Reasons why a patient may not be eligible for laser vision correction — and can anything be done about them?

The laser vision correction procedure is preceded by a thorough eligibility assessment. Whether the procedure can be performed does not depend simply on the degree of the refractive error. During the assessment, the ophthalmologist evaluates, among other things, the condition and shape of the cornea, its thickness, the stability of the refractive error, the ocular surface, and the overall health of the visual system.

One important point to bear in mind is that being deemed ineligible at a particular point in time does not necessarily mean that laser vision correction will never be possible. In some cases, prior treatment may be required, or it may be necessary to wait until the refractive error has stabilised or undergo further diagnostic tests. There are also situations in which the procedure is not recommended for safety reasons.

1. Excessively thin cornea

During the laser vision correction procedure, the laser reshapes the cornea, which is why its parameters must be carefully assessed before the procedure to determine whether the planned correction can be performed safely.

The ophthalmic surgeon also takes into account the cornea’s shape, curvature and steepness, the degree of the refractive error, and the anticipated ablation depth in order to minimise the risk of post-operative complications.

Does a thin cornea rule out laser vision correction? Not necessarily. Whether the procedure can be performed depends on the overall diagnostic findings, as well as on which laser vision correction methods are available and suitable for the individual patient. For patients with appropriate indications, surface-based procedures such as TransPRK or LASEK may be an alternative to flap-based techniques such as Femto LASIK or SBK LASIK. In selected cases, laser vision correction may also be combined with the cross-linking (https://www.artlife.com.pl/posts/laser-vision-correction-with-cross-linking-ndash-combined-procedure-1396.php) procedure, which is intended to strengthen the structure of the cornea. The final decision always requires an individual assessment by the surgeon.

2. Irregular cornea

The cornea does not always have a regular shape. Abnormalities can be detected during corneal topography and tomography, even when the patient has no noticeable symptoms. Particular attention is paid to changes that may indicate keratoconus or other forms of corneal ectasia. The first step is to assess whether the cornea is stable and whether its structure allows the correction to be performed safely.

When corneal abnormalities are present, protecting and stabilising the cornea is the priority. One of the techniques used in such cases is corneal cross-linking, which is intended to strengthen the collagen fibres within the cornea.

It is also possible to combine cross-linking with laser vision correction. At our Centre, we perform, among other procedures, TransPRK combined with cross-linking in patients whose corneal parameters fall outside the normal range.

3. Unstable refractive error

Laser vision correction is designed to correct refractive errors by permanently reshaping the cornea. If the refractive error is still changing, the procedure may not provide a stable correction. For this reason, one of the eligibility criteria is a stable refractive error, meaning that the patient has not required a higher prescription for at least 12 months.

However, this does not necessarily mean that the procedure is permanently ruled out. It may simply need to be postponed, with the refractive error reassessed after a certain period of time. A follow-up assessment is usually carried out after around 6–12 months, although the exact timing depends on the individual patient’s circumstances.

4. Dry eye syndrome

Dry eye syndrome (DES) may be a temporary contraindication to laser vision correction. Before making the decision, the doctor should first determine the underlying cause and severity of the symptoms. It is also important to recognise that not every instance of dry eyes indicates dry eye disease. Symptoms may be associated with, among other things, disturbances of the tear film, dysfunction of the eyelid glands, medication taken or other factors. Why does this matter? A healthy ocular surface affects both the reliability of the measurements taken during the eligibility assessment and the recovery process following the procedure.

Depending on the underlying cause and severity of the symptoms, the doctor may recommend, among other options, lubricating eye drops, anti-inflammatory treatment or other measures to support the proper functioning of the tear film. Once the ocular surface is in a suitable condition, the patient undergoes a further assessment, after which a decision can be made on whether to proceed with laser vision correction.

5. Other eye diseases

During the eligibility assessment, the doctor may detect an eye condition that the patient was previously unaware of. However, not every such condition automatically means that the patient is permanently ineligible for the procedure. What matters most is the type of condition and how advanced it is. Conditions and changes that may be detected during the diagnostic assessment include, among others, keratoconus and other forms of corneal ectasia, glaucoma, cataracts, retinal diseases and degenerative conditions, macular disorders, and other conditions affecting the anterior and posterior segments of the eye.

Does an eye condition always rule out laser vision correction? The answer is not necessarily. In some cases, laser vision correction is contraindicated, while in others, the condition must first be treated or stabilised. If cataracts are diagnosed, cataract surgery is necessary. After a minimum of six months, if a residual refractive error remains, further laser correction may be considered.

The same applies to keratoconus. Untreated keratoconus is a contraindication to laser vision correction. If keratoconus is detected, corneal cross-linking is performed first, and laser vision correction can be reconsidered once the condition of the cornea has stabilised. It is also possible to combine cross-linking with laser vision correction in a single procedure. The decision is always made by the surgeon based on a thorough diagnostic assessment.

The situation is different in the case of degenerative eye conditions (including certain forms of glaucoma and macular diseases) that gradually lead to loss of vision. These conditions are an absolute contraindication to laser vision correction, as the procedure does not treat the underlying cause of the visual deterioration associated with them.

“I’m not eligible” — what happens next?

A negative eligibility assessment does not always mean a definitive “no” to laser vision correction. Depending on the underlying reason, the doctor may recommend:

• treatment followed by a further assessment of the condition of the eye;
• waiting until the refractive error has stabilised;
• additional diagnostic tests;
• choosing a different laser vision correction technique;
• combining laser vision correction with an additional procedure, such as corneal cross-linking;
• not proceeding with the procedure if doing so would involve an unacceptably high level of risk.

The results of the eligibility assessment should always be interpreted in the context of the individual patient. Each laser vision correction method) has specific requirements, and not every clinic offers all of the available procedures. This does not mean, however, that a way of proceeding with the treatment should be sought at any cost. The primary purpose of the eligibility assessment is to ensure the patient’s safety. If the correction can be performed safely, the doctor will select the method best suited to the patient’s ocular parameters. Otherwise, the doctor may recommend postponing the procedure, deciding against it, or considering other alternative methods of correcting the refractive error.

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