Cataract, glaucoma collision sparks MIGS, other innovation

By Fred Gebhart; Reviewed by Alan S. Crandall, MD

The introduction of phaco in 1967 was a defining shift in the treatment of cataracts, glaucoma, and complex infant eyes, as well as expansion in the provision of global eye care into the future.

“I originally trained in the 1970s. With intracapsular, and later, extracapsular surgery, your control of IOP usually was worse,” said Alan S. Crandall, MD, professor and director of Glaucoma and Cataracts, Moran Eye Center, University of Utah School of Medicine, Salt Lake City.

“With phaco, you suddenly have a three- to five-point drop in IOP after cataract surgery,” Dr. Crandall added. “That unexpected collision between phaco and glaucoma sparked a blossoming of technology that has brought us to micro-invasive glaucoma surgery (MIGS) devices and similarly, important innovations in low-tech treatments that are improving eye care around the world.”

Marriage of treatments

The continuing development of phaco created a new category of combined cataract and glaucoma surgery that has become one of the most common ophthalmic surgical procedures in the developed world, Dr. Crandall said.

Intracapsular gave way to extracapsular procedures, but there was little innovation until the often contentious adoption of phaco, he noted.

“There is a clear progression from intracapsular to extracapsular to phaco to small incisions to small implants,” he said.

“The 1980s and 1990s were an exciting time in cataract surgery,” Dr. Crandall said. “But glaucoma surgery was pretty much trabeculectomy; there were some minor adjustments-mitomycin C here, selective laser trabeculoplasty there.”

It would take another decade for advances in cataract to move into glaucoma with successive generations of ever-smaller, ever less-invasive devices, he noted.

Learning from the unexpected lesson that phaco lowers IOP, generations of researchers have been searching for technologies and techniques that can be translated from one disease or treatment area to another.

Pediatric ophthalmology

Surgeons realized that their growing experience with smaller incisions in adult eyes could be translated directly to pediatric eyes. Pediatric conditions-such as Marfan syndrome or ectopic lentis that once had less-than-ideal outcomes-can now be treated much more successfully using Ahmed capsular tension segments and other techniques designed for adult eyes.

“The standard procedure for Marfan syndrome is lensectomy, vitrectomy, and then you sew a lens to the sclera,” Dr. Crandall noted. 

“Then you have fairly high rates of retinal detachment and secondary glaucoma,” he said. “When you apply what we’ve learned from phaco and small incisions and treating complicated adult eyes, you reduce the rate of both retinal detachment and secondary glaucoma in these kids to near zero. It’s a huge change.”

The numbers of patients are relatively small, he noted, simply because the prevalence of complex pediatric eye disease is relatively low. Thanks to technologies developed for complicated adult cataracts, late complication rates in pediatric patients have fallen dramatically.

Global outreach

Though phaco is the leading cataract treatment in advanced economies, the procedure is far too expensive for the vast majority of cataract patients in the rest of the world. Most ophthalmologists worldwide still rely on small incision extracapsular.

“How do you pay for cataract surgery in less-developed countries?” Dr. Crandall asked.

“You do it by helping ophthalmologists in those countries to develop their own centers of excellence where patients who used to fly to London, Japan, the United States, or Australia can get the same first-world phaco and premium IOLs without leaving home,” Dr. Crandall said.

Just one patient treated with phaco in a country, such as India, pays for nine other patients to get a first-rate, small-incision extracapsular cataract removal. Phaco technologies that developed from it are transforming vision care even for patients who cannot afford it, he noted.

Into the future

There is no sign of slowdown in the pace of innovation, Dr. Crandall continued. Lasers continue to increase in performance and versatility. The latest development is a femtosecond laser that can reshape an IOL that has already been placed in the eye.

“Instead of doing a lens exchange, you can change the power of the existing lens by four D, plus or minus,” he said. “You can add or remove astigmatism. You can add or remove multifocal, all with the lens in the eye. And you can do it in 30 seconds.”

Innovation is also transforming low-tech procedures, he said-one of the latest developments being a handheld device (miLOOP, Iantech) that fragments any grade of cataract using a thin, super-elastic filament.

No laser, no phaco, and no external power source are needed, just a steady, surgical hand, he noted.

Alan S. Crandall, MD

e: alan.crandall@hsc.utah.edu

This article was adapted from Dr. Crandall’s delivery of the Charles D. Kelman Lecture at the 2017 meeting of the American Academy of Ophthalmology. He did not indicate any financial interest in the subject matter.