# Image of ‘‘sudden block by the iris’’ before completion of traumatic aniridia: indirect partial support for Navon’s hypothesis

## TL;DR

A rare case of traumatic aniridia shows indirect support for Navon's hypothesis about the iris suddenly blocking during injury.

## Contribution

This case provides indirect evidence for Navon's hypothesis on traumatic aniridia development.

## Key findings

- A patient's iris was seemingly expelled under the conjunctiva after trauma.
- The observed event aligns with Navon's 'sudden block by the iris' hypothesis.
- The case offers partial support for the hypothesis as a precursor to traumatic aniridia.

## Abstract

Traumatic aniridia mainly occurs following blunt trauma to the eyeball. Navon hypothesized that ‘‘sudden block by the iris’’ was a necessary step in the development of traumatic aniridia, but this has not been confirmed.

The patient was a man in his 70s who sustained a right eye injury in a fall onto an umbrella stand. Slit lamp examination of the right eye revealed brownish spherical tissue in the anterior chamber, which was one-third filled with hyphema, and brownish pigmentation was observed beneath the conjunctiva. The next morning, following a dramatic decrease in the hyphema, it was surprising to find that none of the previously observed spherical tissue was present and the iris was absent around the whole circumference. The entire iris had seemingly been expulsed under the conjunctiva via an old surgical wound.

The photograph in this case might show the ‘‘sudden block by the iris’’ hypothesized by Navon almost 30 years ago. The photograph may be one piece of indirect and partial evidence that supports ‘‘sudden block by the iris occurs as a precursor to traumatic aniridia’’.