VISION CORRECTION AND EYE TREATMENTS
Laser Vision Correction
Many patients considering vision correction are tired of relying on glasses or contact lenses every day, whether because of the inconvenience, cost or discomfort associated with prolonged contact lens wear. LASIK and PRK are the two main forms of laser vision correction.
Both procedures reshape the cornea (the clear, dome-shaped surface at the front of the eye) to correct short-sightedness, long-sightedness and astigmatism (a refractive error caused by differences mainly in the shape of the cornea that can result in blurred or distorted vision). Because LASIK and PRK work by reshaping the cornea, they specifically address astigmatism caused by the cornea’s shape. The choice between LASIK and PRK depends on the individual characteristics of your eyes, including corneal shape, thickness, prescription, eye health and visual needs. Dr Robinson carefully assesses each patient’s eyes and determines which procedure, if any, is appropriate based on their vision, eye health and individual needs. His approach is guided by his extensive experience in laser vision correction and a detailed assessment of each patient.
LASIK (Laser-Assisted In Situ Keratomileusis)
What is LASIK Used to Treat?
LASIK is used to correct short-sightedness (myopia), long-sightedness (hyperopia) and astigmatism, the three common refractive errors that affect how the eye focuses light.
The LASIK Procedure
LASIK involves creating a thin flap in the cornea, typically using a femtosecond laser (an ultra-short-pulse laser). The flap is lifted, and an excimer laser (a laser that removes microscopic amounts of corneal tissue with precision) reshapes the exposed stromal bed according to the patient’s refractive error. The flap is then repositioned without the need for sutures.
In Plain Terms: A very thin, hinged flap is created on the surface of the cornea and folded back, much like opening a page in a book. The laser then reshapes the tissue underneath to correct the patient’s vision, and the flap is folded back into place without stitches, where it begins to settle and reattach during the healing period.
Who May Be Suitable for LASIK?
Suitability for LASIK depends on several factors assessed during consultation, including whether the prescription has remained stable, corneal thickness and shape, the amount of corneal tissue that would need to be removed, and overall eye health. The assessment also looks for conditions such as keratoconus (a progressive thinning and bulging of the cornea) and other corneal irregularities that may make LASIK unsuitable.
Patients with thinner corneas or certain corneal characteristics may be better suited to PRK.
Recovery and Expected Results
Many patients experience improved vision soon after LASIK, typically by the next day, although the speed of visual recovery varies between individuals. Some patients experience temporary discomfort on the day of treatment, including a gritty or scratchy sensation.
Recovery can take longer where a patient has a pre-existing dry eye, slower corneal healing, or a higher initial prescription.
PRK (Photorefractive Keratectomy)
What is PRK Used to Treat?
PRK treats the same three refractive errors as LASIK: short-sightedness, long-sightedness and astigmatism.
The PRK Procedure
PRK involves removing the corneal epithelium (the outermost layer of the cornea) with an excimer laser, rather than creating a flap. The excimer laser then reshapes the exposed stromal surface directly. A bandage contact lens is placed over the eye afterwards to protect the cornea while the epithelium regenerates naturally during the early healing period.
In Plain Terms: Instead of folding back a flap of tissue as in LASIK, the very outer layer of the cornea is gently removed by the laser which then reshapes the surface beneath it. That outer layer grows back during the early healing period, protected by a soft contact lens while it heals.
Who May Be Suitable for PRK?
PRK may be considered for patients whose corneal characteristics make LASIK less suitable, including some patients with thinner corneas. It may also be preferred for patients with an active lifestyle or contact sports involvement, where avoiding injuring a corneal flap may be an important consideration.
Suitability is determined through a detailed assessment of the cornea, prescription and overall eye health.
Recovery and Expected Results
Vision is commonly blurred during the first few days of the early healing period following PRK, with visual recovery occurring at 5-6 days to driving vision level, as the corneal epithelium regenerates. Mild to moderate discomfort is common during this period and is generally managed with prescribed eye drops and a bandage contact lens.
Visual clarity develops gradually over the following four weeks,usually reaching 20/20 by then. The time required for vision to stabilise varies between patients, especially where a higher prescription was involved.
LASIK vs PRK: Which Might Apply?
LASIK
LASIK generally allows faster initial visual recovery because the corneal epithelium is not removed in the same way as it is during PRK.
PRK
PRK avoids creating a corneal flap altogether, which is why it may be considered for a patient with thinner or borderline corneal characteristics, or where specific lifestyle factors make avoiding a flap preferable.
Long-term visual outcomes between the two procedures are comparable once healing is complete, although individual outcomes vary. Which procedure, if either, is appropriate for your eyes depends on factors such as corneal thickness, corneal shape, prescription and overall eye health, all of which are assessed individually during consultation.
Potential Risks and Limitations
Like all surgical procedures, LASIK and PRK involve potential risks and limitations. These may include dry eye symptoms, glare, halos, visual fluctuations, infection, inflammation, undercorrection or overcorrection, and rarely a continued need for glasses or contact lenses. LASIK also carries risks associated with the corneal flap. Less common complications may affect visual quality or require further treatment. The risks relevant to an individual patient are discussed during consultation and as part of the informed consent process.
Why an Accurate Assessment Matters
Not every patient is suited to LASIK, and not every patient is suited to PRK. In some cases, neither laser procedure is the appropriate option, and a lens-based or other treatment may be considered instead.
Recommending LASIK for a cornea that is too thin or irregular for it can increase the risk of postoperative corneal complications. This is why corneal thickness, shape and overall eye health are assessed in detail before any laser procedure is recommended, rather than assuming that a patient’s preference determines the most appropriate treatment.
Dr David Robinson draws on more than 28 years of surgical experience in assessing patients for laser vision correction, including LASIK and PRK. His experience includes 8,000 laser vision procedures. He assesses each patient’s eyes individually and explains which procedure is most appropriate based on their eye health, vision needs and suitability.
Common Questions Patients Ask
Is LASIK or PRK painful?
The procedures themselves are generally well tolerated because the eyes are numbed with anaesthetic drops before treatment. Some mild discomfort or a gritty, scratchy sensation is common afterwards. PRK generally causes longer discomfort during the first few days than LASIK where it occurs on the laser day only.
How long do the results last?
Both procedures reshape the cornea to correct the treated refractive error, with the intended effect lasting decades usually. However,particularly near vision can change for other reasons. Presbyopia (the natural, age-related reduction in near focusing ability) develops separately and is not corrected by standard LASIK or PRK.
Can both eyes be treated in the same visit?
Both LASIK and PRK can be performed on both eyes during the same treatment session in just about all patients. Whether this is recommended depends on the individual assessment and the surgeon’s clinical judgement.
What happens if LASIK isn’t suitable for a patient?
PRK may be considered when LASIK is not appropriate, particularly where corneal thickness or other corneal characteristics make a flap-based procedure less suitable. Depending on the reason LASIK is unsuitable, other forms of vision correction may also be considered.
Will vision be perfect after either procedure?
90-95% of patients achieve 20/20 vision and 97-99% achieve 20/40 driving vision without glasses.No procedure can guarantee a specific visual result. The purpose of assessment beforehand is to determine whether the procedure is appropriate and to establish what level of visual outcome may reasonably be expected based on the individual’s corneal measurements, prescription and overall eye health.