My Call Bag Blog

In both ophthalmology and neurology, the optokinetic drum (OKN drum) is a time-honored tool for evaluating optokinetic nystagmus, a reflexive eye movement triggered by motion across the visual field. Traditionally, this drum is a cylindrical device painted with alternating stripes, but it's bulky, inconvenient to transport, and not always accessible on call.

The OKN Drum in My Call Bag brings familiar functionality into a compact, intuitive format on your iPhone with precise speed control, customizable stripe sizes, pediatric-friendly custom imagery, effortless documentation via front-facing camera recording, and on-the-go convenience.

Accurate visual acuity testing at near distances is critical in eye care, yet the most widely used near testing tool, the Rosenbaum card, is known to be unreliable. This problem was highlighted in a landmark 1997 paper by Jonathan C. Horton, MD, PhD, and Matthew R. Jones, MD. They reviewed Rosenbaum cards from different manufacturers and found dramatic inconsistencies in the sizing of optotypes (the letters or symbols used for testing), often resulting in misleading acuity measurements.

The My Call Bag app solves every one of these problems using a precision-based approach to near and intermediate vision testing, with screen-aware calibration, standardized Sloan letters, and TrueDepth camera integration for real-time distance measurement.