【摘要】 目的：评价植入聚甲基丙烯酸甲酯（PMMA）人工晶状体和软性人工晶状体(AcroSof)致后发性白内障的严重程度。 方法：总共100人（110眼）进行了人工晶状体植入术，随机分为两组植入不同类型的晶状体。组I: AcrySof（SA60AT）人工晶状体，组II:PMMA（LX10BD）人工晶状体。分别在术后3，6，12和18mo,通过测定最佳矫正视力和数码照片拍摄评价后囊膜浑浊的密度。 结果：术后3mo, PMMA组后囊膜浑浊的密度明显增加（3.6%），而Acrylic组并未发现增加。术后18mo，显著后囊膜浑浊两组的发生率相比较，Acrylic组（14.5%）较PMMA组（34.5%）低。由于PMMA人工晶状体比AcrySof人工晶状体所致后囊膜浑浊的范围广，故其导致更严重的视力降低。结论：与PMMA人工晶状体相比较，植入AcrySof人工晶状体在一定程度上有助于降低后发性白内障的发生率。
【关键词】 后囊膜浑浊 晶状体上皮细胞 人工晶状体
INTRODUCTION
Uveitis is an inflammation of the uveal tract and anatomically categorized as anterior, intermediate, posterior and panuveitis. The inflammatory form of uveitis can occur either as an isolated disease or as part of a systemic syndrome such as Behcets disease (BD), VKH syndrome and spondyloarthritis. It often affects those aged between 20 and 50. Despite current advances in diagnosis and management, visual loss occurs in 35% 40% of patients with uveitis.
The pathogenesis of uveitis is not well understood. The inheritance pattern of uveitis is complex and influenced by multiple genetic factors[1]. Susceptibility to uveitis has been associated with the MHC genes[2]. Since HLAB27 itself plays only a minor role in the overall genetic background of uveitis[3], other genetic variants like TNFα, CCL2 and CCL5 have been recently suggested to play roles in uveitis. This review introduced the advances in the studies on cytokine and chemokine gene polymorphisms associated with uveitis.
CYTOKINE GENES
Cytokines are regulatory proteins produced by cells in response to a variety of stimuli. They act as mediators of inflammation and can cause tissue damage in chronic inflammatory diseases. Cytokines have been associated with the pathogenesis of uveitis[4].
IL1 Gene IL1 gene contains three related genes that encode the proinflammatory cytokines IL1α, IL1β and their endogenous receptor antagonist IL1ra. Several IL1 gene polymorphisms have been described and associations with uveitis have also been reported. Karasneh et al[5] found that IL1α 899C allele was associated with BD and IL1α 889C/IL1β +5887T haplotype was a risk factor for BD. The IL1α 889 and IL1β+5887 CC/TT combined genotype was significantly more observed in BD patients than in controls. Similarly, Alayli et al[6] also found a significantly increased frequency of IL1α 899C allele in BD patients, IL1β511C allele and CC genotype frequencies were significantly higher in BD patients compared to controls, IL1β +3962 CC genotype was associated with BD susceptibility. In contrast, Coskun et al[7] reported no significant difference in genotype and allele frequencies of IL1β 511 between BD patients and controls, but they identified an increased frequencies of both IL1β +3953 T allele and TT genotype in patients with BD.
Intraocular injection of IL1ra decreases the inflammatory response in anterior uveitis caused by intravitreal injection of IL1 in animal models[8]. Interestingly, patients with chronic uveitis has an increased frequency of the IL1ra T allele than those with recurrent uveitis[9].
IL18 Gene IL18 gene is regarded as a pivotal mediator of Th1 cytokine responses and can enhance the production of TNF α, GMCSF and IFNγ, which were elevated in BD[10]. It has been reported that BD patients have higher serum levels of IL18 than controls, and its concentration is related to disease activity[11]. Giedraitis et al[12] demonstrated that IL18 607A/C and 137C/G polymorphisms in the 5UTR binding affected promoter activity. Though these two polymorphisms have been studied in many inflammatory diseases, only two studies in Korean have been reported on uveitis. Jang et al[13] identified a significant higher frequency of 137GG genotype in BD patients with ocular lesions than patients without ocular lesions, although they didnt find any significantly different distributions of 137 and 607 polymorphisms between patients and controls. Another similar study[14] identified significantly higher frequencies of both 607C allele and CC genotype, and a lower frequency of 607A/137G haplotype in BD patients than controls. These results suggested that IL18 gene may be a susceptibility gene of uveitis.
TNFα Gene TNFα is produced predominantly by macrophages. High serum level of TNFα has been associated with recurrent uveitis, and disease inflammation has been found in TNFreceptordeficient mice in immunecomplexinduced uveitis[15,16]. Kuo et al[17] investigated the associations between TNFα and TNFreceptor gene polymorphisms and idiopathic acute anterior uveitis (IAU) in Caucasians, they found a significant increase in the frequency of TNF857T allele in patients with IAU compared with controls. Menezo et al[9] also found a significant increase in the frequency of TNF308G allele in Caucasian patients with HLAB27 positive anterior uveitis compared to patients negative for HLAB27. In Turkish population, the relation and functional importance of TNFα1031T/C was investigated, the results showed that the frequency of TNF1031C allele was significantly higher in BD patients compared to controls; whereas carrying the T allele render patients were more prone to develop a positive shin pathergy test[18].
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