Applied Anatomy Research Related To Vision Prosthesis Microelectrode Implanted Into Optic Nerve

【Objective】To investigate the relatively safe area of implanting vision prosthesis microelectrode to optic nerve,and to provide anatomic data for operations of optic nerve.【Methods】The courses and external diameters of the arteries and nerves were observed and measured on thirty adult cadaver heads, which were formalized and vascular cast by red emulsion. Four cases of freezed adult cadaver heads(intra-arterial infusion mixed liquids of prepared Chinese ink), the optic nerve that 4～8mm posterior to eyeball was cut in serial sections 20μm in thick. The vessel section count(VSC) and vessel section surface area(VSS) in the 4 quadrants of transverse sections of optical nerve were counted and measured by microscope and Image Advanced 3.0,then data were analyzed using SPSS 13.0.【Results】Opened the lateral orbital wall and paries superior orbitae of adult cadaver heads.From the lateral orbital wall lacrimal artery and nerve went forword to lacrimal gland at (3.83±1.43)mm above the superior margin of external rectus muscle. The interspace between the external rectus muscle and the optic nerve was called external rectus muscle-optic nerve inter- space.There were short ciliary nerves and posterior ciliary artery through it , and its depth was (8.14±0.90)mm. Most of the central retinal artery (CRA) entered optic nerve from the bottom of the nerve, where was behind the eyeball(0.85±0.28)cm, the distance≤4mm was 19.2%,≥8mm was76.9%,entered behind the eyeball 6.5mm was 3.9%. The position of the sheathed arterioles penetrating sheath of optic nerve was :medial 20%,superior 29.3%,lateral 6.7%,inferior 44%. The transverse and vertical diameter of optic nerve were (3.96±0.35)mm and (4.18±0.33)mm at the midpoint between the annulus tendineus communis and posterior pole of eyeball.It was observed from adult cadaver heads(infused with mixed liquids of prepared Chinese ink) that there were plenty of microarteries on the optic nerve sheath,which anastomosed each other and run longitudinaly and anterior-posteriorly. By microscope, it was observed that there was vascular network on the sheath, which erupting small branches to the center of the nerve by vertical mode and the segmental microarterial lay centrally to their corresponding arterioles..The number of cross section of microvasculature was (178.936±8.666),the average of cross section of was (0.001280±0.000035) mm2,and there were no significant differences between the varies quadrants.【Conclution】1. To protect the lacrimal artery and nerve above on the superior margin of external rectus muscle when the optic nerve was exposed in the operation. Pay attention to the structures among the interspace between external rectus muscle and optic nerve.2. It would be safer to implant microelectrode or operate on the optic nerve where was 4～8mm behind the eyeball.3. To minimize the damage to the blood supply of optical nerve, the vision prosthesis microelectrode should be implanted through the lateral of optical nerve.4. The outer diameter of optic nerve was about 4mm,and the CRA run lengthways and anterior-posteriorly in the center of optic nerve. To avoid retinal ischemia,the vision prosthesis microelectrode should be implanted lengthways,and too deeply incision was not suitable.5. There were no differences among the blood supply of each quadrant of optic nerve when it was damaged by traumatism or implanting microelectrode.