| Objectives:To approach the accuracy of introcular pressure(IOP) measured by dynamic contour tonometry(DCT),to compare and analyze the relationship between central corneal thickness(CCT)and IOP value measured by DCT,Goldmann applanation tonometry(GAT)and non-contact tonometry(NCT).Then to study the clinical utility of the ocular pulse amplitude(OPA)measured by DCT in diagnosis and follw-up of glaucoma.Method:Chose 90 single eyes of 90 healthy individuals for IOP measuring from April to July in 2006 randomly.After CCT measurement using KONAN non-contact specularmicroscope,DCT,GAT and NCT were performed in random order.Then compared the measurements of the three tonometries with each other and correlated them with CCT seperately.In addition,chose 127 patients of differente types of glaucoma and 63 cases with suspected glaucoma who would be given 24-hour IOP measurement to perform IOP and OPA measurement with DCT and GAT. Categorize patients with glaucoma into early stage,middle stage,and late stage according to Hoddap criterion.To perform IOP and OPA measurement with DCT pre-operation and post- operation accordingly for 30 patients with glaucoma prepared for trabeculectomy.Results:IOP readings were consistently higher with DCT (17.33±2.71mmHg)than with GAT(14.27±2.81mmHg)and NCT (14.67±2.93mmHg),the mean differences were 3.06±2.01mmHg and 2.67±2.20mmHg(P＜0.001).DCT correlated more significantly with GAT(r=0.736,p=0.000)than with NCT(r=0.699,P=0.000).NCT has worst significant correlation with GAT,r=0.684(p=0.000).For repeated measurement,the coefficients variance(CV)were 5.52%and 6.04%for DCT and NCT separately.GAT and NCT both remarkably correlated with CCT,with coefficients of correlation being 0.370 and 0.508(P＜0.001),while DCT showed no significant correlation with CCT (r=0.051,p=0.639).There was a remarkably negative correlation between CCT and the deviation of DCT and GAT.Every 10-μm increase of CCT would result in a reduction of this deviation for 0.13mmHg.The deviation of DCT and GAT was obviously higher in patients of glaucoma than in healthy individuals with the difference of 1.81±2.66mmHg merely. The mean value of OPA among healthy individuals was 2.56±1.18mmHg. It correlated well with IOP values measured by DCT,but had no correlation with age,eye sides or cup/disc ratio.The OPA values were significantly higher in chronic angle closure glaucoma(CACG)compared with normal tension glaucoma(NTG)and normal subjects,and the differences were 0.61±0.26mmHg(p=0.019)and 0.89±0.36mmHg (p=0.015)respectively.Patients with glaucoma in middle stage had higher OPA values than early stage and late stage(F=1.145)with the differences being 0.76±1.32mmHg(P＜0.05)and 0.53±1.47mmHg(P＜0.05)respectively.Obviously,OPA values were positvely correlated with mean damage(MD)and loss viariance(LV)of visual field,and their coefficiences of correlation were 0.322(P=0.02)and 0.354(P=0.01) respectively.DCT kept a high accordance with GAT in 24-hour IOP measurement,yet there was still difference of 0.41±3.77mmHg (P=0.239).The OPA values showed remarkable fluctuation during 24 hours with the fluctuation range of 0.3mmHg(highest at 6PM and lowest at 10PM).The lOP values measured by DCT consistantly correlated with GAT(r=0.591,P=0.000)in 24-hour IOP measurement with its peak value at 5AM and lowest value at 10PM.The OPA values differed a lot between pre-operation and post-operation of trabeculectomy(P＜0.05) with the difference of 1.89±1.76mmHg.Among thirty patients with glaucoma who were prepared for trabeculectomy,28/30(93.3%)had reduction of OPA values post-operation,and 26/30(92.9%)of these patients formed functioned blebs in a week post operatively.Conclusion:DCT is more repeatable than NCT and can keep high accordance with GAT,moreover,it won't be affected by CCT.The readings of DCT are much closer to real IOP than GAT and NCT.The OPA measured by DCT is useful for classification and treatment of glaucoma,especially for the result assessment in the short-term post-operation of trabeculectomy.
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