(김진형-박세훈)_320~327.hwp

대한안과학회지 2010 년제 51 권제 3 호 J Korean Ophthalmol Soc 2010;51(3):320-327 pissn: 0378-6471 eissn: 2092-9374 DOI : 10.3341/jkos.2010.51.3.320 = 증례보고 = 정상안과펨토초레이저라식수술안에서서로다른 4 가지각막두께측정계들의중심각막두께비교 박세훈 최석규 이도형 김진형 인제대학교의과대학일산백병원안과학교실 목적 : 정상안과펨토초레이저라식수술안에서 4 가지각막두께측정계를통해중심각막두께를비교하고자한다. 대상과방법 : 정상 30 안 ( 그룹 I), 펨토초레이저라식수술후 6 개월이내 30 안 ( 그룹 II), 6 개월이상경과한 30 안 ( 그룹 III) 을대상으로 Orbscan, Pentacam, Galilei, 초음파각막두께측정계의순서로중심각막두께를측정하였다. 결과 : 그룹 I 에서측정계간의두께는통계적차이를보이지않았고 (P =.202, one way ANOVA) 그룹 II 와 III 에서는각각측정계간의통계적인차이가있었다 (P =.000 and P =.000, respectively, one way ANOVA). 그룹 II, III 에서 Orbscan 의중심각막두께의평균값이 Pentacam, Galilei, 초음파각막두께측정계보다통계적으로유의하게얇게측정되었다 (P<0.05, one way ANOVA). 결론 : 4 가지측정계모두정상안에서술전각막두께를재기에적합하나펨토초레이저라식수술안에서는 Orbscan 이다른측정계에비해얇게측정되는경향을보이므로술전후진단에적절한기계를선별하여사용하는것이필요하다. < 대한안과학회지 2010;51(3):320-327> 중심각막두께의정확한측정은각막굴절교정수술전에수술적합성을판단하고술후에는각막확장증등의합병증을진단하기위해중요한검사중하나다. 술전중심각막두께는해당환자의굴절력교정을위한각막실질절제후잔존하는각막실질두께를예측하는데사용되며, 술후발생할수있는의인성각막확장증의발생가능성을판단하여적절한수술방법을선택하는데중요한지표가된다. 만약해당환자에게술후합병증의가능성때문에라식이부적절하다면, 라섹이나에피라식혹은유수정체안내렌즈삽입술등의다른수술법을선택할수있는근거가된다. 한편술후중심각막두께는각막확장증여부를예측하거나진단할때도중요한지표가된다. 1-3 중심각막두께의측정에는다양한방법들이있는데이중초음파각막두께측정계 (Ultrasonic pachymetry) 가표준으로간주되고있지만, 상대적으로높은측정자간변이성및점안마취제의사용, 그리고각막에직접접촉해야하는점들로인해 Orbscan, Pentacam, Galilei 등의비접촉각막두께측정법이개발되 접수일 : 2009 년 6 월 1 일 심사통과일 : 2009 년 11 월 24 일 책임저자 : 김진형고양시일산서구대화동 2240 인제대학교일산백병원안과 Tel: 031-910-7240, Fax: 031-911-7241 E-mail: jhk0924@hanmail.net 어사용되고있다. 4,5 비접촉각막두께측정법은전안부의스캔을통해각막두께를측정하고각막지형도를만드는방식인데, 선두격인 Orbscan이 elevation based-system을기준으로좌우로만지나는 slit beam 을이용한이미지임에비해 Pentacam과 Galilei는회전하는 Scheimpflug 카메라를사용한다. Pentacam은 1대의 360도회전하는 Scheimpflug 카메라를사용하여각막두께에관한정보를제공하고있으나, 6 Galilei는 2대의 Scheimpflug 카메라가 180도씩분리되어회전하면서측정함으로써보다더정확한각막두께에대한정보를제공할수있다. 7 지금까지국내에서정상인또는라식수술환자를대상으로초음파각막두께측정계, Orbscan 및 Pentacam을이용한각막두께측정값을비교한보고들이있었으나, Galilei로측정한값에대해서는아직정확한평가가이루어지지않았다. 8-11 특히미세각막절개도대신펨토초레이저를이용하여수술한라식수술환자의경우에이측정치들의양상이어떠한지에대한연구결과도알려진바가없다. 따라서본연구에서는정상인과펨토초레이저라식수술환자를대상으로하여접촉식각막두께측정계인초음파각막두께측정계와비접촉식각막두께측정계인 Orbscan, Pentacam 그리고 Galilei를이용하여중심각막두께를측정하여이를비교해보고자하였다. * 본논문의요지는 2008 년대한안과학회제 100 회추계학술대회에서구연으로발표되었음. * 본논문은인제대학교학술연구조성비보조에의한것임. 320 www.ophthalmology.org

- 박세훈외 : 중심각막두께측정값의비교 - 60 59 58 57 56 55 54 53 5 51 50 Orbscan Pentacam Galilei US Figure 1. Mean and 95% CI of CCT measurement by Orbscan, Pentacam, Galilei and US in Group I (CI=confidence interval; CCT=central.thickness; US=Ultrasonic pachymetry). 50 49 48 47 46 45 44 43 4 41 40 Orbscan Pentacam Galilei US Figure 2. Mean and 95% CI of CCT Measurement by Orbscan, Pentacam, Galilei and US in Group II (CI= confidence interval; CCT=central. thickness; US= Ultrasonic pachymetry). 50 49 48 47 46 45 44 43 4 41 40 Orbscan Pentacam Galilei US Figure 3. Mean and 95% CI of CCT Measurement by Orbscan, Pentacam, Galilei and US in Group III. (CI= confidence interval; CCT=central. thickness; US=Ultrasonic pachymetry). 대상과방법 본연구는 2006년 5월부터 2008년 5월까지펨토초레이저라식수술 (Femtosecond laser assisted LASIK) 을받은 30명 (60안) 과안과에서연구를위하여자원한자중피험자선정기준에해당되는정상인 15명 (30안) 을대상으로수술을받지않은정상안 30안 (Group I) 및펨토초레이저라식수술후 6개월이내 30안 ( 그룹 II), 펨토초레이저라식수술후 6개월이상경과한 30안 ( 그룹 III) 으로나누어시행하였다. 펨토초레이저를이용한라식 (Femtosecond laser assisted LASIK) 은 IntraLase FS laser (60kHz, AMO, CA, USA) 와 Intralase Software를사용하여컴퓨터제어방식으로일정한두께로각막절편을만든후엑시머레이저 (Technolas 217 Z100 eximer laser, Bausch & Lomb, U.S.A) 를이용하여 6.0 mm의광학부로조사하여각막실질부를절삭하였다. 본연구는환자및자원자의동의를얻은후진행하였으며, 각막질환, 백내장, 녹내장, 망막질환, 약시등의안과적질환이있거나안과수술기왕력이있는환자는연구에서제외하였다. 중심각막두께는서로다른 4가지각막두께측정계인 Orbscan II (Bausch & Lomb, Rochester, NY), Pentacam (OCULUS, Wetzlar, Germany), Galilei (Ziemer Group; Port, Switzerland) 와초음파각막두께측정기 (Advent, Mentor O&O, Norwell, MA, USA) 를사용하여측정하였다. 동일검사자가비접촉방식의 Orbscan, Pentacam, Galilei를순서대로먼저각 3회씩측정한후평균값을측정값으로하였다. Orbscan은제작사에서추천한보정인자 (acoustic equivalent factor) 인 0.92 대신정상안에서측정된새로운보정인자 (acoustic equivalent correction factor) 인 0.95를사용하여각막두께를계산하였다. 그리고 0.5% proparacaine hydrochloride (Alcaine, Alcon, Purrs, Belgium) 으로점안마취한후에접촉방식의초음파각막두께측정계 (default velocity:1640 m/s) 를 5회측정한후평균값을측정값으로하였다. 통계학적분석은 SPSS//PC 12.0 (SPSS Inc, Chicago, Ill) 를사용하였으며네가지기계사이의각막두께측정값의차이에대한비교는 one way ANOVA 와 Scheffé multiple comparison test를이용하였고, P<0.05 일경우통계적으로유의한것으로판단하였다. 또초음파각막두께측정계와다른기계들간에중심각막두께평균값차이와그상관관계를알아보기위해 Bland-Altman plots 및 Pearson 연관계수를이용하여연관성을평가하였다. www.ophthalmology.org 321

- 대한안과학회지 2010 년제 51 권제 3 호 - Table 1. Characteristics of the study groups Group I Group II Group III Patients (eyes) 30 30 30 Sex (M:F) 5:10 2:13 2:13 Age (mean) 27.45±7.49 29.33±7.49 25.92±4.25 Manifest refractive error (SE) (D) * -4.50±1.72-4.25±1.65-4.19±1.61 SE Correction (D) * -4.64±1.70-4.51±1.64 Follow-up duration (Month) 5.80±4.33 11.23±7.26 * SE=spherical equivalent; I=unoperated eyes; II=eyes 1 to 6 months after Femtosecond laser-assisted LASIK; III=eyes 6 months or more after Femtosecond laser-assisted LASIK. Table 2. Corneal thickness measurements in normal and post-femtosecond laser-assisted LASIK eyes using orbscan II, pentacam, galilei and ultrasound pachymetry (Mean±SE, μm) Group Orbscan Pentacam Galilei US * P value I 535.8±40.7 544.5±30.7 554.2±30.4 541.8±31.3 0.202 II 440.3±40.3 478.8±28.6 488.0±30.1 474.7±32.1.000 # III 432.2±51.7 472.5±33.5 482.8±32.9 470.0±33.3.000 # * US=ultrasound; I=unoperated eyes; II=eyes 1 to 6 months after Femtosecond laser-assisted LASIK; III=eyes 6 months or more after Femtosecond laser-assisted LASIK; Corrected Orbscan value=raw Orbscan value 0.95 of custom acoustic correction factor; # p<0.05; one-way ANOVA was used. 결과 대상환자의평균연령은그룹 I에서 27.45±7.49세, 그룹 II에서 29.33±7.49세그리고그룹 III에서 25.92±4.25세이었으며이들의성별분포는그룹 I의경우남자 5명, 여자 10명이었으며그룹 II, III의경우남자 2명, 여자 13명이었다. 평균구면렌즈대응치는그룹 I이 -4.50±1.72D, 그룹 II, III에서 -4.25±1.65D, -4.19±1.61D 이었고, 펨토초레이저라식수술안에서근시교정량의평균구면렌즈대응치는그룹 II, III에서 -4.64±1.70D, -4.51±1.64D 이었다. 펨토초레이저라식수술후평균경과관찰기간은그룹 II, III에서 5.80±4.33개월, 11.23±7.26개월이었다 (Table 1). 네가지측정법으로잰중심각막두께값의비교그룹 I-III에서 Orbscan, Pentacam, Galilei 그리고초음파각막두께측정계로측정된중심각막두께측정값의평균과 95% 신뢰구간의범위는다음과같았다 (Fig. 1, 2, 3). 그룹 I에서중심각막두께 ( 평균값 ± 표준편차 ) 는 Orbscan에서 535.8±40.7 μm, Pentacam은 544.5±30.7 μm, Galilei 는 554.2±30.4 μm, 초음파각막두께측정계는 541.8±31.3 μm으로 Galilei, Pentacam, 초음파각막두께측정계, Orbscan 순으로두껍게측정되었으나, 측정값들끼리통계적으로유의한차이는없었다 (P=.202, one way ANOVA, Table 2). 그룹 II에서중심각막두께 ( 평균값 ± 표준편차 ) 는 Orbscan에서 440.3±40.3 μm, Pentacam 은 478.8±28.6 μm, Galilei 는 488.0±30.1 μm, 초음파각막두께측정계는 474.7±32.2 μm 이었으며, 측정값사이에통계적으로유의한차이를보였으며 (P=.000, one way ANOVA, Table 2), 그룹 III에서 Orbscan는 432.2±51.7 μm, Pentacam은 472.5±33.5 μm, Galilei는 482.8±32.9 μm, 초음파각막두께측정계는 470.7 ±33.3 μm 이었고, 측정값사이에통계적으로유의한차이를보였다 (P=.000, one way ANOVA, Table 2). 펨토초레이저라식수술을받은 II, III군모두정상안에서와같이각막두께는 Galilei, Pentacam, 초음파각막두께측정계, Orbscan 순으로두껍게측정되었다. 그룹 II에서 Orbscan 의중심각막두께의평균값은 Galilei보다 47.7 μm, Pentacam보다 38.5 μm 그리고초음파각막두께측정계보다 34.4 μm 얇게측정되었고 (P<.001 and P<.001 and P=.001, respectively, one-way ANOVA and Scheffé multiple comparison test), 그룹 III에서 Orbscan의중심각막두께의평균값은 Galilei보다 50.6 μm, Pentacam보다 40.2 μm 그리고초음파각막두께측정계보다 37.8 μm 얇게측정되었다 (P<.001 and P=.001 and P=.001, respectively, one way ANOVA and Scheffé multiple comparison test). 그룹 II와 III간의초음파각막두께측정계와 Orbscan의차이값이통계적으로다른지를검증해보았을때유의한차이는없었다 (P=.812, paired t-test). 비접촉성각막두께측정법들의정확도및초음파각막두께측정값과의일치성초음파각막두께측정값을황금기준으로두고각각의측정값들과유의한차이가있는지를 one way ANOVA 322 www.ophthalmology.org

- 박세훈외 : 중심각막두께측정값의비교 - Group Ⅰ Group Ⅱ -1-1 - - -4 50 60 Average of Galilei & US Group Ⅰ -4 30 40 50 60 Average of Galilei & US Group Ⅱ 4 4 - - -4-4 50 60 Average of Pentacam & US Group Ⅰ 30 40 50 60 Average of Pentacam & US Group Ⅱ 4 4 - - -4-4 -6-6 -8-8 50 60 Average of Orbscan & US Figure 4. Bland-Altman plots of Galilei, Pentacam and Orbscan CCT readings against US measurement in Group I. The middle line is the mean and the lines on the side represent the upper and lower 95% limits of agreement (LoA). 30 40 50 60 Average of Orbscan & US Figure 5. Bland-Altman plots of Galilei, Pentacam and Orbscan CCT readings against US measurement in Group II. The middle line is the mean and the lines on the side represent the upper and lower 95% limits of agreement (LoA). www.ophthalmology.org 323

- 대한안과학회지 2010 년제 51 권제 3 호 - -1 - -1 4 - -4 Group Ⅲ 40 50 60 Average of Galilei & US Group Ⅲ 40 50 60 Average of Pentacam & US Group Ⅲ and Scheffé multiple comparison test에의해측정한결과그룹 I에서는통계적으로유의한차이를보이지않았으며, 그룹 II와 III에서초음파각막두께측정계와 Orbscan의차이가통계적으로유의하게나타났다 (P<.001, Table 3). 그룹 I, II, III 모두에서초음파각막두께측정계와 Pentacam, 초음파각막두께측정계와 Galilei는통계적으로유의한차이가나타나지않았다 (P>.05, Table 3). 초음파각막두께측정계와다른측정계들사이의측정값간의일치성을알아보기위해측정값차이의범위를비교하는 Bland-Altman plots 을시행하고, 각측정값간의상관관계를알아보았다 (Fig. 4, 5, 6). 그룹 I에서초음파각막두께측정계와 Orbscan, Pentacam 그리고 Galilei와의평균값의차이는 20 μm 이내로비슷한중심각막두께측정값의신뢰구간을보였고, 각각의측정값은초음파각막두께값과강한양의상관관계를보였다 (Pearson correlation, r =.982, r =.984, r =.932, p<.001, Table 3). 그룹 II, III에서각막두께측정계와 Pentacam 그리고 Galilei와의차이는 10 μm 이내로비슷한중심각막두께측정값의신뢰구간을보였고, 각각의측정값은초음파각막두께값과강한양의상관관계를보였다 (Pearson correlation, r =.983, r =.980, p<.001 in Group II; r =.972, r =.977 in Group III, Table 3). 그러나각막두께측정계와 Orbscan의차이는그룹 II에서 0.5 μm~-69.3 μm으로 69.8 μm의넓은신뢰구간의범주값을보였으며, 그룹 III 에서 11.1 μm~-86.5 μm으로 97.6 μm 의넓은신뢰구간의범주값을보였지만, 각각의측정값은초음파각막두께값과양의상관관계가있었다.(Pearson correlation, r =.903, p<.001 in Group II; r =.918, p<.001 in Group III, Table 3). 4 고 찰 - -4-6 -8-10 -1 40 50 60 Average of Orbscan & US Figure 6. Bland-Altman plots of Galilei, Pentacam and Orbscan CCT readings against US measurement in Group III. The middle line is the mean and the lines on the side represent the upper and lower 95% limits of agreement (LoA). 본연구의결과에의하면, 중심각막두께측정에있어현재까지보편적인기준으로생각되고있는초음파각막두께측정계의결과치와비접촉식측정계인 Orbscan, Pentacam, Galilei로측정한값이수술을하지않은정상안에서는서로간에의미있는차이가없고일치성이높다. 그러나펨토초레이저라식수술을받은경우초음파각막두께측정계와 Pentacam, Galilei로측정한값은강한양의상관관계를보이며비슷한중심각막두께를보였지만 Orbscan으로측정한값은통계적으로유의하게얇게측정되는경향을보였다. 기존연구에서 Ho et al 12 은라식후 Pentacam으로측정한중심각막두께가초음파각막두께측정계에비해 7.5 μm 정도얇게측정되는반면 Orbscan로측정한값은초음파각막두께측정계와의미있는차이가없다고보고하였다. 반 324 www.ophthalmology.org

- 박세훈외 : 중심각막두께측정값의비교 - Table 3. Mean difference, limit of agreements and pearson correlation in corneal thickness measurements for galilei, pentacam, orbscan and ultrasound pachymetry in group I, II and III Group and measurement Mean difference (μm) 95% Limit of agreements (μm) P Value Pearson correlation (R)(p<.001) Group I Galilei-US * 12.3-10.2, 34.9 0.487 0.982 Pentacam-US * 2.7-19.9, 25.3 0.989 0.984 Orbscan-US * -6.1-28.6, 16.5 0.897 0.932 Group II Galilei-US * 13.2-9.0, 35.5 0.412 0.983 Pentacam-US * 4.1-18.2, 26.4 0.964 0.980 Orbscan-US * -34.4-56.7, -12.1 1 # 0.903 Group III Galilei-US * 12.8-13.2, 38.9 0.573 0.972 Pentacam-US * 2.4-23.6, 28.5 0.995 0.977 Orbscan-US * -37.8-63.8, -11.7 1 # 0.918 * US=ultrasound; I=unoperated eyes; II=eyes 1 to 6 months after Femtosecond laser-assisted LASIK; III=eyes 6 months or more after Femtosecond laser-assisted LASIK; Corrected Orbscan value=raw Orbscan value 0.95 of custom acoustic correction factor; # p<0.05; one-way ANOVA and Scheffé multiple comparison test was used. 면 Hassan and Mehravaran 13 은라식전 Orbscan, Pentacam, 초음파각막두께측정계로측정한중심각막두께는유의한차이가없는반면라식후 Orbscan로측정한값이 Pentacam 및초음파각막두께측정계에비해유의하게얇게측정되었다고보고하였고, Kim et al 14 은라식후 Pentacam은초음파각막두께측정계와의미있는차이가없었으나 Orbscan은얇게측정된다고보고하였다. 또 Cheng et al 15 은라식전 Orbscan 과초음파각막두께측정계의중심각막두께측정값의의미있는차이가없는반면라식후에는 Orbscan의측정값이유의하게얇게측정되었다고보고하였다. 이와같이 Orbscan, Pentacam으로측정한라식수술전, 후의중심각막두께값은기존의연구에서다양한결과를보여주었다. 이러한결과들은일반미세각막절개도로수술한라식안에대한결과이고최근에보편화되고있는펨토초레이저라식수술후의결과는아직연구되어진바가없으며, 또한가장최근에나온비접촉식각막두께측정계인 Galilei의측정치에대한연구또한필요한상황이다. Galilei는 2대의 Scheimpflug 카메라가 180도씩분리되어회전하면서각막두께를측정함으로써경사각으로 scan 시발생할수있는오차를보완하면서중심각막뿐아니라주변부각막도정확하게각막두께의정보를제공하고있으며, 각막두께측정시미세움직임에대한오차도 1대의 Scheimpflug 카메라를사용하는 Pentacam보다정확하게보정할수있다는보고가있다. 7 이에보다정확한중심각막두께측정값에대한필요성이점점높아지고있는현시점에서그정확도에대한검토가필요하다. 본연구에서정상안 ( 그룹 I) 을보면서로다른 4가지장 비에서중심각막두께평균값은 Galilei, Pentacam, 초음파각막두께측정계, Orbscan 순으로두껍게측정되었고, 통계적으로유의한차이를보이지않았으며 (P=0.202), 초음파각막두께측정계의평균값과통계학적으로높은일치성을보였다 (Fig. 1, 4). 그러나펨토초레이저라식수술안 ( 그룹 II, III) 을보면서로다른 4가지장비에서중심각막두께평균값은통계적으로유의한차이를보였고 (P<.000), Orbscan 의중심각막두께가 Pentacam, Galilei, 초음파각막두께측정계보다통계적으로유의하게얇게측정되었으며초음파각막두께측정값과의일치성도낮았다. 이는일반라식수술후 Orbscan의측정값이다른측정법에비해얇게측정된다는기존의연구와일치하였다. 그러나수술경과후 6개월이내인그룹 II와 6개월이상인그룹 III에서이런양상이동일하고그측정치차이값도일정한것으로나타난것은기존연구와다른점이기도하다. 15 주목할만한것은 Orbscan 이펨토초레이저라식수술안 ( 그룹 II, III) 에서도초음파각막두께측정계와비교해보았을때낮게측정되는경향을보였는데이는일반라식수술환자에서 Obscan이보정인자 (acoustic equivalent factor) 의사용에도불구하고각막두께가더낮게측정되었다는여러가지보고의결과와일치한다. 15-17 Orbscan에서사용되는광학적각막두께측정은각막조직을통한반사된흩어진광선의측정에의존하므로각막매질에혼탁이있거나광학적인접촉면 (optical interface) 이있으면광선이방해받아측정이어려워진다는단점이있다. Orbscan system 이광학적인접촉면변화나각막투명도의소실에의해영향을받을수있다는보고들도있다. 18,19 특히각막실질의혼탁이중요한역할을하는것으로보이는데각막두께의저측정이단지각막앞면의윤곽 www.ophthalmology.org 325

- 대한안과학회지 2010 년제 51 권제 3 호 - 변화와각막실질경계면의간섭효과만이중요한역할을하는 LASIK군보다각막혼탁이흔한 PRK 군에서더욱높게나타났기때문이다. 16,20 또한펨토초레이저로만든각막절편은미세각막절개도로만든것보다보다더균일하고정확하다는보고를참고하자면, 이는펨토초레이저라식수술후 Orbscan의측정값이미세각막절개도를이용한것보다각막투명도에덜영향을받을것이라생각해볼수있다. 21 따라서저자들은펨토초레이저군와일반 LASIK군에서의양상에차이가있는지를비교하는연구도진행중이다. 그러므로 Orbscan은정상안에서각막두께를측정하는데에는적합하지만라식수술과같은굴절교정수술에서정확한각막두께의측정에는다른각막두께측정계들과보정이필요할것으로보인다. 본연구에서관심있게보았던 Gallilei의측정값은정상안이나펨토초레이저수술안에서가장두껍게측정되는경향을보였고, 초음파각막두께측정값과의일치성도높은편임을알수있었다. Pentacam과 Galilei를비교해보면그룹 I에서 Pentacam은초음파각막두께측정계와각막두께의평균값차이가 2.7 μm였고, Galilei는 12.3 μm였으며, 그룹 II에서는 Pentacam은초음파각막두께측정계와각막두께평균값의차이가 4.1 μm였고, Galilei는 13.2 μm였다. 그룹 III에서는 Pentacam은초음파각막두께측정계와각막두께의평균값차이가 2.4 μm였고, Galilei는 12.8 μm였다. 중심각막두께측정의표준인초음파각막두께측정계와비교해보았을때 Pentacam 그리고 Galilei는각막두께평균값의차이는높은상관관계를보이며통계적으로유의한차이를보이지않았으나 (P>.05), Pentacam이 Galilei보다초음파각막두께측정계와더비슷한각막두께의측정값을나타냈다. 본연구에서는정상안과펨토초레이저라식수술안에서서로다른 4가지각막두께측정계를통해중심각막두께의측정값을비교해보았다. 접촉식방식인초음파각막두께측정계가중심각막두께측정의표준으로사용되고있으나 Pentacam 그리고최근에나온이중샤임플러그전안부사진기 (Dual Scheimpflug analyzer) 인 Galilei는비접촉방식이므로마취가필요없고, 각막접촉에대한환자의불안감이없으며, 접촉으로인한감염위험성이없고, 라식과같은각막굴절교정수술중또는수술직후각막의직접적인접촉이없이도바로각막두께변화를측정할수있는장점을가진다. 또한초음파각막두께측정계와비교해정상안및펨토초레이저라식수술안에서중심각막두께의평균값이유의하게차이가나지않고, 높은상관관계를보여주고있어정상안및굴절교정수술후환자에서도각막두께측정에적합할것으로사료된다. 또비접촉방식인 Orbscan의경 우는정상안에서는다른기계들과통계적으로유의한차이가없었으나펨토초레이저라식수술안에서유의하게낮게측정되는경향을보여다른각막두께측정계들과보정이필요할것으로사료된다. 참고문헌 1) Binder PS. Ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2003;29:2419-29. 2) Price FW Jr, Koller DL, Price MO. Central corneal pachymetry in patients undergoing laser in situ keratomileusis. Ophthalmology 1999; 106:2216-20. 3) Iskander NG, Peters NT, Penno EA, Gimbel HV. Postoperative complications in laser in situ keratomileusis. Curr Opin Ophthalmol 2000;11:273-9. 4) Miglior S, Albe E, Guareschi M, et al. Intraobserver and interobserver reproducibility in the evaluation of ultrasonic pachymetry measurements of central corneal thickness. Br J Ophthalmol 2004;88:174-7. 5) Solomon OD. Corneal indentation during ultrasonic pachometry. Cornea 1999;18:214-5. 6) Rufer F, Schroder A, Arvani MK, Erb C. Central and peripheral corneal pachymetry--standard evaluation with the Pentacam system. Klin Monatsbl Augenheilkd 2005;222:117-22. 7) Menassa N, Kaufmann C, Goggin M, et al. Comparison and reproducibility of corneal thickness and curvature readings obtained by the Galilei and the Orbscan II analysis systems. J Cataract Refract Surg 2008;34:1742-47. 8) Kang PS, Kim JD, Yang YS. Comparison of corneal thickness measurements with the orbscan and ultrasonic pachymetry. J Korean Ophthalmol Soc 2000;41:1697-703. 9) Kim SH, Cho JH, Song BJ. Accuracy of Orbscan Pachymetry Measurements and Ultrasonic Pachymetry before and after LASIK with Orbscan IIR Topography. J Korean Ophthalmol Soc 2002; 43:2513-8. 10) Kwon M, Seoung Y, Hur D. Pachymetric measurements using orbscan after excimer refractive surgery. J Korean Ophthalmol Soc 2004;45:899-907. 11) Shin YJ, Kim, NH, Kim, DH. Comparison of Pentacam with Orbscan. J Korean Ophthalmol Soc 2007;48:637-41. 12) Ho T, Cheng AC, Rao SK, et al. Central corneal thickness measurements using Orbscan II, Visante, ultrasound, and Pentacam pachymetry after laser in situ keratomileusis for myopia. J Cataract Refract Surg 2007;33:1177-82. 13) Hashemi H, Mehravaran S. Central corneal thickness measurement with Pentacam, Orbscan II, and ultrasound devices before and after laser refractive surgery for myopia. J Cataract Refract Surg 2007;33:1701-7. 14) Kim SW, Byun YJ, Kim EK, Kim TI. Central corneal thickness measurements in unoperated eyes and eyes after PRK for myopia using Pentacam, Orbscan II, and ultrasonic pachymetry. J Refract Surg 2007;23:888-94. 15) Cheng AC, Rao SK, Tang E, Lam DS. Pachymetry assessment with Orbscan II in postoperative patients with myopic LASIK. J Refract Surg 2006;22:363-6. 326 www.ophthalmology.org

- 박세훈외 : 중심각막두께측정값의비교 - 16) Prisant O, Calderon N, Chastang P, et al. Reliability of pachymetric measurements using Orbscan after excimer refractive surgery. Ophthalmology 2003;110:511-5. 17) Yaylali V, Kaufman SC, Thompson HW. Corneal thickness measurements with the Orbscan Topography System and ultrasonic pachymetry. J Cataract Refract Surg 1997;23:1345-50. 18) Giessler S, Duncker GI. Orbscan pachymetry after LASIK is not reliable. J Refract Surg 2001;17:385-7. 19) Boscia F, La Tegola MG, Alessio G, Sborgia C. Accuracy of Or- bscan optical pachymetry in corneas with haze. J Cataract Refract Surg 2002;28:253-8. 20) Fakhry MA, Artola A, Belda JI, et al. Comparison of corneal pachymetry using ultrasound and Orbscan II. J Cataract Refract Surg 2002;28:248-52. 21) von Jagow B, Kohnen T. Corneal architecture of femtosecond laser and microkeratome flaps imaged by anterior segment optical coherence tomography. J Cataract Refract Surg 2009;35:35-41. =ABSTRACT= Central Corneal Thickness Measured by Four Different Methods in Normal and Post-Femtosecond Laser-Assisted LASIK Eyes Se Hoon Park, MD, Suk Kyue Choi, MD, Do Hyung Lee, MD, PhD, Jin Hyoung Kim, MD Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea Purpose: To compare corneal pachymetry assessment using four measurement methods in normal and post-femtosecond laserassisted LASIK eyes. Methods: Central corneal thickness was measured sequentially using Orbscan II, Pentacam, Galilei and ultrasonic pachymetry in 30 normal, non-surgical eyes (Group I), 30 eyes one to six months after femtosecond laser-assisted LASIK (Group II), and 30 eyes six months or longer after femtosecond laser-assisted LASIK (Group III). Results: In Group I, corneal thickness measurements were similar for all four methods (P=0.202, one way ANOVA). In Groups II and III, corneal thickness measurements were significantly different (P=0, respectively, one way ANOVA). Compared to the Pentacam, Galilei and ultrasonic pachymetry, Orbscan significantly underestimated the corneal thicknesses in Groups II and III (P<5, respectively, one way ANOVA). Conclusions: Central corneal thicknesses of normal eyes were similar for all four measurements, therefore corneal thickness measurements before refractive surgery using all four measurements is suitable. However measurements obtained with the Orbscan II were thinner than those obtained with the Pentacam, Galilei or ultrasonic pachymetry in post femtosecond laserassisted LASIK eyes. Further studies are needed to determine which instrument is more accurate in measuring central corneal thickness before and after refractive surgery. J Korean Ophthalmol Soc 2010;51(3):320-327 Key Words: Central corneal thickness, Femtosecond laser assisted LASIK, Galilei, Orbscan, Pentacam Address reprint requests to Jin Hyoung Kim, MD Department of Ophthalmology, Ilsan Paik Hospital, Inje University College of Medicine #2240 Ilsan Seo-gu, Daehwa, Goyang 411-706, Korea Tel: 82-31-910-7240, Fax: 82-31-911-7241, E-mail: jhk0924@hanmail.net www.ophthalmology.org 327