By A/Professor Rob Paul, Ophthalmologist, Melville & Nedlands
It’s hard to believe the first laser keratorefractive procedure on humans was performed 40 years ago. It was called PRK (photorefractive keratectomy) and involved manual removal of the corneal epithelium then reshaping of the corneal stroma with an excimer laser.
The procedure was exceptionally painful and had a prolonged recovery. This was superseded by LASIK (laser assisted in-situ keratomileusis) which involved cutting a corneal flap with a mechanical blade and then applying the excimer laser to the underlying cornea. This procedure carried a higher complication rate.
The introduction of the femtosecond laser to perform laser refractive surgery has been one of the greatest modern advances in ophthalmology and its multiple uses extends to cataract surgery and the correction of reading problems (Presbyopia – Latin for ‘old eyes’).
LASIK and SMILE
LASIK is still a premium treatment for most types of vision errors. Short-sightedness (myopia), astigmatism, long-sightedness (hyperopia) and reading problems (presbyopia) can successfully be treated. A femtosecond laser creates a flap on the cornea. This flap is then lifted and an excimer laser reshapes the corneal bed. The femtosecond laser creates the flap in eight seconds and is painless.
Over 40 million people have benefited from this surgery, including Tiger Woods, Usher, Taylor Swift, Brad Pitt and numerous sportspeople.
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Myopia up to 12 points, hyperopia up to six points and astigmatism up to six points can be treated, with 20/20 vision rates between 95-98% the day after surgery.
Small incision lenticule extraction (SMILE) is the next generation in laser eye surgery procedures. It is essentially keyhole laser eye surgery and involves a femtosecond laser creating a lenticule of tissue under the corneal surface and then removal of the tissue through a 3mm incision.
There is no LASIK-like flap or painful scraping of the surface such as in photorefractive keratectomy surgery (PRK).
One of the benefits of this surgery is that it is essentially pain free and takes 10 seconds. Patients experience minimal to no dry eye. Contact sports pose no risk of flap dislodgement unlike LASIK.
There is less biomechanical weakening of the cornea with SMILE as opposed to LASIK. The latter is important as in some patients, laser can lead to an ectasia/keratoconus syndrome, which adversely impacts on vision. Clinical studies suggest results of SMILE are better than LASIK for higher levels of myopia. SMILE can now treat hyperopia.
More than 10 million SMILE procedures have been performed worldwide, and it is the gold standard for this keyhole laser surgery.
Femtosecond laser assisted cataract surgery (FLACS)
Bladeless laser femtosecond treatment for cataract and lens replacement surgery is extremely useful. The laser surgery takes 30 seconds to complete and the subsequent cataract surgery under seven minutes.
The laser creates computer-generated incisions, as well as breaking up the cataract, allowing safe and easy removal. The critical steps are performed with robotic precision.
Unfortunately, FLACS is not available in the public system and health funds do not cover the cost of $1000 per eye. It can be combined with multi-focal implants to maximise near/distance vision.
It is useful in very dense cataracts or complicated eyes such as those with corneal endothelial dysfunction (Fuchs Dystrophy) or very shallow anterior chambers.
Presbyopic Lasik Correction
Presbyopia and the requirement for reading glasses/correction will affect all of us to some degree after the age of 40. It is 100% guaranteed, just like death and taxes.
Lasik has been used to treat reading problems in the past. Traditionally this involves setting one eye for near and one for distance. Whilst this is effective in some it can reduce depth perception and cause an imbalance.
More importantly patients may complain of reduced distance vision or a monocular blur and may not adapt. Studies show that only 70% of patients are satisfied with Lasik monovision.
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Presbyond Laser Blended vision is the fastest growing laser procedure worldwide to correct reading problems. It uses a sophisticated excimer laser algorithm that controls the spherical aberration of the eye.
It increases depth of focus by creating distance and computer vision in the dominant eye and reading and computer vision in the non-dominant eye. This increases depth perception and minimises distance blur compared to Lasik monovision.
Presbymax is another procedure where one or both eyes can have a multifocal-type laser treatment so that depth perception and distance is not compromised significantly. It can also be reversed if patients are not fully satisfied.
It’s no surprise the inventors of femtosecond technology are Nobel laureates.
Key messages
- Femtosecond lasers are the standard of care in Lasik surgery and have allowed the evolution of SMILE keyhole laser surgery
- Cataract surgery is made easier and potentially safer in some cases with FLACS
- Presbyopic laser treatments are a huge advance in laser correction of reading problems.
Author competing interests – nil
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