How advances in phaco benefit glaucoma surgery

February 10, 2018

Advances in phacoemulsification are creating new opportunities for glaucoma surgery, especially in developing countries, according to Alan S. Crandall, MD.

 

Advances in phacoemulsification are creating new opportunities for glaucoma surgery, especially in developing countries, according to Alan S. Crandall, MD.

Dr. Crandall, professor of ophthalmology at the University of Utah, gave an overview of the relationship between the two types of procedure in the Shaffer-Hetherington-Hoskins Lecture at the Glaucoma 360 Annual Glaucoma Symposium.

Bringing the two procedures together can particularly benefit people in the developing world, said Dr. Crandall, who frequently travels abroad to perform the procedures. Glaucoma and cataracts are the leading causes of blindness in many countries, he noted.

"Remember we are all brothers," he said. "Our goal is no more canes."

 

By itself, phacoemulsification can lower IOP 3 to 5 mm Hg in both chronic open-angle glaucoma (COAG) and pseudoexfoliation and is an important treatment for narrow angle glaucoma, he said.

How does it work? It's possible that the procedure creates space, but ultrasound may play a role as well, he said.

Minimally invasive glaucoma surgery (MIGS) combines well with cataract surgery, said Dr. Crandall. One category of MIGS options targets Schlemm's canal. This includes the Glaukos iStent, the Ivantis Hydrus Microstent, the New World Medical Kahook Dual Blade, the Ellex I-Track gonioscopy-assisted transluminal trabeculotomy (GATT), ab-internal canaloplasty and the Sight Sciences Visco360.

Another category of MIGS targets the subconjunctival space. This includes the Alcon Ex-press, the Allergan Xen Gel Stent, and the Santen InnFocus MircoShunt.

 

A third category targets the suprachoroidal space. These include the Alcon CyPass, the Allergan iStent Supra and the SOLX Gold Shunt.

These devices are providing new options for treating pseudoexfoliation glaucoma. Pseudoexfoliation stems from a generalized disorder of the extracellular matrix. The most-strongly associated genetic variants are found in the lysyl oxidase-like 1 (LOXL1) gene. It is associated with pelvic organ prolapse, atrial fibrillation, emphysema, chronic obstructive pulmonary disease, hernias, and aneurysms.

"It shouldn't be a surprise that there are other issues with pseudoexfoliation," said Dr. Crandall. "It's all part of a systemic disease so we need to be more holistic with diagnosis."

Although it is classically associated with northern European heritage, Dr. Crandall has encountered it in Ethiopia, Guatemala, and Mongolia, he said.

Patients with pseudoexfoliation may present with small pupils, capsule, rhexis and zonular issues, sticky cortex, capsule phimosis and late subluxation, he said.

In capsule phimosis, the interval between implantation and explantation is shorter. The capsular contraction exerts tractional forces on the capsular bag and this is transmitted to the zonules.

Lens management in patients with metabolic disorders, especially Marfan syndrome, presents special problems, said Dr. Crandall. He advised taking care to maintain the natural bag and vitreous space.

 

At the beginning of his talk, Dr. Crandall celebrated last year's 50th anniversary of phacoemulsification with a video he made of his first combined cataract and glaucoma procedure. He traced the innovations that have made the procedures more successful and less traumatic over the years.

Recent innovations promise further benefits, he said. These include an IOL whose power can be adjusted by a femtosecond laser. The laser induces a chemical reaction in a targeted area of the IOL, causing a localized increase in hydrophilicity, decreasing its refractive index.

These adjustments can be done quickly and noninvasively with topical anesthesia. They can be done multiple times, with premium functions added or removed, and without the need for special protective spectacles, said Dr. Crandall.

Another promising innovation is the Iantech miLoop, he said. A thin, elastic, self-expanding nitinol filament, the miLoop is designed to fragment lenses while minimizing the use of ultrasonic vibrations.

It is safe and effective for disassembling the nucleus for either extracapsular removal or phacoemulsification, said Dr. Crandall, and is excellent for hard cataracts and effective for pseudoexfoliation and eyes with loose zonules.

Near his John Moran Eye Center in Utah, Dr. Crandall has brought such state-of-the-art cataract and glaucoma procedures to a homeless center, undocumented workers and the Navajo Nation, he said.

Abroad he has done cataract and glaucoma procedures in Ghana and Tanzania among other developing countries.

Dr Crandall is a consultant to Alcon Laboratories, Allergan, Omeros, Glaukos, Ivantis, IanTech, AISCO and Epsilon.