Monovision correction algorithm for presbyopic LASIK achieves good visual acuity results

In a study, most hyperopic patients were satisfied with their outcomes by 3 months.

Issue: February 2017

Patients with hyperopia who were treated with central presbyopic LASIK and a monovision correction algorithm were satisfied with the results and achieved good visual acuity, according to a study.

“Presbyopia constitutes the major patient demand today for refractive surgery, so we must propose a reliable solution to patients between the ages of 45 and 60, especially when there is no cataract or refractive lens exchange needed,” co-author Louis Hoffart, MD, PhD, chair of the Ophthalmology Department at Aix-Marseille University in Marseille, France, said.

The Custom Q algorithm (WaveLight EX500, Alcon) used in the study “is a large improvement of the classical monovision algorithm,” Hoffart told Ocular Surgery News. “It is based on micro-monovision.”

The algorithm induces a central myopia of –2 D to –2.25 D, and the periphery becomes emmetropic by means of asphericity modulation. “However, a delta Q of –0.6 to –0.8 is necessary for compensation of the central portion of the near vision addition,” Hoffart said.

The prospective cohort study, published in the Journal of Cataract and Refractive Surgery, was performed between February 2013 and January 2015. There were a total of 138 eyes of 28 men and 41 women, who had a median age of 53.84 years.

Visual acuity results

“The results are excellent for emmetropic and hyperopic patients,” Hoffart said. At 1 year postop, the mean binocular uncorrected distance visual acuity was 20/20, the mean binocular uncorrected near visual acuity was J2, and the mean binocular uncorrected intermediate visual acuity was 20/20.

The mean keratometry reading in nondominant eyes was also statistically greater than the mean keratometry reading in dominant eyes: 43.93 D vs. 45.85 D.

Regarding safety, 1 month after surgery, one eye (1.22%) lost two lines of corrected distance visual acuity and five eyes (6%) lost one line. These results carried through to later visits.

Also, 18 eyes of 16 patients underwent refractive re-treatment before 1 year postop: in nondominant eyes in seven patients, in dominant eyes in seven patients and bilaterally in two patients.

Patient satisfaction

Overall, patients were satisfied with the original surgery for resuming everyday activities, despite reporting increased halos, blurred vision, diplopia and visual fluctuations that were more prominent at 1 month postop, followed by a return to baseline at 1 year.

The authors speculated that these visual side effects might be caused by postsurgical ocular dryness, refraction evolution or neuroadaptation.

At 1 month, 63 of 69 patients (91.3%) conveyed that they were pleased, increasing to 95% at 3 months. Furthermore, 6 months after surgery, 100% of patients said they would recommend the procedure.

Yet the algorithm is not as effective in treating myopic patients. “In these cases, we still continue to use conventional monovision, with a balance of –1.25 D to –1.5 D,” Hoffart said.

Hoffart said that, as with any presbyopic correction protocol, “patient selection is crucial. You should eliminate amblyopic patients, even a slight amblyopia in the nondominant eye, as well as nonlateralized patients and patients with unrealistic expectations. The word ‘compromise’ should always be explained to the patient.”

The algorithm is nearly the same in all patients, especially those between the ages of 50 and 60 years. “You do not need to be mindful of several parameters, such as anterior chamber depth and preoperative asphericity,” Hoffart said.

The LASIK/algorithm modality seems to attain “interesting results after monofocal IOL implantation to correct residual presbyopia in these patients,” Hoffart said.

Hoffart and his colleagues continue to collect study results. “The stability of the treatment is excellent even after 12 months,” he said. – by Bob Kronemyer

Reference:
Wang Yin GH, et al. J Cataract Refract Surg. 2016;doi:10.1016/j.jcrs.2016.07.031.

For more information:
Louis Hoffart, MD, PhD, can be reached at Service d’Ophtalmologie, Aix-Marseille University, Hopital de la Timone, 264, Rue Saint Pierre 13385, Marseille, Cedex 05, France; email: louis.hoffart@ap-hm.fr.

Disclosure: Hoffart reports he is a consultant to Alcon.