대한안과학회지 2009 년제 50 권제 2 호 J Korean Ophthalmol Soc 2009;50(2):242-246 DOI : 10.3341/jkos.2009.50.2.242 Dynamic Contour Tonometry 와골드만압평안압계의비교 서장원 신동민 노세현 동아대학교의과대학안과학교실 목적 : Dynamic contour tonometry(dct, PASCAL ) 로측정한안압과골드만압평안압계 (GAT) 로측정한안압을비교해보고, 중심각막두께와의관계에대해알아보고자하였다. 대상과방법 : 녹내장 (135 안 ), 녹내장의증 (14 안 ) 및고안압증 (16 안 ) 으로치료중인 83 명 165 안을대상으로하였으며, 각막두께측정은초음파각막두께측정계로측정하였다. 결과 : DCT 로측정한안압과 GAT 로측정한안압사이에는뚜렷한상관관계를나타냈다 (r =0.733, p<0.001). GAT 로측정한안압은중심각막두께와유의한상관관계를가졌고 (r 2 =0.145, p<0.001), DCT 로측정한안압은중심각막두께와유의한상관관계를보이지않았으며 (r 2 =0.012, p=0.081), GAT 와 DCT 로측정한안압의차이는중심각막두께와유의한상관관계를가지는것으로나타났다 (r 2 =0.124, p<0.0001). 결론 : DCT 는신뢰도있는안압측정장비인것으로사료되며, GAT 와는달리중심각막두께에크게영향을받지않고안압을측정할수있을것으로생각된다. < 대한안과학회지 2009;50(2):242-246> 안압의측정은녹내장환자에서뿐만아니라대부분의안과내원환자에게기본적으로시행되는검사중하나이다. 정확한안압의측정은원발성개방각녹내장, 정상안압녹내장또는고안압증의감별수단이될수있을뿐만아니라녹내장환자에서의경과관찰에중요한역할을한다. 1954년에골드만압평안안계가소개된이후, 이안압계는안압측정의대부분에이용되었으며비교적정확한안압을측정할수있었다. 1,2 그러나측정원리상중심각막을편평하게하는데필요한압력을측정하는것으로이는각막의두께를포함한각막의특성에영향을받게되는단점이있었다. 여러연구에서각막의두께 10 µm 변화에따라 0.19 mmhg 부터 0.7 mmhg 까지안압에영향을주는것으로알려졌다. 3-5 고안압증환자에서중심각막두께가두꺼울때, 안압이과측정되어잘못된치료가되어질수있다. 6-8 그러므로중심각막의두께에영향을받지않으면서, 정상인에서의각막두께에따른보정된안압의측정, 또는굴절교정수술전후의안압측정에많은방법들이고안되고있다. 접수일 : 2008 년 7 월 4 일 심사통과일 : 2008 년 9 월 11 일 통신저자 : 노세현부산시서구동대신동 3 가 1 동아대학교병원안과 Tel: 051-240-5227, Fax: 051-254-1987 E-mail: shrho@daunet.donga.ac.kr * 본논문의요지는 2006 년대한안과학회제 96 회추계학술대회에서구연으로발표되었음. 그중파스칼안압계 (dynamic contour tonometry, PAS CAL ) 는세극등현미경에거치하여각막의압평없이각막의변형을초래하지않고각막의특성에영향을받지않게고안된안압계로써센서팁은각막의곡률에최대한가깝게만들어져각막에접촉하여직접적으로안압을측정하게된다. 이안압계는각막의정점과접촉시각막표면의형태변화가거의없게되며, 이론적으로각막내에작용하는모든방향의힘들이각막접촉부분에내장되어있는압력센서로균등하게향하게된다. 여러연구에서파스칼안압계가안압측정의효율과정확도가높음을보고하였다. 9.10 그러나국내에서는아직파스칼안압계와관련된임상연구가미흡하다. 이에저자들은파스칼안압계와골드만압평안압계의상관관계에대해알아보고, 두안압계의중심각막두께에대한영향을알아보고자하였다. 대상과방법 2006년이후본원에서경과관찰중인녹내장 (135안 ), 녹내장의증 (14안) 및고안압증 (16안) 환자 83명 165안을대상으로후향적연구를시행하였으며, 3.5디옵터이상의난시가있거나외상, 안내염증의소견, 각막질환, 이전의굴절교정수술이있었던환자는대상에서제외하였다. 모든대상환자에게골드만압평안압계, 파스칼안압계, 초음파각막두께측정계검사에대한사전정보가주어졌다. 242
- 서장원외 : DCT(PASCAL ) 와골드만안압계 - 골드만압평안압계의측정은 0.5% Proparacaine으로점안마취하고, 누액을형광염색지로염색한후피검자에게여러차례눈깜박임을유도하고, 두차례안압측정후 2 mmhg 이상의차이가나면, 한번더측정하여가까운두측정치의평균값을기록하였다. 약 30분후 0.5% Proparacain으로다시점안마취하고, 동일한검사자에의해 PASCAL (Swiss Microtechnology AB, Port, Switzerland) 로 3회연속안압을측정하였으며, 이의평균값을측정치로하였다. 파스칼안압계 (dynamic contour tonometry, PAS CAL ) 의측정값은계기판에 Q1 (optimum) 부터 Q5 (unacceptable) 까지나타나며, Q4 and Q5 측정치는제외하였다. 10명의환자에서는파스칼안압계측정후골드만압평안압계로재측정하였다. 이는골드만압평안압계측정시각막의압평으로인한파스칼안압계측정치의변화값을알아보고자하였다. 중심각막두께는초음파각막두께측정계 (SP-2000, Tomey, Corp. NAGOYA, MA) 를이용해점안마취후 5회측정한후, 이의평균치를기록하였다. 안압측정의편견을막기위해중심각막두께의측정은가장마지막으로하였다. 통계학적분석은 SPSS (Statistical software, ver. 10; SPSS Inc., Chicago, IL) 를이용하여단순회귀분석과 t- test를시행하였다. 파스칼안압계로측정한안압과골드만압평안압계로측정한안압사이의상관관계, 중심각막두께와두안압계로측정한안압과의관계, 그리고두안압계로측정한안압의차이와의상관관계를조사하였고, 모든경우에 p<0.05 인경우를통계적으로의미가있는것으로보았다. 결과 대상은총 83명, 165안 ( 남자 : 39명 78, 여자 : 44명 87 안 ) 이었고나이는 32.4±8.3세였다. 파스칼안압계로측정한안압의평균은 14.92±2.28 mmhg, 골드만압평안압계로측정한안압의평균은 13.97±3.12 mmhg 로나타났다. 파스칼안압계가골드만압평안압계보다평균 0.95±2.49 mmhg 높게측정되었으며, 중심각막두께는 419 µm부터 657 µm의범위로측정되었다. 두안압계의측정안압사이에는뚜렷한상관관계를나타냈다 (r=0.733, p<0.001)(fig. 1). 중심각막두께에따른안압계의측정안압을비교한결과, 골드만압평안압계로측정한안압은중심각막두께와유의한상관관계를가졌으나 (r 2 =0.145, p<0.001)(fig. 2), 파스칼안압계로측정한안압은중심각막두께와유의한상관관계를보이지않았다 (r 2 =0.012, p=0.081)(fig. 3). 그리 고두안압계로측정한안압의차이 (GAT-DCT) 는중심각막두께와유의한상관관계를가지는것으로나타났다 (r 2 =0.124, p<0.0001)(fig. 4). 파스칼안압계측정후골드만압평안압계로재측정한 10명의환자에서는압평으로인한안압의저하는보이지않았고, 이는골드만압평안압계측정시각막의압평으로인한파스칼안압계의측정치에영향이없었음을알수있었다 ( 차이, 0.5 mmhg 기준 ). 고 찰 안압의측정에있어서중심각막의두께에대한영향은잘알려진사실이다. Figure 1. Pearson correlation of intraocular pressure (IOP) measurements obtained by GAT and DCT (r=0.733, p<0.001). Plot of IOP measurements with GAT against DCT in patients with CCT showing a good correlation between the two methods. GAT= Goldmann applanation tonometer; DCT=dynamic contour tonometer; CCT=central corneal thickness. Figure 2. Influence of CCT on IOP measurements. GAT is significantly influenced by CCT (r 2 =0.145, p<0.001). 243
- 대한안과학회지 2009 년제 50 권제 2 호 - 골드만압평안압계는내부의압력은외부에서가해진힘을압평면의면적으로나눈것과같다는 Imbert-Fick 법칙을이론적바탕으로한압평안압계로, 비교적정확한안압을측정할수있으나각막의표면이정상적이지못할때는정확하지않을수도있으며, 각막의두께나형광염색의농도등에영향을받을수있다. 이중각막두께가얇으면실제안압보다낮게측정되며각막의교원질이증가하여두꺼워지면높게측정된다. 그러나각막부종으로인한이차적인두께증가시에는실제안압보다낮게측정되는결과를보인다. Ehlers et al 5 은중심각막두께 70 µm 감소할때, 골드만압평안압계에의한측정안압은평균 5 mmhg 만큼낮고, 두꺼운각막에서안압이과측정되고얇은각막에서는저측정되는것을연구하였다. 파스칼안압계는이론적으로각막의두께와같은특성에영향을받지않으며각막의곡률에최대한가깝게고안된압력센서팁을이용해안압을측정할수있다. 본연구에서는골드만안압계와파스칼안압계로안압을측정한후, 중심각막두께에따른그연관성을통해, 두안압계를통한안압측정의일치성, 각막의두께에대한독립성에대해알아보고자하였다. 측정방식에있어서는검사자의편견을피하기위해동일한검사자에의해정해진방식으로진행하였으며, 안압의측정에서아날로그방식이검사자의편견에가장예민할수있기때문에골드만압평안압계의측정이제일먼저이루어졌다. 디지털로표시되는파스칼안압계의측정치는객관적으로고려될수있어그다음으로검사하였다. 연구에서골드만압평안압계로안압을측정후압평에의한파스칼안압계로측정한안압이거짓으로낮게측정될수있는문제점이발생할수도있어추가적으로, 10명의환자에서파스칼안압측정후골드만안압계로재측정하였으나안압의하강은보이지않음을알수있었다. 중심각막두께의측정은두께에따라안압측정에검사자의편견이작용할수있으므로마지막에검사하는방식을택하였다. 파스칼안압계로측정한안압의평균은 14.92±2.28 mmhg, 골드만압평안압계로측정한안압의평균은 13.97 ±3.12 mmhg 로나타났으며, 파스칼안압계가골드만압평안압계보다평균 0.95±2.49 mmhg 높게측정되었다. 이는골드만압평안압계가정상군에서비교적낮게측정된다는여러논문의결과와일치하는모습을보이며, 평균적으로높게측정된파스칼안압계가실제안압에더가까울수있음을추측할수있다. 11-15 임상적으로새로운파스칼안압계에서관심있게지켜봐야하는것은, 두껍거나얇은각막에서골드만안압계와비교해서어떠한값을얻는가이다. 여러논문에서골드만안 Figure 3. Influence of CCT on IOP measurements. DCT measurements are CCT independent (p=0.756). Figure 4. Plot of GAT-DCT difference in IOP against the CCT for all patients showing a tendency to increase the difference between the two measurements for increasingly thinner corneas but not for thick corneas. The difference of IOP between GAT and DCT shows a significant correlation with CCT (r 2 =0.145, p<0.001). 압계가중심각막두께에영향을받는다는것은이미알려진사실이다. 16-19 파스칼안압계로측정한안압과골드만압평안압계로측정한안압사이에는뚜렷한상관관계를나타냈다 (Fig. 1). 이것은 Grieshaber et al 20 이개방각녹내장환자를대상으로한연구에서도두안압계가밀접한연관성을가지는것을알수있으며, 새로운기법의파스칼안압계에서골드만압평안압계와의연관성이높다는점은, 주목할만한것으로이는오래전부터사용되어오면서비교적정확한안압을측정할수있다고검증된골드만압평안압계와같이, 안압의측정에있어파스칼안압계가임상적으로바로적용하여사용될수있다는의미를가지게된다. 중심각막두께와두안압계의안압측정에대한관계는골드만압평안압계는중심각막두께에영향을받는것으로나타났으나 (Fig. 2), 파스칼안압계는영향을크게받지않는 244
- 서장원외 : DCT(PASCAL ) 와골드만안압계 - 것으로나타났다 (Fig. 3). 이러한결과는 Francis et al 21 와 Martinez de la Casa et al 22 의연구에서파스칼안압계가골드만압평안압계보다중심각막두께에영향을크게받지않는다는결과와일치하는것을알수있다. 두안압계로측정한안압의차이는중심각막두께가증가할수로양의값을, 중심각막두께가감소할수록음의값을갖게된다 (Fig. 4). 이는중심각막두께가두꺼울수록골드만압평안압계로측정한안압이증가하게되어각막의두께에영향을받지않는파스칼안압계와의차이가커지는것을의미한다. 반면, 중심각막의두께가감소할때측정되는골드만압평안압계의값이실제안압보다낮게측정되어파스칼안압계와의차이가나는것을알수있다. 파스칼안압계의사용에있어서의단점은안압의측정이이전에고안된안압계와비교해어렵다는점이다. 정확한안압의측정을위해골드만압평안압계와비교해센서팁이환자의각막에적어도 4~5초정도접촉해있어야하고, 안압을측정하는동안환자가눈을움직인다거나머리를움직인다면, 정확한안압의측정이이루어질수없다. 본연구에서도 9명의환자에서반대편눈의주시실패, 안진, 협조의부족으로안압을측정할수없었다. 반면에골드만압평안압계는이러한어려운환자에서도숙련된검사자에의해비슷한안압을얻을수있었다. 이러한환자에서는골드만압평안압계가더우수하다고볼수있지만, 파스칼안압계는협조가잘되는환자, 특히라식을받은환자에서와같이중심각막두께가변화된예에서는더욱정확한안압을측정할수있으리라생각된다. 또한, 파스칼안압계는 OPA (Ocular pulse amplitude) 를측정할수있어이완기와수축기의안압을서로비교함으로써맥락막순환에있어혈액볼륨의이동과, 압력의변화에대한연구도가능하게하였다. 이는허혈에의한시신경의손상과시야변화에대한연구에도움이될수있으리라생각된다. 결론적으로파스칼안압계는측정된골드만압평안압계의안압과비교했을때유의한상관관계를가지는것을볼수있었고, 이는임상적으로파스칼안압계의적용이비교적정확한안압의측정이가능하리라생각된다. 각막두께에큰영향을받지않고비교적정확한안압을측정할수있는파스칼안압계를이용해각막반흔이있는환자나굴절교정수술로각막의두께에변화가있는대상에서안압측정시도는좋은연구가되리라생각된다. 참고문헌 1) Troost R, Vogel A, Beck S, et al. Clinical comparison of two intraocular pressure measurement methods: SmartLens dynamic observing tonography versus Goldmann. Graefes Arch Clin Exp Ophthalmol 2001;239:889-92. 2) Whitacre MM, Stein RA, Hassanein K. The effect of corneal thickness on applanation tonometry. Am J Ophthalmol 1993; 115:592-6. 3) Wolfs RCW, Klaver CC, Vingerling JR, et al. Distribution of central corneal thickness and its association with intraocular pressure: the Rotterdam study. Am J Ophthalmol 1997;123:767-72. 4) Doughty MJ, Saman ML. Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol 2000;44:367-408. 5) Ehlers N, Bramsen T, Sperling S. Applanation tonometry and central corneal thickness. Acta Ophthalmol (Copenh) 1975;53: 1974-83. 6) Brandt JD, Beiser JA, Kass MA, Gordon MO. Central corneal thickness in the Ocular Hypertension Treatment Study (OHTS). Ophthalmology 2001;108:1779-88. 7) GordonMO, Beiser JA, Brandt JD, et al. The Ocular Hypertension Treatment study: baseline factors that predict the onset of primary open angle glaucoma. Arch Ophthalmol 2002;120:714-20. 8) Herndon LW, Allingham R, Choudhri SA, et al. Central corneal thickness innormal, glaucomatous, and ocular hypertensive eyes. Arch Ophthalmol 1997;115:1137-41. 9) Siganos DS, Papasterigiou GI, Moedas C. Assessment of the Pascal dynamic contour tonometer in monitoring intraocular pressure in unoperated eyes and eyes after LASIK. J Cataract Refract Surg 2004;30:746-51. 10) Kaufman C, Bachmann LM, Thiel MA. Intraocular pressure measurements using dynamic contour tonometry after laser in situ keratomileusis. Invest Ophthalmol Vis Sci 2003;44:3790-4. 11) Kaufmann C, Bachmann LM, Thiel MA. Comparison of dynamic contour tonometry with Goldmann applanation tonometry. Invest Ophthalmol Vis Sci 2004;45:3118-21. 12) Kniestedt C, Nee M, Stamper RL. Dynamic contour tonometry (DCT) and its dependence on corneal hydration in human cadaver eyes. Arch Ophthalmol 2004;122:1287-93. 13) Wirthlin AC, Siganos DD, Papastergiou G, et al. Dynamic contour tonometry for IOP measurement after LASIK, a comparison with Goldmann tonometry. Synopsis of paper presented at DOC, Nurenberg 2002. 14) Duba I, Wirthlin AC. Dynamic contour tonometry for post-lasik intraocular pressure measure measurements. Klin Monatsbl Augenheilkd 2004;221:347-50. 15) Fresco BB. A new tonometer-the pressure phosphene tonometer: clinical comparison with Goldmann tonometry. Ophthalmology 1998;105:2123-6. 16) Whitacre MM, Stein RA, Hassanein K. The effect of corneal thickness on applanation tonometry. Am J Ophthalmol 1993;115:592-6. 17) Stodtmeister R. Applanation tonometry and correlation according to corneal thickness. Acta Ophthalmol Scand 1998;76:319-24. 18) Velten IM, Bergua A, Horn FK, et al. Central corneal thickness in normal eyes, patients with ocular hypertension, normal-pressure and open-angle glaucomas-a study. Klin Monatsbl Augenheilkd 2001;218:466. 19) Ventura AC, Bohnke M, Mojon DS. Central corneal thickness in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension. Br J Ophthalmol 2001;85:792-5. 245
- 대한안과학회지 2009 년제 50 권제 2 호 - 20) Grieshaber MC, Schoetzau A, Zawinka C, et al. Effect of central corneal thickness on dynamic contour tonometry and Goldmann applanation tonometry in primary open-angle glaucoma. Arch Ophthalmol 2007;125:740-4. 21) Francis BA, Hsieh A, Lai MY, et al. Los Angeles Latino Eye Study Group. Effects of corneal thickness, corneal curvature, and intraocular pressure level on Goldmann applanation tonometry and dynamic contour tonometry. Ophthalmology 2007;114:20-6. 22) Martinez-de-la-Casa JM, Garcia-Feijoo J, Vico E, et al. Effect of corneal thickness on dynamic contour, rebound, and goldmann tonometry. Ophthalmology 2006;113:2156-62. =ABSTRACT= Comparison of Dynamic Contour Tonometry and Goldmann Applanation Tonometry Jang Won Seo, MD, Dong Min Shin, MD, Sae Heun Rho, MD Department of Ophthalmology, College of Medicine, Dong-A University, Pusan, Korea Purpose: To compare dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) and investigate the influence of central corneal thickness (CCT) onintraocular pressure. Methods: In a prospective study of 165 eyes with glaucoma (135 eyes), glaucoma suspect (14 eyes), and ocular hypertension (16 eyes), intraocularpressure was measured with DCT and GAT, and followed by measurement of the CCT with ultrasound pachymetry. Statistical analysis were performed with simple linear regression analysis and t-test using SPSS (Statistical software, ver. 10; SPSS Inc., Chicago, IL). Results: A clear correlation between DCT and GAT was found (r =0.733, p<0.001). The average intraocular pressure was 14.92±2.28 mmhg with DCT and 13.97±3.12 mmhg with GAT, and the intraocular pressure with DCT was 0.95±2.49 mmhg higher than with GAT. A meaningful correlation was shown between GAT and CCT (r 2 =0.145, p<0.001), but was not demonstrated between DCT and CCT (r 2 =0.012, p=0.081). In addition, the difference of intraocular pressure between GAT and DCT (GAT-DCT) showed a significant correlation with CCT (r 2 =0.145, p<0.001). Conclusions: DCT appears to be a reliable method for intraocular pressure measurement, which is not influenced by CCT, unlike GAT. J Korean Ophthalmol Soc 2009;50(2):242-246 Key Words: Central corneal thickness, Dynamic contour tonometry. Address reprint requests to Sae Heun Rho, MD Department of Ophthalmology, College of Medicine, Dong-A University #3-1 Dongdaeshin-dong, Seo-gu, Pusan 602-715, Korea Tel: 82-51-240-5227, Fax: 82-51-254-1987, E-mail: shrho@daunet.donga.ac.kr 246