Abstract
Abstract: :
Purpose: To characterise the optic nerve degeneration associated with the secondary angle closure glaucoma in DBA/2J mice using clinical, electrophysiological and histological examinations. Methods: Intraocular pressure (IOP) readings were recorded with a Tono-Pen XL (Mentor) from 10 to 41 weeks-old of age in female DBA/2J and in female C57Bl/6J mice every 3 weeks. C57 mice have been used as control group. Visually evoked potentials (VEP) signals were recorded in female DBA/2J every months. Latency and amplitude of VEP were studied. An histological analysis was done at every months of age. The total number of myelinized fibers was estimated. Results: The intraocular pressure of DBA/2J mice started to increase (23.8 0.9 mmHg) at 12 weeks of age to be significantly higher at 29 weeks (31.1 2 mmHg) and at 41 weeks (36.5 3.9 mmHg) whereas no significant differences were found in C57Bl/6J mice for the same age (means of 18.5 2.1 throughout the study). Latency of the DBA/2J mice VEP signal slightly increased whereas amplitude decreased significantly from 23 weeks of age. No recordable visual cortical activity were observed at 9 months. Correlation between VEP amplitude and numbers of nerve fibers were assessed. Conclusion: This study was realised in order to characterise visual impairments of a spontaneous glaucoma in DBA/2J mice by using classical ophthalmologic examinations. Increasing IOP recorded with a tono-pen and decreasing VEP signals correlated with the optic nerve fibers number are in accordance with previous results which used different methods (John et al. 1998, IOVS). Beyond the long duration of the studied period, DBA/2J mice are an attractive model for in vivo studies on nerve regeneration and for screening of therapeutic agents.
Keywords: 385 degenerations/dystrophies • 444 intraocular pressure • 489 neuroprotection