ORIGINAL STUDY
Comparing Spectral-Domain Optical Coherence Tomography and Standard Automated Perimetry to Diagnose Glaucomatous Optic Neuropathy Harsha L. Rao, MD, DNB,*w Ravi K. Yadav, B Opt,* Uday K. Addepalli, B Opt,* Viquar U. Begum, B Opt,* Sirisha Senthil, MS, FRCS,* Nikhil S. Choudhari, DNB,* and Chandra S. Garudadri, MD, FRCS*
Purpose: To compare the abilities of standard automated perimetry (SAP) and spectral-domain optical coherence tomography (SDOCT) in diagnosing eyes with glaucomatous optic neuropathy (GON). Methods: In a cross-sectional study, 280 eyes of 175 subjects referred to tertiary eye care center by general ophthalmologists for a glaucoma evaluation underwent retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) imaging with SDOCT. All subjects had at least 2 reliable and repeatable SAP. Two glaucoma experts masked to clinical and SAP results classified the optic nerves into GON and nonglaucomatous groups based on digital optic disc photographs. Ability of SDOCT parameters and SAP to discriminate GON eyes from nonglaucomatous eyes was evaluated using sensitivity, specificity, and likelihood ratios (LR). Results: Experts classified 179 eyes into GON and 101 eyes into nonglaucomatous group. Sensitivity of SAP (69.8%) was significantly lower (P < 0.05) than that of inferior quadrant RNFL thickness (83.8%), average RNFL thickness (77.2%), GCC focal loss volume (FLV, 81.5%), and global loss volume (GLV, 82.6%). Specificity and positive LR of SAP (95% and14.1, respectively) were significantly greater than those of all RNFL parameters, FLV (84.2% and 5.1) and GLV (82.2% and 4.6). Negative LR of SAP (0.32) was significantly inferior to that of inferior quadrant RNFL thickness (0.22), FLV (0.22), and GLV (0.21). Conclusions: Most of the RNFL and GCC parameters of SDOCT had better sensitivities and negative LRs to diagnose GON compared with SAP. The specificities and positive LRs of most SDOCT parameters were inferior to that of SAP.
which enables the imaging of structural changes happening in glaucoma with higher resolution and faster scan rate.1,2 Standard automated perimetry (SAP) is a standard technique of quantifying the VF defects in glaucoma. Although the presence of both structural and functional change is required for diagnosing glaucoma, studies with SDOCT have shown that the correlation between structural and functional abnormality in glaucoma is modest at best,3–6 with some cases showing a structural change before a functional change and a few others showing a functional change before a structural change. Any new imaging technology in glaucoma is usually first evaluated against the SAP. The study design employed is usually a case-control design, defining cases and controls based on the presence or absence of VF defects on SAP. Diagnostic ability of SDOCT in glaucoma has also been evaluated in similar manner by several studies and has been reported to be good.3,7–12 However, considering the not-sogood structure-function relationship in glaucoma, all these studies have only evaluated the diagnostic ability of SDOCT against SAP in glaucoma but have not compared the diagnostic abilities of SDOCT and SAP with each other. The purpose of the current study was to compare the abilities of SAP and SDOCT in differentiating eyes with glaucomatous optic neuropathy (GON), as classified by 2 independent glaucoma experts on masked evaluation of optic disc photographs, from nonglaucomatous eyes.
Key Words: spectral-domain optical coherence tomography, standard automated perimetry, glaucomatous optic neuropathy
(J Glaucoma 2015;24:e69–e74)
G
laucoma is a progressive optic neuropathy characterized by typical optic disc and retinal nerve fiber layer (RNFL) (structural) changes with correlating visual field (VF; functional) defects. Spectral-domain optical coherence tomography (SDOCT) is a recent technique
Received for publication June 8, 2013; accepted March 4, 2014. From the *VST Glaucoma Center; and wCenter for Clinical Epidemiology and Biostatistics, L V Prasad Eye Institute, Banjara Hills, Hyderabad, India. Disclosure: The authors declare no conflict of interest. Reprints: Harsha L. Rao, MD, DNB, Kallam Anji Reddy Campus, L V Prasad Eye Institute, Banjara Hills, Hyderabad 500034, India (e-mails: [email protected]; [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000048
J Glaucoma
METHODS This was an observational, cross-sectional study of subjects referred by general ophthalmologists for a glaucoma evaluation, to a tertiary eye care facility. Informed consent was obtained from all subjects and the Ethics Committee of L V Prasad Eye Institute approved all methodology. All methods adhered to the tenets of the Declaration of Helsinki for research involving human subjects. Inclusion criteria were age 18 years and older, bestcorrected visual acuity of 20/40 or better, and refractive error within ± 5 D sphere and ± 3 D cylinder. Exclusion criteria were presence of any media opacities that prevented good-quality optic disc photographs and SDOCT imaging and any retinal (including macular) disease other than glaucoma which could confound the evaluations. All participants underwent a comprehensive ocular examination which included a detailed medical history, best-corrected visual acuity measurement, slit-lamp biomicroscopy, Goldmann applanation tonometry, gonioscopy, dilated
Volume 24, Number 5, June/July 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
e69
Rao et al
J Glaucoma
fundus examination, SAP, digital optic disc photography, and SDOCT imaging with RTVue (Optovue Inc., Fremont, CA). SAP was performed using a Humphrey Field analyzer, model 750 (Zeiss Humphrey Systems, Dublin, CA), with the Swedish interactive threshold algorithm standard 24-2 test. Reliability criteria were fixation losses, false-positive and false-negative response rates of
Comparing Spectral-Domain Optical Coherence Tomography and Standard Automated Perimetry to Diagnose Glaucomatous Optic Neuropathy Harsha L. Rao, MD, DNB,*w Ravi K. Yadav, B Opt,* Uday K. Addepalli, B Opt,* Viquar U. Begum, B Opt,* Sirisha Senthil, MS, FRCS,* Nikhil S. Choudhari, DNB,* and Chandra S. Garudadri, MD, FRCS*
Purpose: To compare the abilities of standard automated perimetry (SAP) and spectral-domain optical coherence tomography (SDOCT) in diagnosing eyes with glaucomatous optic neuropathy (GON). Methods: In a cross-sectional study, 280 eyes of 175 subjects referred to tertiary eye care center by general ophthalmologists for a glaucoma evaluation underwent retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) imaging with SDOCT. All subjects had at least 2 reliable and repeatable SAP. Two glaucoma experts masked to clinical and SAP results classified the optic nerves into GON and nonglaucomatous groups based on digital optic disc photographs. Ability of SDOCT parameters and SAP to discriminate GON eyes from nonglaucomatous eyes was evaluated using sensitivity, specificity, and likelihood ratios (LR). Results: Experts classified 179 eyes into GON and 101 eyes into nonglaucomatous group. Sensitivity of SAP (69.8%) was significantly lower (P < 0.05) than that of inferior quadrant RNFL thickness (83.8%), average RNFL thickness (77.2%), GCC focal loss volume (FLV, 81.5%), and global loss volume (GLV, 82.6%). Specificity and positive LR of SAP (95% and14.1, respectively) were significantly greater than those of all RNFL parameters, FLV (84.2% and 5.1) and GLV (82.2% and 4.6). Negative LR of SAP (0.32) was significantly inferior to that of inferior quadrant RNFL thickness (0.22), FLV (0.22), and GLV (0.21). Conclusions: Most of the RNFL and GCC parameters of SDOCT had better sensitivities and negative LRs to diagnose GON compared with SAP. The specificities and positive LRs of most SDOCT parameters were inferior to that of SAP.
which enables the imaging of structural changes happening in glaucoma with higher resolution and faster scan rate.1,2 Standard automated perimetry (SAP) is a standard technique of quantifying the VF defects in glaucoma. Although the presence of both structural and functional change is required for diagnosing glaucoma, studies with SDOCT have shown that the correlation between structural and functional abnormality in glaucoma is modest at best,3–6 with some cases showing a structural change before a functional change and a few others showing a functional change before a structural change. Any new imaging technology in glaucoma is usually first evaluated against the SAP. The study design employed is usually a case-control design, defining cases and controls based on the presence or absence of VF defects on SAP. Diagnostic ability of SDOCT in glaucoma has also been evaluated in similar manner by several studies and has been reported to be good.3,7–12 However, considering the not-sogood structure-function relationship in glaucoma, all these studies have only evaluated the diagnostic ability of SDOCT against SAP in glaucoma but have not compared the diagnostic abilities of SDOCT and SAP with each other. The purpose of the current study was to compare the abilities of SAP and SDOCT in differentiating eyes with glaucomatous optic neuropathy (GON), as classified by 2 independent glaucoma experts on masked evaluation of optic disc photographs, from nonglaucomatous eyes.
Key Words: spectral-domain optical coherence tomography, standard automated perimetry, glaucomatous optic neuropathy
(J Glaucoma 2015;24:e69–e74)
G
laucoma is a progressive optic neuropathy characterized by typical optic disc and retinal nerve fiber layer (RNFL) (structural) changes with correlating visual field (VF; functional) defects. Spectral-domain optical coherence tomography (SDOCT) is a recent technique
Received for publication June 8, 2013; accepted March 4, 2014. From the *VST Glaucoma Center; and wCenter for Clinical Epidemiology and Biostatistics, L V Prasad Eye Institute, Banjara Hills, Hyderabad, India. Disclosure: The authors declare no conflict of interest. Reprints: Harsha L. Rao, MD, DNB, Kallam Anji Reddy Campus, L V Prasad Eye Institute, Banjara Hills, Hyderabad 500034, India (e-mails: [email protected]; [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000048
J Glaucoma
METHODS This was an observational, cross-sectional study of subjects referred by general ophthalmologists for a glaucoma evaluation, to a tertiary eye care facility. Informed consent was obtained from all subjects and the Ethics Committee of L V Prasad Eye Institute approved all methodology. All methods adhered to the tenets of the Declaration of Helsinki for research involving human subjects. Inclusion criteria were age 18 years and older, bestcorrected visual acuity of 20/40 or better, and refractive error within ± 5 D sphere and ± 3 D cylinder. Exclusion criteria were presence of any media opacities that prevented good-quality optic disc photographs and SDOCT imaging and any retinal (including macular) disease other than glaucoma which could confound the evaluations. All participants underwent a comprehensive ocular examination which included a detailed medical history, best-corrected visual acuity measurement, slit-lamp biomicroscopy, Goldmann applanation tonometry, gonioscopy, dilated
Volume 24, Number 5, June/July 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
e69
Rao et al
J Glaucoma
fundus examination, SAP, digital optic disc photography, and SDOCT imaging with RTVue (Optovue Inc., Fremont, CA). SAP was performed using a Humphrey Field analyzer, model 750 (Zeiss Humphrey Systems, Dublin, CA), with the Swedish interactive threshold algorithm standard 24-2 test. Reliability criteria were fixation losses, false-positive and false-negative response rates of
