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BLOG: Is there a laterality preference in any ocular disease?
For the longest time, I’ve tried to find an eye disease that happens more in the right eye than in the left eye (or vice versa). Artery occlusion, episcleritis, cataract, anything. It hasn’t been easy, honestly, probably because there would be no reason for a lateral preference. But logic never deterred me before.
Of course, I admit there are situations in which someone’s dominant eye would have a predilection for injury, but these situations are mostly related to ocular trauma. If we take out any “manmade” ocular pathology, the question from the patient remains: “Is there a reason this disease happened in my right eye?”
It’s been 2 years since I wrote about asteroid hyalosis (AH), and it’s probably one of the articles that I get the most comments about. The article cleared up some details about AH for me, but there is still a lot we don’t know. What I didn’t write in that article was that I felt that I see AH more often in people’s right eye. This is a strange thing to admit, and I don’t know what led me to think about the laterality in AH, but once I started thinking about it, every time I saw it I checked to see if my hypothesis was strengthened or not.
So, last year I decided to keep track. The rules were told to everyone in the eye clinic: Whenever you see asteroid, put a tick mark in the “OD” or “OS” column. If you see it bilateral, then put a tick mark in both columns. That’s it, those were the rules. No keeping track of the density of asteroid, the presence of kidney disease or gout, or the eye dominance. We would keep track for an entire year. (We tried to make sure no patient got counted twice, and I think we did a good job.) See the accompanying picture for the official tally toward the end of the year.
From Aug. 1, 2017, to July 31, 2018, we found AH in 67 eyes: 41 right eyes and 26 left eyes. I had a statistician run a chi-square analysis with the expected finding to be 33.5 times in the right eye and 33.5 times in the left eye, and the chi-square value was 3.36, and the P value was 0.067. So, if we consider statistically significant values to have a P < 0.05, then our findings were not significant.
But they were kind of close! Can we call this a trend? Has anyone else out there noticed AH more in right eyes? In the end, I guess I didn’t think there would be a significant predilection for asteroid happening in people’s right eyes, because, why would there be? It should be random. More likely what I was noticing was a type of expectation bias. I formed a hypothesis years ago and focused on the experiences that validated my hypothesis and ignored the ones that ran counter to what I believed to be true. I guess this can happen to all of us, in a lot of facets of our life. But I tried to do an honest job of collecting data (for a year!) and let science guide my beliefs instead of my gut. And I’ll keep trying to do this in my career and my life.
