Virtues of cornea-and lens-based methods for presbyopia

January 1, 2008

Whether a cornea-or lens-based method is preferred for presbyopic surgery is a subject of ongoing debate in ophthalmology. Proponents of each discuss progress to date with the two approaches and look to the future for further advances.

Key Points

In a follow-up presentation, however, I. Howard Fine, MD, discussed why IOLs represent a superior alternative to corneal surgery.

"Based on our experience to date, presbyLASIK may be considered to have a definite place in the surgical treatment of presbyopia, especially in patients with lower hyperopia, for whom it offers distance vision outcomes comparable to wavefront-guided hyperopic LASIK but with the benefit of enhanced near vision," said Dr. Jackson, professor of ophthalmology, University of Ottawa, Ontario, Canada.

"We are seeing that hyperopic presbyopic patients undergoing presbyLASIK would like more near vision over time," said Dr. Jackson, director general, University of Ottawa Eye Institute, The Ottawa Hospital, Ontario. "Therefore, it would be ideal if we could strengthen the near correction without inducing more optical symptoms."

He also looks forward to better outcomes with hyperopic treatments as a result of the introduction of new ablation profiles and more precise alignment techniques as well as to expanding the candidate pool based on myopic patterns that are being investigated.

Dr. Jackson noted that presbyLASIK has several advantages over IOL surgery. The laser ablation is less invasive and avoids the risks of intraocular surgery. Also, it preserves the crystalline lens and existing accommodation.

"PresbyLASIK is performed using established laser vision correction techniques, the results can be enhanced or removed, and it can also be added to pseudophakia," Dr. Jackson said.

He acknowledged presbyLASIK has its disadvantages, however.

"There is always a risk of visual symptoms and loss of quality of vision, and near correction may be insufficient or change, especially with increasing age and depending on pupil size. In addition, it is important to recognize and treat existing ocular surface disease because it may affect the results," said Dr. Jackson.

PresbyLASIK has been performed using a number of ablation patterns. Working with the wavefront-guided platform (Star 4, Advanced Medical Optics/VISX), Dr. Jackson has been investigating a technique that uses the center of the cornea for near vision and the periphery for far. To highlight the favorable outcomes that can be achieved with that approach, Dr. Jackson reviewed the results from the most recent cohort that included 56 eyes of 28 subjects.

"We have found the results are better after bilateral presbyLASIK treatment than monocular or blended vision results for both distance and near," Dr. Jackson said.

The 56 eyes had a mean preoperative sphere of +1.68 D (range +0.5 to +3.5 D) and a mean cylinder of +0.48 D (range 0 to +1.5 D). Results available through 1 year of follow-up showed refractive stability was achieved by 1 month, while distance and near vision continued to improve in many patients throughout the first year.

At 1 year, 86% of patients achieved 20/20 or better UCVA at distance and 90% could read J1 or better unaided at near. All patients could see 20/25 or better at distance and J3 at near, while 88% achieved both 20/25 at distance and J1 for near.