Many people rely on contact lenses to correct their refractive eye error and help them see the world around them clearly. However, this doesn’t make them right for everyone. In fact, there are several groups of people who have a hard time wearing regular contact lenses. Fortunately, this doesn’t necessarily mean that you can’t take advantage of the benefits of contacts. There is another type of lens designed for those patients who for whatever reason are unable to wear ordinary contacts comfortably. These are known as scleral lenses.
What Are Scleral Lenses?
Scleral contact lenses are specially designed for people who might otherwise be unsuitable candidates for wearing contact lenses or who have had trouble wearing them in the past.
What makes scleral lenses different to regular varieties is their size. They are made with a large diameter – much larger than that of ordinary contact lenses. They take their name from the fact that they typically rest on the sclera, which is the white part of the eye. The smallest scleral lenses are approximately 14.5mm in diameter, whilst the largest can be up to 24mm.
Types Of Scleral Contact Lens
There are three different types of scleral contact lens, and these are differentiated by the size of the lens itself and where it makes its primary contact with the front surface of the eye. These varieties are:
- Full scleral lenses. The largest variety, these vault over the surface of the entire cornea and provide the biggest clearance distance between the cornea and the back surface of the lens.
- Mini scleral lenses. These extend over the entire corneal surface and make contact on the anterior sclera.
- Semi-scleral lenses. These lenses come to rest near the junction between the cornea and sclera.
Who Is A Good Candidate For Scleral Lenses?
Scleral lenses are typically recommended for two different groups of patients. The first are patients who have irregular-shaped corneas. This can be a congenital defect or the result of an ocular condition such as keratoconus, in which the cornea bulges like a cone. Since scleral lenses vault over the cornea, corneal shaping irregularities do not prevent a patient from wearing them.
The second are patients who suffer from dry eye disease – a chronic condition which occurs because the eyes either fail to make enough natural lubrication, or the tear film drains too quickly. In scleral lenses, the space between the back of the lens and the cornea acts as a fluid reservoir, trapping tear film and preventing the eyes from drying out.
Scleral Lens Fittings
In order to take advantage of scleral lenses, you will need to attend a special fitting appointment. This is so that we can ensure that you get lenses that are the best fit for your individual needs. This appointment will include several elements including checking the refraction of your eyes and assessing the main, secondary and peripheral curves of your cornea. This information allows us to make an accurate determination of the size and type of scleral lens needed to correct your vision.