Drug therapies improving refractive outcomes

Take-home message: Advances in cataract research and therapies such as new alternatives to topical drops are becoming common in ophthalmologist’s strategies.

By Michelle Dalton, ELS; Reviewed by Robert K. Maloney, MD, and Peter S. Hersh, MD

Lines continue to blur as to what constitutes refractive surgery, and likely will continue to blur well into the future. Multiple compounds-phenylephrine and ketorolac 1%/0.3%, (Omidria, Omeros) and the “Dropless” line (Tri-Moxi/Tri-moxi-Vanc, Imprimis Pharmaceuticals)-are designed for use in cataract surgery, but their goal is to improve refractive outcomes. 2015 was the year they started to get some serious attention.

“I’m no longer using topical antibiotics after cataract surgery. This is the year that my practice changed in that respect,” said Robert K. Maloney, MD, Los Angeles. “The evidence in the literature is very clear that intracameral antibiotics reduce the risk of infections, and there's really no evidence that topical antibiotics reduce the risk of infection.”

Especially as the price of generic topical antibiotics has increased, “there’s a real advantage for a patient in finding alternatives to topical drops,” he said.

Phenylephrine and ketorolac 1%/0.3% has advantages, but Dr. Maloney argues against using the drops indiscriminately, and will only use them in patients with small pupils after dilation, or in patients he expects will have difficulty maintaining a dilation during surgery (such as floppy iris syndrome).

If pupils remain dilated throughout the procedure, postoperative pain is likely reduced, said Farrell “Toby” Tyson, MD, Cape Coral, FL. “Ketorolac is a non-steroidal anti-inflammatory that is depositing into the iris in the ciliary body and reaches back over the subsequent 12-24 hours. That’s a nice aspect of the medication.”

However, others argue the initial price tag (about $400 per case) and the mandate of purchasing up front may be more than most ambulatory surgery centers (ASCs) are willing to do with only a pass-through payment from Medicare and an unclear reimbursement strategy with most secondary insurances. It is just not yet at a point where the return on investment is obvious, they said.

The technology that allows triamcinolone and moxifloxacin; triamcinolone-moxifloxacin-vancomycin (Tri-Moxi and Tri-moxi-Vanc, respectively) to solubilize into a micronized particle suspension can be formulated into either an injectable or a topical (Dropless Therapy and LessDrops, respectively).

Numerous studies have shown the post-cataract surgery infection and inflammation may result in reduced visual outcomes, and until recently, most surgeons have relied upon patient-administered postoperative drops as prophylactics. According to Imprimis, since April 2014, more than 70,000 eye surgeries have used the Dropless formulations, and LessDrops just launched this past year for patients following LASIK, cataract, and other ocular surgeries.

“There’s definitely been a move toward intracameral in the past year,” Dr. Maloney said. “We have seen a rise in the move away from drops, and that’s likely because of these products.”

Nanotechnology

The use of nanotechnology in ophthalmology is in its infancy, but may have far-reaching applications. These may include treatment of oxidative stress, measuring intraocular pressure, using nanotechnologies to treat post-surgery scarring in glaucoma patients, or treating retinal diseases with gene therapy. They are also ideally suited for drug delivery as a topical treatment-the technology is small enough that washout is unlikely. The miniscule proportions of the technology, which are typically less than 100 nm allow nanoparticles to penetrate through mucus layers. This may enhance the duration of action exponentially while allowing for targeted delivery to specific layers or locations within the eye.

“If you can attach a nanoparticle to a drug and to an antibody, and make these target-specific, it’s just hard to imagine that that won't make a profound impact on what we do,” Dr. Maloney said. “I'm excited about the possibilities of this technology.”

Prophylactic treatments

Using Mitomycin-C (MMC) as a therapeutic agent to prevent corneal haze in complicated LASIK flaps (or other surface pathology) is an up-and-coming drug therapy, according to experts, but is not recommended for every patient. A large study showed eyes at risk did not develop haze when MMC was used prophylactically, but 63% of eyes without MMC developed haze, suggesting a potential role in this subset of patients.   

“Many surgeons use a low dose application of Mitomycin-C (0.02% for approximately 10-15 seconds) for all PRK patients, and some use it only for higher corrections,” said Peter S. Hersh, MD, Teaneck NJ.  “We have also been using MMC for some cases of superficial keratectomy (for example, Salzmann’s dystrophy), to mitigate haze and recurrence after the procedure.” 

MMC can also be used as an adjunct to pterygium surgery. However, “you must take great care not to expose the sclera to too much MMC in pterygium surgery, since this might lead to scleral melting,” Dr. Hersh said.

Peter Hersh, MD

E: phersh@vision-institute.com

Dr. Hersh has financial interest with Addition Technology, Avedro Inc., and Synergeyes Inc.

Robert K. Maloney, MD

E: rm@maloneyvision.com

Dr. Maloney has financial interest with Abbott Medical Optics, Alcon Laboratories, Calhoun Vision Inc., and Stromal Medical.