Glaucoma is a general term used to describe damage to the optic nerve. The most common type is called Primary Open Angle Glaucoma (POAG). It is caused by an increase in pressure within the eye, referred to as Intraocular pressure (IOP). A certain amount of pressure inside the eye is important to keep the eye's shape and size. The damage to the optic nerve in glaucoma is usually associated with excessive pressure within the eye. The optic nerve is like a cable. It has many nerve fibers that send messages about what we see from the eye to the brain. When damage to the optic nerve fibers occurs, blind spots develop, leading to loss of visual function. If glaucoma is not treated, damage can progress, causing a loss of peripheral vision. Glaucoma may eventually lead to complete visual impairment loss.
Primary Open Angle Glaucoma (POAG)
This is the most common form of glaucoma. It is a slow developing condition. The pressure in the eye rises slowly, without pain to warn of a problem, whilst the optic nerve is being damaged.
The aqueous humour (watery fluid in the eye) production in the eye is normally balanced by draining fluid out of the eye. If this fluid can not escape or an excess is produced, the pressure in the eye will rise. Some eyes may have moderately raised pressure, but no signs of vision loss or optic nerve damage; this is known as Ocular Hypertension.
In glaucoma, the eye pressure is not always high. Glaucoma can develop where eye pressure is within the statically “normal” range but the optic nerve becomes damaged. This is known as normal or low tension glaucoma.
The iris (coloured part of the eye) and the lens block the movement of fluid between the chambers of the eye, causing pressure to build up in the eye and cause the iris to press on the “drainage system” of the eye.
Angle closure glaucoma may cause sudden blurred vision, headache with pain and redness, usually in one eye first. Treatment may include drops to lower the pressure in the eye, monitoring of the drainage angle, and possibly surgery.
Glaucoma is a leading cause of preventable blindness. Anyone can develop glaucoma; some are at a higher risk than others. Review the checklist that follows to learn if you are at risk.
The more risk factors described below, the more important it is to have your eyes tested regularly for the early symptoms of glaucoma.
In its early stages, glaucoma has no symptoms and blind spots usually go undetected until damage to the optic nerve is significant. 40% of your optic nerve can be damaged before you notice any vision loss. Glaucoma is usually detected during a routine eye test for spectacles. Regular & complete eye examinations by your optician/optometrist is the best way to detect glaucoma.
There are 3 important tests to detect glaucoma. These tests are simple and painless. The tests will give a good indication of whether further examination is necessary or not.
1. Ophthalmoscopy – An examination of the back of the eye and the appearance of the optic nerve to see if there are any signs of glaucoma damage.
2. Tonometry – Measures the level of intraocular pressure (IOP) which is usually done by blowing a puff of air into the eye. An eye specialist will use a different tonometer to determine your IOP.
It is essential that test 1 and 2 are carried out every time you visit your optician or optometrist for spectacles. If either of these 2 tests is abnormal, then you would require test 3 (visual field test).
3. Perimetry (fields test) – This tests the peripheral field of vision, checking that there are no missing areas of vision. Whilst watching a central light on a screen, you will be asked to click a button when other lights are flashed in different positions around it. If you are found to have any suspicious signs of glaucoma, you should be referred to your local eye specialist or eye hospital.
Regular eye tests can help to prevent unnecessary vision loss.
Eye Drops - Glaucoma is usually controlled by taking eye drops daily. You may not notice an improvement in your vision, but the objective of lowering your eye pressure is to prevent further glaucoma damage.
Laser Surgery – may be recommended for different types of glaucoma. In open-angle glaucoma, the drain itself is treated. The laser is used to modify the drain to help control eye pressure, this is called a trabeculoplasty. In closed-angle glaucoma, the laser creates a hole in the iris to improve the flow of aqueous fluid to the drain, this is called iridotomy. During laser treatment a strong beam of light is focused on the drainage area of the eye, this can increase the outflow of fluid from the eye. However, in time the effect of laser treatment tends to wear off
and it is likely that glaucoma medication will have to be continued.
Surgery – is recommended if your ophthalmologist feels it is necessary to prevent further damage to the optic nerve. If it is needed, your ophthalmologist uses fine microsurgical instruments to create a new drainage channel for the aqueous fluid to leave the eye, thereby reducing the pressure. In some cases medical therapy can be discontinued following surgery although careful monitoring of the Intraocular pressure (IOP) and visual field will still be required regularly.
Age-related macular degeneration (AMD) is an eye condition that affects the back of your eye, called the retina. At the center of the retina is the macula. The macula lets you see objects straight ahead, which is called central vision. Macular degeneration damages the macula, which causes you to lose your central vision.
Who does AMD affect?
Age-related macular degeneration mainly occurs in people over 60, so it is called age-related macular degeneration. Today, at least one in ten people around the world over the age of 55 are affected by this illness. Age-related macular degeneration is a progressive condition that can be detected long before vision loss occurs.
The early stages of age-related macular degeneration have no noticeable symptoms. The stages may progress slowly and don’t always result in severe vision loss. Your eye doctor can diagnose early stages with a simple eye examination.
Types of AMD-Dry & Wet
Dry AMD is the most common form of AMD, representing approximately 90% of all AMD cases. However, dry AMD accounts for only 10% of the severe vision loss associated with macular degeneration. Dry AMD is characterized by development of yellow-white deposits underneath your retina, known as drusen, and can also be determined by deterioration of your retina. There is no generally accepted treatment for dry AMD, although vitamins, antioxidants and zinc supplements may slow its progression. Over time, dry AMD cases often develop into wet macular degeneration.
In the normal eye, blood vessels help keep the eye healthy. Wet AMD occurs when abnormal blood vessels start to grow under the center of your retina. These new blood vessels may be very fragile and often leak blood and fluid. The blood and fluid can damage your macula or create a scar on your retina, causing vision problems. Damage to the macula can occur rapidly, causing a noticeable blurring or even loss of central vision. The vision loss may be permanent, because abnormal blood vessels and scar tissue are actually destroying normal retina tissue. Once lost, these light sensitive cells in your retina cannot be replaced.