CXL has transformed the way we think about keratoconus management. As the procedure can stop the progression of keratoconus, early detection and CXL will most likely be a major consideration in the development of clinical pathways for keratoconus.
However, at this point in time, the majority of patients considering CXL are already wearing contact lenses of one sort or another. It is important to consider planning how that contact lens wear is going to be managed before the patient embarks on the CXL procedure itself.
If a patient with normal corneas was to choose to have refractive surgery, there would be a recommendation to leave RGP lenses out for a period of time before surgery.
This is due to the fact that rigid lenses mould the cornea (indeed, the process of Ortho K depends on this happening) and the cornea needs time to return to its normal state before surgery, so that proper assessments can be made.
This process can take around 6 weeks for normals (1) and may take considerably longer for a softer, keratoconic cornea.
Additionally, as a post CXL cornea tends to fluctuate in shape significantly, it is generally advised not to return to RGP for around 2 months post op.
This situation can cause real problems for patients who are reliant on contact lens wear for work, driving etc.
Soft lenses can induce some moulding but nowhere near as much as RGP lens wear (2).
Patients can generally wear their soft lenses up to the day before CXL surgery and, since they flex with corneal shape changes, contact lens wear can be resumed around 5-10 days post surgery.
Thus, it can be beneficial to the patient to be refitted into soft lenses before surgery, so that the operation itself causes the least disruption to the patients life.
Many long term rigid lens wearers develop corneal haze and localised oedematous scarring. Much of this is due to the poor healing qualities of a keratoconic cornea.
Haze and scarring are contra-indications for CXL, so it is useful to understand that some of these issues can be resolved by refitting into soft lenses. If a cornea can be rehabilitated in this way, then the possibility of successful CXL is much higher.
(1) Predicting time to refractive stability after discontinuation of rigid contact lens wear before refractive surgery: Tsai et al 2004
(2) Corneal stability after discontinued soft contact lens wear: Hashemi et al 2008
First, the patient is assessed as a whole, determining which is the worst “seeing eye” and which is in most urgent need of cross linking. This may not be the same eye!
Factors to consider:
Once it has been decided which eye to cross link first, that eye can be refitted into KeraSoft IC.
The first eye to be cross linked is now refitted into KeraSoft IC, taking into account de-moulding effects. Guidelines for this can be found in Refitting from RGPs.
Once the patient has reasonably stable vision, the cornea can be assessed for CXL and the operation can be planned.
The patient can wear the same lens around 5-10 days post CXL, depending on the surgeon’s recommendations.
The patient should be advised that corneal haze and blurriness is entirely normal and to be expected.
Once this cornea is stable enough to provide adequate vision for the patient, then the procedure can be repeated for the other eye.