Laser eye surgery: LASIK, PRK and SMILE – who is it for?

How laser eye surgery works

Clear sight depends on light being focused precisely on the retina. In short-sightedness (myopia) the focus falls in front of the retina, in long-sightedness (hyperopia) behind it, and in astigmatism the cornea is unevenly curved so images are distorted. Glasses and contact lenses compensate for this; laser surgery corrects it by reshaping the cornea – the clear window at the front of the eye.

An excimer laser removes microscopically thin layers of corneal tissue to a calculated profile, while a femtosecond laser makes precise cuts within the cornea. The procedure is done as a day case under anaesthetic drops and usually takes about 10–20 minutes for both eyes, with the laser itself working for only seconds.

Techniques: LASIK, PRK/LASEK and SMILE

There is no single best technique for everyone. The surgeon recommends one based on corneal thickness and shape, your prescription, dry eye, your job and your sports.

Who is a good candidate?

You are more likely to be suitable if you:

• are at least 18 – many clinics prefer over 21;
• have had a stable prescription for at least one to two years;
• have a cornea of adequate thickness and normal shape;
• have no active eye disease and realistic expectations.

Laser surgery is usually not advised, or needs particular caution, with:

• keratoconus or a thin cornea;
• severe dry eye, uncontrolled autoimmune disease or poorly controlled diabetes;
• glaucoma, cataract or retinal disease;
• pregnancy and breastfeeding, when the prescription can fluctuate;
• a very high prescription, where a lens implant may be a better option.

A good surgeon sometimes says no. If you are turned down after the assessment, it is usually to protect your eyes rather than a missed opportunity. Rather than shopping around for a clinic that will simply agree, discuss the alternatives below or stay with glasses and contact lenses.

Alternatives: lens implants and lens replacement

When laser treatment is not suitable, surgical alternatives exist:

• Phakic implantable lens (ICL) – a thin lens is placed inside the eye in front of your natural lens, which is left in place. It is used for high myopia or thin corneas.
• Refractive lens exchange – your natural lens is replaced with an artificial one, as in cataract surgery. It is usually considered after about 45–50, when reading vision has already declined (presbyopia) or an early cataract is present.

For presbyopia – the natural loss of close focus after the early forties – laser can be used for “monovision” (one eye set for distance, the other for near). It does not suit everyone, and it is wise to try it first with contact lenses.

Assessment and preparation

A thorough pre-operative assessment is the best protection against complications. It usually includes:

• an accurate prescription, including measurements after drops that relax focusing;
• corneal topography or tomography to detect hidden keratoconus;
• corneal thickness (pachymetry) and pupil size;
• assessment of the tear film and dry eye;
• eye pressure and a retinal examination.

Soft contact lenses are usually stopped about a week before the assessment and rigid lenses for longer, because they change the shape of the cornea; the clinic will give exact timings. Tell the surgeon about all medicines and medical conditions. On the day, do not drive and avoid eye make-up.

Risks and side effects

Most people are pleased with the result, but laser eye surgery is still surgery and cannot guarantee perfect vision:

• Dry eyes – the most common side effect; usually improves over weeks to months, occasionally lasting longer and needing artificial tears.
• Halos, glare and poorer night vision – most noticeable at first.
• Under- or over-correction – sometimes a top-up treatment or glasses are needed.
• Flap problems with LASIK – wrinkles, displacement after an injury, or cells growing under the flap.
• Infection and inflammation – uncommon.
• Corneal ectasia – rare but serious thinning and bulging of the cornea; careful screening reduces the risk.

Ask for written information on the risks and on who will see you if there is a problem. If you are unsure, a second opinion from another ophthalmologist is reasonable.

Recovery and treatment abroad

After LASIK and SMILE, vision usually improves within a day or two and many people return to work within a few days. After PRK the first 3–5 days are more uncomfortable, with pain and watering, and vision settles over several weeks. For the first weeks you use drops, avoid rubbing your eyes, and stay away from swimming pools, saunas and eye make-up; contact sports wait longer, as advised.

In Bulgaria laser eye surgery is generally done in private eye clinics and is usually not covered by НЗОК, as it is considered a refractive procedure. Some patients choose Istanbul – see eye surgery in Turkey for how to choose a clinic and plan follow-up. New City Clinic arranges consultations and procedures in partner hospitals; ask for the full pre-operative measurements and a written plan so that an eye doctor at home can continue your care.

When to see a doctor

If you are considering laser eye surgery, start with a full examination by an ophthalmologist. After treatment, keep to the follow-up schedule – typically the next day, after a week, after a month and later.

Contact an eye doctor immediately if after surgery you have worsening pain, increasing redness, discharge or a sudden drop in vision. A sudden change in sight years later also needs checking, as it may have another cause such as cataract or retinal disease. People with diabetes or high blood pressure still need regular eye checks regardless of laser correction – an annual health check-up is a good reminder.