Objective    To investigate the alteration of flash visual evoked  potential (F-VEP) and evaluate the effects of the potential on detecting optic nerve function in intraocular hypertension SD rats.     Methods    Total 35 SD rats received a 532-nm wavelength diode laser burning at the trabecular meshwork and episclera veins of the right eyes to establish a model with chronic elevation of intraocular pressure(IOP). Their left eyes were regarded as control. After laser burning the IOP was measured by a tono-pen at 3 d

1 wee

k

1

2

3 and 6 months. The F-VEP was monitored in 10 rats at 2 and 6 months. Others were observed pathologically.     Results    The chronic hypertension were successfully obtained at the right eyes of 30 rats

with their mean IOP [(24.9±4.9) mmHg

]

significantly higher than that of control eyes [(17.4±4.8) mmHg

]

at 2 months. But there was no significant difference on the index at 6 months [(17.1±3.7) vs 18.5±2.8) mmHg

]

. The characteristic and repeatable NPN curve of F-VEP was reliably observed on the both eyes of rats at 2 and 6 months. As the positive and negative reflections was designated as P1 and N1

the amplitude of  N

1

-P

1

 was decreased in comparison with that of the control at 2 months [(13.03±3.11) vs (21.14±3.10) μV

]

and even lasted to 6 months (P0.05). There was no significant difference on the latency of P1 between the 2 group

but it was obviously delayed in 6 months[(74.47±8.05) vs (59.73±4.16 )ms

P0.05

]

. The decreased number of retina ganglin cells and the reduced density of optic nerve fiber in modal eyes were coincide with the variation of F-VEP.      Conclusion    The F-VEP can objectively reflect the optic nerve function in the intraocular hypertension rats model.