I have always believed that only a single refraction and its spherical equivalents can produce the best-corrected visual acuity (BCVA) for any given person. Assuming that human intelligence allows for accurate estimation of Snellen acuity even without crisp vision, there should only be a narrow range of refractions that can be tolerated. After reviewing some refraction notes from a clinician’s office, I’m shocked:

2006: OD: -1.00 -1.50 x 080 OS: -7.00 -0.50 x 040

2007: OD: -1.25 -1.00 x 099 OS: -8.50 +1.00 x 160

2008: OD: -1.00 – 0.75 x 095 OS: -7.50 – 1.00 x 060

Even at first glance, there are multiple inconsistencies in these notes. The refractions came from a large academic practice, and the 2006 and 2007 refractions even came from the same optometrist. The patient had never undergone any eye surgeries, but was an elderly person.

Why the hell was the OS examination from 2007 written in plus cylinder notation? The conversion doesn’t even match up with either of the other two exams. If you look only at the right eye, the axis changed every year, as did the cylindrical power. As far as I understand, there are published tables on the tolerated range of axes for a given astigmatic correction. A correction of 1D with an axis fluctuation of up to 19-degrees (80 to 99) does not seem tolerable.

Unfortunately, I don’t have the acuity for each refraction to verify the results.

medicine ophthalmology

Unless you’ve been in isolation, you have probably heard of Angry Birds, a simple yet addictive game available on most smartphone platforms. It is akin to Scorched Earth, the classic PC game in which you sling grenades at the opposition–the difference in this game is that birds serve as ammunition.

This game is ubiquitous. I see passengers in the subway and bus playing this game. My patient with cellulitis in the emergency room was playing Angry Birds while waiting to be triaged. I saw a medical student playing the game while waiting for rounds to begin.

For 99 cents, this game will occupy you for months. Get it now.

computing computing

I wandered into the local Banana Republic the day after Christmas. They had a 50% off every item in the store if the item was purchased before noon. Luckily for everyone, they passed out tags to all customers who entered the store before noon, since the checkout line was packed. One shopper waited 50 minutes to pay for her items. Click the image for a montage.

misc life

Some of my holiday obligations to family always include fixing computers, rewiring home outlets, repairing broken fixtures, and plumbing.

Yes, plumbing. Sort of like cath-lab work and stenting vessels, right? Nothing like cataract surgery.

One of the plumbing jobs I encountered this year involved this:

Read more…

misc work

Several months ago I released an online intraocular lens calculator featuring three of the commonly used power calculation formulas, as described in the peer-reviewed literature. I received 82 hits on the page the first day it opened, and amassed about 400 total hits in one week. That is considerable for an unadvertised website.

Due to legal pressures, I was forced to remove it online. This is unfortunate, because there are no other freely available, web-based calculators. Granted, most modern A-scan devices have these formulas built into them, but there is something to be said for crunching a few calculations without hunting down the scanner in the building. Too bad.

computing, medicine