In order to guarantee optimum and stable visual quality after any kind of refractive surgery, it is essential that the eye continue to maintain its new shape over time. Ocular biomechanical studies have precisely defined the parameters to be strictly adhered to. In particular, the residual thickness of the cornea after the operation is critical.
In the case of serious refractive disorders or those associated with corneal anomalies, particularly in the case of keratoconus, excimer laser treatment is not recommended since the cornea would be thinned too much and its biomechanical qualities compromised.
A microsurgical approach is preferred in these cases.
Insertion of Phakic Lenses
Phakic lenses are very thin collamer or silicon lenses that are inserted under the iris to modify the path of light rays and focus them on the retina.
This procedure allows even serious refractive errors to be corrected (up to 20/25 dioptres).
A yag-laser iridectomy is performed as an outpatient procedure some days previously to guarantee normal circulation of the acqueous humour after insertion of the phakic lenses.
Surgery is carried out in the operating theatre, using a topical anaesthetic (anaesthetic eye drops).
No pain is felt during or after surgery. Recovery of an excellent visual acuity occurs within one or two days of surgery.
If both eyes need to be treated, one may be operated on a few days after the other.
Patients wishing to undergo this type of procedure must have:
- a large enough anterior chamber of the eye
- a completely transparent natural crystalline lens
- normal eye pressure
- a refractive error within the range available for phakic lenses
If a patient is deemed unsuitable, he/she may resort to a Refractive Lensectomy.
This procedure is aimed at patients whose refractive error can not be corrected with an excimer laser or by inserting phakic lenses.
Technically it is the same procedure as for cataract removal.
The natural lens of the patient is emulsified with ultrasound and an aspherical artificial lens is inserted which is able to cancel the visual error.
The new artificial lens may be monofocal or accommodative (able to focus on both near and distant objects), depending on the needs of the patient.
The implanted lens is inert, does not deteriorate over the years, and it remains intact for a period of time exceeding that of a human lifetime.
Therefore the visual improvement is permanent.