Intracorneal rings or corneal transplant: how the treatment is decided

When glasses and contact lenses are no longer enough to correct keratoconus, two surgical options frequently come up: intracorneal rings and corneal transplant. They are not competitors, but answers to different situations. Here is how this decision is made, step by step, and what distinguishes these two procedures.

Direct answer: rings or transplant, when to choose what?

Key point. Intracorneal rings aim to regularise a cornea that is still sufficiently transparent and thick, mainly to improve contact lens tolerance. A corneal transplant is reserved for more advanced forms, when the cornea is too distorted or opacified. The choice depends on the stage, the thickness, the transparency and your expectations. It is a shared decision, taken after the examinations, on a case-by-case basis.

When contact lenses are no longer enough

In keratoconus, rigid and especially scleral lenses remain for a long time the most effective solution for regaining clear vision: they compensate for the irregularity of the cornea better than glasses. But there comes a point when the fitting no longer holds.

Several situations lead to considering surgery:

• an intolerance to contact lenses: pain, redness, being unable to wear them long enough during the day;
• an insufficient vision despite a careful fitting, because the cornea has become too irregular;
• lenses that no longer stay in place or fail to centre, on a very distorted cornea;
• a cornea that is becoming opacified, which blurs vision even with a perfect optical correction.

The failure or intolerance of contact lenses is not a personal failure. It is simply the sign that the situation needs to be reassessed and that the surgical options suited to the stage should be discussed.

Intracorneal rings: what is the principle?

Intracorneal rings are small segments made of biocompatible material, inserted within the thickness of the cornea. Their purpose is not to replace the cornea, but to regularise it: by redistributing the tensions, they tend to flatten the overly bulging zone and make the surface more regular.

What the rings can offer, according to the Société Française d’Ophtalmologie and the American Academy of Ophthalmology:

• a more regular cornea, therefore sometimes an improved tolerance to contact lenses which become wearable again;
• in certain cases, an improvement in vision with glasses or contact lenses;
• a reversible procedure: the rings can in principle be removed or repositioned.

Their limits must be made clear. The rings do not fully correct vision and do not stop the disease: they replace neither glasses, nor contact lenses, nor monitoring. They are mainly offered when the cornea remains sufficiently transparent and thick, on keratoconus that is not at the most advanced stage.

Corneal transplant: for which situations?

A corneal transplant consists of replacing the diseased cornea, in whole or in part, with a graft of healthy cornea from a donor. In keratoconus, it is considered for advanced forms, when the cornea is too distorted, too thin or opacified for the other solutions to be effective.

Lamellar or penetrating transplant?

There are two main approaches:

• the lamellar transplant, which replaces only the superficial and deep layers of the cornea while keeping the patient’s innermost layer. This is the approach often preferred in keratoconus, because the inner layer there is generally healthy;
• the penetrating transplant, which replaces the full thickness of the cornea. It remains indicated in certain situations, notably when the cornea is very opacified.

The choice between these techniques is made by the specialist surgeon, according to the precise state of the cornea. The transplant is a more demanding surgery than the rings, with a visual recovery that spreads over many months.

How is the treatment decided?

There is no automatic answer. The decision rests on a complete analysis of the eye and on a discussion with you. The elements taken into account are:

• the stage of the keratoconus and its rate of progression;
• the thickness of the cornea, measured by pachymetry, which determines what is technically possible;
• the transparency of the cornea: an opacified cornea points rather towards a transplant;
• your tolerance to contact lenses and the vision achieved with them;
• your age, your expectations and your lifestyle.

In practical terms, we first look for the least invasive solution that addresses the problem. The rings can sometimes defer or avoid a transplant in certain patients. But they are not suitable for everyone: on a very advanced or opacified cornea, the transplant becomes the most appropriate solution. It is this logic of shared decision-making, recommended by the learned societies, that guides the choice.

What aftermath and what follow-up?

The aftermath differs markedly depending on the procedure. After ring insertion, recovery is generally fairly quick, but a delay is needed before reassessing vision and refitting any contact lenses. Wearing lenses often remains necessary afterwards.

After a corneal transplant, the pathway is longer:

• the visual recovery is gradual and may take many months;
• a prolonged local treatment and close follow-up are necessary to monitor the graft;
• glasses or contact lenses often remain useful after the transplant to optimise vision;
• as with any surgical procedure, risks exist and must be explained before the operation.

In both cases, the golden rule of keratoconus still applies: do not rub your eyes, and maintain regular monitoring. Surgery treats a given situation; it does not remove the need for follow-up.

The pathway at the practice

The assessment, diagnosis and orientation are carried out at the Cachan practice: topography, pachymetry, evaluation of corneal transparency and of your tolerance to contact lenses. It is this assessment that makes it possible to establish the indication and to determine whether the rings, the transplant or continuing with contact lens fitting is the option best suited to your situation. The surgical procedure itself is performed in a specialist setting according to the stage and the technique chosen.

FAQ

Frequently asked questions about rings and transplant

Sources

1. Centre de Référence National Kératocône (Pr P. Fournié, Pr D. Touboul), filière SENSGENE — Protocole National de Diagnostic et de Soins (PNDS): Kératocône. Haute Autorité de Santé, novembre 2021. has-sante.fr/jcms/p_3301044/fr/keratocone
2. American Academy of Ophthalmology (AAO) — Corneal Ectasia Preferred Practice Pattern®, 2023. aao.org/education/preferred-practice-pattern/corneal-ectasia-ppp-2023

Further reading

• Keratoconus: symptoms, causes and diagnosis
• Eye rubbing and keratoconus: the habit to stop
• Get in touch with the practice
• Cross-linking: stabilising keratoconus
• Glasses, contact lenses or CXL: how to choose
• Progression: can you go blind?

Keratoconus assessment and surgical orientation at the Cachan practice · Tel. +33 1 45 47 08 11

In summary

Rings and transplant are not opposed: they answer to different stages of keratoconus. The rings aim to regularise a cornea that is still transparent and to improve tolerance to contact lenses; the transplant is reserved for advanced forms. The choice is made after a complete assessment, taking into account the stage, the thickness, the transparency and your expectations. It is a shared decision, never fixed in advance.

This article is intended for informational and educational purposes. It does not replace a medical consultation. Only an examination by an ophthalmologist makes it possible to establish a diagnosis and to propose management suited to your situation.