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PurposeTo review the ability of current imaging technologies to provide estimates of rates of structural change in glaucoma patients.Patients and methodsReview of literature.ResultsImaging technologies, such as confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT), provide quantifiable and reproducible measurements of the optic disc and parapapillary retinal nerve fibre layer (RNFL). Rates of change as quantified by the rim area (RA) (for CSLO) and RNFL thickness (for SLP and OCT) are related to glaucoma progression as detected by conventional methods (eg, visual fields and optic disc photography). Evidence shows that rates of RNFL and RA loss are significantly faster in progressing compared with non-progressing glaucoma patients.ConclusionMeasurements of rates of optic disc and RNFL change are becoming increasingly precise and individualized. Currently available imaging technologies have the ability to detect and quantify progression in glaucoma, and their measurements may be suitable end points in glaucoma clinical trials. [ABSTRACT FROM AUTHOR]

PurposeTo assess the prevalence of atypical retardation pattern (ARP) in scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and to evaluate the factors relating to typical scan score (TSS).MethodsMeasurements of SLP–VCC, SLP–ECC, and the Humphrey field analyzer (HFA) were performed in 105 normal subjects and 82 open-angle glaucoma (OAG) patients. ARP was defined as an SLP image with TSS<80.ResultsPrevalence of ARP with SLP–VCC was 13.3 and 14.6% in normal and OAG eyes, respectively, and that with SLP–ECC (2.9% and 1.2%) was lower than SLP–VCC (P<0.009). TSS with SLP–VCC was significantly correlated with age (partial correlation coefficient (PCC)=−0.22, P=0.003) and refractive error (PCC=0.26, P<0.001) after adjusting for each other. TSS with SLP–ECC was significantly correlated with neither age nor refractive error (PCC=−0.02, P=0.788; PCC=0.10, P=0.177, respectively). In OAG eyes, mean deviation (MD) of HFA was significantly correlated with TSS with SLP–VCC and SLP–ECC (PCC=0.35, P=0.001; PCC=0.23, P=0.039, respectively). In SLP-VCC, MD was significantly correlated with retinal nerve fibrr layer (RNFL) thickness only after excluding eyes with ARP (P<0.001).ConclusionsARP in SLP–VCC measurements was found in more than 10% of normal or glaucomatous eyes, and TSS was significantly lower in older subjects, more myopic eyes, or eyes with more advanced glaucomatous damage. The presence of ARP disturbs the accuracy of RNFL thickness measurement by SLP–VCC. In SLP–ECC measurements, prevalence of ARP was considerably lower and TSS was not affected by age or refractive error, suggesting the advantages of ECC in clinical practices. [ABSTRACT FROM AUTHOR]

Purpose To calculate and validate a linear discriminant function (LDF) for scanning laser polarimetry (SLP) with variable corneal compensation (GDx-VCC) to increase the diagnostic accuracy when using isolated retinal nerve fibre layer (RNFL) parameters to discriminate between healthy and glaucomatous eyes with visual field loss.Methods We prospectively selected two independent samples (teaching and validating sets). The teaching set, comprising 71 consecutive healthy subjects and 73 patients with open-angle glaucoma, was used to calculate the LDF. The validating set, comprising 72 consecutive normal eyes and 76 glaucoma patients, was used to test the performance of the LDF in an independent population. Receiver operating characteristic (ROC) curves were plotted for the validating set to evaluate the diagnostic accuracy of the LDF and the SLP parameters.Results The obtained function was LDF=−12.20+(0.15 × nasal average)−(23.85 × normalized inferior area)+(1.18 × maximum modulation). The areas under the ROC curve were 0.901 and 0.893 for our LDF and 0.893 and 0.877 for the nerve fibre indicator (NFI) in the teaching and validating populations, respectively. There were no significant differences between these values (P=0.743 in the teaching set, and P=0.458 in the validating set). NFI was the SLP-provided parameter with the best sensitivity–specificity balance. Sensitivities were 57.89% for the LDF and 48.68% for NFI at 95% fixed specificity.Conclusions The LDF and NFI were the most accurate SLP parameters for diagnosing glaucoma. The LDF yielded the highest sensitivity at 95% fixed specificity to discriminate between normal and glaucoma subjects.Eye (2009) 23, 593–600; doi:10.1038/eye.2008.50; published online 29 February 2008 [ABSTRACT FROM AUTHOR]

PurposeTo verify whether scanning laser polarimeter with the new variable corneal compensation algorithm (GDx VCC) and scanning laser ophthalmoscopy (Heidelberg Retina Tomograph (HRT)) allow measuring retinal ganglion cell loss in patients with multiple sclerosis (MS).Patients and methodsWe enrolled 23 MS patients with a history of previous demyelinating monocular optic neuritis. Examination included visual evoked potentials (VEPs), scanning laser ophthalmoscopy, and scanning laser polarimeter. HRT was performed to assess optic nerve head (ONH) shape, while GDx VCC was used to evaluate the retinal nerve fibre layer thickness (RNFLt) around the ONH. Statistical analysis was performed comparing results obtained for each eye with the available normative database and with the unaffected fellow eye.ResultsWhen the affected eye group was compared to the fellow-eye group, a significant (P<0.05) difference was found for few GDx VCC parameters. In contrast, no significant correlation was observed between clinical assessment and imaging techniques when the normal database of HRT and GDx VCC was used. A significant association was observed between VEP latency and some GDx VCC parameters.ConclusionsOur results suggested that scanning laser polarimetry could detect loss of ganglion cells following demyelinating optic neuritis, but further studies are needed.Eye (2009) 23, 407–412; doi:10.1038/sj.eye.6703013; published online 9 November 2007 [ABSTRACT FROM AUTHOR]

PurposeA feasibility study comparing retinal nerve fibre layer (RNFL) thickness values obtained with imaging devices against RNFL thickness measurements obtained histologically in a human eye.DesignA single patient scheduled for orbital exenteration, who still possessed a healthy functioning eye.MethodsBefore surgery, the eye was imaged using optical coherence tomography (OCT) and scanning laser polarimetry (SLP). After orbital exenteration, the globe was sectioned, and 100 equidistant RNFL thickness measurements were obtained for each of four concentric rings centred on the optic disc, with diameters of 3.0, 3.5, 4.0, and 4.5 mm.ResultsRNFL thickness was found to be inversely related to the distance from the centre of the optic disc along each radial meridian. Peripapillary RNFL thickness was found comparable for histology, OCT, and SLP. RNFL thickness measured histologically confirmed a ‘double hump’ pattern, peaking at the superior and inferior poles. Histologically derived RNFL thickness (μm), at 3.0 and 3.5 mm diameter ring ranged between 30–135 and 25–115 respectively. In comparison, the 3.0 mm diameter GDx data ranged between 25 and 100, and the 3.4 mm diameter OCT data between 40 and 175.ConclusionsImaging data appear qualitatively similar when compared to the histologically derived data. Quantitative differences may be partly due to scaling differences and histological artefacts. The histological analysis approach demonstrated in this study can potentially serve to validate imaging-derived data, as well as help improve our understanding of RNFL loss in glaucoma.Eye (2009) 23, 171–175; doi:10.1038/sj.eye.6702942; published online 24 August 2007 [ABSTRACT FROM AUTHOR]

PurposeTo characterize which clinical features are associated with the occurrence of atypical birefringence patterns (ABP) occasionally seen with scanning laser polarimetry (SLP).MethodsSixty-one subjects, including glaucoma patients, glaucoma suspects, and normal subjects, underwent a full clinical examination, standard visual field (VF) test, and a GDx-VCC SLP examination. One eye was selected from each patient. The magnitude of ABP was determined in two independent ways: using a support vector machine analysis (typical scan score (TSS)) and by a masked experienced observer. We assessed whether the magnitude of ABP was correlated with age, gender, the refractive state of the eye, corneal polarization axis and magnitude, GDx global parameters (TSNIT and NFI), and the VF status, as evident from glaucoma hemifield test (GHT), mean deviation (MD), and the pattern standard deviation (PSD).ResultsOf the 61 study eyes, 27 (44%) showed an ABP, based on a TSS cutoff (<82.5). A very high correlation was found between the TSS score and the masked experienced observer score (r2=0.80; P<0.001). The following clinical parameters were found, on bivariate analysis, to be significantly correlated with the presence of an ABP: age (r2=0.086; P=0.02); corneal polarization magnitude (r2=0.069; P=0.04); TSNIT (r2=0.16; P<0.001).ConclusionThe presence and magnitude of ABP did not seem to be closely correlated with most clinical parameters. A low, but statistically significant, correlation was found for age and corneal polarization magnitude (r2=0.086 and 0.069, respectively). A low–medium correlation was found for TSNIT (r2=0.16); however, we speculate that this might represent a confounding effect, rather than an underlying association. We conclude that none of the clinical parameters investigated in this study appears to be strongly correlated with the presence of an ABP on SLP scans performed using the commercially available GDx-VCC.Eye (2008) 22, 1378–1383; doi:10.1038/sj.eye.6702897; published online 13 July 2007 [ABSTRACT FROM AUTHOR]

PurposeA scanning laser polarimetry (GDx VCC) equips three different sized measurement circles. In eyes with peripapillary atrophy (PPA), the GDx measurement becomes inaccurate when the circle falls on PPA. The aim of this study was to evaluate performance of the three circles of GDx measurement in eyes with PPA.MethodsThree different sized circles were compared regarding frequency of PPA, which fell on each circle in 282 open-angle glaucoma (OAG) eyes, reproducibility of GDx parameters in 24 normal and 22 OAG eyes, and ability to detect glaucoma in 50 normal and 50 OAG eyes.ResultsPPA was observed in 230 (82%) of 282 OAG eyes. PPA fell on the small circle (default setting), medium, and large circles in 119 (43%), 38 (14%), and 12 (4%) of the 280 OAG eyes. Reproducibility of GDx parameters was not significantly different among three circles in normal eyes (P>0.05), whereas coefficients of reproducibility of TSNIT average (P=0.006) and superior average (P=0.035) were smaller in the smaller circles in OAG eyes. GDx parameters significantly correlated (P<0.001), but were significantly different (P<0.05) between the small and medium circles. The area under receiver operating characteristic curves for dividing OAG from normal eyes using GDx parameters was similar between the small and medium circles.ConclusionsIf the medium circles were used, obstructing influences of PPA on GDx measurement could be avoided more often in Japanese OAG eyes with similar reproducibility and comparable ability to detect glaucoma compared to those with the default small circle.Eye (2008) 22, 173–178; doi:10.1038/sj.eye.6702516; published online 4 August 2006 [ABSTRACT FROM AUTHOR]

PurposeTo evaluate the influence of posterior capsule opacification (PCO) on GDx parameters in a population of pseudophakic, non-glaucomatous patients who underwent Nd:YAG laser capsulotomy (YLC).MethodsThe posterior capsules were photographed with a Topcon digital camera and each image was then entered into the EPCO 2000 software and evaluated independently by three examiners. The EPCO 2000 software was used to calculate the fibrosis index (FI) and the pearl index (PI) for the central 1.5, 2.5, and 3.5 mm of the posterior capsule. Scanning laser polarimetry was performed with GDx before and after YLC. We compared the GDx readings obtained before and after the YLC using paired Student's t-test. The parameters that varied significantly after YLC were subsequently used for regression analysis. Stepwise multiple linear regression was used to analyse the impact of the change in the amount of FI and PI on change in GDx parameters after YLC.ResultsIn total, 158 patients were enrolled (74 men, 84 women). The mean age was 69.46±8.83 years (range 46–83 years). The interobserver agreement among the three experts was found to be good (repeatability coefficient R=1.51, 1.49, 1.49 for observer A vsB, A vsC, and B vsC respectively). One-sample Student's t-test show no difference between all GDx parameters before and after YLC except for Symmetry, Superior/Nasal ratio, Inferior Ratio, and Temporal-Superior-Nasal-Inferior-Temporal (TSNIT). Stepwise multiple regression showed that the two variables of greatest significance for changes in Symmetry were the FI in the central 1.5 and the PI in the central 3.5 mm (P=0.02). Superior/nasal ratio was shown to be most strongly correlated to the FI in the central 1.5 mm and PI in the central 3.5 mm (P<0.001), whereas the variable of greatest significance to Inferior Ratio was PI in the central 3.5 mm (P=0.03). Finally, TSNIT was most strongly correlated to FI in the central 1.5 mm and FI in the central 2.5 mm (P<0.001).ConclusionPresence of capsular fibrosis seems to be more clinically relevant in the central zone, whereas pearls tend to be clinically significant in the central 3.5 mm area. Hence, it might be worthwhile assessing the amount of PCO in pseudophakic patients when performing scanning laser polarimetry. Investigators should ensure that the type of PCO and the size of the area analysed are documented in the notes in order to interpret GDx findings appropriately.Eye (2007) 21, 760–763; doi:10.1038/sj.eye.6702323; published online 7 April 2006 [ABSTRACT FROM AUTHOR]

PurposeTo evaluate the reproducibility of variable corneal compensation (VCC) and the effect of accommodation, cycloplegia, eye selection, focus, and pupil size on this measurement of polarization.MethodsUsing a GDx scanning laser polarimeter, multiple measurements of the VCC were obtained from each eye of 33 healthy, young adults under differing conditions. Pupil size and refraction were independently measured with a pupillometer and an autorefractometer. The effects of eye, instrument focus, pupil diameter, cycloplegia, and accommodation were statistically assessed.ResultsThe reproducibility of a single retardation measurement and its axis, as determined by the standard deviations (SD) of repeated measurements, is ±1.58 nm and 2.10°, respectively. There is a difference in retardation between right and left eyes, of 5.26±9 nm, P=0.002. Increasing pupil size increases retardation. Cycloplegia or defocusing decreases retardation, and pharmacologically induced accommodation has no effect on retardation.ConclusionsThe retardation and its axis are highly reproducible measurements when the pupil is of physiologic size and the GDx is properly focused. There is a consistent difference in VCC retardation between the paired right and left eyes. This difference may reflect equipment-induced measurement artefact and/or an anatomic asymmetry between the paired eyes of the subjects studied. Clinicians should be cautious when comparing interocular VCC measurements between paired right and left eyes and using data pooled from both eyes for age-adjusted, normalized standards.Eye (2007) 21, 333–340. doi:10.1038/sj.eye.6702187; published online 9 December 2005 [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationship between visual acuity and foveal birefringence in patients with neovascular age-related macular degeneration.Methods: In total, 40 patients with choroidal neovascularization underwent macular imaging with scanning laser polarimetry. Bowtie patterns, typically seen in birefringence images of the macula, were evaluated and classified into three categories: (1) regular bowtie present; (2) bowtie present, but disrupted; and (3) no bowtie present. The relation of the bowtie appearance to the best-corrected logMAR visual acuities was tested (ANOVA).Results: Mean visual acuity was best for the group that had regular bowties (mean logMAR=0.34) and differed statistically significantly from the disrupted bowtie group and no bowtie group (P=0.01 and 0.0007). Ages for the three groups did not differ (P=0.31).Conclusions: Appearance of a regular bowtie indicates a substantially intact Henle fibre layer with the potential for good visual function, despite the presence of underlying pathology. Conversely, disruption or absence of a bowtie may indicate severe damage to the photoreceptors, consistent with the finding of poorer visual acuity. [ABSTRACT FROM AUTHOR]

PurposeTo assess the effect of atypical pattern of retardation (APR) on retinal nerve fibre layer (RNFL) measurements made by scanning laser polarimetry (SLP) with variable corneal compensation (GDx-VCC) in glaucomatous eyes.MethodsOne eye each of 30 glaucomatous patients (average mean deviation (MD): −6.4±4.8) with APR on GDx-VCC retardation map were selected. In total, 34 glaucomatous, age- and severity-matched eyes (average MD: −7.0±5.3) and 36 age-matched healthy subjects, both with a normal pattern of retardation (NPR) represented control groups. APR on retardation maps was characterized by alternating peripapillary circumferential bands of low and high retardation, or high retardation areas arranged in a spokelike pattern, or high retardation nasal and temporal splotchy areas. Typical scan score (TSS) was extracted for each included eye. GDx-VCC parameters (mean±SD) in the two groups of glaucomatous eyes were compared with healthy eyes' corresponding values (Mann–Whitney U-test). Areas under receiver operating characteristic (AUROC) curves were generated to assess the APR effect on the parameters' diagnostic ability.ResultsAll parameters discriminated adequately between healthy and glaucomatous eyes with NPR (AUROCs ≥0.9 for nine parameters). On the contrary, considering healthy and glaucomatous eyes with APR, four thickness parameters could not separate the two groups and AUROCs ≥0.85 appeared only for Inferior and Superior Ratio, NFI, Max Modulation.ConclusionAPR may void the effect of custom compensation and provide spurious RNFL thickness measurements. When a printout of glaucomatous eyes with APR is evaluated, it is proper to rely on ratios, modulation parameters, and NFI, since the diagnostic ability of thickness parameters is significantly reduced.Eye (2006) 20, 769–775. doi:10.1038/sj.eye.6701997; published online 8 July 2005 [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate the interdevice reproducibility of retinal nerve fibre layer (RNFL) thickness measurements obtained with the commercially available GDx-VCC, a scanning laser polarimeter with variable (individualized) corneal compensation. METHODS: A prospective instrument validation study in which 13 GDx-VCC devices were tested. One eye each, from three normal subjects were used to test each of the devices, on the same day, by an experienced operator. Variability and reproducibility for each of five GDx parameters were calculated. RESULTS: For each of five tested GDx parameters, the coefficient of variation and 95%confidence interval range (µm), for the 13 devices, respectively, were: TSNIT avg: 5.1%, 3.84?µm; Superior avg: 5.3%, 4.82?µm; Inferior avg: 6.1%, 5.50?µm; TSNIT standard deviation: 8.6%, 2.92?µm; and nerve fibre indicator (NFI): N/A, 5.69. Item reliability (Cronbach's alpha) for the five GDx parameters are: TSNIT-Avg: 0.97, Sup-Avg: 1.00, Inf-Avg: 0.84, TSNIT-SD: 0.99, NFI: 0.99. CONCLUSIONS: With the commercially available GDx-VCC, our results indicate that RNFL measurements appear reproducible across devices.Eye (2005) 19, 308-311. doi:10.1038/sj.eye.6701472 Published online 30 July 2004 [ABSTRACT FROM AUTHOR]

PURPOSE:To investigate the influence of subfoveal choroidal neovascularisation (CNV) on macular imaging performed using scanning laser polarimetry (SLP) of the retinal nerve fibre layer. METHODS:SLP was performed on 22 consecutive patients with angiographically verified CNV, and on 23 healthy control subjects. One eye per subject was evaluated using the GDx Nerve Fibre Analyser. Regularity of the corneal retardation on the macular SLP images was assessed according to three criteria: (1) magnitude of the‘macular ratio’, defined as the ratio of mean retardation values along two axes (the axis with the maximum retardation and the perpendicular one, corresponding in healthy eyes to minimum retardation); (2) the values of GDx parameters which are independent of quadrant position (ellipse modulation and ellipse average); and (3) the frequency of the regular‘bow-tie’polarisation pattern. RESULTS:‘Macular ratio’was significantly higher in the CNV group than in the control group (P«0.001). Ellipse modulation did not differ between the groups, but ellipse average was higher in the CNV group (P=0.016). The variance for each of these two parameters was significantly higher for the CNV group (P«0.001 for both comparisons). A‘bow-tie’pattern polarisation was seen in 23 of the 23 control eyes, but only in 7 of the 22 CNV eyes (P«0.001). CONCLUSION:The results show that CNV influences the macular image obtained with SLP. This suggests that measurements with SLP may be disturbed for eyes with CNV when the customised corneal compensation method, which makes use of the macular retardation image, is employed.Eye (2005) 19, 117-122. doi:10.1038/sj.eye.6701431 Published online 7 May 2004 [ABSTRACT FROM AUTHOR]

PURPOSE:To investigate the differences between the results of scanning laser polarimetric (SLP) measurements of the retinal nerve fibre layer thickness (RNFLT) made using two different corneal-polarisation techniques; customised (SLP-C), and fixed-angle (SLP-F) compensations. METHODS:Both SLP-C and SLP-F were performed on 37 consecutive phakic patients with chronic open-angle glaucoma, and on 14 healthy control subjects. One randomly selected eye per subject was evaluated. RESULTS:Both SLP-C and SLP-F parameters were able to discriminate between the glaucoma group and the control group, except in the case of the ellipse modulation, which differed significantly between the two groups with SLP-C (P=0.017), but not with SLP-F (P=0.056). When SLP-C and SLP-F values were compared, inferior maximum thickness and ellipse standard deviation were significantly lower with SLP-C in both groups (P<0.05 for each parameter). Superior maximum thickness was significantly lower in glaucoma with SLP-C than with SLP-F (P=0.006) and tended to be lower with SLP-C than with SLP-F in the control group (P=0.053). In the glaucoma group, it was only with SLP-C that a significant (positive) correlation between the superior maximum thickness and the inferior hemifield mean sensitivity (MS) (r=0.653, P<0.001), and between the inferior maximum thickness and the superior hemifield MS (r=0.420, P=0.023) was found. The other global and sectoral SLP parameters showed significant correlation with the corresponding visual field parameters with both techniques. CONCLUSION:Our findings suggest that SLP measurements with customised compensation provide more realistic results for RNFLT than those made with the conventional fixed-angle compensation.Eye (2005) 19, 152-158. doi:10.1038/sj.eye.6701429 Published online 7 May 2004 [ABSTRACT FROM AUTHOR]

Existing methodologies for imaging the optic nerve head surface topography and measuring the retinal nerve fibre layer thickness include confocal scanning laser ophthalmoscopy (Heidelberg retinal tomograph), optical coherence tomography, and scanning laser polarimetry. For cross-sectional screening of patient populations, all three approaches have achieved sensitivities and specificities within the 60-80th percentile in various studies, with occasional specificities greater than 90% in select populations. Nevertheless, these methods are not likely to provide useful assistance for the experienced examiner at their present level of performance. For longitudinal change detection in individual patients, strategies for clinically specific change detection have been rigorously evaluated for confocal scanning laser tomography only. While these initial studies are encouraging, applying these algorithms in larger numbers of patients is now necessary. Future directions for these technologies are likely to include ultra-high resolution optical coherence tomography, the use of neural network/machine learning classifiers to improve clinical decision-making, and the ability to evaluate the susceptibility of individual optic nerve heads to potential damage from a given level of intraocular pressure or systemic blood pressure. [ABSTRACT FROM AUTHOR]

Purpose To assess the influence of visually significant cataract on the measurement of nerve fibre layer thickness by scanning laser polarimetry (GDx) in glaucoma patients undergoing phacoemulsification cataract extraction.Method and Subjects All subjects with primary glaucoma participating in a prospective trial of glaucoma surgery who subsequently underwent cataract extraction were eligible. A single trained observer using the GDx nerve fibre layer analyser (LDT) performed pre- and post-operative measurements of nerve fibre layer thickness (NFLT). NFLT parameters, best-corrected LogMAR visual acuity, and automated visual fields were assessed before and after phacoemulsification cataract extraction with implantation of an acrylic intraocular lens.Results A total of 49 subjects were assessed: 22 (45%) had POAG and 29 (55%) PACG; all were Asian (36 (73%) were Chinese), with mean age 67.1 (±7.6 SD) and mean ‘LOCS III’ lens opacity grading 11.4 (±3.1 SD). Visual acuity significantly improved (mean LogMAR 0.5 vs 0.15, P<0.0001). Corrected pattern standard deviation (6.1 vs 6.4, P=0.2) and mean deviation (-17.7?dB vs -17.0 P=0.91) were little changed after cataract removal. Pseudo-phakic measurements of NFLT were significantly different from pre-op values. Measures of absolute thickness (including the average thickness, ellipse, ellipse average, superior and inferior averages, superior integral) were significantly greater than preoperative values (all P<0.01), whereas ratios and measures of symmetry (symmetry, superior/nasal) were unchanged (all P>0.1) and ‘the number’ was smaller (P=0.04). Differences in measured NFLT were most strongly correlated with posterior subcapsular cataract (average thickness, P=0.01).Conclusions Removal of cataract resulted in greater absolute measurements of NFLT but ratio values were unchanged. Scanning laser polarimetry measurements can change significantly after cataract extraction. New baseline measurements may be required.Eye (2004) 18, 163-168. doi:10.1038/sj.eye.6700600 [ABSTRACT FROM AUTHOR]

Purpose To detect differences in retinal nerve fibre layer (RNFL) measurements between patients with acute angle-closure glaucoma (AACG) and normal subjects using scanning laser polarimetry.Methods This was a comparative cross-sectional study, where 32 eyes of 32 patients with AACG and 28 eyes of 28 normal subjects were imaged using scanning laser polarimetry (The Nerve Fibre Analyzer GDx, Laser Diagnostic Technology Inc., San Diego, CA, USA). The average RNFL thickness in four quadrants and various GDx parameters between the two groups were compared using Mann-Whitney tests with Bonferroni correction.Results There were no significant differences in RNFL measurements for the average thickness, ellipse average, inferior, superior, nasal, and temporal average values between the AACG eyes and normal eyes. There were significant differences in some GDx parameters, including superior/nasal ratio (P=0.036), superior ratio (P=0.01), the GDx number (P=0.003), inferior ratio (P<0.001), maximum modulation (P<0.001), and ellipse modulation (P<0.001).Conclusions Various GDx parameters exhibit significant changes in patients following short-duration AACG episodes, making GDx RNFL measurements useful for the diagnosis and follow-up of AACG.Eye (2004) 18, 9-14. doi:10.1038/sj.eye.6700517 [ABSTRACT FROM AUTHOR]