Development of Intractable Glaucoma Implant Device Using Excimer Laser

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The increased intraocular pressure with aqueous outflow failure causes glaucoma. In healthy human intraocular pressure is maintained at a normal physiological level, between 8 to 18mmHg. When pressure exceeds 21 mmHg, a diagnostic of glaucoma may be predicted.A new implant designed to pump the aqueous humor and regulate its outflow was created. We investigated several porous PTFE paying special attention to air permeation characteristics. We later reported that porous PTFE films with a 10 μm inner pore diameter could be penetrated by BSS (Balanced Salt Solution) at pressure of 20 mmHg Unfortunately, a PTFE material tends to become fragile with increased pore diameter. In order to circumvent this problem, a material with smaller pore diameters that are easily penetrated by water at low pressure must be developed. We reported elsewhere upon a method of photochemical substitution of hydrophilic or lipophilic groups on fluorocarbon surfaces. The pore inner surface of porous PTFE was made hydrophilic using these techniques that were then applied to liquid separation filters. With this knowledge we were able to develop a device that regulate/control the flow rate of the aqueous humor at a low-pressure differential. BSS cannot penetrate PTFE 3 μm pores even at 300mmHg pressure, but using 193nm photon radiation (1000 shots at 15 mJ/cm^2) transformed the material allowing flow at pressure of 20 mmHg. It was also shown that BSS transmission flow rate was proportional to OH radical substitution density. Experimental results confirmed the processing method as aqueous flow began at 20 mmHg and animal studies showed treated samples to be biocompatible, therefore indicating the potential for this material to be used in intraocular pressure control implants.