What is Blue Cone Mono-Chromatism
The video above portrays a decent picture of how I experience Blue Cone Monochromatism (BCM). The condition, also called Blue Cone Monochromacy, is incredibly rare. The only people I’ve met with the condition reside in my family and, even then, there’s only a small number of us.
Per Orphanet, the prevalence of people in the United States born with the condition is around 1 in 100,000 (2013). That means there’s less than 5,000 people stateside that have been diagnosed and are living with BCM; however, I’m sure people may be diagnosed at other times in life given the rarity of the condition. The odds aren’t high that I’ll ever encounter someone outside of my family that lives with it. Additionally, being born with BCM allows me to identify as someone who’s visually impaired, low vision, blind, or whichever term I’m comfortable with. This is because my visual acuity is 20/200 in my right eye and 20/350 in my left. If you don’t know what that means, that’s okay. The important takeaway is that I don’t see well.
So, he doesn’t see well. What does that mean?
That’s a great question. The difficulty in explaining this lay in the fact that I don’t know how sighted people see and vice versa them for me. I mention this because any explanation I give may be difficult to process without the context of experiencing vision loss. But, through my description and your imagination, we may end up painting a fuller picture. This website also provides a nice overview of symptoms from a more generalized perspective (GARD, 2025). Let’s run through some aspects of BCM below.
Light Sensitivity: I’ll start with light sensitivity (photophobia). It is what it sounds like for the most part and the beginning video depicts a severe example of it. For others this may be accurate, but my experience doesn’t tend to align 1:1 with it. I mostly just end up squinting a lot without my sunglasses. My eyes get fatigued pretty quickly when I don’t use my polarized lenses but there are plenty of occasions where I roll without them for a variety of reasons. My main nemesis with this area of my vision comes from glare. It can stem from reflections off of the snow, water, windows, etc. Light sensitivity is easily one of the biggest concerns I contend with most often as it impacts how I travel, what I bring with me, where I sit, and so much more. From my experience, people tend to reach for their sunglasses when I do. The distinction I make is that, if I don’t use my eye protection, I’ll be impacted more than the average sighted person.
Color Blindness: I think most people know someone who experiences color blindness; however, BCM’s color blindness manifests pretty severely. I don’t see in black, white, and gray. In fact, I see my own version of the full spectrum of colors. It’s likely the yellow, blue, red, or whichever color that I see isn’t identical the one you see. I know the difference between my gray and my green, my red and my black, etc., and this indicates to me that my brain is trying to fill in some blanks to help me out. Unfortunately, my brain, despite its best efforts, contributed to my failing of a color matching test in middle school by over 90%. This doesn’t mean I couldn’t tell that there weren’t colors present. I just couldn’t tell which one was which. Also, I don’t see colors exclusively in shades of blue; I can tell the grass is green, firetrucks are red, and the sky is blue. Context helps with this, but I also see these colors as distinctly different rather than siblings of the same color.
Visual Acuity: I mentioned earlier that my visual acuity is 20/200 in my right eye and 20/350 in my left eye. This means that what someone with 20/20 vision sees at 200 feet I can see at 20 feet with the same ratio applying to my other eye. Put simply, I can see far away but can only discern details when things are close. Most of what I read I bring up close to my right eye and I’m able to read just fine. I’m able to read some billboards, signs, etc., too, from a distance if the contrast is distinct, the font is big, and if I’m focused enough. I wear glasses occasionally and they do help a little with distance viewing.
Miscellaneous: I’ll use this section as a catch-all for the rest. Because of the different acuities in each of my eyes, my depth perception is generally off-kilter. Throughout my life I’ve gotten better at recognizing this but I find it still causes me issues sometimes, notably with activities involved with catching or hitting things. I’ve been hit in the face and have broken my fair share gym equipemnt, etc. as a result. Nystagmus is mentioned in the video but it’s not something that impacts me much anymore. As a child the shaking of my eyes would increase if I became tired or was focusing intensely on something. Nowadays, my nystagmus is barely noticeable and will only present itself if I’m sleep deprived or extremely focused on one thing for a prolonged period of time. Astigmatism is also present but it’s always played such a minor role that I actually don’t know much about it besides it making the light from street lamps look funny.
Piecing it all together…
My hope is that someone reads this and gathers a better understanding of how I see. Conversationally, it can be difficult to sum up all of the different aspects of BCM concisely, so creating a page that people can refer to can be productive. I think this is especially relevant when resources, despite their best efforts, paint an incomplete or inaccurate picture of how I specifically view the world. This also points to the fact that variety exists in all aspects of life, so it makes sense that others with BCM may see differently than me, too.
While it can be tiresome to explain the intricacies of living with an extremely rare eye condition, I can also understand people’s curiosities around it. It’s tough to understand and equally difficult to explain; however, it ultimately boils down to this: I see pretty well for a visually impaired person and I’m beyond thankful for the quality of life I’ve been afforded despite my condition.
References
Genetic and Rare Diseases Information Center. (2025, May). Blue cone monochromatism. https://rarediseases.info.nih.gov/diseases/917/blue-cone-monochromatism
Orphanet. (2013, August). Blue cone monochromatism. https://www.orpha.net/en/disease/detail/16#menu