Dept of Elect Engineering USP (Ophthalmic Instrumentation Division), Av Trabalhador sao-carlense 400, S Carlos, SP 13566-590, Brasil.
Biomed Eng Online. 2009 Dec 8;8:37. doi: 10.1186/1475-925X-8-37.
High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed. The final intention of this prototype is to be an evaluation tool for guided suture and as an outcome diminish the postoperative astigmatism.
The system consists of hand held ring with 36 infrared LEDs, that is to be projected onto the lachrymal film of the cornea. The image is reflected back through the optics of the ocular microscope and its distortion from the original circular shape is evaluated by developed software. It provides keratometric and circularity measurements during surgery in order to guide the surgeon for uniformity in suturing.
The system is able to provide up to 23D of astigmatism (32D - 55D range) and is +/- 0.25D accurate. It has been tested in 14 volunteer patients intraoperative and has been compared to a commercial keratometer Nidek Oculus Hand-held corneal topographer. The correlation factors are 0.92 for the astigmatism and 0.97 for the associated axis.
The system is potentially efficient for guiding the surgeon on uniformity of suturing, presenting preliminary data indicating an important decrease on the residual astigmatism, from an average of 8D - for patients not submitted to the prototype guidance - to 1.4D - for patients who have actually been submitted to the prototype guidance - after the first 24 hours post-surgery and in the subsequent weeks. It also indicates that the surgeon should achieve circularity greater or equal to 98% in order to avoid postoperative astigmatisms over 1D.
CAAE - 0212.0.004.000-09.
高散光通常是在组织移植或任何其他涉及角膜缝合的手术后，由于角膜缝合，导致的。其中一个原因是，该过程非常依赖于外科医生缝合相同缝线的技能。为了评估不平整对残余散光缝合的影响，开发了一种眼科手术支撑原型。该原型的最终目的是成为引导缝合的评估工具，并减少术后散光。
该系统由带有 36 个红外 LED 的手持环组成，该环将被投射到角膜的泪膜上。图像通过眼部显微镜的光学系统反射回来，其从原始圆形的变形由开发的软件进行评估。它在手术过程中提供角膜曲率计和圆形度测量，以指导外科医生进行均匀缝合。
该系统能够提供高达 23D 的散光（32D-55D 范围），精度为+/-0.25D。它已经在 14 名志愿者患者的术中进行了测试，并与商业角膜曲率计 Nidek Oculus 手持式角膜地形图仪进行了比较。相关因素为散光的 0.92 和相关轴的 0.97。
该系统对于指导外科医生进行均匀缝合具有潜在的效率，初步数据表明，在手术后的头 24 小时和随后的几周内，残余散光显著降低，从未接受原型引导的患者的平均 8D 降至实际接受原型引导的患者的 1.4D。它还表明，外科医生应该实现大于或等于 98%的圆形度，以避免术后散光超过 1D。
CAAE - 0212.0.004.000-09。
