May 20, 2019
2 min read

LASIK surprises and how to avoid them

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One of the disappointments for both the patient and refractive surgeon is to have a good visual result of 20/20 unaided in daylight but an “unhappy” patient because of the unwanted symptoms of GASH — an acronym for glare, ghosting, starburst, halos and reduced contrast sensitivity that can present in low light conditions. These symptoms are usually a surprise in that the patient does not expect it and the surgeon did not predict it.

Noel Alpins
Noel Alpins

In a presentation at a recent meeting of the American-European Congress of Ophthalmic Surgery, I demonstrated how a high ORA (ocular residual astigmatism) greater than 1 D, present in between 34% and 46% of LASIK candidates, will result in postoperative corneal astigmatism greater than 1 D, rendering the patient at risk for GASH. I described a case study patient suffering with all of the GASH symptoms who at night had to drive his car with his mobile phone light directed at his eyes to reduce pupil size and manage his debilitating symptoms. The syndrome is predictable and avoidable, and when there is an ORA greater than 1 D preoperatively and corneal astigmatism postoperatively of more than 1 D, it is termed “PALS” for predictable avoidable LASIK surprise. This is an underrecognized syndrome that has come to the forefront of LASIK dissatisfaction.

In 2017, Maria C. Arbelaez, MD, demonstrated in a study that eyes treated using Vector Planning (Figure 1) had 41% less corneal astigmatism but the refractive cylinder between the two groups was the same. Interestingly, the case study patient was treated by the same laser as in Dr. Arbelaez’s study, the Schwind Amaris 1050 latest generation, demonstrating this prevailing problem with refraction-based treatment parameters.

Vector Planning
Figure 1. The method of Vector Planning incorporates both corneal and refractive parameters in the treatment plan after the ORA has been calculated. TIA = target induced astigmatism vector; R = refractive astigmatism; C = corneal astigmatism.

Source: Noel Alpins, AM, FRANZCO, FRCOphth, FACS

With standard traditional manifest refraction, as well as wavefront-based treatments, too much astigmatism was being directed at and left on the cornea postoperatively. No recent excimer laser has addressed the problem and recommended that a “safe” low astigmatism button be made available to surgeons to be able to employ Vector Planning routinely to reduce the unexpected symptoms of GASH.

Until this is achieved, the ORA/Vector Planning calculator is available for free to all ophthalmic surgeons at

Disclosure: Alpins reports he has a financial interest in ASSORT Surgical Management System, which holds trademarks and patents in Vector Planning.