by Ryan Rodriguez, MD

Save On Bulbs !!!

As the cost of maintaining an eye clinic or center goes up every year, we try our best to minimize on expenses. One of the consumables that we can definitely save on is our slitlamp bulb which can cost from 2,000 to 4,000 pesos each.

The slitlamp is possibly the most used and abused instrument in our clinic.
Whether you’ve been practicing for decades or just starting out, it still
remains as an integral and indispensable part in our patient examination
and treatment.


One way to extend the life of the bulb is to make sure you turn off your instruments after using it. However, we oftentimes forget to switch it off thereby shortening the bulbs’s lifespan as well as contributing to an increase in our electricity bills. This is especially true for slitlamps that still use halogen lamps compared to those using LED. Just today alone, I called the attention of several residents and interns a couple of times because they kept on forgetting to switch off their slitlamps after examining a patient.

An automatic shut-off mechanism installed in slitlamps could address this problem and there are several ways to do this:
1. Persistent audio feedback like when we forget to turn
    off the headlights in our cars after removing the key from the ignition.
2. Mechanical switch placed under the chin rest or forehead rest that turns the
    light on and off.
3. Proximity sensor that detects objects using infrared light.

I decided to go with the latter one since it offers more advantage and flexibility. You’ve probably noticed the automatic hand dryers and faucets in hotels and malls which turns on when it detects your hand near it and turns off when you remove your hand. Both of these are equipped with proximity sensors and help save electricity and water.

It would be a good idea then if your instruments can be installed with the same proximity sensors so they can automatically turn off when not in use. With a bit of rewiring, some technical know how on soldering electronic   components and a little imagination, the same kind of sensor can be attached to your slitlamp. The kit was assembled inside a housing small enough to be placed adjacent to the main switch making it convenient. It runs on 6 to 12 volts power adapter and has an override switch in case the device malfunctions or you need to position the patient in a different way. The transmitter-receiver module (1) can be placed on either side of the forehead rest, has a sensing distance of about 12cm and connected to the main component (2). It is constantly transmitting infrared light and when an object goes near it, the infrared light is reflected back to the receiver thereby triggering the switch that turns the light on. Depending on the setting, the light will turn off automatically when the object is removed anywhere between 0 to 40 seconds.

So with enough patience in acquiring, assembling and installing the necessary parts, unnecessary expenses
can be limited.

Watch the short video below to see the how the proximity sensor works.




About The Author

Ryan is a dedicated ophthalmologist by profession but is a self proclaimed techie at heart. His passion lies on tinkering with your latest Apple gadget, flying a drone, and taking apart your slitlamp, indirect ophthalmoscope, other electronics and putting them back again, though most times there are extra screws and parts left behind. He is fascinated with God's wonderful creation of the planets and stars, and wants to become an astronaut someday.