Videokeratograph (VKS) for monitoring corneal curvature during surgery

Arquivos Brasileiros de Oftalmologia

Luis Alberto Vieira De Carvalho¹  Antonio Carlos Romão²  Silvio Tonissi²  Fátima Yasuoka²  Jarbas C. Castro²  Paulo Schor²  Wallace Chamon² 

[1] ,EyeTec Equipamentos Oftálmicos Ltda

关键词: Corneal topography;    Keratometry;    Placido disc;    Topografia da córnea;    Ceratometria;    Discos de Plácido;   

DOI  :  10.1590/S0004-27492002000100007

来源: SciELO

【 摘 要 】

Purpose: We have developed an instrument for computerized surgical videokeratography. A corneal central region of approximately 7.00 mm in diameter may be analyzed, providing the surgeon with information of the power and the astigmatism. Methods: The system is based on a fiber optic Placido disc projecting cone, which is attached to the objective lens of a Zeiss compatible surgical microscope. At the beam splitter we installed a monochromatic high resolution camera. A frame grabber is installed on a PC and images are digitized at a 480x640 resolution. Image processing is used for edge detection of rings. Results: Calibrating curves based on 4 spherical surfaces were generated and approximately 3600 points are calculated for each examination. Preliminary measurements on 10 healthy corneas were compared with those of an EyeSys System 2000 Corneal Topographer. Mean deviation was 0.05 for radius of curvature, 0.24 D for the power and 5.0 degrees for the cylinder. Conclusions: This surgical VKS, with some hardware and software improvements, may be used to reduce residual astigmatisms in conventional cataract and keratoplasty. It could also be used to gather preoperative data in corneal topography assisted LASIK.

【 授权许可】

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