Initially, 200 data points were measured and attempts were made to reduce the aberrations. Over the past 15 years with the evolution of customization technology, precise detection and mapping of aberrations has become possible.
Three custom LASIK systems are currently available:
Modern wavefront-guided LASIK (iDesign Advanced Wave Scan, Johnson & Johnson Vision) targets 1,200 aberration data points in the optical system
Wavefront-optimized LASIK (Wavelight, Alcon) uses laser beam application techniques that optimize corneal asphericity to maintain good quality of vision day and night
Topography-guided LASIK (Contoura Vision, Wavelight, Alcon) aims at correcting corneal aberrations by mapping 22,000 elevation and depression points on the corneal surface
With custom LASIK, eyecare practitioners can offer patients better vision than ever. For example, in the recent FDA studies of topography-guided Contoura Vision LASIK and wavefront-guided iDesign LASIK, nearly two thirds of patients achieved better than 20/16 uncorrected vision.7
Today, “better than 20/20” is the new 20/20.
As LASIK evolved, so did the relationship between optometrists and ophthalmologists. Proper patient selection, counseling, and thorough pre- and post-LASIK exams are as crucial to successful outcomes as surgical skill, nomograms, and laser technology.
Related: Quality of life after LASIK
The role of the optometrist
Optometrists are the leaders in diagnosing ametropias. At the conclusion of an eye exam, the optometrist will inevitably discuss ametropia correction. In a post-teenage young adult with a healthy ocular system and clear natural lens, glasses, contact lenses (both soft and gas permeable lenses), and refractive surgery should all be considered.
For patients, LASIK is the noun that loosely, albeit incorrectly, is used to cover all refractive surgeries, including PRK, small incision lenticular extraction (SMILE), implantable collamer lens (ICL), and refractive lens exchange (RLE).
In pre-op management, optometry’s first role is to educate the patient about refractive surgery options and counsel the patient about the procedure(s) he may benefit from the most.
The optometrist is also well positioned to leverage her long-term relationship with the patient to determine what procedure will best fit the patient’s lifestyle and vision needs.
If LASIK is the best choice, the OD can communicate to the surgeon whether full distance, monovision, or undercorrection OU will be best as well as the post-op refractive goal.
The initial surgery work-up in the modern optometric office can supply the patient with a near total representation of LASIK candidacy:
Refraction: Both dry (non-cycloplegic) and wet (cycloplegic) will provide a baseline numerical starting point to guide the laser treatment. The wet refraction will aid in preventing over-minusing. Based on refraction alone, the optometrist can counsel the patient whether he is within the range for laser vision correction, including LASIK, or whether ICL or RLE would be better.
Slit-lamp exam: This will help to define any abnormal anterior segment pathology. Slit lamp combined with corneal staining (sodium fluorescein and lissamine green) is a great way to assess dry eye. In the presence of dry eye, aggressively starting treatment can pave the way for successful and accurate laser refractive surgery.
In the time period between the optometrist’s visit and refractive surgery evaluation, dry eye can be successfully managed. Today, there are many options for successful dry eye management before and after LASIK. Epithelial basement membrane dystrophy and significant corneal scars detected on slit-lamp exam would steer the patient toward PRK rather than LASIK.
Corneal topography/tomography: Such imaging is an important tool in assessing corneal shape and symmetry as a screener for ectasia risk. If a topography/tomography is unavailable, measuring keratometry (K) values with an automated device or manual keratometer will provide the Ks and show the quality of the mires.
Pachymetry: This measurement is also a useful guideline because it will help guide tissue ablation abilities for corneal laser surgery.
1. Free Patents Online. Method for Modifying Corneal Curvature. Available at: http://www.freepatentsonline.com/4840175.pdf. Accessed 10/7/19.
2. McAlinden C. Corneal refractive surgery: past to present. Clin Exp Optom. 2012 Jul;95(4):386-98.
3. Reinstein DZ, Archer TJ, Gobbe M. The history of LASIK. J Refract Surg. 2012 Apr;28(4):291-8.
4. Bloomberg Business. LASIK Surgery: How IBM’s Dr. James Wynne Discovered It. Available at: https://www.youtube.com/. Accessed 10/7/19.watch?v=yzavwVLefPw
5. Sandoval HP, Donnenfeld ED, Kohnen T, Lindstrom RL, Potvin R, Tremblay DM, Solomon KD. Modern laser in situ keratomileusis outcomes. J Cataract Refract Surg. 2016 Aug;42(8):1224-34.
6. Eydelman M, Hilmantel G, Tarver ME, Hofmeister EM, May J, Hammel K, Hays RD, Ferris F 3rd. Symptoms and Satisfaction of Patients in the Patient-Reported Outcomes With Laser In Situ Keratomileusis (PROWL) Studies. JAMA Ophthalmol. 2017 Jan 1;135(1):13-22.
7. Moshirfar M, Shah TJ, Skanchy DF, Linn SH, Kang P, Durrie DS. Comparison and analysis of FDA reported visual outcomes of the three latest platforms for LASIK: wavefront guided Visx iDesign, topography guided WaveLight Allegro Contoura, and topography guided Nidek EC-5000 CATz. Clin Ophthalmol. 2017 Jan 4;11:135-147.
8. Schallhorn J. Challenging conventional wisdom about LASIK. Presented at: American Society of Cataract and Refractive Surgery annual meeting; May 3-7, 2019; San Diego.
9. Optical Society of America. How a leftover Thanksgiving dinner gave us LASIK surgery. Available at: https://phys.org/news/2013-11-leftover-thanksgiving-dinner-gave-lasik.html. Accessed 10/7/19.