BLOG: The cocktail napkin talk

Over the past few years I have been fortunate to do a little traveling around the country to talk about my favorite topic, blue light. What I have found is that there is a wide range of clinical understanding among our colleagues, ranging from little knowledge to exceptional knowledge. In fact, I am often surprised to discover which type of practitioner falls within which camp.

I have had thought-provoking conversations with ODs who are everyday clinicians (like me) with a keen interest in preventive eye care for the simple desire to protect their patients. On the other hand, I have had seasoned optometric educators ask me the most rudimentary of questions and have been in classes where the instructor states something that is false from a basic anatomical level. Here are a couple of examples:

While attending a state optometric association conference, I visited a vendor’s booth for nutritional supplements and had a discussion with a colleague on the benefits of raising macular pigment. She was very excited about the prospect of helping her patients and said, “You have to show this to my professor, I will be right back!” Um, ok. A few minutes later, I look up to find one of the conference lecturers chastising me that retinal pigment epithelial (RPE) cells are post mitotic, and the only way more are created is through injury repair, and that supplements have no bearing. The fact that this experienced educator had macular pigment and RPE mixed up yet was willing to discredit the use of supplements was a bit shocking.

While enjoying an excellent lecture on age-related macular degeneration, the topic of blue light and prevention was touched upon. The lecturer stated that in addition to protecting RPE cells from photo-oxidative damage, macular pigment also protects intrinsically photosensitive retinal ganglion cells (RGCs) from blue light, thus enhancing sleep. (More on ipRGCs in a future blog). While I offered a gentle correction, I thought to myself how well intentioned but factually incorrect education might create a potentially dangerous flow of bad information from physician to patient.

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Now don’t get me wrong, I have nothing but the utmost respect for the optometric educators described above as well as for all of those who put hundreds of hours into preparing and giving lectures for all of our benefit. Yet it is likely impossible to be completely knowledgeable on all subjects pertaining to the eye. A major limiting factor may be the lack of education regarding the pathogenesis of AMD.

We currently have an extremely bright fourth-year optometry student in rotation at our practice. When discussing blue light protection, macular pigment, carotenoid supplementation, etc., he is always eager to learn, as he states: “We did not cover this in class.” Fair enough, there are only so many hours in an already-packed optometric curriculum.

Nonetheless, it is my personal belief that, as optometrists, we have the responsibility of protecting our patients from AMD by limiting modifiable risk factors, a big one being blue light exposure. It seems that when I attend optometric conferences, I often learn as much about new clinical ideas during social events as I do in class. So, unwittingly, my “cocktail napkin talk” was born. It is really a quite simple, yet effective, tool in teaching colleagues how macular pigment protects photoreceptors and RPE cells. Here is how you do it:

Macular pigment

On a cocktail napkin, draw a line; this represents Bruch’s membrane. A quarter of an inch above it, draw another parallel line with perpendicular lines running between the two lines; these are RPE cells. About an inch above the RPE cells, draw a line with an indentation representing normal macular contour, as you would see on an OCT line scan of the macula. From edge to edge of the indentation, draw a heavily shaded line; this is the macular pigment. Now, draw an arrow signifying incident light on the macula, and describe how the macular pigment attenuates blue wavelength light before it can affect the underlying photoreceptor and RPE cells. Explain that it is cumulative lifetime exposure to blue light that causes oxidative stress within RPE cells, leading to free radical damage to photoreceptors and AMD. Filtering blue light with a healthy layer of macular pigment imparts long-term protection to the RPE.

That’s it: a straightforward, effective and factually correct way of communicating the anatomical location and protective function of macular pigment. Just remember that this explanation is intended as a simple introduction. I did not go into individual carotenoid constituents of macular pigment or what is likely macular pigment’s main role, enhancing vision. I will save that for another napkin.

References:

Beatty S, et al. Surv Ophthalmol. 2000;45:115-134.

Tomany SC, et al. Arch Ophthalmol. 2004;122:750-757.