Two is not necessarily better than one: A double lens in a pre-metamorphic adult axolotl (Ambystoma mexicanum)

Vet Ophthalmol. 2022 Sep 24. doi: 10.1111/vop.13027. Online ahead of print.


An 8-year-old female pre-metamorphic axolotl (Ambystoma mexicanum) was examined for a suspected anterior lens luxation. Slit-lamp biomicroscopy revealed two lens-like structures in the anterior chamber of the right eye (OD), each with cataractous change. Ultrasound biomicroscopy and optical coherence tomography (OCT) were performed without sedation, and revealed small lenticular structures each with distinct nuclei and cortices. Although a distinct connection of the two lenticular structures could not be definitively ruled out, the structures appeared separate. Each of the lenticular structures was closely associated with its respective iris leaflet. This report demonstrates application of advanced imaging for diagnostic use in axolotl ophthalmology, showing that imaging of the lens can be performed without sedation, topical anesthetic, nor contact gel with high diagnostic quality. Although two distinct lenses were diagnosed with no historical evidence of trauma, the small sizes of each lenticular structure, with no detectable connection between them, are suggestive of a possible regenerative abnormality. This report opens discussion for the regenerative capabilities of the pre-metamorphic adult axolotl and possible implementations of their use in regenerative medicine research for the development of future therapies.

Keywords: Mexican axolotl; amphibian; ophthalmology; optical coherence tomography; salamander; ultrasound biomicroscopy.