Central Corneal Thickness and Optic Disc Hemorrhag

Authors: Liang Xu Haitao Zhang Ya Xing Wang Jost B Jonas

Publish Date: 2008/03/01

Volume: 126, Issue: 3, Pages: 435-436

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Abstract

Central corneal thickness CCT has been described to be a predictor for the development of primary openangle glaucoma and the progression of glaucomatous visual field defects in the Ocular Hypertension Treatment Study1 and other investigations23 Correspondingly a previous investigation by Herndon and colleagues3 found that CCT was the most consistent predictor of the degree of glaucomatous damage in their hospitalbased crosssectional study However CCT also influences applanation tonometry so it has remained unclear whether the reported findings are due to the dependence of intraocular pressure measurements on CCT and a corresponding selection artifact of patients or whether a thin cornea may predispose the eye to a higher glaucoma susceptibility Since optic disc hemorrhages can indicate progression of glaucomatous optic neuropathy and because most of the previous investigations were hospitalbased studies with a possible referral bias it was the purpose of our populationbased study to assess whether CCT influences the development of disc hemorrhagesThe Beijing Eye Study is a populationbased cohort study in northern China4 The medical ethics committee of the Beijing Tongren Hospital approved the study protocol and all of the participants gave informed consent according to the Declaration of Helsinki Of 5324 individuals aged 40 years or older residing in the study area 4439 individuals 2505 women participated in the eye examination response rate 834 in the year 2001 as described in detail previously4 In 2006 the same population was invited for a reexamination with 3251 subjects participating response rate 733 All of the participants underwent a standardized ophthalmic examination including CCT measurement by slitlamp optical coherence tomography Only 1 randomly selected eye was taken for statistical analysis Glaucoma was defined by the appearance of the optic nerve head as described recently Table4Of the 3251 subjects CCT measurements were available for 3100 subjects 954 32 of them 10 showed an optic disc hemorrhage The CCT was slightly greater in the hemorrhagic group mean SD CCT 569 5 338 μm than in the nonhemorrhagic group mean SD CCT 556 0 330 μm P = 03 after application of the Bonferroni method to correct for performing multiple statistical analyses P = 06 Figure Including glaucomatous eyes n = 77 only the CCT did not vary significantly between the hemorrhagic group n = 5 eyes 6 mean SD CCT 5718361 μm and the nonhemorrhagic group n = 72 eyes 94 mean SD CCT 5493 314 μm P = 24 with the hemorrhagic group having slightly thicker corneas than the nonhemorrhagic groupThe findings point against a thin cornea as an associated factor for disc hemorrhages in glaucoma56 Because disc hemorrhages are usually associated with glaucoma progression the results do not support a thin cornea to be a pathogenic risk factor for glaucoma progression

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