Eye Health
Astigmatism is the optical term for more than one point of focus. It occurs when the surface of the cornea or crystalline lens is not spherical. Light from an object does not focus exactly on the retina but at two separate points. An astigmatic eye has curves that are steeper in one direction than the other. An example of this could be where the cornea is not spherical and shaped more like a rugby ball than football – of course this is not noticeable by just looking at someone’s eyes. As a result, the eye is unable to focus a point or object into a sharp focused image on the retina. There are two types of astigmatism, regular and irregular. Irregular astigmatism is often caused by a corneal scar or scattering in the crystalline lens and cannot be corrected by standard prescription lenses, but may be corrected by contact lenses or mild astigmatisms can be treated by laser eye surgery. Regular astigmatism arising from either the cornea or crystalline lens can be corrected by a toric lens.
A cataract is a clouding of the lens in your eye and can develop in one or both eyes. The lens is normally clear and sits behind the iris – the coloured part of the eye. The lens helps focus light to produce a sharp image on to the retina at the back of the eye and changes shape to allow you to see close objects. A cataract acts like a frosted glass coating that scatters light, causing blurring and lack of clarity.
Diabetes can lead to a condition called Diabetic Retinopathy as well as other eye conditions. Diabetic retinopathy (damage to the retina) is caused by complications of diabetes mellitus, which can eventually lead to blindness. It is especially important that patients suffering from diabetes have their eyes checked regularly.
Glaucoma is the name given to a group of eye conditions where the optic nerve is damaged at the point where it leaves the eye. The optic nerve carries images from the retina, the light sensitive membrane attached to the inner surface of the eye, to the brain. There are four main types: Chronic glaucoma (slow onset) Acute glaucoma (sudden onset) Secondary glaucoma (caused by another eye condition) Congenital or developmental glaucoma (a condition in babies caused by malformation of the eye) Regular eye tests are important. The risk of glaucoma increases with age and if left untreated it can cause blindness.
Conjunctivitis is an inflammation of the conjunctiva. The conjunctiva is the thin layer that covers the white of the eye and the inside of the eyelids. It can affect one or both eyes, causing discomfort. The causes of conjunctivitis can be bacterial, viral, allergic or from another source. If you have mild symptoms of discomfort, a red eye and some white/yellow/green discharge, you can usually treat it with over the counter antibiotics from your pharmacist. Any pain or severe redness or inflammation should be checked out by your GP immediately. Conjunctivitis can be very contagious, so ensure you wash your hands thoroughly after touching your face and try not to share towels and face-cloths.
The retina is the light sensitive membrane attached to the inner surface of the eye. Light enters the eye and falls on the retina allowing us to see images, these are transmitted along the optic nerve to the brain where they are processed so we can see. The macula is a small area in the middle of the retina with the greatest amount of light sensitive cells and is used for fine-detailed central vision. Macular degeneration is a painless disorder that can affect either eye, causing progressive loss of central and detailed vision.
A person with myopia or short sight can see clearly objects close to them, but not far away. Myopia is caused by the shape of the eye; either the eyeball is slightly too long or the cornea (the clear covering of the front of the eye) is too steeply curved. Myopia is corrected by spectacles or contact lenses with lenses which are ‘minus’ or concave in shape. So if you’re short sighted, your prescription will have a minus lens power, e.g. -2.50D.
Presbyopia describes the condition where the eye exhibits a progressively diminished ability to focus on near objects. It is a perfectly natural condition that eventually affects everyone but because the effects are gradual, you may not notice that anything is wrong with your eyesight initially. However, as the condition progresses, you may find yourself struggling to read small print or books unless they are held at arm’s length. With presbyopia, there are many factors (such as deterioration of lens elasticity) that affect the eyes ability to accommodate over varying distances; causing light (and therefore images) to be focused behind the retina. This leads to the eyesight becoming blurred. Presbyopia can be easily corrected with glasses or contact lenses with a combination of options such as, varifocals, bi-focals, separate glasses or mono vision for contact lenses only. Mono-vision is where we correct one eye for distance and the other for reading.
Dry eye is a common medical condition and is caused by a problem with the drainage, evaporation or production of tears. Tears are moved across the eye when you blink to lubricate the front surface of your eye, wash away debris, protect against infection and to help stabilise vision.