I noticed this logo on one of my boxes of table salt. I guess I should use salt the next time I want to shoo away a pigeon.

misc humor

We’ve learned in ophthalmic optics that a minus lens (concave) will minify images, while plus lenses do the opposite. I have been taught by several ophthalmologists to note the size of a patient’s eye through the glasses they’re wearing. If it looks big, then they’re hyperopic. Small = myopia. Easy, right?

Wrong.

In some cases, it is obvious that someone is myopic by the disproportionate size of the eye. To me, most of the cases are not obvious at all.

Years ago when I was still a medical student, Harry Knopf, one of the private attendings at WashU had told me to look at the temples, not the eyes. The refractive error can be estimated by looking at the temple border. Read more…

medicine medicine, ophthalmology

Damn, I don’t want to know what’s behind this door…it may cause bilateral cataracts, however.

misc humor

Dimmer switches are a great option to control the amount of lighting needed in a certain venue. This also serves to limit unnecessary energy costs. What people don’t realize is that combining dimmer switches with compact fluorescent bulbs (CFL) is usually counterproductive; you not only get impure light, but also a shortened lifespan of the bulb.

I wrote about CFL’s in a previous entry. Many of these bulbs have come a long way, and produce high quality lighting. However, the standard CFL’s don’t play well with dimmer switches. Our amphitheater in the eye institute uses CFL’s on the dimmer, and the lights do not dim. In fact, they flicker.

Dimmer switches contain a triac circuit that cuts off the current to save electricity. This works for incandescent bulbs to cut back on heat production. With CFL’s, the interrupted current from a dimmer prevents adequate charge of the gas to produce light. The result is a dim, flickering light.

Installation of dimmable CFL’s would remedy the problem partially, but still may not be effective without changing the switch as well. Most dimmer switches are rated down to 40W of power–any draw below this cannot be controlled adequately. Given that most CFL’s draw less than 40W of power, one would need to replace the entire circuit.

The solution? I can think of two ways:

1. Continue using incandescent bulbs for your dimmer switches
2. Replace your dimmer switch
   with one rated for use with CFL’s, and replace your bulbs with dimmable CFL’s

misc tech