[Shifts in the diameter of continuous circular capsulorhexis based on the Gullstrand eye model with the Callisto Eye System during cataract surgery].

Objective: To investigate the disparity between the set value of the capsulorhexis ring diameter in ophthalmic surgical navigation systems and the actual capsulorhexis ring diameter projected onto the lens surface. Methods: It was a cross-sectional study. Based on the Gullstrand eye model, the theoretical diameter of the capsulorhexis ring projected onto the lens plane through the cornea was calculated using the law of refraction in the Callisto Eye System. When the anterior chamber depth (ACD) ranged from 2.0 to 4.0 mm and the corneal curvature ranged from 40.00 to 48.00 D, the capsulorhexis ring diameters were calculated after projecting capsulorhexis rings with set diameters of 5.5 mm and 6.0 mm onto the lens plane. Additionally, 40 patients (40 eyes) aged 40 to 85 years who underwent cataract phacoemulsification combined with intraocular lens implantation at the Sixth People's Hospital of Shanghai Jiao Tong University School of Medicine were selected to validate the theoretical calculations. Among them, 15 were male, and 25 were female, and they were divided into three groups based on the ACD: group A (13 eyes) with ACD<3.0 mm; group B (16 eyes) with 3.0 mm≤ACD<3.5 mm; group C (11 eyes) with ACD≥3.5 mm. One week after surgery, anterior segment images of the eyes were taken, and the actual capsulorhexis ring diameter was measured using the Photoshop image processing software and compared with the set and calculated values. Results: When the capsulorhexis ring diameters were set at 5.5 mm and 6.0 mm and the corneal curvature was calculated based on the Gullstrand Eye model at 43.05 D, a linear negative correlation was found between ACD and the capsulorhexis ring diameter projected onto the lens plane (P<0.001). When the ACD was set at 2.5, 3.0, and 3.5 mm, and the capsulorhexis ring diameters were set at 5.5 and 6.0 mm, a linear negative correlation was observed between corneal curvature and the capsulorhexis ring diameter projected onto the lens plane (P<0.001). When the capsulorhexis ring diameter was set at 5.5 mm and the patient ACD and corneal curvature data were used for calculations, the capsulorhexis ring diameters projected onto the lens plane for groups A, B, and C were (5.09±0.05) mm, (4.97±0.05) mm, and (4.91±0.07) mm, respectively. When the capsulorhexis ring diameter was set at 6.0 mm, they were (5.56±0.05) mm, (5.44±0.05) mm, and (5.37±0.08) mm, respectively. One week after surgery, the actual measurements of capsulorhexis ring diameters for groups A, B, and C were (5.44±0.20) mm, (5.27±0.28) mm, and (5.25±0.41) mm, respectively, and the differences compared to the calculated values were not statistically significant (all P>0.05), but the differences compared to the set values were statistically significant (all P<0.001). Conclusion: The capsulorhexis ring diameter projected onto the lens surface by the Callisto Eye system was reduced by 7.33% to 10.48% compared to the set value, and the degree of reduction increased with the increase of ACD and corneal curvature.目的： 探讨眼科手术导航系统中的撕囊环直径设定值与实际投影至晶状体表面的撕囊环直径的差异。 方法： 横断面研究。基于Gullstrand眼模型，依据折射定律计算Callisto Eye眼科手术导航系统中通过角膜投射至晶状体平面上的撕囊口理论直径。在前房深度（ACD）为2.0~4.0 mm和角膜曲率为40~48 D范围变化时，计算设定为直径5.5和6.0 mm的撕囊环投射至晶状体平面后的撕囊环直径。另选取40例（40只眼）于上海交通大学医学院附属第六人民医院眼科行白内障超声乳化吸除联合人工晶体植入术的40~85岁患者对理论计算结果进行验证，其中男性15例，女性25例，并按ACD分为3组：A组（13只眼），ACD<3.0 mm；B组16只眼，3.0 mm≤ACD<3.5 mm；C组11只眼，ACD≥3.5 mm。术后1周拍摄术眼眼前节图像，利用Photoshop图像处理软件测量实际撕囊口直径，并与设定值和计算值进行比较。 结果： 撕囊环直径分别设定为5.5和6.0 mm时，代入Gullstrand眼模型的角膜曲率43.05 D进行计算，发现ACD与投射至晶状体平面上的撕囊环直径均呈线性负相关（P<0.001）；设定ACD分别在2.5、3.0和3.5 mm时，撕囊环直径分别设定为5.5和6.0 mm，角膜曲率与投射至晶状体平面上的撕囊环直径均呈线性负相关（P<0.001）。撕囊环直径设定为5.5 mm时，代入患者术眼的ACD及角膜曲率数据进行计算，系统投射至A、B、C 3个组术眼晶状体平面上的撕囊环直径分别为（5.09±0.05）、（4.97±0.05）、（4.91±0.07）mm；撕囊环直径设定为6.0 mm时则分别为（5.56±0.05）、（5.44±0.05）、（5.37±0.08）mm。术后1周，实际测量A、B、C组撕囊口直径分别为（5.44±0.20）、（5.27±0.28）、（5.25±0.41）mm，与理论计算值的差异均无统计学意义（均P>0.05），但与设定值的差异均有统计学意义（均P<0.001）。 结论： Callisto Eye眼科手术导航系统投射至晶状体表面的撕囊环直径较设定值存在缩减现象，其程度随ACD及角膜曲率的增加而增加，可达7.33%~10.48%。.