Iris Pair Symmetry Iris Pair Symmetry with Rotoscope Viewerwith Rotoscope Viewer

By Jon MilesAll images obtained with

Miles Research Iris Camera

www.milesresearch.com

What is Iris Rotoscoping?What is Iris Rotoscoping?

Iris Rotoscoping is a method of viewing an iris pair (right and left images) by flashing the images repeatedly, alternating at about 4 cycles per second.

The purpose is to appreciate and gauge the relative amounts of symmetry between the two irises.

The method is to register the two images with the pupil centroid at the image center.

Source images are typically iris images cropped to 1200x1100 (about 100 pixels/mm)

How does Iris Rotoscoping How does Iris Rotoscoping work?work?

These PowerPoint files are set up to automatically show a picture and it’s pair alternating at 250 ms intervals for 50 cycles (25 seconds). Then type the RightArrow or click to go to the next pair.

This series includes a pair of each subject (last 4 images) with the LE image flipped around a vertical axis for comparing reflection symmetry.

Symmetry is seen as points of similarity between the two rotoscoped images, where fiber topology is similar.

What does it show?What does it show?

Translation symmetry (between left & right iris) dominates at the deeper stromal layers; the irises appear to have been made from the same “blueprint”, with added variations.

Reflection symmetry, due to bilateralism and the eccentric pupil (pupil center is typically offset a fraction of a mm in the upper medial direction), is also evident.

Two aspects of similarity are considered here: textural and chromatic. Textural properties are expressed in terms of fiber separation and aggregation. Chromatic properties are expressed in terms of pigment deposits (brightness, color).

What does it mean?What does it mean? According to the Perinatal Dynamic Loading Hypothesis,

the texture of the iris is likely to undergo catastrophic topological changes during and soon after birth, as iris fibers are flexed during miosis to new extremes.

A person’s two iris patterns are more similar to each other than to anyone else’s. The difference between the two iris patterns reflect (in part) the different local influences on the morphogenesis during gestation.

The reflection similarities between the two iris textures are due to the approximately symmetric loading perinatally, due to bilateral symmetry of the ocular tissues.

What is symmetry?What is symmetry? There are three basic types of plane symmetry:

Translation (p: p) Rotation (p:d) Reflection (p:q)

The macroscopic appearance of the iris shows a reflection symmetry due to bilateralism.

A closer look at the iris texture reveals a translational symmetry at the finer levels of textural detail.

This may be due to the fact that extraocular muscle innervation occurs with the right-medial & left lateral synchronized, and vice versa.

Picture ComparisonsPicture Comparisons

Now – on to the slide show!You can use the left & right arrow keys to

navigate through the image pairs.You can also click the Rotoscope button for

a 25-second display of the images at 4 frames per second.

Rotoscope

RE

for next image

LE

Rotoscope

RE

for next image

Rotoscope

for next image

Rotoscope