As you might remember in this post we saw an interesting characteristic in the visual fields. I got in touch with Koen Vermeer from the Rotterdam Ophthalmic Institute and he was kind enough to inform me about a small problem with the dataset that is currently solved.

From the Rotterdam Ophthalmic Data Repository website:

February 18, 2015 - Problem found (and fixed) in longitudinal glaucomatous visual field data set

An observation by Angel de la Llama on his EyeData blog triggered us to revisit the longitudinal visual field data set. As it turned out, there was a mix-up in some of the IDs of the visual fields. This does not affect which visual fields are included - only their ID was affected. This problem concerned less than 4% of the visual fields. We advise you to download the latest version of the data set and rerun your analyses.

So I downloaded the latest version (they have a new website for the data by the way) and rerun the code as advised and here is the result:



That is more what I had expected. Now there is only one point per eye gaining sensitivity on average and actually very little (0.2 dB for OD and 0.8 dB for OS).

Mystery solved !

I have been looking around the Eurostat database again and this time I found another interesting dataset to plot, well today plot is a map. This time is the retail sale and other suppliers of optical glasses and other vision products in euros per inhabitant and by country. Like in the last dataset from eurostat I visited not all the countries have the latest data so be aware that the data for each country is from the most recent year with available data, you can find details about the dataset here.




 You can click on the image to enlarge it. The code to reproduce the map is here


In the article Laser in-situ keratomileusis for refractive error following radial keratotomy,  table 1 is about the preoperative and postoperative (1 year) refractive status. I am going to make two plots with the data from that table.

The first one is the prelasik spherical equivalent (SE) with the one year postlasik SE, the colour of the points is related to the postop uncorrected visual acuity (UCVA), as you can see there are only 4 values for that visual acuity but the table has just 18 observations. Here is the result:



As expected the higher UCVA are close to the zero SE postop although in the point with -2 postop SE and UCVA of 0.66 the visual acuity might be an error or taken with a pinhole. In the second plot I will look at the cumulative percentage of observations when we lower the best corrected visual acuity (BCVA), preop and postop:



Here we can see that before lasik all patients had 0.5 or better BCVA and over 25% had 1 or better while after lasik all had 0.66 or better BCVA and around 60% had 1 or better. You can find the code to reproduce the graphics here.