[New biconcave prism contact lens for vitreous surgery in gas-filled eyes].
PURPOSE: To obtain a surgical contact lens with adequate operative field in vitreous surgery of gas-filled eyes. METHODS: We designed a new biconcave prism contact lens for gas-filled eyes by improving the material and the design of the lens (prism angle, radius and area of front concave of the lens). The operative field was calculated by a simulation using the ray tracing method for cases of simultaneous phaco-vitrectomy surgery, vitrectomy of pseudophakic eyes, and vitrectomy without phaco-surgery. For this study, a prototype of the newly designed lens was made and used for vitrectomy of gas-filled eyes. RESULTS: The calculated operative field was about 47 degrees (central angle) for vitrectomy of pseudophakic eyes and vitrectomy without phaco-surgery. In cases of simultaneous phaco-vitrectomy surgery, the operative field can be varied continuously from 47 to 145 degrees (central angle) by adjusting the viscoelastic material in the anterior chamber. Appropriate visual field, good binocular vision, and visibility of the peripheral region were obtained in the vitrectomy of gas-filled eyes. CONCLUSION: The newlydesigned contact lens is useful for viewing the fundus during the vitrectomy of gas-filled eyes.