摘要
【研究背景】盲和低视力是世界范围内严重的公共卫生和社会经济问题。目前估计全世界有盲人3.7千万、低视力者1.24亿。据世界卫生组织(WHO)统计,全世界80%的盲是可以避免的。如果及时采取恰当的措施,有的就能被预防或控制而恢复视力,如白内障、屈光不正等。为此,1999年WHO、国际防盲机构和非政府组织提出了“视觉2020,享有看见的权利”的防盲治盲全球性战略目标,力争到2020年在全球消除包括白内障、沙眼、河盲、儿童盲、屈光不正与低视力等导致的可避免盲。在世界很多地区未矫正的屈光不正已成为视力损害的首要原因。2008年的数据表明,全球共有1.45亿患者由于未矫正的屈光不正而致低视力,800万人致盲。我国现有盲人约500万,低视力人口约710万,是世界上盲和低视力最严重的国家之一。随着经济社会的发展、人口的增加和老龄化,盲和低视力人数也在不断增加,我国防盲治盲工作面临着巨大挑战。WHO于1973年提出了盲和视力损伤的分类标准(即最佳矫正视力标准,best corrected visual acuity, BCVA),山东省防盲治盲办公室于2008年4月至7月组织的对我省4个县(市、区)50岁以上人群进行的盲与低视力流行病学调查中,采用了这一分类标准。然而BCVA标准不能反映盲与视力损伤患者真实的生活状况,而应用WHO于2003年提出的日常生活视力(presenting visual acuity, PVA)这一新概念对盲与低视力人群进行评估,则会真实的反映出盲与低视力患者的实际日常生活状况。
【目的】采用PVA标准,对山东省盲与低视力流行病学调查中滕州市和济南市槐荫区50岁以上人群盲与低视力状况进行了统计分析,并与采用BCVA标准统计的流行病学调查结果进行比较。
【方法】采用多阶段分层随机整群抽样方法,抽取乳山市、滕州市、鄄城县、济南市槐荫区为样本县(市、区)。按50岁以上人群双眼盲患病率P=2.65%、可信度取95%计算,采取25%双眼盲患病率的相对误差,应用单纯随机抽样计算样本大小的公式：n=Z2(P)(1-P)／B2,P=0.0265,B(率的绝对差值)=0.0265×0.25,95%可信度时Z=1.96,计算得n=2258。假设抽样作用系数为1.8,调查受检率为90%,计算出本调查每个县(市、区)所需样本人数为2258×1.8／0.9=4516人。2008年4月至7月,我院参与了滕州市、济南市槐荫区两地50岁以上人群盲与低视力流行病学调查工作。调查队分为两个检查组,每组由1名高年眼科医生和1名低年眼科医生、1名验光师、2名眼科辅助人员组成。调查方案参照全国眼病流行病学方案进行。采用国际标准视力表检查远视力。对未配戴或不经常配戴远用矫正眼镜者,检查裸眼视力；经常配戴远用矫正眼镜者,检查戴镜后视力。上述视力即为PVA。对任一眼PVA≤0.5者进行电脑验光及主观试镜,然后检查BCVA。并进行眼压、裂隙灯显微镜及眼底检查。根据WH01973年制定的盲与低视力分类标准,双眼BCVA均<0.05者为双眼盲；只有一眼BCVA<0.05,另眼≥0.05者为单眼盲；双眼BCVA均<0.3、但≥0.05者为双眼低视力；只有眼BCVA<0.3、但≥0.05,另眼≥0.3者为单眼低视力。并分别以BCVA和PVA为标准分析单、双眼盲和单、双眼低视力患病情况及其病因。
【结果】滕州市、济南市槐荫区两地共检录8933人,实查7956人,总受检率为89.06%。其中滕州市受检4916人(61.8%),济南市槐荫区受检3040人(38.2%)；男性3557人(44.7%),女性4399人(55.3%)；50-59岁组4014人(50.5%)；60-69岁组2084人(26.2%)；70-79岁组1433人(18.0%)；80岁及以上组425人(5.3%)。
以BCVA为标准,双眼盲患病率为1.34%；单眼盲患病率为4.47%；双眼低视力患病率为1.97%；单眼低视力患病率为4.27%。随着年龄的增长,单、双眼盲及单、双眼低视力患病率均有增高的趋势(P=0.000)。单、双眼盲及单眼低视力患病率无性别差异(p>0.05),女性双眼低视力患病率高于男性(P=0.014)。滕州市与槐荫区双眼盲及双眼低视力患病率的差异无统计学意义(P>0.05)；滕州市单眼盲及单眼低视力患病率显著高于槐荫区(单眼盲P=0.005；单眼低视力P=0.000)。双眼盲前五位病因依次为白内障、角膜混浊／瘢痕、青光眼、黄斑变性(老年／高度近视)、视神经萎缩；单眼盲前五位病因依次为白内障、角膜混浊／瘢痕、眼球缺失／萎缩、屈光不正／弱视、黄斑变性(老年／高度近视)；双眼低视力前五位病因依次为白内障、屈光不正／弱视、黄斑变性(老年／高度近视)、视神经萎缩、其它视网膜／脉络膜改变；单眼低视力前五位病因依次为白内障、屈光不正／弱视、黄斑变性(老年／高度近视)、角膜混浊／瘢痕、视神经萎缩。
以PVA为标准,双眼盲患病率为1.58%；单眼盲患病率为5.09%；双眼低视力患病率为3.51%；单眼低视力患病率为6.83%。随着年龄的增长,单、双眼盲及单、双眼低视力患病率均有增高的趋势(P=0.000)。双眼盲及单眼低视力患病率无性别差异(p>0.05)；女性单眼盲及双眼低视力患病率高于男性(单眼盲P=0.040；双眼低视力P=0.001)。滕州市与槐荫区双眼盲患病率的差异无统计学意义(P=0.187)；滕州市单眼盲及单、双眼低视力患病率高于槐荫区(单眼盲P=0.017；单眼低视力P=0.002；双眼低视力P=0.037)。双眼盲前五位病因依次为白内障、角膜混浊／瘢痕、黄斑变性(老年／高度近视)、屈光不正／弱视、青光眼；单眼盲前五位病因依次为白内障、屈光不正／弱视、角膜混浊／瘢痕、眼球缺失／萎缩、黄斑变性(老年／高度近视)；双眼低视力前五位病因依次为白内障、屈光不正／弱视、黄斑变性(老年／高度近视)、视神经萎缩、其它视网膜／脉络膜改变；单眼低视力前五位病因依次为屈光不正／弱视、白内障、黄斑变性(老年／高度近视)、角膜混浊／瘢痕、视神经萎缩。
以BCVA为标准的双眼盲患病率(1.34%)与以PVA为标准的双眼盲患病率(1.58%)的差异无统计学意义(P=0.210)；以BCVA为标准的单眼盲患病率(4.47%)与以PVA为标准的单眼盲患病率(5.09%)的差异亦无统计学意义(P=0.900)。而以PVA为标准的双眼低视力患病率(3.51%)显著高于以BCVA为标准的双眼低视力患病率(1.97%)(P=0.000),以PVA为标准的单眼低视力患病率(6.83%)亦显著高于以BCVA为标准的单眼低视力患病率(4.27%)(P=0.000)。
【结论】在滕州市及济南市槐荫区农村50岁以上人群中,单、双眼盲及单、双眼低视力的患病率均随着年龄增长有增高的趋势；以BCVA为标准,白内障是单、双眼盲和单、双眼低视力的主要病因；以PVA为标准,白内障是单、双眼盲和双眼低视力的主要病因,而屈光不正及弱视是单眼低视力的主要病因；未矫正的屈光不正对单、双眼低视力患者的日常生活视力有较大影响。
[Background] Blindness and low vision are serious public health and social economic problem in the world. Worldwide, an estimated 37 million people are blind, and an additional 124 million are severely visually impaired. According to WHO's statistics,80% of blindness are avoidable. If correct methods are adopted, blindness caused by cataract, refractive error, etc. can be prevented or controlled. Therefore, WHO, international blindness prevention institution and non-government organization proposed a global initiative:vision 2020, the right to sight, to eliminate avoidable blindness of the world in 2020. In many regions of the world, uncorrected refractive error becomes the main reason of visual impairment. By the data of 2008, there are 145 million low vision persons and 8 million blind persons caused by uncorrected refractive error. Our country is one of the most serious blindness and low vision country of the world including 5 million blind persons and 7.1 million low vision persons. The criteria of blindness and low vision according to best-corrected distance visual acuity (BCVA) were introduced by WHO in 1973. The new criteria of blindness and low vision according to presenting distance visual acuity (PVA) were introduced by WHO in 2003.
[Purpose] Describe the prevalence of blindness and low vision with presenting and best-corrected distance VA among older adults in rural populations in Tengzhou and Huaiyin.
[Design] Population-based, cross-sectional study.
[Methods] Geographically defined cluster sampling was used in randomly selecting a cross-section of residents from a representative rural county including Rushan, Tengzhou, Juancheng and Huaiyin within Shandong Province in mainland China. Epidemiological investigation of blindness and low vision among adults aged 50 years and above was carried out in Tengzhou and Huaiyin from April to July,2008. Participants were enumerated through village registers. Eligible persons were invited to local examination sites for visual acuity (VA) testing and eye examination. Main outcome measures were presenting and best-corrected distance VA. Based on WHO's blindness and low vision criteria (1973), bilateral blindness was defined as BCVA of less than 0.05 in both eyes; unilateral blindness was defined as BCVA of less than 0.05 in one eye, equal or more than 0.05 in the other eye; bilateral low vision was defined as BCVA of less than 0.3, equal or more than 0.05 in both eyes; unilateral low vision was defined as BCVA of less than 0.3 and equal or more than 0.05 in one eye, equal or more than 0.3 in the other eye. Prevalence and causes of bilateral and unilateral blindness and low vision were respectively calculated and analyzed based on BCVA and PVA criteria.
Of 8933 enumerated eligible persons,7956 (89.06%) were examined and tested for VA. Based on criteria of BCVA, the prevalence of bilateral blindness, unilateral blindness, bilateral low vision and unilateral low vision were 1.34%,4.47%,1.97% and 4.27%, respectively. Bilateral and unilateral blindness and low vision were associated with older age with best-corrected VA(P<0.01). There were no differences in prevalence of bilateral blindness, unilateral blindness and unilateral low vision among male and female (P>0.05). The prevalence of bilateral low vision was higher in female than male (P<0.05). There were no differences in prevalence of bilateral blindness and bilateral low vision between Tengzhou and Huaiyin (P>0.05). The prevalence of unilateral blindness and unilateral low vision in Tengzhou were significantly higher than in Huaiyin (P<0.01). The first five causes of bilateral blindness were cataract, corneal opacity, glaucoma, macular degeneration, optic atrophy; the first five causes of unilateral blindness were cataract, corneal opacity, eyeball absence or atrophy, refractive error and amblyopia, macular degeneration; the fist five causes of bilateral low vision were cataract, refractive error and amblyopia, macular degeneration, optic atrophy, other retinal and choroidal disorders; the first five causes of unilateral low vision were cataract, refractive error and amblyopia, macular degeneration, corneal opacity, optic atrophy.
With presenting VA, the prevalence of bilateral blindness, unilateral blindness, bilateral low vision and unilateral low vision were 1.58%,5.09%,3.51%,6.83%, respectively. Bilateral and unilateral blindness and low vision were associated with older age with presenting VA (P<0.01). There were no differences in prevalence of bilateral blindness and unilateral low vision among male and female (P>0.05). The prevalence of unilateral blindness and bilateral low vision were higher in female than male (P<0.05). There were no differences in prevalence of bilateral blindness between Tengzhou and Huaiyin (P>0.05). The prevalence of unilateral blindness, bilateral low vision and unilateral low vision in Tengzhou were higher than in Huaiyin (P<0.05). The first five causes of bilateral blindness were cataract, corneal opacity, macular degeneration, refractive error and amblyopia, glaucoma; the first five causes of unilateral blindness were cataract, refractive error and amblyopia, corneal opacity, eyeball absence or atrophy, macular degeneration; the first five causes of bilateral low vision were cataract, refractive error and amblyopia, macular degeneration, optic atrophy, other retinal and choroidal disorders; the first five causes of unilateral low vision were refractive error and amblyopia, cataract, macular degeneration, corneal opacity, optic atrophy.
There were no differences in prevalence of bilateral blindness and unilateral blindness between best-corrected VA and presenting VA (P>0.05). The prevalence of bilateral low vision and unilateral low vision based on presenting VA were significantly higher than those based on best-corrected VA (P<0.01).
[Conclusion] Among older adults in rural populations in Tengzhou and Huaiyin, the prevalence of blindness and low vision was associated with older ages. Blindness prevention programs targeting the rural elderly should be expanded. Cataract was the leading cause of bilateral and unilateral blindness and low vision with best-corrected VA, and was the leading cause of bilateral and unilateral blindness, bilateral low vision with presenting VA. While refractive error and amblyopia were the leading cause of unilateral low vision with presenting VA. Greater attention should also be given to correction of refractive error.
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