examinations can detect and monitor the progression of retinopathy. If retinopathy becomes severe, treatment can prevent loss of vision and blindness in most cases.
Glaucoma is the name given to a group of eye diseases relating to fluid pressure causing damage to the optic nerve and nerve fibres inside the eye. If left untreated it leads to blindness.
Open angle glaucoma, or chronic glaucoma, is the most common type. It develops very slowly and loss of sight is gradual and painless. Open angle glaucoma affects about two in every hundred people over the age of 40. However, this increases over the age of 70 to one person in ten.
Acute angle closure glaucoma is less common. The drainage channels inside the eye become blocked causing a sudden increase of fluid pressure. This causes severe pain and redness.
Occasionally, glaucoma can develop from other eye conditions that cause an increase of pressure in the eye. This is called secondary glaucoma. It may happen as a result of eye injuries or inflammation within the eye.
Glaucoma is sometimes present from birth. This is called congenital glaucoma and happens when there is a structural abnormality affecting the way fluid drains from the eye.
There are several tests that an optometrist can do to detect the signs of glaucoma. These include:-
1) ophthalmoscopy, to look at the optic nerve at the back of the eye,
2) perimetry, to assess any field of view damage, and
3) tonometry, which physically measures the fluid pressure inside the eye.
Early detection and treatment of glaucoma can prevent blindness.