Seeing beyond the PR of refractive surgery
hoosing the right refractive eye surgeon is like finding the right financial adviser. GPs and their patients must be wary of companies offering only one type of treatment that may potentially promote their technology even though others may be more suitable.
Refractive surgery covers numerous procedures to correct refractive errors (the need for spectacles). For some years refractive surgery has been synonymous with laser eye surgery but the scope of procedures available today is increasing dramatically and there are now many ways to deal with correction of errors.
It is crucial that refractive surgeons offering a comprehensive range of treatments counsel patients. This ensures they are offered the most suitable treatment and a chance to state a preference, and patients should consider consulting a 'comprehensive refractive surgeon'.
What are the different techniques?
Techniques today for correcting refractive errors include laser and non-laser treatments. Laser treatments basically sculpt and reshape the cornea with an EXCIMER laser. In a myopic eye, the central cornea is flattened, whereas in a hyperopic eye (longsighted) the central cornea is steepened. Astigmatism (an elliptical shape to the cornea analogous to a rugby ball) can also be treated by a different laser profile. Within the laser treatment modalities are three main procedures.
Photorefractive keratectomy (PRK) is the original laser treatment. It has the longest track record and involves scraping the epithelium of the cornea away and lasering the Bowman's layer beneath.
While highly successful in dealing with refractive errors, this procedure can be painful. Another disadvantage, particularly with the early generations of lasers, was development of haze occasionally causing disabling visual problems.
Laser in situ keratomileusis (LASIK)
involves lifting a thin flap of corneal tissue of approximately 130 to 180 microns via mechanical blade. This is placed on the eye with the aid of a suction ring. An automated device runs across the ring, cutting a flap of corneal tissue of a designated thickness.
The public often wrongly assume that problems with laser treatment are due to the laser.
By and large, any serious or devastating complications in laser eye surgery are due to malfunctioning or poor flap production. Complications include creating a button hole within the cornea, or a partial cut in addition to the development of folds within the flap or subsequent infection.
These complications clearly do not arise in PRK. Therefore, LASIK must be considered to have higher risks than PRK. Consumer pressure drives surgeons into performing LASIK because the visual rehabilitation is faster and the pain factor much less serious, even though the scope for complications is higher. LASIK has the advantage of usually being performed simultaneously and bilaterally and the haze associated with PRK is extremely rare. It is also felt a higher range of refractive error can be treated with LASIK than with PRK.
Laser epithelial keratomileusis (LASEK) is a relatively new procedure, essentially a hybrid procedure between LASIK and PRK. Unlike LASIK, where the flap of corneal tissue is elevated with a keratome blade-cutting device, in LASEK the epithelium is lifted off with a small trephine and an alcohol solution.
Mechanical errors and flap-related problems are completely eliminated with LASEK, hence its better safety profile.
The pain associated with PRK and haze are less of a problem. Hence, LASEK can be perceived as a suitable compromise of advantages between the two procedures without as many concurrent risks. Some refractive surgeons see LASEK as no more than a glorified PRK. Again, it is usually performed unilaterally, on just one eye at a time.
Non-laser procedures are usually reserved for patients where safety parameters would be exceeded in normal laser technology. High refractive error or a relatively thin cornea suggest laser surgery may be risky. These procedures have an element of reversibility that laser procedures do not have.
Implantable contact lens or phakic refractive lens are surgical procedures where a minute lens is implanted into the patient's eye through a small incision. These need to be done in proper operating facilities in sterile conditions and in a hospital setting.
These are particularly beneficial in patients with higher refractive errors or where laser safety parameters would be exceeded. They have the beauty of being reversible, since an implantable lens can be removed. They need to be performed by experienced intraocular surgeons.
Clear lens extraction is not dissimilar to cataract surgery. The patient's own crystalline lens is removed and replaced with an implant lens similar to that in cataract surgery. Again, this is an intraocular procedure, which needs to be performed by experienced surgeons.
It is particularly useful when patients have reached the presbyopic age group, as at that stage the crystalline lens has lost its elasticity. An implant lens of the appropriate power can be used for distance prescription but reading glasses will be necessary for near vision, as with all presbyopic patients.
Accommodative intraocular lenses are now available which go some way towards offsetting presbyopia and can change shape similar to the human crystalline lens, restoring accommodation.
Costs may depend on various promotions offered by companies, but laser eye surgery can cost anything between £500 and £1,250 per eye, depending on whether PRK, LASEK or LASIK is chosen. The average price for implantable contact lenses is around £2,500, and for a clear lens extraction about £2,000.
What qualification and experience should the operating doctor have?
Surgeons performing refractive surgery should be qualified consultant ophthalmic surgeons, experienced in both corneal and intraocular surgery and able to offer a variety of embracing and comprehensive treatments rather than only one particular modality. Surgeons should have undergone extra training and refractive surgical fellowships organised by recognised societies such as the American Society of Cataract and Refractive Surgery or the European Society of Cataract and Refractive Surgery.
Should both eyes be done at once?
Perceived wisdom is that LASEK and PRK are usually offered as unilateral procedures but LASIK is usually a bilateral procedure. Intraocular procedures such as implantable contact lenses and clear lens extraction should usually be done one eye at a time to prevent infection.
How should patients decide?
Patients need to be aware of the possible risks of flap-related problems, haloes and glare and the incidence of regression. With intraocular procedures, the risks of infection need to be stressed. A very lengthy and detailed consent should be taken and signed in conjunction with the surgeon. The possibility of any further questions should be raised at this point. Haloes can be a problem, particularly in patients who have large pupils (tendency to dilate at night). It is crucial to perform pupil measurements in dark-adapted conditions to minimise risk.
A realistic expectation of side-effects need to be discussed with each individual, since patient factors may affect these. Unfortunately, refractive surgery has been taken out of medical hands too much and placed far too often in business organisations that market very aggressively.
Practising what they preach
To date, several UK ophthalmologists have had refractive surgery and, as yet, as far as I am aware, all of them have been very satisfied with the outcome.
Refractive surgery has been taken out of medical hands too much by aggressive business concerns~