The Evolution of LASIK

Much better aberrometry measurements as well as refined flap parameters have actually continuously enhanced LASIK results – but there is still much work to be done.
Contemporary LASIK is not a single-system procedure. It integrates 3 different technologies– an excimer laser, a femtosecond laser as well as a wave-front aberrometer – every one of which have undergone numerous developments over the previous twenty years. Explaining to patients how these advanced technologies combine to provide exceptional outcomes can be a problem.
While all excimer lasers deliver very exact 193-nm laser pulses, the pulse delivery formulas and the refinement of the aberrometry systems that measure the eye and also notify the laser are a major component of just how we differentiate our results today. One more important factor is the way in which the flap is designed. We created the term EAGLE Vision to more intuitively share to my patients what modern LASIK can currently provide for clients. EAGLE Vision stands for Elliptical-flap, Aberrometry-Guided, Laser-Enhanced Vision. An elliptical flap takes advantage of the asymmetrical placement of the pupil on the cornea.

Measurements innovations
We now have the capability to gauge the whole ocular micro-zonal refraction with elegant detail and precision, to educate the excimer laser and also specifically assist the laser pulse delivery onto an established stromal grid. The wave-front sensor, has a fivefold greater number of lenslets than its precursor (the WaveScan) did, recording greater than 1,200 spots over a 7.0-mm pupil. When speaking with patients about this improvement, we use the analogy of a high-definition television with even more pixels on the exact same display. They comprehend how that enhances the image the device is capturing of their eye as well as equates that level of accuracy onto their cornea.
Better measurement provides much better options, much better therapy and also much better outcomes.
Along with wave-front aberrometry, the modern LASIK studio also incorporates 5 other simultaneous measurements, including pupillometry, keratometry, full-gradient topography, corneal size and also autorefraction. Since every one of these are captured on the exact same fixation axis, they are spatially registered to one another, making the info even more relevant. The enhancement of topography information specifically helps to reconstruct a specific mathematical representation of the corneal surface, which can then be used to guide our surgery. The added measurements additionally allow us to further refine the flap form and diameter customization (see Flap innovations listed below).
With this modern device, we can determine scotopic pupils as small as 4.0 mm, and our treatment prescriptions have been expanded to include wave-front-guided PRK, monovision treatments, and also a more comprehensive variety of astigmatism modification than in the past. I also explain to patents that as the analysis aspects of the treatment have increased, we are not only able to enhance the ablation pattern however, to more consistently rule out patients that have a greater risk of ectasia as well as must not have Lasik and also may instead benefit from PRK, collagen cross linking, or observation. Better measurement indicates much better selection, far better treatment and also far better outcomes.

Flap Innovations
Combined with the gains in treatment preparation, we also consider it really crucial that this system permits us to tailor flap criteria – consisting of hinge location/width, and flap diameter, shape as well as thickness – helping more in accomplishing optimum results. Because the temporal corneal quadrant is without a doubt the largest, it makes it possible for many more flap style changes as follows.

Here are the modifications in flap design we have worked with throughout the years and believe to have made a huge difference in our results:
1. Temporal pivoted, elliptical form
Elliptical machine flaps, are 4 to 10 percent longer in the horizontal than the vertical axis, honoring the fundamental corneal shape. Elliptical shaped flaps can easily be accommodated by rotating the hinge to the most expansive (temporal) corneal quadrant. Since the pupil is always supero-nasal, a temporal quadrant-based hinge positions the hinge as far from the pupil center as possible. This spacing ensures a big exposed surface to make sure that the flap hinge does not interfere with the large-diameter optical zone ablation patterns required for wave-front-guided, topography-refined therapies.
Along with better visual acuity end results, we have actually additionally observed less complaints of early postoperative dysphotopsias since developing these flap patterns. The elliptical machine flap, coupled with a temporal joint, also keeps any type of opaque bubble layer (OBL) farther away from the pupil, preserves more of the temporal long ciliary nerves (particularly when the “pocket” is additionally deleted), and also provides for better protection in cooperation with the facial bones – considering that the temporal quadrant is the only one without a surrounding bony prominence – in the unlikely event of perioperative blunt trauma.
2. Wide hinge
With the temporal hinge adoption, we have additionally gone from a 45 ° hinge angle to a much broader 65 ° -70 ° angle, which we believe reduces dry eye (by protecting even more of the ciliary nerve fibers) and likewise brings about a more tectonically steady flap. Our individual experience has been that a much more broadly secured – widely-hinged – flap reduces the incidence of epithelial ingrowth, microstriae and slid flaps, as it much more firmly fits back onto the bed with much less misalignment that can lead to very early flap striae. Subtle misalignment can also endanger the advantages of the highly improved ablation pattern.
In embracing such a strategy, the flap oftentimes doesn’t even need to be fully mirrored to the hinge margin in order to provide the whole ablation to the exposed stromal bed (because of its horizontal elongation). In such situations, the effective hinge angle becomes also larger than 70 °. In our experience, these much wider-hinged flaps have actually also decreased our observed incidence of dry eye, both subjective (patient-related experience) as well as objective (minimized epithelial surface punctate discoloration or SPK).
3. Thinner flaps
Because there is much less threat of flap slippage with a wide hinge, doctors can additionally really feel much more comfortable making thinner femtosecond laser flaps. We consistently make a 95- to 100-µm flap, and also believe that in time, with ever more improvement of femtosecond lasers, we may even test the widely held view that 95 µm is the thinnest desirable flap limit. Slim flaps, if without microstriae, may augment the visual advantages accompanying highly refined ablation patterns, whereas a thick flap can dampen the surface area transmission of the exquisitely precise sculpting profile. A thin flap additionally guarantees a thicker residual stromal bed, maintaining corneal structural stability, reducing ectasia risk as well as increasing the likelihood of future improvement candidateship.
When new technologies come, we are lured to evaluate our outcomes by our successes. Experienced surgeons, nevertheless, learn to evaluate their results based upon their failings.

Headed in the ideal direction
Better measurement capacities and better flap modification have integrated to increase our patient experience. Progressively, we are seeing patients attain vision that is close to their real retinal possibility. As an example, we just recently got a message from a Wimbledon champion/patient, saying loudly that his son (also a patient and a growing athlete), was checked at the National Health Center in Holland and observed to currently have uncorrected acuity of 20/10 OD, 20/8 OS and 20/8 binocularly following his recent LASIK treatment. Not every person will certainly attain 20/8 – or value the titratable effect of vision on performance the way expert athletes do – yet situations like this one emphasize that we are ultimately delivering on a promise that for several years was aspirational.
Several researches have actually currently revealed that custom, wavefront-guided LASIK can often achieve even much better uncorrected visual acuity after surgical treatment than the very best pair of glasses. In our method, nearly half of patients are achieving uncorrected acuity after surgery that is much better than their finest corrected visual acuity before surgery.
The entire sector may be beginning to move in this direction. While our system is still the only system with individualized wavefront evaluation as well as info further improved by corneal surface topography, there are currently various other systems that notify the laser beyond straightforward refraction. While these others are mostly using corneal surface topography, some are adding minimal population-averaged spherical aberration refinement. The fad for “smarter” lasers looks set to progress.
We also have new treatments such as small-incision lenticule extraction (SMILE). We’re optimistic about SMILE’s potential, particularly when the lenticules can be made thinner, more superficial as well as with shaping patterns for remedying all types of refractive errors – not simply short-sighted astigmatism.
We am motivated that corneal refractive surgical treatment continues to progress in new as well as exciting ways and which raises the accuracy as well as sophistication of what we can offer patients. Today, LASIK as we’ve explained it above is the only method to dependably reach the objective to which we aim for our patients – not just to throw out their glasses and experience quick visual healing, however to see considerably better following surgery than ever before.

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