Tan Anna C S, Wang Jie Jin, Lamoureux Ecosse L, Wong Wanling, Mitchell Paul, Li Jialiang, Tan Ava Grace, Wong Tien Y
Singapore National Eye Centre, Singapore.
Ophthalmic Epidemiol. 2011 Aug;18(4):164-70. doi: 10.3109/09286586.2011.594205.
Cataract is the major cause of blindness worldwide yet there is no consensus on its assessment and definition. This study compares age-related cataract prevalence derived from two commonly used methods: clinical assessment using the Lens Opacity Classification System (LOCS III) and photographic grading using the Wisconsin Cataract Grading System (Wisconsin System).
The Singapore Malay Eye Study is a population-based study of 3,280 Singapore Malays aged 40-80 years. Presence of nuclear, cortical and posterior sub-capsular cataract was assessed clinically during slit-lamp examination using LOCS III, and via slit-lamp and retro-illumination photographic grading using the Wisconsin System. Analyses were conducted to determine agreement in cataract prevalence estimates between the two grading Systems and approaches.
Poor agreement was found between severity levels of the two grading scales for all three cataract types. Using currently accepted cut-offs to define nuclear (≥ 4 on both LOCS III and Wisconsin System), cortical (≥ 2 in LOCS III, ≥ 25% in Wisconsin) and PSC (≥ 2 in LOCS III, ≥ 5 % in Wisconsin) cataract, the LOCS III overestimated the prevalence of significant cataract as compared to the Wisconsin System, with nuclear cataract prevalence, 27.5% (LOCS III) versus 17.0% (Wisconsin System), cortical cataract prevalence, 27.9% versus 7.0% and posterior sub-capsular cataract prevalence, 7.8% versus 5.1%.
The prevalence of cataract in a population varies substantially by measurement methods, with systematically different estimates found using the two most frequent cataract grading systems. This study re-emphasizes the need for global standards to assess and define cataract for epidemiologic and clinical studies.
白内障是全球失明的主要原因，但在其评估和定义上尚未达成共识。本研究比较了两种常用方法得出的年龄相关性白内障患病率：使用晶状体混浊分类系统（LOCS III）进行临床评估和使用威斯康星白内障分级系统（威斯康星系统）进行照片分级。
新加坡马来人眼研究是一项基于人群的研究，纳入了3280名年龄在40 - 80岁的新加坡马来人。在裂隙灯检查期间，使用LOCS III对核性、皮质性和后囊下白内障的存在情况进行临床评估，并通过裂隙灯和后照法照片分级，使用威斯康星系统进行评估。进行分析以确定两种分级系统和方法在白内障患病率估计方面的一致性。
对于所有三种白内障类型，两种分级量表的严重程度水平之间的一致性较差。使用目前公认的临界值来定义核性白内障（LOCS III和威斯康星系统均≥4）、皮质性白内障（LOCS III中≥2，威斯康星系统中≥25%）和后囊下白内障（LOCS III中≥2，威斯康星系统中≥5%），与威斯康星系统相比，LOCS III高估了显著白内障的患病率，核性白内障患病率分别为27.5%（LOCS III）和17.0%（威斯康星系统），皮质性白内障患病率分别为27.9%和7.0%，后囊下白内障患病率分别为7.8%和5.1%。
人群中白内障的患病率因测量方法而异，使用两种最常用的白内障分级系统会得出系统性不同的估计值。本研究再次强调了为流行病学和临床研究评估和定义白内障需要全球标准。
