Specialty lenses: keratoconus, scleral and ortho-k
Fittings that do not come out of a box. They mean several visits, a corneal map first, and lenses made for one particular eye. It is the most hand-made part of the trade, and the part that will not fit into a quick visit.
When the cornea stops being regular
Spectacles correct regular surfaces well. When the cornea is distorted, by keratoconus, by old surgery, by scarring or after a graft, you reach a point where adding prescription improves nothing: the image is not out of focus, it is deformed.
A rigid contact lens works differently. It forms a regular optical surface in front of the cornea, and the tear film fills the gap between the two. What is gained from there depends on the individual eye, and it is established by trying, not by promising.
Scleral lenses: the lens that never touches the cornea
It is a large-diameter rigid lens that vaults over the cornea and rests on the sclera, the white of the eye, which is far less sensitive. The space underneath is filled with saline before it goes in.
That gives it two advantages. The first is comfort: nothing rubs the part that hurts. The second is that the cornea spends the day bathed in fluid, which is also taken into account in very dry eyes.
They look alarming the first time, because they are noticeably bigger than an ordinary contact lens. In practice, plenty of people who could never tolerate a small rigid lens wear a scleral all day.
Orthokeratology: the lens you wear asleep
An ortho-k lens goes in at bedtime and comes out in the morning. Overnight it gently reshapes the surface of the cornea, and the day is spent without spectacles or lenses. The effect is temporary: stop wearing them and the cornea returns to its own shape within days.
It makes sense for anyone who cannot or will not wear lenses during the day: dust, building sites, swimming pools, contact sport. It is also one of the options considered in myopia management for children, where the lens goes in at home and the school day is spent with nothing on.
In exchange it asks for discipline. Every night, with hygiene taken seriously, and with follow-up appointments. There is a range of prescriptions it will handle, and if your eye falls outside it we will say so at the first visit rather than trying anyway.
What the process actually involves
It starts with topography: a point-by-point map of the surface of your cornea, which is what allows a starting design to be chosen. Then a trial lens goes in, we watch how it sits and how it moves, and the parameters are corrected.
The final lens is made for that eye and reassessed when it arrives. It does not always come right first time, and that is not a setback: it is how the method works. Expect several appointments spread over weeks.
- Corneal topography of both eyes
- Trial lens in the consulting room and assessment of the fit
- Order of the definitive lens with the adjusted parameters
- A handling session: inserting, removing, cleaning and storing
- Regular follow-up, and liaison with your ophthalmologist if a case is open
Common questions
I have been told I have keratoconus. Do you treat it?
No, and that should be clear. Monitoring keratoconus and deciding on treatment belong to an ophthalmologist. What we do here is the optical half: fitting the lens you see through while your case stays with the person who should be holding it.
Does a rigid lens hurt?
You feel it, particularly in the first days, and there is a settling-in period that is no mystery but does have to be gone through. With a scleral the sensation is usually much less, because the lid does not run over an edge sitting on the cornea.
I had laser surgery years ago and I see halos at night.
That is a common enquiry and it deserves a topography. A treated cornea can be left with an optical zone that runs out when the pupil opens after dark. We will tell you whether a specialty lens changes anything in your case, and equally if it does not.
If I start ortho-k, am I stuck with it?
No. The reshaping is reversible: stop wearing the lenses and the cornea returns to its own form within days, along with your usual prescription. What is true is that while you use them, they have to go in every night, because the effect does not bank up.
The information on this site is for general guidance and does not replace a professional consultation. If you have symptoms, please see your optometrist, hearing aid audiologist or doctor.
