Keratoconus
Keratoconus is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve.
Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light all often reported by the patient. If both eyes are affected, the deterioration in vision can affect the patient's ability to drive a car or read normal print.
It is typically diagnosed in the patient's teenage years and attains its most severe state in the twenties and thirties. Once patients reach their forties the cornea begins to stiffen up naturally and this slows or even stops the progression of the keratoconus. This observation has led to the development of a treatment called collagen cross-linking. Riboflavin and ultraviolet light are used to stiffen the lens by three hundred percent.
In most cases, corrective lenses are effective enough to allow the patient to continue to drive legally and likewise function normally. Further progression of the disease may require treatment (such as Cross-linking CR-3) or surgery including INTACS or a corneal transplant (deep anterior lamellar keratoplasty or penetrating keratoplasty). Mr Ball is one of a handful of surgeons who is able to offer the full range of treatments for keratoconus.
To schedule a consultation
Please call 0845 6430 466 or fill in the web form to your right and we’ll get in contact with you.
Higher order aberrations
When you wear a pair of spectacles the spherical error (short sightedness or long sightedness) and cylinder (astigmatism treatment) are ground into the spectacle lens.
The sphere and cylinder are not the only imperfections in the optical system preventing people from seeing clearly. The other errors in the way the eye focuses the light are called higher order aberrations.
There are various higher order aberrations, but the most important of them is spherical aberration. Positive spherical aberration occurs because light from the edge of a spherical lens is brought to focus closer to the lens than light passing through the centre of the lens. This creates a slight blur around the image, which the eye is attempting to bring into focus.
The average cornea has positive spherical aberration. In the young eye the crystalline lens balances this with negative spherical aberration. After the age of thirty-five the lens changes and develops positive spherical aberration. This means that the combined focusing elements of the eye have positive spherical aberration.
In modern laser eye surgery the higher order aberrations of the eye can be measured with an aberrometer. This information is used in the treatment profile created for the eye by the laser. This is sometimes called wavefront LASIK.
This means that laser eye surgery can address the shortsightedness, longsightedness and astigmatism, and also the higher order aberrations. This is why many people enjoy better quality vision after laser eye surgery than they did when wearing their glasses.
We measure the spherical aberration in PRELEX and in cataract surgery. The lens implant used is matched to compensate for this, again improving the optical quality of the eye after surgery.
To schedule a consultation
Please call 0845 6430 466 or fill in the web form to your right and we’ll get in contact with you.
