There exists a large variety of extraocular eye movement disorders. For example, there are some 40 variants of nystagmus. Some nystagmus patterns are quite difficult to learn from verbal descriptions. For those who rarely encounter patients with nystagmus, a successive approach elimination [ A] may be the best road to diagnosis. However, with experience, diagnosis can often be obtained at a glance, by pattern recognition.
Experience may best by gained by watching videos of real patients. There are several sources on the web, among which the Neuro-ophthalmology Virtual Education Library, NOVEL [1], and the Canadian Neuro-ophthalmology Group [2] may be the most comprehensive. The present library is terser and focuses on the actual patterns of movement and their names. The videos might be best viewed side-by-side with a neuro-ophthalmogy textbook. Incidentally, the title of this section, EOM+, refers to its inclusion not only of nystagmus and common extraocular eye movement disorders but also of disorders of pupil dynamics.
The video clips are quite short (mostly less than half a minute) and also heavily cropped to obtain quick downloads and immediate repeats. Whenever possible, the presentations approximate natural size. To avoid excessively long listings, the clips have been loosely organized by the following categories:
Each category is presented in its own browser window, with its own name list located below the video frame. Select a clip by clicking on its name. Several windows can be kept open at the same time, allowing cross-category comparisons.
The category named Random selection does not not provide descriptive names, only code numbers. This category is meant for testing naming skills. Try to name each selection properly, perhaps with the aid of the elimination approach [ A], before looking up the name associated with the code number.
Most records were produced on Super-8 film, before the era of digital video. Because filming required a bright illumination, most tests of pupillary light responses had to resort to alternate covering rather than the swinging flashlight test [ B]. Alternate covering normally results in a transient dilatation of the non-covered pupil and the rates and degrees of dilatation are normally symmetrical between the eyes. Covering the pupil of an eye with a relative afferent pupillary defect generates a smaller change in the contra-lateral pupil.
All videos are in the .mp4 format and require a HTML5-capable browser. The code numbers shown in the clips and lists serve internal housekeeping.
Tech notes The Super-8 film originals were scanned at 720 x 576 pixel resolution, in the avi file format, by a commercial service. The scans were edited in Serif MoviePlus 5, using pans, zooms and rotations as required to make the eyes fill the viewing frame. A grayscale transform neutralized variations in skin renditions. The edited scans were transferred to the flv file format using the Riva Encoder at 480 x 140 pixels. Due to decreasing support for the flv format, conversion to mp4 was made in 2016, using the Miro Video Converter.