Toward emmetropia: More advances, more improvements
Refractive, corneal surgery in 2016 saw gains in therapies for keratoconus, presbyopia
Presbyopia has been the final frontier in the refractive arena for a while, and over the course of time, the approaches to correction of presbyopia have surpassed monovision in numbers and creativity.
However, in cataract and refractive surgery, the mainstay of presbyopia correction remains monovision, which requires careful patient selection, as well as considerations, such as previous corneal surgeries, thin corneas, signs of keratoconus, and ocular comorbidities that may be relative or absolute contraindications for monovision refractive surgery.
Monovision LASIK and monovision PRK procedures are easily successful in patients with myopia and astigmatism, according to Dimitri Azar, MD, but are more challenging in patients with hyperopia and the outcomes are less reliable.
Another surgical option for presbyopia correction is PresbyLASIK, which creates a multifocal corneal lens effect using three major techniques: multifocal transitional profile, central PresbyLASIK, and peripheral PresbyLASIK.
The success rates are relatively low, but Dr. Azar believes that the procedure has great potential.
Interestingly, Dr. Azar and two French collaborators, Damien Gatinel, MD, and Jacques Malet, MD, have hypothesized that the success of PresbyLASIK might be driven by the pupillary position during accommodation.
“When the patient accommodates, the lens power increases and the pupil decreases in size,” said Dr. Azar, Dean, College of Medicine, professor of ophthalmology, University of Illinois, Chicago. He and his collaborators are inventors on several patents for this technology, which is not yet in clinical practice.
“When this occurs, if the pupillary position is traced in the accommodative and non-accommodative positions, the positions are not concentric,” he said. “If this information is known for a particular patient, we might be able to design the multifocal corneal shape to consider the pupillary position in the unaccommodated state versus that in the accommodated state and, therefore, in principle, improve the likelihood of success of PresbyLASIK.”