Objective: To study the effectiveness of a traditional Chinese medicine (TCM) used for soothing the liver and unblocking the orifices to determine if it can protect the optic nerve from high intraocular pressure in glaucoma by observing retinal ganglion cell (RGCs) counts and the ultrastructure and morphological changes of the retina and optic nerve in rats; to develop an effective TCM prescription to protect the optic nerve from glaucoma. Methods: In this experimental study, the 4th formula TCM prescriptions for unblocking the orifices to improve vision is based on the therapeutic principles of soothing the liver and unblocking the orifices. In this research study, 90 SD rats were used as experimental animals. Chronic high intraocular pressure (IOP) was established in rat models by injecting carbomer solution into the anterior chamber of the right eyes. The models were first divided into 3 groups based on different IOP time frame windows (1 week, 2 weeks, 3 weeks). Then each IOP group was divided into a model group (non-treated, 5 rats), negative control group (5 rats), positive control group (treated with a neurotrophic solution, 5 rats), low-dose treatment group (treated with 10 gkg-1 d-1 4th formula for blocking orifices, 5 rats), middle-dose
treatment group (20 gkg-1 d-1, 5 rats) and high-dose treatment group (40 gkg-1 d-1, 5 rats). The rats in the treatment groups were given TCM prescriptions by intragastric administration. RGC counts were observed by a CMIAS series digital medical image analysis system. The ultrastructure of the retina and optic nerve was observed by electron microscopy. The data were analyzed by one-way ANOVA and LSD methods. Results: 1. RGC counts gradually reduced along with the duration of high intraocular pressure (F=87.67, 29.69, 33.38, 38.03, 33.67, 23.36, all P<0.001). Comparing the high- and middle-dose treatment groups with the positive and negative control groups (IOP at 1 week, 2 weeks, 3 weeks), the survival of RGCs significantly increased with the oral administration of the 4th formula for unblocking the orifices to improve vision and the differences were statistically significant (P<0.001). 2. In the model and negative control groups, the retinal structures were disordered, the retinal membrane was thinning, the mitochondria showed cavitation degeneration and cellular atrophy and necrosis were observed. In contrast, in every treatment group, disorder of the retinal structures was alleviated, the thickness of the retinal membrane slightly increased, and cavitation degeneration and cell atrophy were relieved. 3. In model and negative control groups, the arrangement of optic nerve axons was disordered, the density of axons was reduced, microfilament was dissolved, the mitochondria showed cavitation degeneration, organelles were swelled and damaged and the myelin sheath had degenerated. In contrast, in every treatment group, the edema of the myelin sheath of the optic nerve and mitochondria were relieved and medullary cord degeneration was repaired. Conclusions: The 4th formula for unblocking orifices to improve vision can improve the survival microenvironment of RGCs in rat models with high intraocular pressure, protect undamaged cells, repair mildly damaged RGCs, delay or prevent the descending changes of some damaged cells and reduce the apoptosis of RGCs. Therefore, the 4th formula for unblocking orifices to improve vision has protective effects on optic nerve damage from glaucoma.