October 2014

 

REFRACTIVE SURGERY

 

A unique drop


by Maxine Lipner EyeWorld Senior Contributing Writer

 
   

Liquid Vision drops create a reversible, smaller pupil so that the central light rays for both distance and near vision are always in focus optically. This is known as the pinhole effect. Source: Terry Kim, MD

Pharmacology option could expand presbyopia treatment possibilities

Imagine a presbyopic patient getting the near vision he craves simply by instilling a drop in the eye every day. Such is the promise of Liquid Vision (Presbyopia Therapies, Coronado, Calif.), according to Terry Kim, MD, professor of ophthalmology, Duke University Eye Center, Durham, N.C. There are plenty of surgical approaches to presbyopia correction, such as customized ablations of the cornea, conductive keratoplasty, corneal inlays, scleral expansion bands, and lens extraction followed by implantation of a multifocal or accommodative lens, he noted. This idea (of using a drop) may seem shocking, but its quite simple in terms of having a pharmacologic treatment for presbyopia, Dr. Kim said. In the U.S., Liquid Vision is scheduled to enter phase 2 trials next year, with preliminary studies going on outside of the country.

Liquid Vision drops, he explained, create a reversible, smaller pupil through which the central light rays for both distance and near are focused optically. At the heart of the approach is a pinhole effect. Because you create miosis with this pinhole effect, near vision is greatly improved and distance vision remains unchanged or even improved with this unique formulation, he said.

Targeting pupil constriction

While the mixture here is a proprietary one, Dr. Kim said the ingredients have been used for years and are safe and effective. It is unlike other pharmacologic approaches that have been tried. For example, it is different from the use of pilocarpine and Alphagan (brimonidine tartrate, Allergan, Irvine, Calif.).

Its not pilocarpine, Dr. Kim said, adding that with Liquid Vision there is no accommodation; there is only miosis. When accommodation is induced with agents like pilocarpine, it diminishes distance vision and basically creates a myopic eye, he said. Pilocarpine acts on the ciliary muscle as well as the pupil sphincter muscle, which is why you get accommodation along with the miosis. Its also why you get the brow aches and decreased distance vision, Dr. Kim said. Patients can also get red eyes. The key with Liquid Vision is that it only affects the pupil sphincter muscle and not the ciliary muscle. Proof of this important difference has been demonstrated on anterior segment OCT where pupil constriction is clearly evident but without any shallowing of the anterior chamber. You dont get the brow ache [or] the rednessyou only get the desired pinhole effect, which also increases the depth of field, he said. The goal with these drops is to modulate the pupil so that it produces a constriction of anywhere from 1.5 mm to 2 mm. It causes miosis but it does not affect the ciliary muscle, so you dont get accommodation, which is why the distance vision stays intact, he said. By creating pupil constriction in that ideal zone of 1.5 mm to 2 mm, you get improved near vision and improved (or certainly not compromised) distance vision. So far, Liquid Vision has been used more than 200 times in more than 40 eyes. There has been a preliminary trial performed in Mexico by David Castillejos, MD, and in all of these patients, near acuity improved without adversely affecting distance acuity, Dr. Kim said. In the preliminary trials, which included patients ranging in age from 46 to 63, near visual acuity improved 3 to 7 lines on the Jaeger scale without compromising distance vision. Were getting marked improvement in functional near vision, Dr. Kim said. This is not simply intermediate vision as seen with the accommodating IOL. Vision here was also tested at 14, 16, and 20 inches, so patients are getting a range of near vision as well, he said.

A binocular approach

Liquid Vision can be used in both eyes. In contrast, the pilocarpine drop produces a kind of monovision and is only used in one eye. With the Liquid Vision drops, there is binocular distance and near vision without any compromise of distance acuity. This will last about 8 hours and is truly reversible, he said. You can choose to add an additional drop if you want a longer effect. If someone woke up at 5 a.m. and instilled a drop, they could put in another drop 8 hours later.

Liquid Vision is safe, Dr. Kim said. There are none of the risks that we get with the presbyopia surgical procedures that have limited effectiveness, questionable safety, and questionable long-term results, he said. You dont induce any corneal scarring or irregularity. He views the Liquid Vision drops as the safest option with no glare and good depth perception because both eyes are treated. The only downside noted was that a minority of younger patients noticed an initial visual dimming effect with the drop. The effect went away over time. After a few days of use, they notice less and less of this, Dr. Kim said. Because the Liquid Vision drops produce a pinhole effect, they could also be used to help those with visual complaints due to corneal scars, irregular astigmatism from a poor ablation, or optical irregularities from a poor ablation or multifocal IOL. Its not only going to help with near vision, but also with distance vision in patients who have problems with glare, halos, or other visual or optical aberrations, he said. He views Liquid Vision as having a lot of promise for presbyopia. [In presbyopia correction], everything that weve seen so far has been inadequate or involves an intricate surgical procedure, Dr. Kim said. The problem is presbyopia is a progressive condition that gets worse with age. Liquid Vision is not sensitive to age. We have patients in their early 40s or late 60s who have the same benefits without the side effect profile [of other methods], he said. I think this is hopefully going to be a great addition to the pharmacotherapy thats going to help patients who are frustrated with their loss of near vision and looking for an option thats safe and effective without undergoing surgery, Dr. Kim said.

Editors note: Dr. Kim has financial interests with Presbyopia Therapies.

Contact information

Kim
: terry.kim@duke.edu

A unique drop A unique drop
Ophthalmology News - EyeWorld Magazine
283 110
216 76
,
2016-07-08T15:40:38Z
True, 10