What is corneal ring implantation, and how does it work?
Corneal ring implantation is an eye operation in which one or two small, curved segments of clear plastic (usually PMMA) are placed inside the cornea to reshape it. They are called intracorneal ring segments, and the best-known designs are Intacs, Ferrara rings and the full-circle MyoRing. In keratoconus the cornea thins and bulges into a cone, which makes vision distorted and glasses less useful. The rings are placed in a narrow tunnel in the mid-layer of the cornea, away from the central vision. They act like a support under a tent: they flatten the central cornea, make its shape more regular and can reduce astigmatism and short-sightedness.
The rings do not remove tissue and they can be taken out or exchanged, which is why they are considered a reversible option. This guide explains how they work, what the evidence says, how they compare with cross-linking and a transplant, what they cost in Turkey compared with the UK, US and Germany, and how to choose a hospital. For the wider range of cornea care see our eye treatments in Turkey.
Do corneal rings actually work for keratoconus?
For many suitable patients, yes, with an important limit. Studies of Intacs and similar rings, including the evidence behind US Food and Drug Administration approval of Intacs for keratoconus, show that they reduce corneal steepness and astigmatism and often improve uncorrected and spectacle-corrected vision. A frequent practical benefit is that people who could no longer wear contact lenses can wear them again. The limit is that rings change the shape but do not stop the underlying weakening. Keratoconus can continue to progress after rings, which is why many surgeons combine them with corneal cross-linking. Results are variable: some people gain several lines of vision, some gain little, and a small number need the rings repositioned or removed. A surgeon should never promise that you will be free of glasses.
Corneal rings, cross-linking or a corneal transplant?
These treatments do different jobs. Cross-linking strengthens the cornea to halt progression, rings reshape it, and a transplant replaces diseased tissue when the cornea is too scarred or thin. The table sets out how they compare.
| Treatment | Best suited to | Typical limits |
|---|---|---|
| Corneal rings | Keratoconus or ectasia with clear central cornea and contact lens intolerance | Does not stop progression on its own; not for advanced scarring |
| Cross-linking | Progressing keratoconus, to stabilise the cornea | Aims to stop worsening, not to restore shape |
| Corneal transplant | Advanced thinning or scarring | Larger operation, long healing, rejection risk |
| Specialist contact lenses | Mild to moderate disease, first-line vision correction | Comfort and fit problems in some patients |
See our guides to corneal cross-linking and corneal transplant. Because the three are complementary, a surgeon may plan rings first and cross-linking at the same session or a few weeks later.
Who is a good candidate for corneal rings, and who is not?
Good candidates have keratoconus or post-laser ectasia in the mild to moderate range, a clear central cornea, enough thickness where the tunnel will sit (often about 400 µm or more, depending on the ring and the surgeon), and cannot achieve good vision with glasses or lenses. Many are in their twenties to forties. Rings are less suitable when the cone is very advanced, the cornea is scarred in the centre, there has been a hydrops (sudden swelling from a break in the cornea), the cornea is too thin, or the eye has active infection or inflammation. Patients whose keratoconus is still progressing should discuss cross-linking first or at the same time. The surgeon decides after a full examination with corneal topography and a thickness map.
How is the procedure done, step by step?
The preparation uses corneal topography and thickness measurements to choose the ring size, thickness, position and number of segments, sometimes with a nomogram or software. On the day, the eye is numbed with drops and a small lid holder is placed. A femtosecond laser then cuts the tunnel at the planned depth in a minute or two, or the surgeon makes it by hand with fine instruments. The ring segments are slid into the tunnel through a small incision, positioned and checked, and the incision is closed with a stitch if needed. The operation takes about 20 to 30 minutes per eye, and you go home the same day with a protective shield and drops. Most surgeons treat one eye at a time, though both may be done in a visit.
Corneal ring implantation cost in Turkey compared with the UK, US and Germany
The ranges below are approximate per eye for the procedure with the rings, and they are not hospital quotes. Each hospital confirms its price in a written quote.
| Country | Approximate cost per eye |
|---|---|
| Turkey | €900 – €2,500 |
| United Kingdom | €2,500 – €5,000 |
| United States | €3,000 – €6,500 |
| Germany | €2,000 – €4,500 |
What changes the price: the ring type and number of segments, laser-assisted or manual tunnel creation, whether cross-linking is added in the same visit, one or both eyes, and the diagnostic scans. A package normally includes the examinations, the operation, the rings, follow-up checks in the first days and eye drops. Ask what happens if a ring needs to be repositioned and whether that is covered.
Recovery after corneal ring implantation, and how long to stay in Turkey
The eye is usually red, watery and light-sensitive for a few days, and vision can be blurred or fluctuate for several weeks as the cornea settles. A first check takes place the next day and another after about a week. Most people stay in Turkey four to seven days so that the surgeon can examine the eye, adjust the drops and make sure the rings are in place before you fly. You can usually return to desk work after a few days, but avoid rubbing the eye, swimming and dusty places for about two weeks, and avoid contact sport until the surgeon agrees. If cross-linking was added, expect a slower first week. Vision settles over about three months, and new glasses or lenses are normally fitted after that.
What are realistic results of corneal ring implantation?
There are few striking before-and-after photographs, because the change is inside the eye. The meaningful "before and after" is the topography map, which shows a flatter and more regular central cornea, together with your measured vision. Realistic goals are less distortion, a lower prescription, better spectacle-corrected vision and renewed contact lens tolerance. Unrealistic goals are perfect vision without correction or a permanent cure of keratoconus. The effect is usually stable once the cornea has settled, but the disease itself needs monitoring, with check-ups every six to twelve months.
Risks and complications
Every eye operation carries risks. Reported problems with ring segments include glare and halos at night, double or ghost images, infection, inflammation, a ring moving or being pushed out (extrusion), deposits around the ring, thinning of the tissue over a ring, a shift in prescription and, rarely, a need to remove the ring or move to a transplant. The risk of serious vision loss is low but not zero, which is why the standard of the unit matters. Information about corneal conditions is available from the NHS, the American Academy of Ophthalmology and the Royal College of Ophthalmologists; your surgeon should go through the risks for your eye before consent.
How to choose a surgeon and hospital, and questions to ask
Look for a cornea specialist who performs ring implantation regularly, a hospital with a femtosecond laser and corneal topography, and a written plan and price before you pay a deposit. Red flags include a quote with no scan, a promise that you will no longer need glasses or that keratoconus will be "cured", and no plan for cross-linking when the disease is progressing. Read how our process works and use the free quote page to send your topography and a recent prescription. Questions to ask:
- Which ring design do you recommend for my cornea, and why?
- Is the tunnel made by laser or by hand, and how many of these have you done?
- Should cross-linking be combined, and in the same session?
- What is the cost per eye, and is a repeat adjustment covered?
- How many days must I stay, and who will review me at home?
Hospitals with Eye Surgery in Turkey
Frequently asked questions
It is an operation in which small clear plastic ring segments are placed in a tunnel inside the cornea to flatten and regularise its shape. It is mainly used for keratoconus and for ectasia after laser eye surgery.
For suitable patients it usually reduces corneal steepness and astigmatism and often improves vision or contact lens comfort. It does not cure keratoconus or always stop progression, so cross-linking is often added.
Approximate prices are about €900 to €2,500 per eye in Turkey, against about €2,500 to €5,000 in the UK. The price depends on the ring type, the technique and whether cross-linking is included; the hospital confirms it in writing.
The eye is numbed with drops, so the operation itself is not usually painful. Afterwards the eye can feel gritty, watery and light-sensitive for a few days, which is eased with drops and rest.
Light sensitivity and blurred vision settle over days to weeks, and vision stabilises at about three months. Most people avoid eye rubbing and swimming for about two weeks.
Yes. The segments can be taken out or exchanged if there is a problem or the result is not as expected. This reversibility is one reason surgeons use them, although the cornea may not return exactly to its earlier shape.
They do different jobs. Cross-linking strengthens the cornea to halt progression, while rings reshape it. Many surgeons combine them, and the best sequence depends on the stage of your keratoconus.
Most people still need glasses or contact lenses, though often a weaker prescription or a more comfortable fit than before. A surgeon should not promise that you will be free of correction.
The main risks are glare, halos, infection, ring movement or extrusion and thinning of tissue over the ring. Serious vision loss is uncommon. Your surgeon should explain the risks for your eye.
Most patients stay four to seven days, so the surgeon can check the eye the next day and after about a week and confirm the rings are in place before you fly.