LASIK and laser refractive surgery

Laser eye surgery is the world’s most frequently performed elective surgical procedure and was first performed over 25 years ago. It is estimated that over 20 million treatments have been performed to date and can result in complete freedom from corrective lenses until the onset of presbyopia, the natural requirement to wear reading glasses with age. Laser vision correction is surgery so any questions you have should be answered to your satisfaction before you undertake to have the treatment.  It is important that you understand the options including the alternatives, the risks and limitations of the procedure itself, and feel confident with your surgeon before you commit to any surgical treatment. David Anderson underwent the procedure himself so understands fully how life changing the procedure can be but also how important it is to be fully informed about the surgery.

David Anderson underwent the procedure himself so understands fully how life changing the procedure can be

David Anderson has been performing laser eye surgery for over a decade specializing in laser eye surgery for 18 months as Corneal and Refractive Fellow at Moorfields Eye Hospital in 2001 before moving to University Hospitals Southampton as Consultant in 2003. For patients with normal corrected vision prior to treatment and targeted for distance visual correction, over 99% will achieve the driving visual standard without spectacle correction* following one treatment of LASIK. The results are similar for surface laser procedures and are subject to continuous annual audit.

For patients who do not achieve clear vision following a first treatment, an enhancement may be offered to optimize treatment and is highly effective in treating any residual refractive correction. Fewer than 3% of patients* undergoing LASIK will require an enhancement procedure. Suitable candidates for excimer laser correction should have healthy eyes with a good standard of vision when wearing glasses or contact lenses and a stable prescription within the treatable range.

* Annual audit – Internet Based Refractive Analysis

Z-LASIK

Excimer laser eye surgery works by reshaping the cornea which is the transparent front coat of the eye. This encourages light rays entering the eye to focus successfully on, or close to the retina.

Z-LASIK involves the application of laser treatment to the deeper layers of the cornea under a protective flap, combining two different laser procedures. The result is a quicker return of vision and refractive stability following LASIK compared with LASEK or PRK.

A drop of anaesthetic is placed in the eye. A speculum is put in place to keep the eye open and tape protects the eyelashes. The first type of laser called a Zeimer Femtosecond laser ( http://www.ziemergroup.com ) is used to create a corneal flap. During this time the eye being treated is unable to see, this is normal and lasts for under 30 seconds. The flap is then lifted to expose the deeper tissue of the cornea to which the laser treatment is applied using a second type of laser called an excimer laser. David Anderson uses the WaveLight® Allegretto Wave® Eye-Q Laser (https://www.myalcon.com/products/surgical/wavelight-allegretto-wave-eye-q-laser/index.shtml ). The treatment is painless and typically takes less than 30 seconds. The flap is floated back into place and checked. Eye drops are applied.

If the flap created is not judged to be satisfactory the excimer laser treatment is not applied. It may be necessary to postpone the surgery, but this occurs only rarely. If it is not possible to create a flap using the laser, the surgeon may, using their professional judgment, offer the patient the opportunity to switch to a surface procedure e.g. LASEK.

The eye should not be painful after treatment although it may prickle a little and be watery for a few hours. Eyes are often very sensitive to light for several hours after treatment (photophobia) and sunglasses are recommended. Review is performed the following day.

Vision normally begins to improve after a few minutes and moderate vision is often achieved by the following day. Within 1 to 4 weeks most treated eyes have clear vision but it can take up to 12 weeks for the best optical quality to be achieved. There will be an imbalance in vision between treatment of the first and second eyes if they are treated separately.

The creation of the corneal flap carries the risk of complications not present with surface laser treatment. In addition to the risk of an unsatisfactory flap being created there is a possibility that the flap may be created without leaving a hinge in which case it will need to be carefully repositioned and very rarely stitched into place. In extreme cases complications due to infection, corneal perforation or other damage to the corneal flap could be sight threatening and may require further corrective surgery.

LASEK and PRK

Surface laser treatments do require a longer period of recovery with more discomfort post-operatively than LASIK but are safer for patients with thinner corneas. For therapeutic treatments e.g. following previous surgery, infection or injury, surface laser treatments are often preferred to LASIK.

A ring is placed over the treatment zone of the cornea and a solution is applied that allows the surface layer of cells to be gently lifted and folded to one side. The laser is then applied to reshape the cornea. The treatment zone is then inspected and a decision is made as to whether the cornea will heal more quickly and comfortably with the surface cells replaced (LASEK) over the treatment zone or removed and allowed to fully regenerate (PRK). In both treatments a protective contact lens is placed on the eye to minimize post-operative discomfort and eyedrops are used to prevent infection and keep the eye comfortable during the healing period.

Vision improves over the week following treatment and is reasonably stable after a month, although it can take up to three months for the best visual quality to be achieved.

BENEFITS AND RISKS OF LASER EYE SURGERY

Laser vision correction is a major ophthalmic undertaking that has the potential for complications that could affect your sight.  However these risks and complications can be minimized by careful selection of suitable candidates for treatment, surgeon experience, and good compliance by the patient with the instructions before, during and after the laser procedure.

At the present time excimer laser treatment is not recommended during pregnancy, nor for breast-feeding mothers. It can also be difficult to assess the healing response for patients with medical conditions such as diabetes and your general medical history must be taken into account in determining whether you are suitable for treatment.

Laser treatment can be effective in correcting myopia, astigmatism and hyperopia. However, it cannot overcome the problem of presbyopia.  This is an age-related decline in the ability of the lens in the eye to change focus and enable you to read or undertake close work at the usual distance.

If you undergo laser treatment and become normal sighted, you will need to wear spectacles for reading once you become naturally presbyopic which typically occurs in the mid to late forties.

Treatment by either LASIK, LASEK or PRK can result in problems with scarring or haziness of the cornea, glare, haloes around bright lights, recurrent problems with the epithelium of the cornea causing pain or discomfort, infection, permanent long-sight or short-sight requiring correction with spectacles or contact lenses. In LASIK there can be additional complications related to the flap including ulceration of the cornea, loss or distortion of the flap, infection and inflammation under the flap.

The potential complications will be explained at the your initial consultation and examination.  If you decide to proceed with treatment you will be given an Informed Consent Form that details the potential risks and complications that you must read and sign before proceeding.

Laser treatment may result in reactivation of old Herpes viral infection – if you have had presumed Herpes infection of the eye you should make this known.

Although the aim of excimer laser treatment is to improve unaided distance vision and reduce or eliminate the need for corrective lenses or spectacles, treatment remains unpredictable due to individual healing responses and the resulting level of vision cannot be guaranteed.

ALTERNATIVES TO LASER EYE SURGERY

The most common alternative to laser eye surgery is to continue to wear spectacles or contact lenses.

The surgical alternatives to laser eye surgery to correct refractive errors include intra-ocular lens implant surgery with a phakic lens implant, clear lens extraction or refractive lens exchange, corneal inlays and much less commonly, incisional corneal surgery.