Pupillary Pathways

Can New Eye Drop Really Clear Cataracts?

Posted by Amanda Dexter on Nov 13, 2015 7:30:00 AM
Amanda Dexter
Dr. Amanda K. Dexter received her optometric training at Southern California College of Optometry in Fullerton, California, where she was Class of 2010 Valedictorian. She also completed a residency in Primary Care and Ocular Disease at the Veteran's Affairs Hospital in San Diego, California. Dr. Dexter is the Manager and Program Coordinator for OptoPrep, the premiere online study resource for the NBEO Part I & II.

I’m sure by now most of you have seen articles on social media about new eye drops that will dissolve cataracts and eventually prevent the need for cataract surgery in the future.

You have also probably had friends, family members, and even patients ask you if these drops really work. So… do they really work? Is cataract surgery really going to become obsolete? 

As we all know, the human lens is comprised largely of crystalline proteins that are assembled into a very highly ordered configuration. This macro-structure is essential for maintaining the transparency of the lens and producing its refractive index. With age (and other environmental factors), disruption of the protein interactions results in alterations to their delicate arrangement, subsequently causing protein aggregation and cataract formation. 

Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people. Currently, the only treatment available to treat cataracts is surgical removal of the crystalline lenses; however, new research on alternative methods appears to be promising. With knowledge on the pathophysiology of cataract formation, scientists have been on a hunt for drug compounds that could stick to and stabilize the natural state of crystalline lens proteins and prevent them from clumping together, thus preventing cataract formation. 

A naturally occurring steroid called lanasterol sparked the interest of researchers when they became aware of two children in China who had inherited a congenital form of cataracts that had never affected either of their parents. It was discovered that these siblings shared a genetic mutation that had prevented the production of lanasterol. So, the parents had the ability to produce lanasterol and did not develop cataracts, but their children were unable to produce lanasterol and did form cataracts. 

This idea allowed the researchers to propose that the steroid lanasterol may halt disrupted crystalline proteins from clumping together and causing a loss of transparency of the lens material. Using lanasterol as a base for eye drops, researchers conducted three different types of experiments using human lenses in a lab, rabbits, and dogs with naturally occurring cataracts. In all studies, there was a clinically significant response to the drug, with severe cataracts clearing to almost complete transparency. 

So, the studies have shown that these new eye drops do play a key role in inhibiting lens protein aggregation, thus reducing or reversing cataract formation, but let’s not get carried away yet. There are some limitations and flaws that I see in the initial experiments, and these areas must be addressed before this potential treatment makes headway in the medical community. 

  • The initial study only lasted for a few months, so the cataracts are likely to have recurred after the drops were discontinued. Therefore, patients would have to continue to use these eye drops the keep their lenses transparent. Who knows how much these drops would cost when they hit the market. And if they are used for many years, would it really be more cost effective as compared to one-time cataract surgery?
  • Although the transparency of the crystalline lenses increased with the eye drops, the tests did not prove that there was any improvement in visual acuity. It is possible that the lens may become clearer, but visual acuity could still be at a level that is considered unacceptable to the patient, in which cataract surgery may still be necessary. 
  • What happens to the refractive error when the drops are used? One of the great benefits of cataract surgery is that the refractive error of the patient can be integrated into the intraocular lens implant so that the patient can reduce his or her reliance on glasses. Over the past few years we have even seen an increase in refractive lens exchange procedures (early cataract surgery) because the technology involved with cataract surgery and lens implants that we have available today provides a desirable visual outcome even for those without cataracts to begin with. 
  • Several potential drugs over the past decade have touted the ability to prevent or reverse cataract formation, and have even begun FDA trials, but none have successfully completed them at this time. 

Another idea that I found extremely interesting when reviewing the studies and research is that the scientists believe that in addition to clearing cataracts, this type of drug may have broader implications in treatment of other diseases that involve abnormal protein-aggregation. This includes neurodegenerative diseases such as Alzheimer’s and Parkinson’s, as well as diabetes. 

In summary, it appears as though this new type of eye drop does show promising results when it comes to increasing the transparency of the crystalline lens in animals and human lenses in vitro. Much more research will need to be completed to determine the efficacy in vivo, as well as finding the place that this drug may have in the treatment of cataracts in our patients. If successful, this medication could also have a huge impact on us as optometrists as the treatment of cataracts would transition from a primarliy surgical to a non-surgical procedure. 

 

-Dr. Dexter 

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