Optimizing outcomes with accommodating IOLs

May 6, 2017

All presbyopia-correcting IOLs have pros and cons, and because they have different performance characteristics that can meet the vision needs of a range of patients, Steven G. Safran, MD, said that he uses all the available technologies.

All presbyopia-correcting IOLs have pros and cons, and because they have different performance characteristics that can meet the vision needs of a range of patients, Steven G. Safran, MD, said that he uses all the available technologies.

Dr. Safran provided pearls for achieving success and dealing with complications when implanting accommodating IOLS (Crystalens AO and Trulign Toric IOLs, Bausch + Lomb).

“The keys to success with these implants include proper patient selection, setting realistic patient expectations, hitting the refractive targets, performing meticulous surgery with a focus on avoiding lens epithelial cell-mediated capsule contraction, and intervening early to prevent or treat complications,” said Dr. Safran, private practice, Lawrenceville, NJ.

He noted that the most important complications of the accommodating IOLs are variable/unstable refractive outcomes and Z syndrome (asymmetric vault). The causative factors for these events are the same-capsular fibrosis leading to contraction and use of an IOL that is oversized for the capsular bag.

“Therefore, success with these IOLs involves avoiding capsular bag fibrosis and situations where the lens will be placed under destabilizing contraction forces by the capsular bag,” Dr. Safran said.

Patient selection

 

Patient selection

With those goals in mind, his recommendations for patient selection included avoiding short eyes (<22 mm axial length) because they are at increased risk of unpredictable hyperopic outcomes due to posterior displacement of the optic (the “U syndrome”). In addition, these eyes are at increased risk of Z syndrome.

“In eyes <22 mm, there is increased risk of tension and pressure on the IOL and so it can get pea-podded back or the optic can become tilted if the forces are asymmetric,” Dr. Safran said.

Although myopic eyes generally have good outcomes with accommodating IOLs, he suggested considering a capsular tension ring if the axial length is >27 mm. Other anatomic considerations for patient selection include avoiding eyes with weak zonules or increased capsule contraction forces, such as those with pseudoexfoliation, proliferative diabetic retinopathy, or narrow angle glaucoma.

In addition, if the axial length is <26 mm, Dr. Safran recommended using the toric version of the accommodating IOL and avoiding the AT52 model of the Crystalens AO lens with a 12-mm overall length.

“The Trulign Toric is 11.5 mm in all powers,” he explained.

Setting realistic patient expectations means counseling patients that they should have good vision from distance to about arms’ length but should expect to need glasses for reading smaller print.

For a refractive target, Dr. Safran said he aims for plano to -0.25 D in the dominant eye and between plano and -0.75 D in the nondominant eye, but with a target of -0.4 D.

He noted that he likes to create a capsulorhexis that is slightly smaller than the optic to maximize the opportunity for achieving 360° overlap of the IOL rim.

“This will provide more stable refractive outcomes and reduce the risk of vitreous prolapse if Nd:YAG capsulotomy is needed in the future,” Dr. Safran explained.

As another surgical pearl, he said he spins the lens to make sure the haptics are properly and evenly seated in the equator of the capsular bag.

Of critical importance, he focuses on achieving meticulous removal of cortex and lens epithelial cells to prevent capsular contraction and fibrosis.

Addressing the Z syndrome

 

Addressing the Z syndrome

Dr. Safran explained that the Z syndrome develops because of asymmetric contraction forces acting on the IOL. As one side of the IOL is pushed forward and the other side posteriorly, myopic astigmatism and coma are induced.

To prevent this complication or reverse it at an early stage, Dr. Safran said he evaluates all patients at 4 to 6 weeks with a dilated retroillumination examination, looking for what he described as “guitar string” striae in the posterior capsule. If present and only if the back of the IOL is completely in contact with the posterior capsule, he performs Nd:YAG capsulotomy.

He cautioned, however, against intervening with the laser if the Z syndrome is established with a vaulted haptic.

“Nd:YAG laser treatment in this situation is often ineffective and can complicate future surgical options,” Dr. Safran explained.

Options for managing established Z syndrome are less than optimal. For that reason, Dr. Safran said that he now mostly resorts to IOL replacement with a non-accommodating IOL.

“Laser vision correction can be performed, but it will not address coma from a tilted IOL," he said. "Previously I attempted IOL repositioning, but the Z syndrome recurrence rate was about 50%, even with placement of a capsular tension ring, and so I have abandoned that approach.” 

Dr. Safran is a speaker for Bausch + Lomb.