What is keratoconus (conical cornea)?

Keratoconus is a condition in which the cornea loses its natural shape and begins to protrude forward until it takes the shape of a cone. Over time, the cornea becomes thinner and an irregular astigmatism (cylinder) and high myopia (myopia) are created, which lead to a change in the number in the glasses. If the condition is not treated, it may cause vision loss and blindness.

​The above structural changes in the cornea cause a gradual decrease in vision, double vision, halos and glare, visual distortion and progressive myopia. Often, these changes will lead to the inability to fit glasses or soft contact lenses. Sometimes, if the cornea becomes too thin, can develop "" Hydrops"" which causes sudden corneal edema and sudden loss of vision.

Fitting contact lenses and improving vision in keratoconus:

It is possible to improve vision in keratoconus depending on the condition of the cornea, the thickness, the cylinder, the numbers and the degree of keratoconus. Due to the abnormal cylinder, the best method to improve vision and eliminate the cylinder in the cornea with keratoconus is a contact lens. There are different types of contact lenses, each of which has its own advantages and disadvantages: Soft contact lenses without a cylinder (Toric soft contact lenses): these lenses are normal soft lenses that are suitable for keratoconus cases with a cornea without a boring cylinder or a minimal cylinder. Toric soft contact lenses: these lenses are soft lenses but at the same time they are toric lenses that aim to correct a corneal cylinder. These lenses are suitable for cases of keratoconus with a cornea with a cylinder that visually affects but relatively a straight and not distorted cylinder. Soft-K lenses: These lenses are soft lenses but thick in the center. They are suitable for cases of keratoconus with a cornea with a deformed cylinder and a small to medium degree and myopia of a small to medium degree. Small hard lenses (RGP): These lenses are hard and relatively small lenses, 5-6 mm in size. These lenses are suitable for keratoconus cases with a distorted cylindrical cornea and a small to medium degree and a small to medium degree of myopia.

Semi-scleral contact lenses: These lenses are hard lenses but with a size of 13-15 mm. These lenses are suitable for cases of keratoconus with a distorted cylindrical cornea and medium to high degree and myopia of medium to high degree.

Scleral contact lenses: These lenses are hard lenses but with a size of 15-20 mm and sometimes more. These lenses are suitable for cases of keratoconus with a cornea with a deformed cylinder and a high to very high degree and a high to very high degree of myopia. Hybrid contact lenses: These lenses are hard in their center but soft in their periphery. These lenses are suitable for cases of keratoconus with a cornea with a distorted cylinder and a small to medium degree and myopia of a small to medium degree.

How is the process of fitting contact lenses for keratoconus carried out?

The matching process takes at least an hour and sometimes even more. During the adjustment, a repeated eye test is performed. Repeated corneal mapping and measurements of corneal curvature and corneal diameter are performed. In accordance with the above, and as a start a lens will be selected empirically and a compatibility test for this type of lens is performed. If the lens is not comfortable for the patient and does not sit well and is not well centered on the cornea, switch to another type of lenses for adjustment. Keep repeating this process until you find a lens that fits and is comfortable for the patient.

If the lens is comfortable for the patient and gets along well with it, and it sits and is well centered on the cornea, a repeat refraction test is performed and the amount of residual refractive error is checked. Keep doing this until you get the best evidence available. 

 According to the above, the number and type of the lens are ordered.