Decoding Color Vision

HOT TOPIC

10-Year Results of Accelerated CXL in Pediatric Patients With Kerataconus

A new study in the journal Eye showed that accelerated epithelium-off corneal cross-linking (CXL) yielded substantial results.

The Dresden protocol for CXL is used by most clinics; however, it is time-consuming and relatively unpleasant for both patients and clinic staff, so many international clinics have been offering an “accelerated” version for numerous years. This version is not approved in the United States due to FDA protocols/acceptance. The study used a cohort of pediatric patients who received the accelerated epithelium-off CXL and evaluated their 10-year visual, refractive, and tomographic outcomes. A total of 197 eyes of 97 children with a mean age of 14.5 years were included.

The children in the study had improved uncorrected and corrected distance visual acuities in all postoperative periods compared with their preoperative status. They also showed increased spherical equivalent refraction (likely because they got more myopic as they got older), lower keratometry values (indicating flattening of the cornea), and a decrease in the thinnest corneal thickness, which were all significant at the 10-year postoperative mark compared with preoperatively. Most notably, re-progression of keratoconus was found in only 9.1% of patients and corneal haze in 7.4% of patients, with only permanent corneal haze occurring in 2.3% of patients.

My Two Cents

We perform the FDA-approved Dresden protocol at Williamson Eye Center, so I wasn’t entirely sure what “accelerated” epi-off CXL was. From my research—and after reaching out to my excellent Glaukos rep—I learned that this accelerated form of cross-linking involves a shorter “treatment time” with ultraviolet (UV)/light energy. Therefore, the patient still receives the same amount of riboflavin 5’-phosphate ophthalmic solution (Photrexa) or riboflavin 5’-phosphate in 20% dextran ophthalmic solution (Photrexa Viscous); however, the treatment time with the UV light from the light system is shorter, with higher UV irradiances and a higher total UV energy dose.

Interestingly, even if we wanted to try the accelerated version, our machines cannot be altered to change the UV or energy, which is a wise move by Glaukos. We have had tremendous success with iLink Corneal Cross-Linking as Glaukos designed it and the FDA approved it; however, anything that could improve our patient's comfort and increase clinic efficiency must be monitored!

OUTSIDE THE LANE

One Step Closer in Understanding Color Vision

In a new study in The Journal of Neuroscience, researchers at the University of Rochester identified rare retinal ganglion cells (RGCs) that could potentially fill some gaps in our understanding of color perception. The retina has three types of cones that detect color, each sensitive to either short, medium, or long wavelengths of light. The RGCs transmit this input from the cones to the body’s central nervous system.

The University’s color vision research gained notoriety in the 1980s when researcher David Williams mapped the “cardinal directions” that explained color detection. However, discrepancies exist between how the eye detects color and how color appears to humans. Scientists hypothesized that although most RGCs follow the cardinal directions, they may also work with small numbers of noncardinal direction RGCs to create more complex perceptions.

The University of Rochester team identified some of these elusive noncardinal RGCs in the fovea that could explain how patients see color. To make this discovery, the team employed adaptive optics, which uses a deformable mirror to overcome light distortion and gain unprecedented access to the RGCs. Astronomers first developed this technology to reduce image blur found in ground-based telescopes. (Read more here.)

My Two Cents

Another impressive use of space-age technology in an attempt to understand a foundational question related to the human body: How do we see color? As our treatments for different retinal diseases seem to improve exponentially each year, advances such as this will hopefully pave the way for breakthroughs of the future to happen. Great job, University of Rochester!

CAN YOU RELATE

Health care workers seem to be the worst about taking care of their own health care needs—and I definitely fit that mold. For the past few weeks, I haven’t felt too “sharp.” I’ve had a nagging cough, and a few nights ago, I ended up getting the worst earache of my life. I broke into a cold sweat, manifested a fever, and felt horrible in general.

I decided to try my health insurance’s “virtual visit” through their app. It was a disaster.

The setup seemed simple enough. You log in to the app, select a doctor who interests you, fill out your chief complaint, and any other pertinent information (along with your credit card information, of course). You can also see how many patients are ahead of you.

I went through precisely four different doctors after filling out my chief complaint and “paying,” only to get an error message telling me that the doctor was no longer seeing patients. Finally, I chose the doctor at the top of the list, who never seemed to have any patients waiting to see her. Everything went through perfectly, and I sat in her waiting room for approximately 30 minutes without hearing anything. After just about blowing a gasket, I decided to try another doctor. The process went smoothly, and I could “see” him immediately. After asking me three or four questions while never actually looking up at the screen at me, I was given a script for an antibiotic, and the screen shut off. It was basically a phone visit.

As the pain got worse through the night, I found myself in the ER for the first time in my life. It turned out I had a horrific amount of earwax blocking my ear for “quite some time,” and it needed to be removed to allow the “festering and prolonged ear infection” to start to dissipate.

The point here is that although telemedicine is all the rage right now—and we use it to some degree at my clinic—it is far from perfect, and my personal experience with it was highly negative. There will always be a place for that human touch needed for good medical care, and I am so proud to be a part of a profession that excels at it!