The effect of panretinal photocoagulation on confocal laser scanning ophthalmoscopy and stereo photographic parameters of optic disk topography in patients with diabetic retinopathy / Efeito da panfotocoagulação retiniana na oftalmoscopia confocal de varredura a laser e parâmetros da estereofotografia do disco óptico em pacientes com retinopatia diabética

ABSTRACT Purpose: To determine the effect of panretinal photocoagulation on optic disk topographic parameters in non-glaucomatous patients with proliferative diabetic retinopathy. Methods: This was a prospective, single-center, observational study. Thirty-eight eyes of 26 patients with diabetes underwent panretinal photocoagulation for proliferative diabetic retinopathy. Stereoscopic disk photographs and optic nerve head parameters were evaluated using the Zeiss fundus camera and the confocal scanning laser ophthalmoscope (Heidelberg Retinal Tomograph), respectively, at baseline and 12 months after the completion of panretinal photocoagulation. Results: Thirty-eight eyes of 26 patients (15 female) with a mean age of 53.7 (range 26-74) years were recruited. No significant difference was found between the stereo photography determined mean horizontal and vertical cup-to-disk ratio before and after panretinal photocoagulation treatment (p=0.461 and 0.839, respectively). The global values of the optic nerve head parameters analyzed with the HRT3 showed no significant change from baseline to 12 months, including the disk area, cup area, rim area, cup volume, rim volume, cup-to-disk area ratio, linear cup-to-disk ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and cross-sectional area. Conclusion: Our results suggest that panretinal photocoagulation does not cause morphological optic disk changes in patients with diabetic proliferative retinopathy after 1 year of follow-up.

RESUMO Objetivo: Determinar o efeito da panfotocoagulação retiniana nos parâmetros topográficos do disco óptico em pacientes não glaucomatosos com retinopatia diabética proliferativa. Métodos: Este é um estudo observacional pros­pectivo e unicêntrico. Trinta e oito olhos de 26 pacientes dia­béticos foram submetidos à panfotocoagulação retiniana para retinopatia diabética proliferativa. As estereofotografias e os parâmetros do disco óptico foram avaliados usando o retinógrafo Visucam da Zeiss e o oftalmoscópio confocal de varredura a laser (Heidelberg Retinal Tomograph), respectivamente, no início e 12 meses após a conclusão da panfotocoagulação. Resultados: Trinta e oito olhos de 26 pacientes (15 mulheres) com média de idade de 53,7 anos (intervalo de 26-74) foram recrutados. Nenhuma diferença significativa foi encontrada entre a média horizontal e vertical para relação escavação/disco óptico determinadas pelas estereo­fotografias antes e após o tratamento com panfotocoagulação retiniana (p=0,461 e 0,839, respectivamente). Os valores globais dos parâmetros do disco óptico analisados com a tomografia de varredura a laser não mostraram nenhuma mudança significativa entre o início até os 12 meses, incluindo disk area, cup area, rim area, cup volume, rim volume, C/D area ratio, linear C/D ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness e cross-sectional area. Conclusão: Nossos resultados sugerem que a panfotocoagulação retiniana não causa alterações morfológicas no disco óptico em pacientes com retinopatia diabética proliferativa após um ano de seguimento.

Scanning laser polarimetry in glaucoma.

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White‑on‑white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Análise de regressão logística na combinação de métodos propedêuticos no diagnóstico do glaucoma / Logistic regression analysis in the combination of diagnostic methods in glaucoma

OBJETIVOS: Estudar a habilidade diagnóstica do tomógrafo retiniano de Heidelberg (HRT II), GDx analisador de fibras nervosas (GDx), perimetria azul-amarelo (SWAP), tecnologia de frequência duplicada (FDT) isoladamente e em conjunto no diagnóstico do glaucoma. MÉTODOS: Sessenta glaucomatosos e 60 pacientes normais foram submetidos a exames de HRT II, GDx, SWAP e FDT. HRT foi considerado alterado quando pelo menos uma região do anel neurorretiniano esteve fora dos limites da normalidade, conforme a análise de regressão de Moorfields. GDx alterado foi definido quando pelo menos um índice foi considerado pelo programa do equipamento como fora dos limites normais, excluindo-se o índice simetria, ou ainda quando no gráfico "the deviation from normal graph" apareceu um quadrante com significância abaixo de 5%. O FDT foi considerado anormal quando pelo menos uma região testada apresentou-se com defeito severo ou com a presença de dois defeitos moderados contíguos. Para o SWAP foram adotados os critérios de anormalidade propostos por Anderson. Análise de regressão logística foi realizada. RESULTADOS: Quando foram estudadas as tecnologias isoladamente, a análise de regressão logística apresentou melhores índices de razão das chances para glaucoma com exames positivos para o HRT (22,49), seguido pelo SWAP (21,71). FDT (3,97) e GDx (2,73). Quando se associaram exames positivos de diferentes tecnologias, as razões das chances aumentaram. Nos casos com exames de HRT, FDT e SWAP fora dos limites normais, a razão das chances foi de 252,6 e com HRT, SWAP e GDx alterados, 173,1. Quando associamos exames positivos de diferentes tecnologias, a razão das chances dos pacientes serem glaucomatosos aumentou consideravelmente, chegando a 689,7 com todos os exames fora dos limites normais, o que ocorreu em 26 pacientes deste estudo. CONCLUSÕES: A análise de regressão logística confirmou que a presença de exames alterados de HRT ou SWAP apresentam as maiores razões das chances de glaucoma. A associação de exames alterados aumentou a razão das chances, principalmente, quando o HRT e o SWAP estavam fora dos limites normais.

PURPOSES: In this research was studied the diagnostic ability of the Heidelberg Retinal Tomograph (HRT II), GDx nerve fiber analyzer (GDx), Short-wavelenght Automated Perimetry (SWAP) and Frequency-doubling technology (FDT), all of them together and also separately in the diagnosis of glaucoma. METHODS: Sixty glaucomatous patients and 60 normal ones were submitted to examination with the technology of HRT II, GDx, FDT and SWAP. In the interpretation of HRT, based on the Moorfields regression analysis, were considered abnormal when at least one area of the neuroretinal ring was outside the bounds of normality. GDx was defined as altered, when it was observed that at least one index was considered by equipment program as outside of normal limits, excluding the index symmetry, or when "the deviation from normal graph" appeared a quadrant with significance below 5%. The FDT was considered abnormal when at least one region tested presented with severe defects, or two contiguous moderate defects in at least two reliable tests. For SWAP was adopted the abnormality criteria proposed by Anderson. Logistic regression analysis was performed. RESULTS: When the technologies were studied separately, the Logistic regression analysis showed better odds ratio rates to test positive for glaucoma with HRT (22.49), followed by EAP (21.71), FDT (3.97) and GDx (2.73). When positive tests were associated with different technologies, the odds ratios increased. In cases with HRT, FDT and PAA tests, outside normal bounds, the odds ratio was 252.6. Concerning the HRT, GDx and PAA the result have changed to 173.1. When we associate positive tests from different technologies, the odds ratio of glaucomatous patients have increased considerably, reaching 689.7 with all the tests outside normal bounds, which have happened with 26 patients of this study. CONCLUSIONS: The Logistic Regression analysis confirmed that the abnormal tests of HRT and PAA have shown to be the highest reasons for glaucoma occurrence. The association of abnormal tests increased the odds ratio, especially when the HRT and PAA were out of normal bounds.

Measurement and comparison of retinal nerve fiber layer thickness in different stages of diabetic retinopathy patient with type 2 diabetes / 中华实验眼科杂志

Background Diabetic retinopathy (DR) is one of the leading causes that result in adult irreversible blindness in many countries.Recent researches suggest that neurodegeneration is an important component of DR.To realize the disease process of retinal neutron is very important for prevention and treatment on DR.Objective This study was to investigate the change of retinal nerve fiber layer thickness in patients with type 2 diabetes mellitus.Methods Ninety-six eyes of 48 patients with type 2 diabetes mellitus were enrolled in Peking Union Medical College Hospital.The patients were assigned into non-diabetic retinopathy (NDR) group,background diabetic retinopathy(BDR) group,proliferative diabetic retinopathy (PDR) group and panretinal photocoagulation (PRP) group based on the fundus finding and fundus fluorescein angiography(FFA),and 24 normal subjects with matched age were included as control group.RNFL thickness was measured by GDxVCC system,including temporal,superior,nasal,inferior,total,(TSNIT) average,superior average,inferior average,TSNIT standard deviation and nerve fiber indication.The datas of the RNFL thickness were analyzed and comparison among different groups by one-way analysis of variance and Student Newman Keuls test.Results The TSNIT averages of the NDR group,BDR group,PDR group and PRP group were(56.54±5.28),(56.92±6.49),(53.04±6.14) and(53.17±9.30) μm,respectively,while that of the control group was (59.04±4.37) μm.The TSNIT average,superior average,inferior average,TSNIT standard deviation of the PDR group and PRP group compared with control group were significantly decreased,and the nerve fiber indication of the PDR group and PRP group was significantly increased (P =0.002,0.000,0.002,0.000,0.001 ;P =0.002,0.000,0.001,0.000,0.000).Compared with the control group,the TSNIT average,superior average,inferior average,TSNIT standard deviation were insignificantly decreased,and the nerve fiber indication was insignificantly increased in the NDR group and BDR group (P =0.187,0.235,0.333,0.106,0.202 ;P=0.262,0.063,0.072,0.098,0.062).Conclusions The decline of the RNFL thickness appears prior to DR findings.The RNFL thinning of PDR and PRP patients suggests the degeneration of neurons and atrophy of axonal.The neurodegeneration is an important component of DR.

Glaucoma Progression Detection by Retinal Nerve Fiber Layer Measurement Using Scanning Laser Polarimetry: Event and Trend Analysis

PURPOSE: To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. METHODS: Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). RESULTS: Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (+/-standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 +/- 0.148 microm/yr vs. -0.218 +/- 0.151 microm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. CONCLUSIONS: RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

Role of imaging in glaucoma diagnosis and follow-up.

The purpose of the review is to provide an update on the role of imaging devices in the diagnosis and follow-up of glaucoma with an emphasis on techniques for detecting glaucomatous progression and the newer spectral domain optical coherence tomography instruments. Imaging instruments provide objective quantitative measures of the optic disc and the retinal nerve fiber layer and are increasingly utilized in clinical practice. This review will summarize the recent enhancements in confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography with an emphasis on how to utilize these techniques to manage glaucoma patients and highlight the strengths and limitations of each technology. In addition, this review will briefly describe the sophisticated data analysis strategies that are now available to detect glaucomatous change overtime.

Scanning Laser Polarimetry and Optical Coherence Tomography for Detection of Retinal Nerve Fiber Layer Defects

PURPOSE: To compare the ability of scanning laser polarimetry with variable corneal compensation (GDx-VCC) and Stratus optical coherence tomography (OCT) to detect photographic retinal nerve fiber layer (RNFL) defects. METHODS: This retrospective cross-sectional study included 45 eyes of 45 consecutive glaucoma patients with RNFL defects in red-free fundus photographs. The superior and inferior temporal quadrants in each eye were included for data analysis separately. The location and presence of RNFL defects seen in red-free fundus photographs were compared with those seen in GDx-VCC deviation maps and OCT RNFL analysis maps for each quadrant. RESULTS: Of the 90 quadrants (45 eyes), 31 (34%) had no apparent RNFL defects, 29 (32%) had focal RNFL defects, and 30 (33%) had diffuse RNFL defects in red-free fundus photographs. The highest agreement between GDx-VCC and red-free photography was 73% when we defined GDx-VCC RNFL defects as a cluster of three or more color-coded squares (p<5%) along the traveling line of the retinal nerve fiber in the GDx-VCC deviation map (kappa value, 0.388; 95% confidence interval (CI), 0.195 to 0.582). The highest agreement between OCT and red-free photography was 85% (kappa value, 0.666; 95% CI, 0.506 to 0.825) when a value of 5% outside the normal limit for the OCT analysis map was used as a cut-off value for OCT RNFL defects. CONCLUSIONS: According to the kappa values, the agreement between GDx-VCC deviation maps and red-free photography was poor, whereas the agreement between OCT analysis maps and red-free photography was good.

The influence of age on retinal nerve fiber layer thickness in adults / 复旦学报（医学版）

Objective To evaluate the association of age and retinal nerve fiber layer (RNFL) thickness by means of scanning laser polarimetry in a sample of healthy Chinese eyes. Methods One hundred and fifty eyes of 150 healthy subjects underwent RNFL scan in two different modes (Variable Cornea Compensation,VCC;Enhanced Cornea Compensation,ECC) of Glaucoma Diagnosis Variable Cornea Compensation Nerve Fiber Analyzer.The parameters included temporal-superior-nasal-inferior-temporal (TSNIT) average,superior average,inferior average,TSNIT standard deviation,and nerve fiber indicator (NFI). Results Mean values of TSNIT average,superior average,inferior average,TSNIT standard deviation and NFI in VCC mode were (57.12±6.26),(69.35±4.21),(67.59±7.06),(25.46±4.02),(17.35±7.59),while the parameters' values in ECC mode were (56.15±5.32),(68.24±6.63),(66.90±2.40),(24.80±6.76),(18.84±8.51),respectively.The differences between the values of VCC and ECC modes were not statistically significant.The parameters' values of total subjects were associated with age.But there were no significant associations between age and parameter values in the eyes of those older than 40 years old subjects. Conclusions There are no significant differences between the RNFL values detected by VCC and ECC modes in 150 healthy Chinese eyes.Age has influence on RNFL thinning in 21-70 years old healthy eyes,but not in the eyes of older than 40 years old people.

Determination of the retinal nerve fiber layer thickness in diabetic patients with no manifested diabetic retinopathy / 复旦学报（医学版）

Objective To investigate whether there is a thinning of the retinal nerve fiber layer (RNFL) in the eyes of diabetic patients and to analyze the relationship between RNFL thickness and several diabetic risk factors. Methods Forty-two type 2 diabetes mellitus patients aged 47-70 years were enrolled in this study. All the subjects underwent ophthalmologic examinations and glaucoma diagnosis (GDx) nerve fiber analyzer scanning with two different modes: variable cornea compensation (VCC) and enhanced cornea compensation(ECC).The GDx parameters included the temporal-superior-nasal-inferior-temporal average (TSNITave), superior and inferior averages, the TSNIT standard deviation and the nerve fiber indicator (NFI). The receiver operating characteristic (ROC) was applied to study the diagnostic ability of indices. The association between risk factors and the NFI was studied. Results The area under the curve for the ROC of the NFI was the largest for both the ECC and VCC modes. There was a significant relationship between age and RNFL thinning. However, there was no significant association between diabetic duration and fasting blood glucose with RNFL thinning. The influence of age on NFI was greater in diabetic patients than in control subjects. Conclusions Age has an important influence on the NFI of diabetic patients. Diabetic patients with normal ocular fundus may have RNFL thinning.

Comparison of Stratus OCT and GDx VCC in Detecting Localized Retinal Nerve Fiber Layer Defects

PURPOSE: To compare the abilities of optical coherence tomography (Stratus OCT) and scanning laser polarimetry with variable corneal compensation (GDx VCC) in detecting localized retinal nerve fiber layer (RNFL) defects of red free photography METHODS: Thirty six normal subject and 50 patients with localized RNFL defects were included in this study. Only one eye per subject was considered. The peripapillary RNFL was divided into 12 clock-hour sectors and localized RNFL defects were evaluated in these 12 sectors. To compare the diagnostic performance of Stratus OCT and GDx VCC based on the findings of red-free photography, we calculated the sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of each analyzer using a criterion of 1 > or = clock hours abnormal at the <5% level. RESULTS: The sensitivity (78.6%), specificity (94.4%), and AUC (0.872) of Stratus OCT were not significantly different from those of GDx VCC (83.3%, 94.4%, and 0.882, respectively) (McNemar test, p=0.75, 1.00, and 0.82, respectively). However, the sensitivity (64.0%) of Stratus OCT for superior RNFL defect was significantly lower than that (84.8%) for inferior defect (Fisher's exact test, p=0.02). CONCLUSIONS: The sensitivity of the sector average of Stratus OCT and the deviation map of GDx VCC were fair in discriminating localized RNFL defects, and the specificity of those were excellent. In addition, the diagnostic performance was not significantly different between two analyzers.

Relationship between Scanning Laser Polarimetry with Enhanced Corneal Compensation and with Variable Corneal Compensation

PURPOSE: To evaluate the structure-function relationships between retinal sensitivity measured by Humphrey visual field analyzer (HVFA) and the retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC) in glaucomatous and healthy eyes. METHODS: Fifty-three eyes with an atypical birefringence pattern (ABP) based on SLP-VCC (28 glaucomatous eyes and 25 normal healthy eyes) were enrolled in this cross-sectional study. RNFL thickness was measured by both VCC and ECC techniques, and the visual field was examined by HVFA with 24-2 full-threshold program. The relationships between RNFL measurements in superior and inferior sectors and corresponding retinal mean sensitivity were sought globally and regionally with linear regression analysis in each group. Coefficients of the determination were calculated and compared between VCC and ECC techniques. RESULTS: In eyes with ABP, R2 values for the association between SLP parameters and retinal sensitivity were 0.06-0.16 with VCC, whereas they were 0.21-0.48 with ECC. The association of RNFL thickness with retinal sensitivity was significantly better with ECC than with VCC in 5 out of 8 regression models between SLP parameters and HVF parameters (P<0.05). CONCLUSIONS: The strength of the structure-function association was higher with ECC than with VCC in eyes with ABP, which suggests that the ECC algorithm is a better approach for evaluating the structure-function relationship in eyes with ABP.

The Retinal Nerve Fiber Layer Analysis in Eyes with Small Optic Disc

PURPOSE: Eyes with small optic disc may be infirm to glaucomatous damage but suitable and objective methods for monitoring glaucomatous optic nerve damage in small optic disc are limited. The purpose of this study was to evaluate the usefulness of the retinal nerve fiber layer (RNFL) analysis using scanning laser polarimetry in patients with small optic disc. METHODS: 63 patients with small optic disc were recruited in this study. Eyes with average disc diameter 1.617 mm or less which was 33 percentile by topographic scanning system in our normal population study were enrolled. There were 26 patients with normal tension glaucoma and 37 patients with normal visual fields. Each patient underwent RNFL analysis using GDx VCC. Measurements of axial length, intraocular pressure, refractive error, disc diameter and cup/disc ratio were fulfilled. Findings were compared with independent t-test between 2 groups. GDx VCC parameters were analyzed with multiple logistic regression analysis. RESULTS: No differences in age, axial length, intraocular pressure, refractive error and disc diameter were apparent between the two groups. However, significant differences were detected in GDx VCC parameters including TSNIT average, Superior average, TSNIT standard deviation, NFI, Superior ratio, Inferior ratio, Sup/nasal, Maximum modualation, Superior maximum and Normalized superior area (p<0.001). The RNFL damage of superior area was prominent. CONCLUSIONS: In the patients with small optic disc, it is hard to detect the pathologic glaucomatous change by their disc morphologies. Therefore, RNFL analysis could be useful for a glaucoma screening of the patients with small optic disc.

Diagnostic Ability of Scanning Laser Polarimetry with Enhanced Corneal Compensation in the Eye with Typical and Atypical Retadation Pattern

PURPOSE: To investigate the relationship between the SLP-VCC parameters and the SLP-ECC parameters in the eyes with typical retardation pattern (TRP) and atypical retardation pattern (ARP), and the sensitivities and specificities of the SLP-VCC parameters and the SLP-ECC parameters in the eye with TRP and ARP. METHODS: In this prospective study, 72 eyes with TRP images (30 glaucomatous and 42 normal eyes) and 53 eyes with ARP images (28 glaucomatous and 25 normal eyes) were recruited. For each group, we analyzed relationship between each parameters of GDx-VCC and GDx-ECC and the diagnostic ability of GDx-ECC by using the ROC curve. RESULTS: In the eyes with TRP, TSNIT average was significantly lower by GDx-ECC than GDx-VCC in the control group. Inferior average was significantly higher by GDx-ECC than GDx-VCC in both glaucomatous and normal group. TSNIT standard deviation was significantly higher by GDx-ECC than GDx-VCC in both groups. NFI was significantly lower by GDx-ECC than GDx-VCC in both groups. TSS (typical scan score) was significantly higher by GDx-ECC than GDx-VCC in both groups. In the eyes with ARP, TSNIT average was significantly lower by GDx-ECC than GDx-VCC in both groups. Superior and Inferior average was not different between GDx-ECC and GDx-VCC. TSNIT standard deviation was significantly higher by GDx-ECC than GDx-VCC in both groups. NFI was not different between groups. TSS was significantly higher by GDx-ECC than GDx-VCC in both groups. Comparison of ROC curve for the SLP parameters revealed no difference between VCC and ECC. TSNIT standard deviation, however, showed relatively high value in GDx-ECC compared with GDx-VCC. CONCLUSIONS: GDx-ECC has comparable diagnostic ability in discriminating glaucomatous and normal eyes with GDx-VCC and TSNIT standard deviation by the GDx-ECC algorithm could be a useful parameter in discriminating glaucomatous and normal eyes.

GDx-VCC Performance to Discriminate Normal, Pre-perimetric Glaucomatous Eyes

PURPOSE: This study was designed to assess the diagnostic value of scanning laser polarimetry with variable corneal compensation (GDx-VCC) in the diagnosis of preperimetric glaucoma. METHODS: The study included 132 eyes of 132 patients with normal intraocular pressure, including 38 normal eyes, 60 eyes with pre-perimetric glaucoma, and 34 eyes with early glaucoma. The parameters of GDx-VCC were analyzed and compared in these groups using ANOVA. The parameter with the most powerful diagnostic value was defermirred by an ROC curve, and it's sensitivity and specificity were calculated. RESULTS: Among GDx-VCC parameters, NFI was the most valuable parameter that could detect pre-perimetric glaucoma in normal eyes. A cut-off value of 12 was the optimal NFI value, which offered the highest sensitivity and specificity in discriminating between normal and pre-perimetric glaucomatous eyes. However, there were no statistically significant differences in GDx-VCC parameters between pre-perimetric and early glaucomatous eyes. A statistically significant correlation was found between NFI and visual field indices in early glaucomatous eyes. CONCLUSIONS: GDx-VCC can be useful as a screening test for early detection of pre-perimetric and early glaucoma with normal intraocular pressure.

Discriminating Ability of Scanning Laser Polarimetry with Variable Corneal Compensation in Normal and Glaucomatous Eyes

PURPOSE: We investigated the diagnostic ability of scanning laser polarimetry with variable corneal compensation (GDx VCC) parameters to distinguish glaucomatous eyes with different degrees of visual field abnormality from normal eyes. METHODS: Subjects were divided into a control group (n=47) and an early to moderate glaucoma group (n=100). The latter included 53 early glaucoma patients (mean deviation > -6dB with a Humphrey Field Analyzer). Using a receiver operating characteristic (ROC) curve, the diagnostic power of GDx VCC parameters was analyzed and the correlations between those parameters and Humphrey Field Analyzer (HFA) indices were statistically analyzed. RESULTS: Nerve fiber indicator (NFI) provided the best discriminating ability with the highest area under the ROC curve (AUROC) value for detecting eyes with early to moderate perimetric glaucoma. TSNIT average showed the highest AUROC value for detecting eyes with early perimetric glaucoma. The optimal NFI cut-off value to discriminate between the control group and early to moderate group was 22, offering the best combination of sensitivity (88.0%) and specificity (83.0%). The optimal TSNIT average cut-off value to discriminate between the control group and early glaucoma group was 53.49 micrometer, providing the best combination of sensitivity (84.9%) and specificity (85.1%). Most of the thickness parameters showed higher AUROC values than those of the ratio or modulation parameters. A statistically significant correlation was found between the GDx VCC parameters and HFA indices. CONCLUSIONS: Measurement of the retinal nerve fiber layer (RNFL) by scanning laser polarimetry with variable corneal compensation is useful in discriminating between normal and glaucomatous eyes.

Comparison of Retinal Nerve Fiber Layer Measurements between NTG and HTG using GDx-VCC

PURPOSE: To compare quantitative polarimetric measurements in eyes with NTG and HTG using GDx-VCC. Both groups were matched by age and glaucoma stage based on the Humphrey visual field test. METHODS: We retrospectively reviewed the records of 146 patients who underwent Humphrey field analysis (HFA) and GDx-VCC. We compared outcomes of retinal nerve fiber layer (RNFL) parameters among the three groups by ANOVA and between each pair of groups using the Tukey-Kramer Post-Hoc test. We also evaluated the sensitivity and specificity of GDx-VCC in detecting glaucoma in each group. RESULTS: The mean age and HFA mean deviation (MD) were 55.6+/-9.5 years and -0.8+/-1.5 dB in 47 control patients, 59.4+/-9.0 years and -5.77+/-4.38 dB in 49 NTG patients, and 59.4+/-11.7 years and -8.09+/-6.77 dB in 51 HTG patients, respectively. All thickness parameters were lower in HTG patients compared to NTG patients, but there were no significant differences in ratio parameters between age-matched early HTG and NTG patients. The sensitivity of GDx-VCC was significantly higher in both early and total HTG patients compared to the respective groups of NTG patients. CONCLUSIONS: Compared to eyes with NTG, eyes with HTG showed reduced RNFL thickness and ratio parameters when patients were age and visual field matched. GDx-VCC appeared to be more sensitive in detecting RNFL damage in HTG patients.

Scanning Laser Polarimetry Using Variable Corneal Compensation in Detection of Localized Visual Field Defects

PURPOSE: To evaluate the ability of scanning laser polarimetry parameters and a novel deviation-map algorithm to discriminate between healthy and early glaucomatous eyes with localized visual field defects confined in one hemifield. METHODS: In this prospective case-controlled study, 61 glaucomatous eyes with localized visual field defects and 66 normal controls were enrolled. Humphrey field analyzer 24-2 glaucoma hemifield test and scanning laser polarimetry (GDx-VCC ) were used. RESULTS: There were significant differences in the mean parametric values of TSNIT average, superior average, inferior average, and TSNIT SD (P<0.05) between the glaucoma group and normal subjects. The sensitivity of each GDx-VCC variable was as follows: TSNIT average, 47.5%; superior average, 31.1%; inferior average, 47.5%; and TSNIT SD, 24.6% (when abnormal was defined as P<0.05). The overall sensitivities combining each probability scale and severity score at 80%, 90%, and 95% specificity were 90.2%, 72.1%, and 59%, respectively. There was a statistically significant correlation between the GDx-VCC severity score and the visual field severity score (P<0.05). CONCLUSIONS: GDx-VCC parameters may not be sufficiently sensitive to detect glaucomatous patients with localized visual field damage. Our algorithm using the GDx-VCC deviation map may enhance the understanding of GDx-VCC in terms of the locality, deviation size, and severity of localized RNFL defects in eyes with localized visual field loss.

Correlation Between Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry in Glaucoma Suspects and Glaucomatous Eyes

The aim of this study was to determine the relationship between the frequency doubling technology (FDT) screening algorithm and parapapillary retinal nerve fiber layer (RNFL) thickness in the eyes of glaucoma suspects and patients with open angle glaucoma. FDT C20-1 screening program and a scanning laser polarimetry (SLP) system (GDx-NFA) was used to assess 53 glaucomatous eyes, 53 glaucoma suspects and 36 normal control eyes. In glaucomatous eyes, there were correlations between the FDT the screening algorithm and RNFL retardation values in several polarimetric indices, most significantly "inferior thickness" (r = -0.321, P = 0.029). In the eyes of glaucoma suspects, however, we observed no correlation between the FDT results and RNFL retardation values (r = 0.080, P > 0.05, "inferior thickness"). In glaucomatous eyes, the abnormal scores obtained with FDT screening program correlated negatively with RNFL retardation values, as measured by SLP. Despite poor correlation between the FDT abnormal score and RNFL retardation value in glaucoma suspects, detection of abnormality using the FDT screening protocol may aid in the assessment of early glaucomatous structural damage.

Differentiating Patients with Glaucoma from Glaucoma Suspects by Retinal Nerve Fiber Layer Assessment Using Nerve Fiber Analyzer

PURPOSE: To evaluate the difference of retinal nerve fiber layer measurements as obtained by Nerve Fiber Analyser according to visual field defects in subjects with large Cup-to-Disc ratio (C/D ratio>or=0.6) and to determine which predictable parameters are useful in glaucoma diagnosis. METHODS: Fifty one normal subjects, 17 patients with glaucoma, 18 glaucoma suspects based on optic disc appearance and visual field defect participated. Nerve fiber layer thickness assessments using scanning laser polarimeter (Nerve Fiber Analyzer II software version 2.1.; Laser Diagnostic Technologies, Inc., San Diego, California, U.S.A.) were measured in normal subjects, patients with glaucoma, and glaucoma suspects. Measured nerve fiber layer thickness parameters were compared each other. RESULTS: Superior to inferior ratio (S/I ratio) was only statistically significant parameter to differentiate glaucoma from glaucoma suspects having glaucomatous optic nerve head. CONCLUSIONS: Superior to inferior ratio (S/I ratio) is useful parameter to predict differentiating patients with glaucoma from glaucoma suspects.

The Relationship between the Duration of IOP Elevation during LASIK and Nerve Fiber Layer Thickness Measured by GDx(R)

PURPOSE: To determine the effect of temporary intraocular pressure (IOP) elevation during laser in situ keratomileusis (LASIK) on retinal nerve fiber layer measurement by scanning laser polarimetry in a clinical trial. METHODS: The duration of IOP elevation was recorded during LASIK and scanning laser polarimetry (GDx(R) Retinal Nerve Fiber Analyzer. Laser Diagnostic Technologies, Inc, San Diego, California) measurements were performed in 60 eyes of 30 consecutive patients before and after the LASIK procedure. RESULTS: The mean duration of IOP elevation during LASIK was 27.2+/-4.5 seconds. The mean retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry were 73.2+/-12.8 micro meter preoperatively, 65.6+/-12.7 at postoperative 1 month and 66.0+/-9.8 micro meter at postopertive 3 months. The mean postoperative 1 month and 3 months values showed significantly reduced RNFL thickness. But, there was no relationship between the duration of IOP elevation and the amount of nerve fiber layer thickness reduction. (R2=0.064, p=0.627) Furthermore, there were no interval change between the retardation values of postoperative 1 month and 3 months (p=0.706). CONCLUSIONS: There was no relationship between the duration of IOP elevation during LASIK and the postoperative reduction of RNFL thickness measured by scanning laser polarimetry. When using scanning laser polarimetry as a helpful diagnostic and follow-up tool for glaucoma, care should be taken in the interpretation of the result after LASIK procedure. If a comparison is likely to be needed in the future, this image should be obtained after the LASIK procedure to set the postoperative baseline.