Laser vision correction has been the most common and successful refractive procedure in North America over the past 2 decades. Clinical outcomes have been excellent when respecting the indications and contraindications of the procedure, utilizing advanced technology, surgical competence, and careful follow-up care. After more than 20 years of performing laser vision correction at the Bochner Eye Institute, this is my top list of factors to ensure outstanding patient outcomes:
1. Rule out keratoconus and pellucid marginal degeneration (PPMD)
LASIK is a contraindication in eyes with keratoconus and PPMD. Creating a flap in a structurally weak cornea can lead to cornea ectasia. There are many clinical signs of keratoconus and PPMD but the most helpful involve topographical and pachymetry imaging utilizing Pentacam technology. Findings of clinical value include: A. Inferior to superior steepening of greater than 1.6 D; B. Central steepening of 48 D or greater; C. Elevation of posterior cornea of 17 microns or greater; and D. Area of corneal thinning that corresponds to the area of anterior and posterior corneal elevation.
2. Rule out dry eyes
Dry eye syndrome especially with a superficial punctate keratopathy can delay the visual recovery. Patients with severe dry eyes should not undergo laser vision correction. Patients with mild to moderate dry eyes if treated aggressively preoperatively may be satisfactory candidates for LASIK. Dry eye treatments may include preservative-free artificial tears, oral omega fatty acids, lubricating gels or ointments, Restasis drops, hot compresses to the lids if plugged meibomian glands, or the Lipiflow procedure. Bochner Eye established a Dry Eye Clinic to try to rehabilitate patients and enhance their comfort and visual function.
3. Femtosecond flap creation
Femtosecond technology has revolutionized the safety of LASIK. The creation of a thin flap that has the same thickness in the centre and periphery reduces the risk of serious complications. Unfortunately discount laser centres continue to utilize a mechanical microkeratome that exposes patients to significantly higher risks. Femtosecond lasers have eliminated the risks associated with mechanical micrkeratomes, which include: button holes, free flaps without a hinge, partial flaps, and irregular flaps.
4. Surgical competence
Although excimer lasers and the creation of femtosecond flaps have added some automation to the procedure there are many steps that require surgical care. A skilled surgeon will insure proper centration of the corneal flap, a dry corneal bed prior to and during the excimer ablation, satisfactory patient fixation during the excimer ablation, minimal irrigation beneath the flap, and careful repositioning of the corneal flap.
5. Postoperative care
Although complications are uncommon using advanced technology, the identification of any early complications and proper management can insure an excellent outcome. Most early complications include visually significant striae, diffuse lamellar keratitis, and an epithelial defect. The rare complications are microbial keratitis and corneal ectasia. If the refractive outcome is not satisfactory then an enhancement can be performed. It is typically best to wait at least 4 months for an enhancement to ensure refractive stability.
6. Maintenance and Calibration of Equipment
A laser centre must insure proper calibration and maintenance of all the equipment. Excimer laser and femtosecond technology require frequent maintenance checks to be sure optimal function. A dedicated technical staff that is experienced with daily calibration of the equipment and ensures regular maintenance is critical to achieving outstanding results.
7. Communication between the surgeon and comanging doctor
Communication between the surgeon and comanging doctor about any patient concerns or general education concepts is vital for optimal care. At the Bochner Eye Institute, communication can be accomplished with a phone call, email, or fax.
8. Ability to customize excimer laser ablations using either topographically-linked, wavefront-guided, or wavefront-optimized techniques
The surgeon should be able to choose the right technology for the right patient to achieve the best possible outcome. Technology continues to advance with more sophisticated treatment options. When patients have any corneal irregularity, a topographically-linked ablation is the treatment of choice to smooth the corneal surface. Eight Pentacam images, representing 20,000 data points per image, are transferred to the excimer laser system and a customized laser ablation is performed. In addition, we now have the ability to centre the excimer ablation over the line-of sight and not the centre of the pupil using a topographically-linked ablation. We all recognize that a patient’s refractive error is aligned with the line-of sight, which is not necessarily the centre of the pupil. By performing the laser ablation over the line-of sight we can enhance the refractive accuracy especially in hyperopic patients.
9. Presbyopic Considerations
Understanding the patient’s lifestyle can allow one to customize the treatment. There are many options for the correction of presbyopia including reading glasses, monovision LASIK, KAMRA or other corneal inlays, monovision with an aspheric implant, or multifocal implant with refractive lens exchange. There are advantages and disadvantages to each option. Factors that can influence a presbyopic decision include the value of stereoscopic distance vision and/or stereoscopic near vision, early crystalline lens changes, requirements of night time driving, and personality traits that can play a role in dealing with any visual imperfections. At Bochner we explore all the presbyopic options with our patients before a decision is made for final treatment.
10. Realistic Patient Expectations
Although over 98% of patients undergoing LASIK at Bochner have excellent uncorrected visual acuity there are some patients that may require an enhancement. As we all know, laser surgery is performed on human tissue and not on a piece of plastic. As a consequence there can be an individual variation in outcome as a result of the laser interaction with the cornea, as well as a difference in postoperative healing. At the Bochner Eye Institute, laser enhancements are performed at no charge. This life-time warranty has been our policy for over 20 years.
By Dr Raymond Stein