Errors of Refraction

Shortsightedness or Myopia is relatively common. Most people use glasses or contact lenses to cope, but there are many vision correction options available including:

• Laser eye surgery
• implantable contact lenses
• Laser lens replacement surgery

Patients who are shortsighted have a steep cornea and/or a long eye. This means that the point of focus falls short of the retina and the patient will struggle to focus on things in the distance.

The longer the eye and/or steeper the cornea the higher the level of shortsightedness. Shortsightedness can be corrected by flattening the cornea and making it less powerful. This moves the point of focus backwards to fall onto the retina.

Higher prescriptions require a higher correction and removal of more tissue–suitability is thus dependent on adequate corneal thickness to perform the correction safely

Farsightedness or Hypermetropia is a common form of visual imparment. When the eye recieves an image it focuses this behind the eye rather than on the back of the eye. Strong glasses or contact lenses are required to help bring the rays up to focus on the retina. Farsighted individuals typically have excellent vision when young but find they need glasses to read in their 30’s and eventually need glasses for all activities.  Correction options include:

• Laser eye surgery
• Implantable Contact Lenses
• Laser Refractive Lens Exchange

​

Correcting Hyperopia

If the cornea is flat, then IntraLASIK with the Zyoptix Wavefront algorithm is a good option for correction. Plus 5.00 Dioptres and in selected cases more can be treated and the advantage of the Wavefront treatment is the ability to create wide zones with less tissue removal – bespoke and personalised for the individual eye.

Presbyopia: If you are over 42 and your near sight is gradually being lost and you require READING GLASSES, it is probably caused by increasing hardness of the lens in your eye – the lens can no longer change shape enough to focus. Supracor IntraLASIK can now be used to treat Presbyopia correcting vision at all distances.

For those over 50, a good option for vision correction is Laser Lens Exchange also known as Lens Replacement surgery with implantation of high performance Trifocal lens implants.

There are a number of other criteria that a suitable candidate requires

• Healthy eyes with no disease
• No abnormalities in corneal shape (e.g. keratoconus)
• Prescription within the range of correction
• Do not have a profoundly lazy eye (amblyopia)
• Are not pregnant or nursing
• Are in good general health

There are a number of options available to treat farsightedness, but they generally fall into 3 categories.

• Laser Eye Surgery
• Laser Refractive Lens Exchange
• Implantable Contact Lenses

Astigmatism is often found in combination with shortsightedness and farsightedness and contributes to blurry vision. This occurs because the cornea is shaped like a rugby ball rather than a football. Depending on how light rays enter the cornea, they may be focused to different points – see the diagram below.

Options for Correction of Astigmatism

Nonsurgical options for treatment of astigmatism include spectacles with cylindrical lenses or contact lenses.

There are many options available for permanent correction of astigmatism and these include:

• Laser eye surgery
• Laser astigmatic keratotomy
• Laser Limbal relaxing incisions
• Toric Implantable Contact Lenses
• Toric Intraocular Lenses

Presbyopia

Why are reading glasses needed ?

With advancing age, (beyond the age of 40) the natural lens in our eye becomes harder and less able to change shape. In earlier life, the lens alters fine focus at nearby objects by changing shape. This enables us to read without glasses. The ability to do this decreases over time and as the lens hardens, reading glasses are required. Vision at near gets poorer and poorer with age and stronger glasses are required every few years. Eventually the crystalline lens becomes cloudy and this is known as a cataract.