Staining and peeling of the internal limiting membrane in the cat eye.
OBJECTIVE
To investigate the cat vitreomacular interface using trypan blue (TB) and indocyanine green (ICG) and to determine the validity of the cat model in terms of staining and peeling of the internal limiting membrane (ILM).


METHODS
Lensectomy and vitrectomy were performed in four eyes of two cats. The ILM of two eyes was stained with TB (0.15%). ILM peeling was performed in one eye. Two eyes were stained with ICG (0.5%). One eye was illuminated for 3 min. Light and transmission electron microscopy and confocal microscopy were performed.


RESULTS
Clinically, both dyes stained the cat ILM similar to human ILM. TB staining resulted in a normal ultrastructure and antigenity of the retina. ILM peeling was associated with intraretinal bleeding. There were fragments of Müller cells adherent to the retinal side of the ILM, and Müller cell endfeet were ruptured and avulsed. ICG staining of the ILM followed by illumination caused severe inner retinal damage. ICG without illumination resulted in focal ILM detachments associated with tearing of Müller cell endfeet.


CONCLUSIONS
The cat can be used as a model to study the effect of TB and ICG on the central area of the cat retina, as previous results from clinical and experimental postmortem settings in human eyes were confirmed in the current study. Peeling of the ILM as a sheet as performed in human macular surgery is not feasible. Differences in the ultrastructure of the ILM and a strong adhesion of the ILM to Müller cell endfeet may account for this observation.
Gandorfer
Arnd
A
Moorfields Eye Hospital, Vitreoretinal Research Unit, London, United Kingdom. arnd.gandorfer@med.uni-muenchen.de
Rohleder
Matthias
M
Charteris
David G
DG
Sethi
Charanjit
C
Kampik
Anselm
A
Luthert
Philip
P
D000818:Animals; D001485:Basement Membrane / Q000473:pathology* / Q000601:surgery* / Q000648:ultrastructure; D002415:Cats; D004396:Coloring Agents / Q000009:adverse effects; D005240:Feasibility Studies; D007208:Indocyanine Green / Q000009:adverse effects; D008027:Light; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D013508:Ophthalmologic Surgical Procedures / Q000009:adverse effects; D012160:Retina / Q000473:pathology; D012166:Retinal Hemorrhage / Q000209:etiology; D013194:Staining and Labeling; D014343:Trypan Blue
D004396:Coloring Agents; D014343:Trypan Blue; D007208:Indocyanine Green