Scanning laser ophthalmoscopy and optical coherence tomography imaging of spectacular ecdysis in the corn snake (Pantherophis guttatus) and the California king snake (Lampropeltis getulus californiae).
OBJECTIVE
One of the singularities of the eyes of snakes is the presence of the spectacle, a transparent and vascularized integument covering the cornea. The spectacle is completely renewed during ecdysis. Combined scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and conventional macrophotography were used to image this phenomenon.


METHODS
A spectral OCT/SLO examination and macrophotography were performed in four healthy adult corn snakes (Pantherophis guttatus) and one healthy adult California king snake (Lampropeltis getulus californiae) the day before the start of ecdysis and then daily during ecdysis.


RESULTS
In all animals, ecdysis lasted 5 days. The spectacle was hardly visible at baseline, but became obvious at day one, while the subspectacular space became larger and the superficial cornea presented a hyperechoic band. At day two, eye surface became translucent, and at the same time, vascularization of the spectacle was visible using SLO. At day 3, the vascularization was no longer visible, while the subspectacular space increased and the eye surface remained translucent. At day 4, the eye surface was transparent and the superficial hyperechoic band started to become less bright. At day 5, the old spectacle was shed and all the parameters returned to baseline.


CONCLUSIONS
We hypothesize that the echogenicity modifications of the anterior cornea correspond to major metabolic activity associated with new spectacle formation. This increased metabolic activity may contribute to the neovascularization and play an important role in the accumulation of fluid in the subspectacular space, facilitating the shedding of the old spectacle.
Clinique La Borde Rouge, 150 rue Edmond Rostand, 31200, Toulouse, France.
Guillaume
G
Cazalot
Franck
F
Rival
Adeline
A
Linsart
Pierre-François
PF
Isard
Marion
M
Tissier
Robert Louis
RL
Peiffer
Thomas
T
Dulaurent
D000818:Animals; D000869:Anterior Eye Segment / Q000033:anatomy & histology*; D018978:Molting / Q000502:physiology*; D019721:Ophthalmoscopes / Q000662:veterinary*; D009887:Ophthalmoscopy / Q000662:veterinary*; D012911:Snakes / Q000033:anatomy & histology*; D013045:Species Specificity; D041623:Tomography, Optical Coherence / Q000662:veterinary*
OCT; SLO; cornea; ecdysis; snake; spectacle