Detection ability of glaucomatous localized retinal nerve fiber layer defects with spectrum-domain optical coherence tomography

Abstract

목적: 스펙트럼영역 빛간섭단층촬영기를 이용하여 망막신경섬유층 지도와 기존의 유두주위 망막신경섬유층 두께, 황반부 내층망막 두께의 녹내장성 국소적 망막신경섬유층 결손의 검출력을 알아보고 비교하고자 하였다. 방법: 무적색 망막신경섬유층 사진에서 국소적 망막신경섬유층 결손이 있는 64안과 정상 72안을 대상으로 스펙트럼영역 빛간섭단층촬영기(3D OCT-2000 Topcon, Tokyo, Japan)로 촬영하였다. ImageJ 소프트웨어를 이용하여 무적색 망막신경섬유층 사진, 두께지도, significance map(yellow pixels, <5% level)에서 국소적 망막신경섬유층 결손의 너비와 면적을 측정하였다. 국소적 망막신경섬유층 결손 면적(망막신경섬유층 사진, 두께지도, significance map)과 구조적(시신경유두, 망막신경섬유층, 황반부 내측망막), 기능적(시야 지표) 측정치들과의 상관관계를 분석하였다. 유두주위 망막신경섬유층 두께(4 분면, 12 분면, 36 분면)와 망막신경섬유층 지도(thickness, significance)의 정상치 5% 미만인 경우를 비정상으로 분류한 것과 정량적 측정치를 사용하여 민감도, 특이도, receiver operating characteristic curves 하의 면적(AUCs)을 구하였다. 결과: 망막신경섬유층 결손 면적과 구조적-기능적 측정치들과의 관계는 유의하였다(유두주위 평균 망막신경섬유층 두께 r≥-0.709, mean deviation r≥-0.794, pattern standard deviation r≥0.768, 전부 p<0.001). 두께지도(민감도 96.9-98.4%, 특이도 86.1-98.6%, AUCs 0.915-0.992)와 significance map (민감도 96.9-98.4%, 특이도 88.9-95.8%, AUCs 0.937-0.983)은 36 분면 유두주위 망막신경섬유층 두께 (민감도 92.2%, 특이도 87.5%, AUCs 0.898)를 제외하고는 다른 파라미터들보다 국소적 망막신경섬유층 결손의 검출력이 우수하였다. 4 분면 유두주위 망막신경섬유층 두께는 비교적 특이도(97.2%)는 높았으나 민감도(65.6%)는 낮았다. 망막신경섬유층 결손 검출의 민감도는 유두주위 망막신경섬유층과 황반부 내측망막에서 망막신경섬유층 결손 너비, 면적, 두께와 관련이 있었다. 그러나 두께지도와 significance map에서는 망막신경섬유층 결손 면적, 두께와 무관하게 비교적 일정한 민감도를 보였다. 결론: 스펙트럼영역 빛간섭단층촬영기를 이용한 망막신경섬유층 두께지도와 significance map은 기존의 유두주위 망막신경섬유층 두께와 황반부 내층망막보다 국소적 망막신경섬유층 결손을 검출하는 데 더 효과적이었다. 또한 국소적 망막신경섬유층 결손 면적과 구조적-기능적 측정치들과는 밀접한 관련이 있었다. |Purpose: To evaluate and compare the ability for detecting glaucomatous retinal nerve fiber layer (RNFL) defects of RNFL maps with conventional circumpapillary RNFL thickness and macular inner retina thickness measurements using spectral domain optical coherence tomography (SD-OCT). Design: Prospective, comparative case series. Participants: Sixty-four eyes from 64 glaucoma patients with localized RNFL defects and 72 age-matched normal control participants who visited the glaucoma clinic at Hanyang University Medical Center from September 2010 to December 2011. Methods: Sixty-four eyes with localized RNFL defects in red-free RNFL photograph (31 superior defects and 48 inferior defects) and 72 healthy eyes were included. All participants were imaged with SD-OCT (3D OCT-2000 Topcon, Tokyo, Japan). The area and angular width of localized RNFL defect were measured using an ImageJ software on the RNFL thickness map, significance map (yellow pixels, <5% level) and red-free RNFL photographs. The RNFL defect areas (RNFL photograph, RNFL thickness map, and significance map) were analyzed by their correlations with structural (optic nerve head, RNFL, and macular inner retina) and functional (visual field indices) parameters. The sensitivity, specificity, and area under the receiver operating characteristic curves (AUCs) were calculated for circumpapillary RNFL thickness (4 sector, 12 sector, 36 sector), macular inner retina thickness, and RNFL maps (thickness, significance) according to the quantitative measurements and a <5% level of classification. Main Outcome Measures: Sensitivity, specificity, and AUCs Results: The relationship between RNFL defect area and structural-functional parameters was significant (r≥-0.709 for average circumpapillary RNFL thickness, r≥-0.794 for mean deviation, r≥0.768 for pattern standard deviation, all p<0.001). The thickness map (sensitivity 96.9-98.4%, specificity 86.1-98.6%, and AUCs 0.915-0.992) and significance map (sensitivity 96.9-98.4%, specificity 88.9-95.8%, and AUCs 0.937-0.983) showed superior performance in detecting the localized RNFL defects compared with other parameters except for 36 sector circumpapillary RNFL thickness (sensitivity 92.2%, specificity 87.5%, and AUCs 0.898) (almost all P<0.05). The 4 sector circumpapillary RNFL thickness had a relatively high specificity (97.2%) but sensitivity was low (65.6%). The sensitivity for detecting RNFL defects was related to the angular width, area, and thickness of the RNFL defects in circumpapillary RNFL (4 sector, 12 sector) and macular inner retina measurements. But the RNFL thickness and significance map showed constant sensitivity regardless variations of area, thickness of the RNFL defects. Conclusion: The RNFL thickness and significance maps imaged by SD-OCT could be used to identify localized RNFL defects more effectively than circumpapillary RNFL thickness and macular inner retina thickness measurements. In addition, structural and functional parameters are closely related to RNFL defect areas.; Purpose: To evaluate and compare the ability for detecting glaucomatous retinal nerve fiber layer (RNFL) defects of RNFL maps with conventional circumpapillary RNFL thickness and macular inner retina thickness measurements using spectral domain optical coherence tomography (SD-OCT). Design: Prospective, comparative case series. Participants: Sixty-four eyes from 64 glaucoma patients with localized RNFL defects and 72 age-matched normal control participants who visited the glaucoma clinic at Hanyang University Medical Center from September 2010 to December 2011. Methods: Sixty-four eyes with localized RNFL defects in red-free RNFL photograph (31 superior defects and 48 inferior defects) and 72 healthy eyes were included. All participants were imaged with SD-OCT (3D OCT-2000 Topcon, Tokyo, Japan). The area and angular width of localized RNFL defect were measured using an ImageJ software on the RNFL thickness map, significance map (yellow pixels, <5% level) and red-free RNFL photographs. The RNFL defect areas (RNFL photograph, RNFL thickness map, and significance map) were analyzed by their correlations with structural (optic nerve head, RNFL, and macular inner retina) and functional (visual field indices) parameters. The sensitivity, specificity, and area under the receiver operating characteristic curves (AUCs) were calculated for circumpapillary RNFL thickness (4 sector, 12 sector, 36 sector), macular inner retina thickness, and RNFL maps (thickness, significance) according to the quantitative measurements and a <5% level of classification. Main Outcome Measures: Sensitivity, specificity, and AUCs Results: The relationship between RNFL defect area and structural-functional parameters was significant (r≥-0.709 for average circumpapillary RNFL thickness, r≥-0.794 for mean deviation, r≥0.768 for pattern standard deviation, all p<0.001). The thickness map (sensitivity 96.9-98.4%, specificity 86.1-98.6%, and AUCs 0.915-0.992) and significance map (sensitivity 96.9-98.4%, specificity 88.9-95.8%, and AUCs 0.937-0.983) showed superior performance in detecting the localized RNFL defects compared with other parameters except for 36 sector circumpapillary RNFL thickness (sensitivity 92.2%, specificity 87.5%, and AUCs 0.898) (almost all P<0.05). The 4 sector circumpapillary RNFL thickness had a relatively high specificity (97.2%) but sensitivity was low (65.6%). The sensitivity for detecting RNFL defects was related to the angular width, area, and thickness of the RNFL defects in circumpapillary RNFL (4 sector, 12 sector) and macular inner retina measurements. But the RNFL thickness and significance map showed constant sensitivity regardless variations of area, thickness of the RNFL defects. Conclusion: The RNFL thickness and significance maps imaged by SD-OCT could be used to identify localized RNFL defects more effectively than circumpapillary RNFL thickness and macular inner retina thickness measurements. In addition, structural and functional parameters are closely related to RNFL defect areas.