Scanning Laser Polarimetry with Enhanced CornealCompensation for Detection of Axonal Loss in Band
Atrophy of the Optic Nerve
MÁRIO L. R. MONTEIRO, FREDERICO C. MOURA, AND FELIPE A. MEDEIROS
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PURPOSE: To compare the abilities of scanning laserolarimetry (SLP) with enhanced corneal compensationECC) and variable corneal compensation (VCC) modesor detection of retinal nerve fiber layer (RNFL) loss inyes with band atrophy (BA) of the optic nerve.DESIGN: Cross-sectional study.METHODS: Thirty-seven eyes from 37 patients withA and temporal visual field defect from chiasmal com-ression and 40 eyes from 40 healthy subjects weretudied. Subjects underwent standard automated perim-try and RNFL measurements using an SLP devicequipped with VCC and ECC. Receiver operating char-cteristic (ROC) curves were calculated for each param-ter. Pearson correlation coefficients were obtained tovaluate the relationship between RNFL thickness pa-ameters and severity of visual field loss, as assessed byhe temporal mean defect.
RESULTS: All RNFL thickness parameters were signif-cantly lower in eyes with BA compared with normal eyesith both compensation modes. However, no statistically
ignificant differences were observed in the areas underhe ROC curves for the different parameters betweenDx VCC and ECC (Carl Zeiss Meditec, Inc, Dublin,alifornia, USA). Structure-function relationships alsoere similar for both compensation modes.CONCLUSIONS: No significant differences were found
widely used noninvasive clinical method to evaluatethe retinal nerve fiber layer (RNFL) mainly in
ccepted for publication Nov 27, 2007.From the Division of Ophthalmology, University of São Paulo Medical
chool, São Paulo, Brazil (M.L.R.M., F.C.M., F.A.M.); and the Hamiltonlaucoma Center, Department of Ophthalmology, University of Califor-ia, San Diego, La Jolla, California (F.A.M.).
oInquiries to Mário L. R. Monteiro, Av. Angélica 1757 conj. 61,
atients with glaucoma.1,2 SLP uses a confocal scanningaser ophthalmoscope with an integrated polarimeter tostimate quantitatively the thickness of the RNFL byeasuring the change in polarization of the incident light
s it double-passes through the birefringent RNFL. Themount of retardation in the reflected light is proportionalo the RNFL thickness,3 although a contribution of ante-ior segment birefringence also is present and has to beompensated for.4
The latest commercially available SLP device, the GDxCC (Carl Zeiss Meditec, Inc, Dublin, California, USA),as an integrated variable corneal compensator (VCC)hat determines and neutralizes the eye-specific anterioregment polarization axis and magnitude and providesore exact RNFL thickness measurements than the earlier
xed corneal compensation (FCC) technology.5–7 How-ver, shortly after the introduction of the GDx VCC,everal scans showing atypical retardation patterns (ARP)ere observed in some patients. These scans show irregularatches of elevated retardation values that do not matchhe expected retardation based on the RNFL anatomiceatures. ARPs seem to result from poor signal-to-noiseatio as a consequence of light scattering in the eye.8 Toompensate for a decrease in signal, the instrument auto-atically increases the gain to augment the polarization
ignal, which paradoxically increases the noise from deepertructures such as the sclera. ARPs are more common inlder and myopic eyes and in eyes with thin retinaligment epithelium.9 ARPs produce artifactual patchyreas of increased RNFL thickness in regions usuallyssociated with decreased thickness, particularly in theemporal and nasal areas of the peripapillary retina.10
An enhanced algorithm (enhanced corneal compensa-ion [ECC]) has been developed to improve the signal-to-oise ratio and to eliminate artifacts associated with ARPshile still allowing compensation for the anterior segmentirefringence.11,12 The GDx ECC introduces a large,reviously established birefringence bias to shift the mea-urement of total retardation into a higher value regionnd to boost the signal-to-noise ratio. Several studies inlaucoma patients have found ECC to be superior to VCCith regard to diagnostic accuracy and the correlationetween RNFL measures and visual function.10,13–15
The pattern of RNFL loss in patients with lesions of the
ptic chiasm represents an interesting model to evaluate
he ability of any instrument to detect loss of RNFL in theasal and temporal sectors of the optic disk. In patientsith extensive mid-chiasmal lesions and showing severeitemporal hemianopia with preserved nasal field, the crossederve fibers originating in the nasal hemiretina are lost,ith preservation of the uncrossed fibers, which originate
n the temporal hemiretina and penetrate the optic nervehrough the superior and inferior arcuate fiber bundles.herefore, RNFL loss occurs predominantly on the nasalnd temporal sides of the optic disk. Such a pattern may bedentified on ophthalmoscopy as band atrophy (BA) ofhe optic nerve and is an important clinical sign in theiagnosis of patients with chiasmal compression and instimating the chances of improvement of visual fieldefects after decompression of the optic pathway.16
In a previous study, we demonstrated that GDx FCC hasoor sensitivity to detect axonal loss in the temporal andasal regions of the optic disk in patients with BA of theptic nerve.17 In another study, we found that GDx VCCignificantly improved detection of RNFL loss in theemporal quadrant when compared with GDx FCC, buttill performed worse than optical coherence tomographyOCT).18 Because the introduction of ECC presumablymproves SLP performance by eliminating or reducingRPs in the nasal and temporal areas of the peripapillary
etina, we designed a study to compare the ability of GDxCC and GDx VCC to detect RNFL loss in patients withA of the optic nerve.
METHODS
HIS WAS AN OBSERVATIONAL, PROSPECTIVE, CROSS-
ectional study. Participants were recruited for exami-ation at the Department of Ophthalmology of theniversity of São Paulo Medical School between May 1,
003 and October 31, 2005. A total of 37 eyes of 37atients (21 male) with temporal hemianopia from chias-al compression and 40 eyes from 40 normal age- and
ender-matched controls (21 male) were studied. Allatients with a history of chiasmal lesions had beenubmitted to previous treatment of the suprasellar lesionnd had stable visual field defects and visual acuity (VA)or at least one year before study entry.
All subjects underwent a complete ophthalmologic exam-nation including visual field evaluation. Visual field testingas performed using the Goldmann perimeter (Haag-StreitG, Bern, Switzerland). The V-4-e, I-4-e, I-3-e, I-2-e, and
-1-e stimuli were used to draw the isopters. Kineticeterminations were followed by static presentation of thetimuli, particularly in the central 30-degree area, to searchor localized defects. In addition, all patients also under-ent standard automated perimetry (SAP) using the 24-2
ull-threshold strategy (Humphrey Field Analyzer; Carl- a
AMERICAN JOURNAL OF48
eiss Meditec, Dublin, California, USA). Visual field andLP examinations were performed on the same day orithin a maximum period of two weeks.The inclusion criteria for the study were best-corrected
A of 20/30 or better in the study eye; age between 15 and0 years; spherical refraction within � 5 diopters (D);ylinder refraction within � 4 D; intraocular pressure lesshan 22 mm Hg; and reliable visual field. A reliableumphrey visual field test was defined as one with fewer
han 25% fixation losses, false-positive responses, or false-egative responses. Patients with a history of intraocularressure elevation, with clinical signs of glaucomatousptic neuropathy or optic disk anomaly, were excluded.Patients with BA were required to have complete or
artial temporal hemianopia on Humphrey and Goldmannerimetry and a nasal hemifield within normal limits onoth tests. A normal nasal hemifield on Goldmann perim-try was defined as the presence of normal I-4-e, I-2-e, and-1-e isopters. On SAP, a normal hemifield was defined ashe absence of any cluster of at least three points with P �05 on the pattern deviation plot. Only one eye of eachatient was selected for analysis. In 31 patients, only oneye met the inclusion criteria. For the six patients in whomoth eyes fulfilled the inclusion criteria, one eye waselected randomly for analysis. The severity of visual fieldefect in patients with BA was determined by calculatinghe temporal mean defect (TMD). This was performed byveraging the values of the total deviation plot for the 22emporal points of the SAP threshold 24-2 test, excludinghe two points immediately above and below the blindpot.
The control group consisted of normal healthy volun-eers recruited from among the hospital staff. All normalubjects had normal ophthalmic findings and normal SAPisual fields. A normal SAP visual field was defined as aattern standard deviation (PSD) within the 95% confi-ence limit and a glaucoma hemifield test result within theormal range. Healthy control eyes also had healthy-
ooking optic disks and RNFLs. One eye of each healthyubject was included for analysis, and the selection be-ween right or left eye was performed to match theelection in patients with BA.
SCANNING LASER POLARIMETRY: The thickness ofhe peripapillary RNFL was determined using a commer-ially available GDx device using VCC and ECC technol-gies (software version 5.4.0; Carl Zeiss Meditec). Thepherical equivalent refractive error of each eye was enterednto the software to allow the GDx to focus on the retina.he general principles and operation of SLP have been
eported previously.2 In brief, the device uses a diode laserith a wavelength of 780 nm to create a polarized laseream aimed at the retina.3 The reflected light double-assing the RNFL is used to obtain the retardation image
t that point. The GDx VCC uses a variable corneal
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olarization compensator that allows eye-specific compen-ation of anterior birefringence. After determining the axisnd magnitude of corneal polarization in each eye byacular scanning5, three appropriately compensated reti-al polarization images per eye were obtained automati-ally and were combined to form each mean image used fornalysis. With the ECC software, the corneal polarizationompensator was adjusted automatically to introduce a biasetardation of approximately 55 nm and to position thelow axis of polarization close to vertical. This adjustmentias boosts the signal and thus overcomes low sensitivityhat can make retardation measurements susceptible toptical and electronic noise. After image acquisition, theias was subtracted to obtain the final RNFL retardationalues.9
The quality of the reflectance image and retardance imageor cornea and macula was reviewed for even illumination,entering, and appropriate corneal compensation. Imagesere considered to be of high quality if sharply focusedith even illumination and well centered on the opticerve, with minimal eye movement. All images had auality score of at least 8.RNFL thickness images obtained in both compensationodes were divided into four segments: superior 120
egrees (with 0 degrees at the 12-o’clock position, 295 to5 degrees), nasal 70 degrees (55 to 125 degrees), inferior20 degrees (125 to 245 degrees), and temporal 50 degrees245 to 295 degrees). These segments were used to calcu-ate the different parameters of the nerve fiber analysis.he GDx VCC parameters investigated in this study were
To quantify the presence of ARPs on GDx VCC scans,e used the software-provided parameter typical scan score
TSS). The TSS is a continuous variable ranging from zeroo 100 and is the result of a support vector machinenalysis of SLP data labeled for training based on theubjective appearance of each scan (typical vs atypical).SS is based on the slope, standard deviation, and averageagnitude of RNFL thickness measurements from the edge
f the optic disk extending outward to 20 degrees. LowSS scores indicate atypical scans and high TSS scores
ndicate typical ones. As in earlier studies, TSS values ofess than 80 indicated atypical images.11,15
STATISTICAL ANALYSIS: RNFL thickness values ob-ained in the GDx VCC and GDx ECC mode wereompared using the paired t test. The histogram analysisnd the Shapiro-Wilk test confirmed that the distributionsatisfied the normality assumption. GDx VCC and GDxCC-obtained RNFL thickness values of eyes with BA alsoere compared with values from normal controls using thetudent unpaired t test.Receiver operating characteristic (ROC) curves were used
o describe the ability of GDx VCC and ECC parameters to V
GDX ECC IN BANOL. 145, NO. 4
iscriminate eyes with BA from healthy eyes. The method ofeLong and associates was used to compare areas under theOC curves (AUCs).19 The sensitivity at 80% and 95%
pecificity was calculated for each parameter. Pearson corre-ation coefficients were used to evaluate the relationshipetween RNFL thickness parameters and TMD-determinedeverity of visual field loss.
P values less than .05 were considered statisticallyignificant. The statistical analyses were carried out withhe SPSS software version 15.0 (SPSS, Inc, Chicago,llinois, USA).
RESULTS
TOTAL OF 37 EYES FROM 37 PATIENTS WITH TEMPORAL
emianopia and 40 eyes from 40 normal subjects weretudied. Thirty-two patients had pituitary adenoma, threead craniopharyngioma, and two had suprasellar meningi-ma. The mean age � standard deviation (SD) was 44.5 �2.1 years (range, 18 to 72 years) in BA patients and2.7 � 10.9 years (range, 18 to 71 years) in normalubjects (P � .39, Student unpaired t test). The averageAP mean deviation (� SD) and SAP TMD in BAatients were �8.25 � 5.13 decibels (dB) and �17.91 �1.2 dB, respectively. The funduscopic examination re-ealed signs of BA of the optic disk and RNFL in all 37yes with temporal hemianopic field defect.
Table 1 shows comparisons of VCC and ECC values forhe different RNFL thickness parameters in eyes with BAnd normal controls. In eyes with BA, the parameteremporal average was significantly lower with ECC thanith VCC. In normal subjects, RNFL thickness measure-ents were significantly lower with ECC than with VCCode for TSNIT average, nasal average, and temporal
verage.We also compared RNFL thickness measurements in
yes with BA of the optic nerve vs healthy eyes for theDx VCC and GDx ECC. All RNFL thickness parametersere significantly lower in eyes with BA than in normalyes for both compensation modes (P � .001 for allomparisons). Table 2 shows AUCs and sensitivities atxed specificities for GDx VCC and GDx ECC. Theverage thickness parameter had the largest ROC curverea in both compensation modes (0.97 and 0.96, for GDxCC and ECC, respectively; P � .45). No statistically
ignificant difference was observed in the AUCs for theifferent parameters between GDx VCC and ECC. Forhe nasal average parameter, ROC curve areas were 0.93nd 0.88 for GDx VCC and ECC, respectively (P � .19).or the temporal average, ROC curve areas were 0.77 and.72, respectively (P � .46).Table 3 shows the associations between GDx VCC
nd ECC thickness parameters and TMD values. With
CC, the highest correlation was observed for the
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arameter superior average (r � 0.72; R2 � 52%; P �001). With ECC, the highest correlation also wasbserved for the parameter superior average (r � 0.70;2 � 49%; P � .001; Figure). The parameter nasal average
TABLE 1. Comparison of Mean Values (� Standard DeviationFiber Layer Thickness Parameters (in �m) with Areas under
Comparison between patients with band atrophy and controls we
ECC (P � .001 for all comparisons, Student t test).
*Paired t test. Significant values appear in boldface.
TABLE 2. Area under the Receiver Operating Characteristic CFiber Layer Parameters of Scanning Laser Polarimetry with V
Compensa
Parameter
ROC Curve Area (SD)
P value*GDx VCC GDx ECC Sp
TSNIT average 0.97 (0.01) 0.96 (0.02) 0.45
Superior average 0.93 (0.02) 0.93 (0.02) 0.96
Inferior average 0.94 (0.02) 0.95 (0.02) 0.48
Nasal average 0.93 (0.03) 0.88 (0.03) 0.19
Temporal average 0.77 (0.05) 0.72 (0.05) 0.46
ECC � enhanced corneal compensation; SD � standard deviatio
corneal compensator.
*Method of De Long and associates.
TABLE 3. Associations between GDx VCC and GDx ECC SParameters and Temporal
GDx VCC RFNL Thickness Parameters R* P value
TSNIT average 0.64 <.001Superior average 0.72 <.001Inferior average 0.51 .001Nasal average 0.38 .022Temporal average �0.003 .98
ECC � enhanced corneal compensation; RNFL � retinal nerve fi
variable corneal compensator.
*Pearson correlation coefficient. Significant values appear in bold
as significantly correlated with TMD in both compensation 9
AMERICAN JOURNAL OF50
odes. No statistically significant correlation was found forhe parameter temporal average in either mode.
In eyes with BA of the optic nerve, TSS differedignificantly between images produced with VCC (mean,
CC and ECC GDx Scanning Laser Polarimeter Retinal Nerveeceiver Operating Characteristic Curves and Sensitivities atof the Optic Nerve and Normal Controls
4.5; SD, 11.9; range, 56 to 100) and ECC (mean, 99.8;
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D, 1.2; range, 93 to 100; P � .001, paired t test). Inormal eyes, the corresponding values were 91.2 � 15.3range, 35 to 100) in VCC mode and 99.4 � 2.5 (range, 87o 100) in ECC mode (P � .001). Four (11%) of 37 eyes withA and seven (18%) of 40 normal eyes had a TSS of less than0 in the VCC mode. None of the 77 eyes evaluated in thewo groups had a TSS of less than 80 in the ECC mode.
DISCUSSION
N THE PRESENT STUDY, WE FOUND THAT SLP RNFL THICK-
IGURE. Scatterplots demonstrating scanning laser polarimetry supeand atrophy of the optic nerve (Top) with variable corneal compens
ess measurements in eyes with BA of the optic nerve were T
GDX ECC IN BANOL. 145, NO. 4
ignificantly lower than in healthy eyes, regardless of theompensation mode used (i.e., VCC or ECC). However,o significant differences were observed between these twoompensating modes in their ability to detect RNFL loss inatients with BA of the optic nerve.Previous studies performed in patients with glaucoma
emonstrated a better performance of the GDx ECCompared with VCC for detection of RNFL loss, particu-arly in the presence of ARPs. Toth and Hollo evaluated7 eyes with glaucoma and 19 healthy eyes with ARPssing both VCC and ECC.15 The presence of ARPs oneripapillary SLP VCC images was assessed by using the
verage parameter vs temporal mean defect values in the 37 eyes withand (Bottom) with enhanced corneal compensation. dB � decibels.
rior aation
SS score (TSS values � 80 were taken as an indication
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f the presence of ARPs). The authors observed that theNFL parameters TSNIT average, superior average, and
nferior average, as well as the nerve fiber indicator, wereignificantly lower with ECC than with VCC, and con-luded that the ECC technology substantially improvesolarimetric image analysis on eyes showing atypical po-arization patterns.15 Reus and associates evaluated GDxCC and VCC in 177 subjects, including 29 healthyubjects, 70 patients with glaucoma and 78 subjects withcular hypertension, and observed that the two modesiffered with regard to the shape of the peripapillaryetardation graph, as the modulation was markedly largern the ECC graph.14 The authors concluded that the ECCode provides a better assessment of RNFL morphologic
eatures than the VCC mode and may enhance the clinicalsefulness of GDx VCC in glaucoma management. In aecent study, Medeiros and associates showed that theDx ECC performed significantly better than VCC for
iagnosing glaucoma in patients with more severe atypicalatterns of retardation.20 For example, for patients withSS values of 20, indicating severe atypia, the estimatedOC curve area from a regression model for the nerve fiber
ndicator parameter was 0.910 for GDx ECC, but only.684 for GDx VCC.The above-mentioned studies have concentrated on
nvestigating parameters related to the superior and infe-ior peripapillary RNFL, because glaucomatous damage issually more prominent on these areas. The study ofemporal and nasal peripapillary RNFL, however, is particu-arly important for other diseases, including hereditary, toxic,ompressive, and traumatic neuropathies. In the currenttudy, we investigated whether the addition of ECCepresents an improvement in the diagnostic ability of SLPo detect damage in the nasal and temporal areas, com-ared with the GDx VCC. To the best of our knowledge,his is the first study to make a comparison of theiagnostic accuracy of these two methods in patients withA of the optic nerve, a particularly useful model to study
he quantification of RNFL loss in the nasal and temporaluadrants of the optic disk. Our findings indicated that thewo compensation modes, ECC and VCC, were equallyccurate as diagnostic tools in eyes with BA of the opticerve and healthy controls. The AUCs of the RNFLarameters studied were similar for the two modes for allarameters investigated (Tables 1 and 2).Our results may seem somewhat surprising because the
limination or reduction of ARPs in the GDx ECC scansould be expected to improve the ability of this instru-ent to detect RNFL loss in the temporal and nasal areas
f the peripapillary retina.10,13–15,20 ARPs are knownignificantly to affect measurements obtained on thesereas, which in turn significantly affects the performance ofhe GDx VCC. The absence of difference in the perfor-ance of GDx ECC and GDx VCC may be explained by
he relatively small number of eyes with substantial ARP
ncluded in our study. Although mean TSS values were fi
AMERICAN JOURNAL OF52
ignificantly lower with VCC than with ECC both in eyesith BA and in normal controls, ARPs (defined as TSS �0) were present in only a small number of eyes with BA11%) and normal controls (18%). In fact, the overallean VCC TSS value (92.8) of the population included in
ur study was considerably higher than values reported inrevious studies using the VCC. For example, Bowd andssociates, Sehi and associates, and Reus and associateseported average VCC TSS values of 85.4, 86.3, and 82.0,espectively.10,13,14 The reason for the low incidence ofRP in our study population may be explained, at least in
art, by the relatively younger age of our patient popula-ion when compared with studies evaluating patients withlaucoma, because ARPs are known to be more commonn older subjects.
We also evaluated the relationship between functionaloss, as measured by SAP, and structural loss, as measuredy the two SLP compensating modes, in patients with BAf the optic nerve. Slight improvements were seen on thetructure-function relationships measured by ECC com-ared with VCC, especially for the nasal sector. However,elationships remained weak and nonsignificant for theemporal sector with both compensating modes. Similarndings have been reported for patients with glaucomatousisual field loss. Mai and associates evaluated the relation-hip between RNFL retardation and SAP visual field sensi-ivity in 68 patients with primary open-angle glaucoma andoncluded that ARPs weakened the structure-function rela-ionship.21 More recently, Bowd and associates appliedinear and logarithmic regression analyses to the associa-ions between RNFL and visual field sensitivities (decibelhreshold measurements) in six corresponding sectors us-ng SLP VCC and ECC measurements in 127 eyes withlaucoma or suspected glaucoma.10 Structure-function as-ociations (R2) ranged from 0.03 (temporal RNFL) to 0.22supertemporal RNFL) for VCC and from 0.01 (temporalNFL) to 0.26 (supertemporal RNFL) for ECC. Associa-
ions were slightly stronger for ECC than for VCC,lthough differences were only significant for the infero-emporal RFNL segment.10
The quantification of axonal loss in BA of the opticerve can be important in the diagnosis and managementf patients with chiasmal compression usually resultingrom tumors such as pituitary adenomas, craniopharyngio-as, and meningiomas. In such patients, the absence ofNFL loss is a good prognostic indicator for visual recoveryfter successful treatment. Patients with visual field defectut without BA of the optic nerve are expected to havearked visual improvement after chiasm decompression,hereas patients with severe RNFL loss are unlikely to
ecover as much. An optimal correlation between visualeld and RNFL would be very useful, particularly inatients with recurrent or residual suprasellar lesions wheneciding whether further surgery would be useful for visualmprovement. Theoretically, an ideal RNFL and visual
eld structure-function correlation would allow one to
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efine whether visual field defects are the result of dysfunc-ional retinal ganglion cells from current chiasmal com-ression or of dead retinal ganglion cells from previousold) compression established before tumor recurrence.22
Structure-function associations between RNFL parame-ers and the TMD in eyes with BA of the optic nerve inhe present study indicate that both GDx VCC and ECCompare well with several corresponding OCT values. In arevious study, we found Pearson correlation values of.63, 0.54, 0.53, and 0.45 for OCT parameters correspond-ng to average thickness and thicknesses in the superior,nferior, and nasal quadrant, which are very similar to theresent findings using VCC and ECC (Table 3).18 In fact,LP correlation values observed in the best GDx VCC andCC parameter of the superior quadrant measurement0.72 and 0.70, respectively) were slightly superior to theest OCT parameter (average RNFL, 0.63). However,alues from the temporal quadrant indicate a great discrep-ncy between our OCT data and that of SLP. Whereas the
earson correlation value between the TMD and the OCT i
polarimetry. Ophthalmology 2003;110:719–725.
1
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GDX ECC IN BANOL. 145, NO. 4
NFL in the temporal quadrant was 0.41, the correspond-ng values with GDx VCC and ECC were �0.003 and.023, respectively. In view of these findings, OCT stilleems to be better than SLP in assessing RNFL loss in eyesith BA of the optic nerve. Our data suggest that atypical
etardation patterns cannot account for the lower ROCurve areas observed in the temporal quadrant in thistudy, because both ECC and VCC performed poorly toetect loss in this segment. The reason for such poorerformance is unclear; however, it may be related toariations of birefringence of the nerve fibers in theifferent quadrants of the peripapillary retina and theirffect on retardation measurements obtained by SLP (Zhou, written communication, October 16, 2007).In conclusion, we were not able to find significant differ-
nces between the diagnostic accuracy of GDx ECC and thatf VCC for detection of BA of the optic nerve. The use ofDx ECC does not seem to provide a better evaluation ofNFL loss on the temporal and nasal sectors of the peripap-
llary retina in subjects with BA of the optic nerve.
HIS STUDY WAS SUPPORTED BY A GRANT 05/55326-1 FROM FUNDAÇÃO DE AMPARO A PESQUISA DO ESTADO DE SÃO PAULOAPESP, São Paulo, Brazil. The authors indicate no financial conflict of interest. Involved in design and conduct of study (M.L.M., F.C.M.); collectionnd management of data (M.L.M., F.C.M.); analysis and interpretation of the data (M.L.M., F.C.M., F.A.M.); and preparation, review, approval of theanuscript (M.L.M., F.C.M., F.A.M.). Approval from the Institutional Review Board Ethics Committee was obtained for the study from Comissão detica para Análise de Projetos de Pesquisa (CAPPesq), Hospital das Clínicas of the University of São Paulo Medical School, São Paulo, Brazil. The study
ollowed the principles of the Declaration of Helsinki and informed consent was obtained from all participants. ClinicalTrial.gov identifier:CT0039122.
REFERENCES
1. Tjon-Fo-Sang MJ, de Vries J, Lemij HG. Measurement bynerve fiber analyzer of retinal nerve fiber layer thickness innormal subjects and patients with ocular hypertension. Am JOphthalmol 1996;122:220–227.
2. Weinreb RN, Shakiba S, Zangwill L. Scanning laser pola-rimetry to measure the nerve fiber layer of normal andglaucomatous eyes. Am J Ophthalmol 1995;119:627–636.
3. Weinreb RN, Dreher AW, Coleman A, Quigley H, Shaw B,Reiter K. Histopathologic validation of Fourier-ellipsometrymeasurements of retinal nerve fiber layer thickness. ArchOphthalmol 1990;108:557–560.
4. Greenfield DS, Knighton RW, Huang XR. Effect of cornealpolarization axis on assessment of retinal nerve fiber layerthickness by scanning laser polarimetry. Am J Ophthalmol2000;129:715–722.
5. Zhou Q, Weinreb RN. Individualized compensation of an-terior segment birefringence during scanning laser polarim-etry. Invest Ophthalmol Vis Sci 2002;43:2221–2228.
6. Greenfield DS, Knighton RW, Feuer WJ, Schiffman JC,Zangwill L, Weinreb RN. Correction for corneal polarizationaxis improves the discriminating power of scanning laserpolarimetry. Am J Ophthalmol 2002;134:27–33.
7. Choplin NT, Zhou Q, Knighton RW. Effect of individualizedcompensation for anterior segment birefringence on retinalnerve fiber layer assessments as determined by scanning laser
8. Susanna JR, Medeiros FA. Enhanced corneal compensation(ECC). In: Susanna JR, Medeiros FA, eds. The optic nervein glaucoma. Rio de Janeiro, Brazil: Cultura Médica, 2006:363–372.
9. Bagga H, Greenfield DS, Feuer WJ. Quantitative assessmentof atypical birefringence images using scanning laser pola-rimetry with variable corneal compensation. Am J Ophthal-mol 2005;139:437–446.
0. Bowd C, Tavares IM, Medeiros FA, Zangwill LM, SamplePA, Weinreb RN. Retinal nerve fiber layer thickness andvisual sensitivity using scanning laser polarimetry with vari-able and enhanced corneal compensation. Ophthalmology2007;114:1259–1265.
1. Toth M, Hollo G. Evaluation of enhanced corneal compen-sation in scanning laser polarimetry: comparison with vari-able corneal compensation on human eyes undergoingLASIK. J Glaucoma 2006;15:53–59.
2. Zhou Q, Kninghton R. Nerve fibre analyser GDx: new tech-niques. In: Iester M, Garway-Heath D, Lemij H, eds. Optic nervehead and retinal nerve fibre analysis. DogmaSavona, Italy 2005:117–119.
3. Sehi M, Guaqueta DC, Greenfield DS. An enhancementmodule to improve the atypical birefringence pattern usingscanning laser polarimetry with variable corneal compensa-tion. Br J Ophthalmol 2006;90:749–753.
4. Reus NJ, Zhou Q, Lemij HG. Enhanced imaging algorithmfor scanning laser polarimetry with variable corneal com-pensation. Invest Ophthalmol Vis Sci 2006;47:3870 –
3877.
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1
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5. Toth M, Hollo G. Enhanced corneal compensation forscanning laser polarimetry on eyes with atypical polarizationpattern. Br J Ophthalmol 2005;89:1139–1142.
6. Unsold R, Hoyt WF. Band atrophy of the optic nerve. Thehistology of temporal hemianopsia. Arch Ophthalmol 1980;98:1637–1638.
7. Monteiro ML, Medeiros FA, Ostroscki MR. Quantitative anal-ysis of axonal loss in band atrophy of the optic nerve usingscanning laser polarimetry. Br J Ophthalmol 2003;87:32–37.
8. Monteiro ML, Moura FC. Comparison of the GDx VCCscanning laser polarimeter and the Stratus optical coherencetomograph in the detection of band atrophy of the opticnerve. Eye. Forthcoming.
9. DeLong ER, DeLong DM, Clarke-Pearson DL. Comparing
the areas under two or more correlated receiver operating
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characteristic curves: a nonparametric approach. Biometrics1988;44:837–845.
0. Medeiros FA, Bowd C, Zangwill LM, Patel C, Weinreb RN.Detection of glaucoma using scanning laser polarimetry withenhanced corneal compensation. Invest Ophthalmol Vis Sci2007;48:3146–3153.
1. Mai TA, Reus NJ, Lemij HG. Structure-function relationshipis stronger with enhanced corneal compensation thanwith variable corneal compensation in scanning laserpolarimetry. Invest Ophthalmol Vis Sci 2007;48:1651–1658.
2. Danesh-Meyer HV, Carroll SC, Ku JY, et al. Correlation ofretinal nerve fiber layer measured by scanning laser polarim-eter to visual field in ischemic optic neuropathy. Arch
Ophthalmol 2006;124:1720–1726.
OPHTHALMOLOGY APRIL 2008
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ário L. R. Monteiro, MD, is a Professor of Ophthalmology and Director of the Neuro-ophthalmology and the Orbitaliseases Services at the University of São Paulo Medical School, São Paulo, Brazil. He received his medical degree and
ompleted a residency in ophthalmology at University of São Paulo and a neuro-ophthalmology fellowship at theniversity of California, San Francisco, with Prof William F. Hoyt. His main research interests include disorders of the
ptic nerve and chiasm.
GDX ECC IN BAND ATROPHYOL. 145, NO. 4 754.e1
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rederico Castelo Moura graduated from the Federal University of Ceará and completed a residency in Ophthalmologynd a Fellowship in Neuro-ophthalmology and Orbital surgery at the University of Sao Paulo Medical School. Dr Moura’sain research interests include band atrophy of the optic nerve and Graves orbitopathy.
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