Retinoscopy is one of the more difficult exams to master in ophthalmology. It allows us to obtain one’s refractive error objectively. This is useful in children who are too young to be tested subjectively on an eye chart, or in those who are not verbal.

The optics behind retinoscopy is elegant. In a perfectly round cornea without refractive error, light entering the eye is focused directly onto the retina. The reflection of light appears as a homogeneous red reflex to the examiner. In a hyperopic eye, the cornea is underpowered–light becomes focused behind the retina. As the examiner streaks the light through the pupils, the retinal reflex moves in the same direction as the light beam from the retinoscope–this appearance is dubbed “with motion”. With-motion is created from uncrossed light rays traversing the surface of the retina.

Conversely, myopic eyes focus light in front of the retina. Light rays on the retina are crossed, and produce a red reflex that moves in the opposite direction of the the streak (against motion).

For many people, against motion is difficult to discern, especially if there is with motion in another axis. I have probably overlooked this finding in dozens of kids with small amounts of myopic astigmatism, hopefully without dire consequences.

Last week, however, I successfully identified myopia through retinoscopy in a 5 year-old. The refraction was -1.00 + 4.50 x 085 in the right eye.

A celebration for this momentous event is in hand…

medicine ophthalmology

For the entire last year, the only true surgeries that I’ve performed as primary surgeon were pterygia–those bat-winged conjunctival growths on the medial bulbar conjunctiva. I would typically rip the entire bat-wing off with some Westcott scissors and scrape down the cornea with a #57 blade. Most of the time, I used a battery-powered diamond burr to smooth out the cornea–that’s how the wimps do it. Afterward, I transpose a part of the superior bulbar conjunctiva over to cover the exposed wound. It typically took me 30 minutes (on a good day) to finish the case.

In these cases, I never entered the eye (intentionally).

Last week, I performed an anterior capsulotomy on a 10-month old girl. This involved loading up the Accurus vitrectomy surgical system to chew up the phimosis that developed after cataract surgery. This was a relatively simple procedure, involving an anterior chamber maintainer and another 23G port for instrumentation. However, it was my first attempt at intraocular surgery. The feeling is different. When you’re working inside the eye, there is a sense of uncertainty, even when you have direct visualization of your work. The eye is like a ball–you’re working on the inside without opening it up.  It was an even stranger feeling to run the vitrectomy system without ever having performed cataract surgery.

Running the vitrector (without having broken a posterior capsule) was a blast. The little pieces of capsule eddied toward the probe head at different rates, depending on how much I depressed the foot pedal. Before I knew it, I had chewed up the phimosis, and the case was completed.

I feel that I have been initiated.

medicine ophthalmology

Many DSL providers offer a free (after rebate) DSL modem/router combo in return for an annual contract. For most of us without spare tech gadgets lying around, this is a great option to get online quickly. For the internet provider, this is a means to fulfill an agreement with the hardware manufacturers.

Unfortunately for the consumer, the modems provided are crap.

For instance AT&T offers some customers a variant of a DSL router manufactured by 2Wire. While the modems themselves are easy to install and relatively maintenance-free, I’ve heard nothing but trouble from those that experience problems. One of my friends’ 2Wire modems fizzled out soon after the 1-year warranty agreement by AT&T. The modem booted up, but the power light would remain red. Hard resets and power cycling did nothing to the modem. The model was a 2700-HGB. AT&T suggested to her to buy a new modem (for >$79). I found several online accounts similar problems with these modems, and it turns out to be a faulty capacitor in the modem or a faulty power supply.

The power supply unit offered by 2Wire cannot be purchased separately. However, several electronic devices in the market use a similar 5.1V head. The quick fix for the 2Wire 2700H-GB power supply is a PSP power adapter (like this). For a mere $5, you can get your modem back and running again. If it doesn’t work, you’re only down $5.

computing tech