兔角膜损伤面积测量的图像处理方法

目的：研究兔角膜前板层切除模型中，定量分析损伤面积的图像处理方法。方法：新西兰兔6只，切除双眼角膜前板层，直径8mm，约1／3角膜厚度。每日滴1％荧光素染色，裂隙灯钴蓝光下拍摄照片，放大16倍，连续7天。将照片用联想Mustek扫描仪以100dpi扫入计算机，Photoshop软件描绘损伤边缘并剪切，保存为jpg文件。在CPAS软件中打开该文件，阈值化后进行人工调整，达到全部阈值化的目的。利用CPAS的计算功能算出该面积的像素数，并转化为实际面积mm^2。对6张损伤1小时角膜照片做面积分析，与实际面积比较。对1～7天的角膜损伤照片任选12张，做3名不同操作人员之间的损伤面积比较。结果：对6张角膜损伤1小时的面积做图像分析，平均值为51．14mm^2，实际损伤面积为50．24mm^2，相差仅为0．2％，两组之间无显著性差异(P=0．12)。对12张角膜损伤照片3名操作人员测量的损伤面积平均值分别为18．26mm^2、19．81mm^2和18．85mm^2，三组之间均无显著性差异(F=0．044，P=0．957)。结论：利用CPAS软件和Photoshop软件进行兔角膜损伤面积的定量分析，方法可靠、准确，但在图像处理过程中须对阈值化进行人工调整。

Calculating the damaged cornea area in rabbit with an image analyzing system

Objective:To investigate the quantitative image analyzing method for calculating the areas of corneal damage in rabbit model.Methods:Anterior keratectomy of 8 mm diameter and 1/3 cornea thickness was performed on both eyes of 6 rabbits.1% fluoroscein were dropped to the injured eyes,and photographs were taken a time per day for a week.The photographs were scanned with Mustek scanner at 100 dpi.The boundary of the injured cornea was described with Photoshop software,then saved in a jpg format.The file was opened with colour pellet analyzing system(CPAS) software.Automated threshold was taken and then adjusted manually by the operator.The pixels of the area was calculated and converted into actual area in mm 2 by the pixels of 1 mm 2 in damaged area.The damaged area in the six eyes 1 hour after operation was calculated with image analyzing method and compared with the actual area.Twelve pictures were randomly selected and the damaged areas measured by three different operators were compared.Results:The damaged areas of all photographs 1 hour after damage were calculated and the averaged area was 51.14mm 2,as the actual area was 50.24mm 2,there was a 0.2% difference.No significant difference was found between the two groups(P=0.12).The damaged areas in the 12 photographs were analyzed by three operators,and the averaged areas were 18.26mm 2,19.81mm 2 and 18.85mm 2 respectively,showing no significant difference among the three operators(F=0.044,P=0.957).Conclusion:The image analyzing method with Photoshop and CPAS software in quantitatively calculating the damaged area of cornea was accurate and dependable,but the threshold should be adjusted manually during the image process.