About Keratoconus

Keratoconus (from Greek: kerato- horn, cornea; and konos cone), is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea, the clear part of the eye you see through, cause it to become thinner. The normal pressure in the eye pushes against this thinner cornea, causing it to become more cone shaped and distorted. It is this distortion that makes seeing through glasses difficult, as spectacle lenses can only properly correct vision in an eye with a regular shape. The distortion also produces optical aberrations – this causes streaking, blurring and multiple images which in itself can cause headaches when reading or using a computer.

Keratoconus used to be considered quite rare (1 in 10,000 ) but it is now accepted that in the UK and US, it is around 1 in 2,500. In certain ethnic groups and geographical locations, the incidence can be much higher than this but it is difficult to be accurate because these figures come from studies rather from collecting data from the general population. A recent study in the UK showed that East Indians (Asians) had a younger onset and a more than fourfold level of incidence compared to white populations. Males seem to be at higher risk than females and the incidence is around 7% in Downs Syndrome.

It is quite often diagnosed in adolescence and is usually active for around ten years and then stabilises. It can often occur in one eye only and usually one eye is worse than the other. There appears to be a strong connection to allergies, asthma etc and eye rubbing is often quoted as being related. Certainly a lot of people with keratoconus rub their eyes, but whether this is causative or symptomatic is difficult to prove.

The main difficulty with keratoconus is that vision with glasses can become very distorted, to the point that the person cannot function at school or at work. It can be improved very much by wearing contact lenses. These smooth out the corneal distortions and can give the keratoconic “normal vision”. However, it is an unfortunate fact that most keratoconics have very sensitive eyes so that the rigid lenses that work best visually may also be the most uncomfortable. These lenses can also lead to corneal scarring if fitted too flat on the eye, so care has to be taken to ensure a good fit. There are a whole range of lenses that have been developed for keratoconus – most of them are relatively expensive and more complicated to fit than the disposable lenses that are readily available at opticians.

It is a difficult condition for others to understand. Many do not realise that without contact lenses, keratoconics may have the same vision as someone registered partially sighted blind but with them, they can see normally. They also cannot understand why they simply can’t use glasses like anyone else when they haven’t got their lenses in! The climate conditions in the Caribbean (and the AC in many buildings) can make contact lens wear very uncomfortable and many simply either cannot wear them or afford the specialist contact lenses that are necessary to see.