改良的潜在视功能检测仪在重度白内障中的应用

The application study of modified potential vision meter in severe cataracts

目的通过对潜在视功能检测仪的改良,使其能顺利完成对重度白内障患者术前潜视力的检测,并尽量使预测结果不受患者视力的影响。方法简化潜在视功能检测仪的系统成像模型,进行理论分析,将系统改进为采用偏离理想参数的结构,在系统出瞳处形成沿轴长度约3mm、直径≤0.1mm的细长成像光束,使成像光束能够穿透重度白内障患者的晶状体并在其眼底成像,完成术前潜视力的测量。为了保证在非理想参数时,不同视力患者的潜视力预测结果具有统一标准,通过理论推导出非理想参数下结果补偿校正公式,保证测量结果的准确性。并选取150例白内障患者进行临床使用效果的评价。结果改良后的潜在视功能检测仪测量了出瞳光束沿轴分布曲线,能够满足重度白内障患者的检测需要。在临床使用效果的评价中,效果良好,达到了国外同类产品的检测水平。结论改良的仪器能够完成对重度白内障患者的术前预测,使用效果达到国外同类产品水平。

Objective To measure the potential vision of eyes with severe cataract and obtain more precise results by improving the potential vision meter （PVM）. Methods Theoretical analysis was done with a simplified optical model to find the factors that interfere with the testing of eyes with severe cataract. The optical system of the PVM was improved by using non-ideal parameters so that an imaging beam that was less than 0.1 mm in diameter and about 3 mm in length was formed at the exit pupil of the system. The long thin imaging beam can pass through a small aperaturc in an opaque lens with severe cataract, thus making the measurement possible. To obtain accurate test results for eyes with different refractive errors, a potential vision calibration expression was derived. One hundred and fifty eyes with cataract were tested to estimate the effectivity for use in the clinic. Results The distribution of the beam diameter along the axis near the exit pupil of the improved PVM was measured; the imaging beam could penetrate eyes with severe cataracts. The clinical trial showed that the improved PVM met international standards for similar instruments presently in use. Conclusion The improved PVM can be used to test eyes with severe cataract, and the test met international standards for similar instruments presently in use.