대한안과학회지 2009 년제 50 권제 3 호 J Korean Ophthalmol Soc 2009;50(3):418-423 DOI : 10.3341/jkos.2009.50.3.418 접수번호 : 50-3-08-01 녹내장안에서망막신경섬유층두께와중심각막두께의상관관계분석 성경림 김동윤 남윤표 울산대학교의과대학서울아산병원안과학교실 목적 : 빛간섭단층촬영으로측정한망막신경섬유두께와중심각막두께의관련성을고찰하고자하였다. 대상과방법 : 녹내장 100 안, 녹내장의증 99 안에서시야검사, 빛간섭단층촬영, 중심각막두께를측정하고지표들의관련성을 Pearson correlation 분석을통해알아보았다. 중심각막두께와망막신경섬유두께의상관관계를 mixed effect model 을통해분석하였고얇은각막군 (553.6 µm >) 과두꺼운군으로 (553.6 µm ) 나누어양군간에세지표, 시야검사 mean deviation (MD), pattern standard deviation (PSD), 망막신경섬유두께의차이를비교하였다. 결과 : 전체대상안에서중심각막두께와망막신경섬유두께의관련성은관찰되지않았다 (R 2 =0.00, p=0.88). 녹내장군과녹내장의증군에서중심각막두께와망막신경섬유두께는각각유의한상관관계를보이지않았다 (p=0.11, p=0.46). 얇은각막군과두꺼운각막군간에세지표는유의한차이를보이지않았다 (p=0.38, 0.32, 0.44). 결론 : 녹내장과녹내장의증군에서중심각막두께는망막신경섬유두께와유의한관련성을보이지않았다. < 대한안과학회지 2009;50(3):418-423> Ocular Hypertension Treatment Study (OHTS) 는대규모의전향적인연구결과중심각막두께가고안압증에서원발개방각녹내장으로진행하는중요한위험인자임을발표하였다. 1 최근대규모의다른다기관공동연구에서도비슷한결과를보고하여중심각막두께는원발개방각녹내장의진단과진행에영향을미칠수있는중요한요인으로인식되고있으며여러각도에서연구되고있다. 2 중심각막두께는녹내장의진단과관련하여크게두가지관점에서고려되어야한다. 첫째는현재까지알려진녹내장의가장중요한위험인자인안압을측정하는표준방법은 Goldmann 압평안압측정법이며이측정에중심각막두께가영향을줄수있다는것이다. 이것은이론적으로각막두께가일정하다고가정한상태에서고려된안압측정법이며중심각막이얇으면안압은실제보다낮게측정되고두꺼울수록높은것으로측정된다. 3 따라서중심각막두께를보정한다면정상안과고안압증그리고녹내장에대한분류가달라질수있을것이다. Choi et al 4 은정상안압성녹내장으로분류된환자들중 22.58% 가원발개방각녹내장으로재분류될것이며 56.65% 의두꺼운중심각막두께를가진고안압증환자들이정상안으로분류될수있을것이라고발표한바가있다. 중심각막 접수일 : 2008 년 8 월 1 일 심사통과일 : 2008 년 12 월 9 일 통신저자 : 성경림서울시송파구풍납동 388-1 울산대학교서울아산병원안과 Tel: 02-3010-3680, Fax: 02-470-6440 E-mail: sungeye@gmail.com 두께에따른안압의보정은여러연구에서시도되었지만합치되는결과는아직없는상태이다. 5-7 이는중심각막두께외에도 Goldmann 압평안압측정에영향을줄수있는알려져있지않은각막의다른생역학적특성이있을수있음을시사하며이에대해서는연구가더필요할것으로사료된다. 두번째고려해야될사항은중심각막두께와녹내장과관련된기능적 (functional), 구조적 (structural) 손상의지표들과의관련성이다. 중심각막두께와녹내장의기능적손상즉, 시야검사지표들과의관련성에대해서는 Herndon et al 8 이중심각막두께와초진시원발개방각녹내장정도와의관련성을 Advanced Glaucoma Intervention Study score를통해서알아본결과중심각막두께는초진시녹내장정도와유의하게관련되어있다는보고를하였다. Kim and Chen 9 은여러종류의개방각녹내장환자들에있어서앏은각막두께가녹내장진행의요인임을, 우리나라에서는 Kim et al 10 이원발개방각녹내장에서중심각막두께가녹내장의진행과관련되어있음을보고한바가있다. 한편녹내장성손상의구조적지표인시신경유두나망막신경섬유층과중심각막두께에대한연구는상대적으로적은편이다. Choi et al 11 은정상안압성녹내장에서 stereoscopic optic disc photography로측정한시신경유두의 cup disc ratio가중심각막두께와관련되어있음을보고한바있다. 녹내장의구조적손상은기능적손상에선행되는것으로알려져녹내장을조기진단할수있는방법으로가능성이제기되어왔지만이손상을보다객관적이고정량화시킬수있는측정법이적었던측면이있다. 이에저자들은최근 418
- 성경림외 : 망막섬유두께와각막두께의상관관계 - 에녹내장의구조적손상을보다객관적이고정량화시켜서측정하는진단방법으로많이사용되며여러연구에서그진단성을평가받은빛간섭단층촬영으로측정한망막신경섬유층두께와 12-19 시야검사를통해얻은기능적손상지표그리고중심각막두께와의관련성을알아보고자본연구를시행하였다. 본연구의주된관심사는중심각막두께와망막신경섬유층두께로측정한녹내장의구조적손상과의관련성을고찰하는데있었으므로중심각막두께에따른인위적인안압의보정, 그리고보정된안압에의한녹내장의분류등은시행하지않았다. 대상과방법 이연구는 2008년 3월에서 6월까지서울아산병원안과녹내장클리닉을방문하여녹내장혹은녹내장의증으로진단받은환자들중본연구의기준에해당하는경우연속적으로선택된환자들을대상으로시행한후향적연구이다. 모든환자들은시행되는검사에대하여설명을들었고동의하였으며모든검사과정과분석은 Declaration of Helsinki 에의거하여실행되었다. 모든환자들은전안부세극등검사및안저검사, Goldmann 압평안압계를이용한안압측정, 초음파를이용한중심각막두께측정 (Pachette2 pachymetry; DGH Technology Inc.; Exton, PA, USA) Humphrey 자동시야계검사 (Carl Zeiss Meditec, Dublin, USA) 에의한 SITA 24-2 시야검사, 그리고빛간섭단층촬영 (Stratus Optical coherence tomography, Carl Zeiss Meditec, Dublin, USA, software version. 4.0.1) 에의한망막신경섬유층두께측정을시행하였다. 최대교정시력이 20/30 이상인경우, 구면렌즈대응치값이 ±6디옵터이내, 난시가 ±3디옵터이내이며, 전안부검사및전방각경검사에서정상소견을보이는경우대상에포함되었다. 녹내장의증은시야검사상정상소견을보이지만 0.6 이상증가된시신경유두함몰, 양안간에 0.2 이상의시신경유두함몰비의차이, 시신경유두의국소결손, 시신경유두출혈, 시신경섬유결손등전형적인녹내장성시신경우두변화가관찰되는경우혹은 Goldmann 압평안압계를이용한안압측정에서 2회이상 21 mmhg 로측정되어고안압증으로분류된경우를포함하였다. 녹내장성시신경유두변화와함께녹내장성시야가신뢰할만한시야검사에서 2회이상확인된경우녹내장으로진단하였다. 2회이상의안압측정에서모두 21 mmhg 미만으로측정된경우는정상안압성녹내장으로정의되었다. 녹내장성시야손상은 Glaucoma hemifield test (GHT) 에서 outside normal limit 소견을보이면서 pattern standard deviation (PSD) 이정상의 5% 이하로 분류되는경우로정의하였다. 시야검사는신뢰도지표상주시상실이 20% 미만, 가음성과가양성반응이 15% 미만인경우에만분석에포함되었다. 녹내장이외에시야에영향을줄수있는다른안과적, 신경학적이상이있는경우는제외하였다. 양안모두연구기준에부합할경우단안이무작위로선택되었다. 빛간섭단층촬영을이용한망막신경섬유층두께의측정은 fast retinal nerve fiber layer (RNFL) mode를이용하여측정하였고평균망막신경섬유층두께값을 (average RNFL thickness) 결과분석에사용하였다. 빛간섭단충촬영에서얻은 image의 signal strength가 6 이상인경우, 그리고 scan circle이시신경유두의중심에잘위치한경우를신뢰할수있는 image 로대상에포함시켰으며망막신경섬유층분리측정의실패 (segmentation algorithm failure) 정도가 15% 를넘는경우제외되었다. 중심각막두께는 3회측정치의평균값을분석에이용하였다. 전체대상안의중심각막두께와빛간섭단층촬영에의해측정된망막신경섬유층두께의관련성그리고시야검사상의 mean deviation (MD), PSD와의관련성을각각 Pearson correlation 분석을통해알아보았다. 녹내장과녹내장의증군으로구분하여각군에서중심각막두께와망막신경섬유층두께의상관관계를환자의나이, 성별, 빛간섭단층촬영에서얻은 image의 signal strength, 그리고구면렌즈대응치를 covariate로포함시킨 linear mixed effect model을통해분석해보았다. Lee et al 20 은 224명을대상으로한연구에서한국인정상안의평균중심각막두께는 553.6 µm로보고한바있다. 본연구에서는이를기준으로두군즉, 얇은각막군 (553.6 µm 미만 ) 과두꺼운각막군으로 (553.6 µm 이상 ) 나누어양군간에망막신경섬유층두께, MD, PSD의차이가있는지를 Mann-Whitney U test를이용해분석해보았다. SPSS version 15.0 (SPSS Inc., Chicago, IL, USA) 이통계분석에사용되었다. 결과 녹내장환자 100명 ( 남자 32명, 여자68명 ) 의 100안과녹내장의증환자 99명 ( 남자 43명, 여자 56명 ) 의 99안이분석에포함되었다. 100안의녹내장안중 81안은정상안압성녹내장으로진단되었다. 녹내장군의평균연령은 54.0±13.6 세로 49.2±12.1세의녹내장의증군과차이를보였다. 시야검사상의 MD, PSD, 그리고빛간섭단층촬영에서측정한평균망막신경섬유층두께는두군간에통계적으로유의한차이를보였으나구면렌즈대응치와중심각막두께는차이를 419
- 대한안과학회지 2009 년제 50 권제 3 호 - Figure 1. Correlation between average RNFLT * measured by OCT and CCT in glaucoma and glaucoma suspect subjects (R 2 =0.00, p=0.88). * RNFLT=retinal nerve fiber layer thickness; CCT=central corneal thickness; OCT=optical coherence tomography. 보이지않았다 (Table 1). 중심각막두께와빛간섭단층촬영에의해측정된망막신경섬유층두께의관련성, 시야검사상의 MD, PSD와의관련성을각각 Pearson correlation 분석을통해알아본결과이세가지지표모두중심각막두께와의관련성은관찰되지않았다 (R 2 =0.00, 0.01, 0.01, p=0.88, 0.11, 0.14, Fig. 1, 2, 3). 녹내장군에서중심각막두께와망막신경섬유층두께의상관관계를환자의나이, 성별, 빛간섭단충촬영에서얻은 image 의 signal strength, 그리고구면렌즈대응치를 covariate로포함시킨 linear mixed effect model을통해분석해보았을때통계적으로유의한관련성을보이지않았다 (p=0.11). 녹내장의증군에서도같은방식으로분석했을때중심각막두께와망막신경섬유층두께는유의한관련성을 Figure 2. Correlation between VF MD * and CCT in glaucoma and glaucoma suspect subjects (R 2 =0.01, p=0.11). * MD=mean deviation; CCT=central corneal thickness; VF=visual field. 보이지않았다 (p=0.46). 중심각막두께 553.6 µm를기준으로얇은각막군 (553.6 µm 미만 ) 과두꺼운각막군으로 (553.6 µm 이상 ) 나누어양군간의 MD, PSD, 망막신경섬유층두께를 Mann-Whitney U test를이용해비교했을때모두통계적으로유의한차이를보이지않았다 (Table 2). 고 찰 중심각막두께가고안압증에서녹내장으로진행하는중요한요인중하나라는 OHTS의보고이후중심각막두께와녹내장의관련성에대한연구가많아지고있다. 중심각막두께를고려하여계산된안압을보정한분석에서도이관련성은제기되어서중심각막두께는안압측정외에도녹내장영역에서고려되어야할점들이있음을시사하고있다. 21,22 Table 1. Comparison of age, CCT, * VF MD, PSD and average RNFLT П assessed by OCT # between glaucoma and glaucoma suspect groups (mean±sd ** ) Glaucoma (n=100) Glaucoma suspect (n=99) p value Age (year) 54.0±13.6 49.2±12.1 0.005 CCT (µm) 541.6±40.0 544.7±35.9 0.57 VF MD (db) -5.05±5.24-0.29±1.30 <0.001 VF PSD (db) 4.76±3.75 1.67±0.38 <0.001 Average RNFLT (µm) 89.6±18.9 102.0±12.70 <0.001 Spherical equivalent (diopter) -1.32±2.88-1.20±2.54 0.67 * CCT=central corneal thickness; VF=visual field; MD=mean deviation; PSD=pattern standard deviation; П RNFLT=retinal nerve fiber layer thickness; # OCT=optical coherence tomography; ** SD=standard deviation. 420
- 성경림외 : 망막섬유두께와각막두께의상관관계 - Figure 3. Correlation between VF PSD * and CCT in glaucoma and glaucoma suspect subjects (R 2 =0.01, p=0.14). * PSD=pattern standard deviation; CCT= central corneal thickness; VF=visual field. 그중하나는중심각막두께와녹내장정도 (severity) 와의관련성일것이다. 시야검사로본녹내장의정도와중심각막두께가관련되어있다는보고가있었다. 8 녹내장의기능적손상정도와중심각막두께가관련되어있다면구조적인손상의지표또한관련되어있어야할것으로사료된다. 고안압증에서중심각막두께와망막신경섬유층두께의관련성은보고되어있으며 23,24 최근의연구에서정상안에서는이두지표가관련되어있지않다는보고가있었으나 25 녹내장환자에서는녹내장손상의구조적지표인망막신경섬유층두께와중심각막두께의관련성에대한연구결과가아직보고된바가없다. 이에저자들은이연구를계획하게되었다. 저자들이관찰한바, 녹내장군과녹내장의증군모두에서중심각막두께는망막신경섬유층두께와유의한관련성을보이지않았다. 이의원인은여러가지로추측될수있을것이다. Early Manifest Glaucoma Trial (EMGT) 의연구 결과에의하면녹내장의진행에영향을주는기본인자를 5년간의추적결과로분석하였을때중심각막두께는녹내장의진행과상관관계를보이지않았으나 26 11년간추적한결과에서기본안압 (baseline IOP) 이높은경우에서는기본중심각막두께 (baseline CCT) 가녹내장진행에유의한예측인자인것으로나타났다. 27 이연구에서저자들은 21 mmhg 를기준으로고안압군과저안압군으로나누어각각의군에서기본중심각막두께 (baseline CCT) 가녹내장의진행에미치는영향을살펴보았는데고안압군에서는각막두께 40 μm 감소에따라 hazard ratio 1.42 (p=0.023) 으로유의한결과를보였으나저안압군에서는 1.05 (p=0.7655) 로녹내장의진행에영향을미치지않는요인으로분석되었다. 이는실제녹내장으로진단된환자들중에서도기본안압의정도혹은개개인의특성등이나밝혀지지않은요인에따라중심각막두께는녹내장의증에서녹내장으로의이환혹은녹내장의진행에영향을미치는군과영향을미치지않는군이혼합되어있음을시사한다고할수있다. 연구대상녹내장환자들의 80% 이상이정상안압성녹내장인본연구에서중심각막두께와녹내장의구조적손상지표인망막신경섬유층두께그리고기능적인시야검사의지표들과관련되어있지않다는결과는 EMGT의저안압군에서중심각막두께와녹내장진행이관련되어있지않다는연구결과와부합되는측면이있다. 즉중심각막두께는고안압증에서녹내장의로의이환과기본안압이높은환자들에서녹내장진행에영향을주는것으로나타났으나상대적으로안압이낮은군에서는영향이적은것으로볼수도있을것이다. 물론모든안압측정법의표준은현재로써는 Goldmann 안압측정법이며이방법이중심각막두께에영향을받는다는사실은항상고려되어야한다. 중심각막두께가망막신경섬유층두께와상관관계를보이지않는다른원인으로생각해볼수있는것은이두가지지표의분포가상당히넓다는점이다. 정상적으로각각넓은범위에분포하고있는두지표의관련성을찾아보는것은기술적으로어려운측면이있다. 이에저자들은중심각 Table 2. Comparison of age, CCT *, VF MD, PSD and average RNFLT П assessed by OCT # between thin cornea (CCT<553.6 µm) and thick cornea (CCT>553.6 µm) groups (mean±sd ** ) Thin cornea (n=132) Thick cornea (n=67) p value Age (year) 52.5±11.7 49.8±15.5 0.27 CCT (µm) 521.9±21.7 585.0±21.7 <0.001 MD (db) -2.99±5.0-2.05±3.3 0.38 PSD (db) 3.43±3.3 2.81±2.6 0.32 Average RNFLT (µm) 95.9±17.9 95.9±16.2 0.44 * CCT=central corneal thickness; VF=visual field; MD=mean deviation; PSD=pattern standard deviation; П RNFLT=retinal nerve fiber layer thickness; # OCT=optical coherence tomography; ** SD=standard deviation. 421
- 대한안과학회지 2009 년제 50 권제 3 호 - 막두께와망막신경섬유층두께에영향을줄수있다고고려되는여러 covariate들을포함시킨분석을시행하였으나그관련성은발견되지않았다. 28 그외에망막신경섬유층두께가객관적이고정량화시킬수있는지표이지만녹내장성구조적손상을측정하는간접적인지표이기때문에관련성이약화되었을가능성도있다. 녹내장병인고찰에서주목받고있는사상판 (lamina cribrosa) 과각막이조직학적으로연관되어있기때문에중심각막두께는녹내장영역에서중요한의미를갖는다. 사상판의두께나가소성등이녹내장의병인에관련될것이라는추측이있으나이를측정하는것은현재의진단장비로써는어렵고한계가있는실정이다. 29 따라서이사상판과발생학적으로같은기원을가지는각막이이특성을대체할수있는측정법으로 (surrogate measure) 의미를가질수있다. 23 중심각막두께혹은각막의가소성 (plasticity) 등각막의구조적혹은생역학적인특성을측정하여직접접근하기어려운사상판의특성을유추하고안압변화에따른사상판의반응, 그리고이에수반되는녹내장성시신경병리를고찰하는연구는녹내장의병인분석을위한흥미로운주제일것이다. 결론적으로, 본연구결과에의하면녹내장과녹내장의증군에서중심각막두께는녹내장의구조적손상지표인망막신경섬유층두께와기능적손상을측정하는시야검사의지표들과유의한관련성을보이지않았다. 이는중심각막두께가녹내장의진행에미치는영향이선별적일수있음을시사한다. 녹내장이초기에환자가자각할수있는증상이없는질환이니만큼, 발병시바로내원하기어렵기때문에어떤인자가녹내장의발병혹은진행을보는요인이될것인가하는것을단면적인연구 (cross sectional study) 에서고찰하는것은매우어려운일이다. 따라서각막두께와시신경섬유두께로측정한녹내장성손상과의관련성을보다정확하고객관적으로파악하고, 연구결과가임상적의미를갖기위해서는녹내장의진행과기본중심각막두께의관련성을장기적으로추적하는연구 (longitudinal study) 가반드시필요할것으로사료된다. 참고문헌 1) Gordon MO, 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. 2) Miglior S, Pfeiffer N, Torri V, et al. Predictive factors for open-angle glaucoma among patients with ocular hypertension in the European Glaucoma Prevention Study. Ophthalmology 2007;114:3-9. 3) Allingham R, Damji K, Freedman S, et al. Intraocular Pressure and Tonometry. In : Allingham RR, Damji K, Freedman S, et al. Shields Textbook of Glaucoma, 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2005; chap. 2. 4) Choi, YJ, Kim JH, Sohn YH. Influence of central corneal thickness on diagnosis of glaucoma. J Korean Ophthalmol Soc 2003;44:2823-8. 5) Ehlers N, Bramsen T, Sperling S. Applanation tonometry and central corneal thickness. Acta Ophthalmol 1975;53:34-43. 6) Wolfs RC, 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. 7) Doughty MJ, Zaman ML. Human corneal thickness and its impact intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol 2000;44:367-408. 8) Herndon LW, Weizer JS, Stinnett SS. Central corneal thickness as a risk factor for advanced glaucoma damage. Arch Ophthalmol 2004;122:17-21. 9) Kim JW, Chen PP. Central corneal pachymetry and visual filed progress in patients with open angle glaucoma. Ophthalmology 2004; 111:2126-32. 10) Kim JH, Lee EK, Kim CS, Lee NH. Central corneal thickness and visual field progression in primary open angle glaucoma. J Korean Ophthalmol Soc 2007;48:1088-95. 11) Choi HJ, Kim DM, Hwang SS. Relationship between central corneal thickness and localized retinal nerve fiber layer defect in normal-tension glaucoma. J Glaucoma 2006;15:120-3. 12) Budenz DL, Chang RT, Huang X, et al. Reproducibility of retinal nerve fiber thickness measurements using the stratus OCT in normal and glaucomatous eyes. Invest Ophthalmol Vis Sci 2005;46:2440-3. 13) Burgansky-Eliash Z, Wollstein G, Chu T, et al. Optical coherence tomography machine learning classifiers for glaucoma detection: a preliminary study. Invest Ophthalmol Vis Sci 2005;46:4147-52. 14) Huang ML, Chen HY. Development and comparison of automated classifiers for glaucoma diagnosis using Stratus optical coherence tomography. Invest Ophthalmol Vis Sci 2005;46:4121-9. 15) Leung CK, Chan WM, Yung WH, et al. Comparison of macular and peripapillary measurements for the detection of glaucoma: an optical coherence tomography study. Ophthalmology 2005;112:391-400. 16) Medeiros FA, Zangwill LM, Bowd C, et al. Evaluation of retinal nerve fiber layer, optic nerve head, and macular thickness measurements for glaucoma detection using optical coherence tomography. Am J Ophthalmol 2005;139:44-55. 17) Kanamori A, Nagai-Kusuhara A, Escano MF, et al. Comparison of confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography to discriminate ocular hypertension and glaucoma at an early stage. Graefes Arch Clin Exp Ophthalmol 2006;244:58-68. 18) Lalezary M, Medeiros FA, Weinreb RN, et al. Baseline optical coherence tomography predicts the development of glaucomatous change in glaucoma suspects. Am J Ophthalmol 2006;142:576-82. 19) Manassakorn A, Nouri-Mahdavi K, Caprioli J. Comparison of retinal nerve fiber layer thickness and optic disk algorithms with optical coherence tomography to detect glaucoma. Am J Ophthalmol 2006;141:105-15. 20) Lee ES, Kim CY, Ha SJ, et al. Central corneal thickness of Korean patients with glaucoma. Ophthalmology 2007;114:927-30. 21) Brandt JD, Beiser JA, Kass MA, Gordon MO. Central corneal thickness in the Ocular Hypertension Treatment Study (OHTS). Ophthalmology 2001;108:1779-88. 22) Brandt JD. Central corneal thickness--tonometry artifact, or something more? Ophthalmology 2007;114:1963-4. 422
- 성경림외 : 망막섬유두께와각막두께의상관관계 - 23) Henderson PA, Medeiros FA, Zangwill LM, Weinreb RN. Relationship between central corneal thickness and retinal nerve fiber layer thickness in ocular hypertensive patients. Ophthalmology 2005;112:251-6. 24) Kaushik S, Gyatsho J, Jain R, et al. Correlation between retinal nerve fiber layer thickness and central corneal thickness in patients with ocular hypertension: an optical coherence tomography study. Am J Ophthalmol 2006;141:884-90. 25) Mumcuoglu T, Townsend KA, Wollstein G, et al. Assessing the Relationship Between Central Corneal Thickness and Retinal Nerve Fiber Layer Thickness in Healthy Subjects. Am J Ophthalmol 2008; 146:561-6. 26) Leske MC, Heijl A, Hussein M, et al. Factors for glaucoma progression and the effect of treatment: the early manifest glaucoma trial. Arch Ophthalmol 2003;121:48-56. 27) Leske MC, Heijl A, Hyman L, et al. Predictors of long-term progression in the early manifest glaucoma trial. Ophthalmology 2007;114:1965-72. 28) Stein DM, Wollstein G, Ishikawa H, et al. Effect of corneal drying on optical coherence tomography. Ophthalmology 2006;113:985-91. 29) Lesk MR, Hafez AS, Descovich D. Relationship between central corneal thickness and changes of optic nerve head topography and blood flow after intraocular pressure reduction in open- angle glaucoma and ocular hypertension. Arch Ophthalmol 2006;124: 1568-72. =ABSTRACT= Relationship Between Central Corneal Thickness and Retinal Nerve Fiber Layer Thickness in Glaucomatous Subject Kyung Rim Sung, MD, PhD, Dong Yoon Kim, MD, Yoon Pyo Nam, MD University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Korea Purpose: To evaluate the correlation between central corneal thickness (CCT) and retinal nerve fiber layer thickness (RNFLT) as determined by optical coherence tomography (OCT) in glaucomatous subjects. Methods: One hundred eyes diagnosed with glaucoma and 99 glaucoma suspect (GS) eyes were tested by visual field (VF), OCT, and ultrasonic pachymetry. The relationship between CCT and RNFLT measurements was assessed by Pearson correlation analysis. A mixed effect model was employed to determine the relationship between CCT and RNFLT in glaucoma and GS groups. We divided the patients into two groups depending on the thickness of their corneas: Thin (< 553.6 µm) and thick ( 553.6 µm), and compared three parameters: VF mean deviation (MD), pattern standard deviation (PSD), and RNFLT between the two groups. Results: There were no significant correlations between CCT and RNFLT in any participant (R 2 =0.00, p=0.88). There was no significant relationship between CCT and RNFLT in glaucoma and GS groups (p=0.11, p=0.46). There were no statistically significant differences in MD, PSD, or RNFLT between the thin and thick cornea groups (p=0.38, 0.32, 0.44). Conclusions: CCT is not significantly associated with RNFLT in glaucoma and GS subjects. J Korean Ophthalmol Soc 2009;50(3):418-423 Key Words: Central corneal thickness, Optical coherence tomography, Retinal nerve fiber layer thickness Address reprint requests to Kyung Rim Sung, MD, PhD Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center #388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea Tel: 82-2-3010-3680. Fax: 82-2-470-6440, E-mail: sungeye@gmail.com 423