Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC).

Purpose: To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Materials and Methods: Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). Results: The mean age of subjects was 57.6 ± 11.7 years (18 males, 14 females). Mean TSNIT average thickness (μm) pre- and post-cataract surgery was 49.2 ± 14.1 and 56.5 ± 7.6 (P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 ± 15.3 and 21.6 ± 11.8 (P = 0.001). Conclusions: Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

Relationship between the Retinal Thickness Analyzer and the GDx VCC Scanning Laser Polarimeter, Stratus OCT Optical Coherence Tomograph, and Heidelberg Retina Tomograph II Confocal Scanning Laser Ophthalmoscopy

PURPOSE: To assess the relationship between the retinal thickness analyzer (RTA) parameters, and those of the GDx VCC scanning laser polarimeter (GDx VCC), Stratus OCT optical coherence tomography (Stratus OCT), and Heidelberg retinal tomograph II confocal scanning laser ophthalmoscopy (HRT II). METHODS: Twenty-nine primary open-angle glaucoma patients were retrospectively included in this study. Measurements were obtained using the RTA, GDx VCC, Stratus OCT, and HRT II. We calculated the correlation coefficients between the parameters of RTA and those of the other studies. RESULTS: Among the optic disc parameters of RTA, the cup volume was best correlated with Stratus OCT (R=0.780, p<0.001) and HRT II (R=0.896, p<0.001). Among the posterior pole retinal thickness parameters, the posterior pole abnormally thin area (PPAT) of the RTA and the inferior average of the GDx VCC were best correlated (R=-0.596, p=0.001). The PPAT of the RTA and the inferior maximum of the Stratus OCT were best correlated (R=-0.489, p=0.006). The perifoveal minimum thickness (PFMT) of the RTA and the cup shape measurement of the HRT II were best correlated (R=-0.565, p=0.004). CONCLUSIONS: Many RTA optic disc parameters were significantly correlated with those of the Stratus OCT and HRT II. The RTA posterior pole retinal thickness parameters were significantly correlated with those of the GDx VCC, Stratus OCT and HRT II. The RTA optic disc and posterior pole retinal thickness parameters may be valuable in the diagnosis of glaucoma.

The correlation between the structural parameters provided by the Heidelberg retina tomography (HRT) and laser diagnostics glaucoma scanning system (GDx) in primary open angle glaucoma / 眼科

Objective To investigate the correlation between the structural parameters provided by the Heidelberg retina tomogra- phy (HRT) and the structural parameters provided by laser diagnostics glaucoma scanning system (GDx), to discuss whether the correla- tion between them be used to make a more accurate diagnosis. Design Case control study. Participants Thirty-two patients (49 eyes) with primary open angle glaucoma and 15 patients only with abnormal GDx results. Methods The patients underwent examination with HRT, GDx. The relations between the topographic parameters of GDx Ecc and HRT were analysed by linear regression. F test was used to analyse whether there was a spatial correspondence between the GDx Ecc and HRT I]. Maim Outcome Measures The topographic parameters generated by GDx Ecc and HRTⅡ. Results In glaucoma group, among the topographic parameters generated by GDx Ecc and HRTⅡ. The correlation between NFI and rim area was significant (r=-0.68,P=-0.000). The spatial correspondence between GDx Ecc and HRTⅡwas also significant. In control group, NFI and rim area also had the significant correlation among the parameters of optic nerve head and retinal nerve fiber layer (r=-0.79, P=0.001). But there was no spatial correspondence between the GDx Ecc and HRTⅡ. Conclusions There is a spatial correspondence between GDx and HRT, but this correspondence doesn't existence in patients only with abnormal GDx result. This difference can be used to make a more accurate diagnosis.

Normal Retinal Nerve Fiber Layer Thickness in the Peripapillary Region of Koreans Measured by Scanning Laser Polarimeter

PURPOSE: To measure normal retinal nerve fiber layer thickness (RNFLT) in the peripapillary region of Koreans using a scanning laser polarimeter, the nerve fiber analyzer (GDx VCC). METHODS: Two hundred ninety-nine eyes of 299 healthy subjects (156 men, 143 women) were recruited for this study. No subject had diabetes mellitus, hypertension, or any other neurologic disorders. All subjects were normal at ophthalmologic examination, which was assessed by slit-lamp biomicroscopy using a 90-diopter lens, Goldmann applanation tonometry, and Humphrey visual field analysis. Using the GDx VCC, we analyzed the mean value of each parameter in GDx VCC (average at global, superior, inferior, superior maximum and inferior maximum) and evaluated the difference between men and women and each decade of age. RESULTS: Mean RNFLT parameters in GDx VCC were global 56.42 +/- 6.84 micrometer, superior 70.51 +/- 8.70 micrometer, inferior 67.55 +/- 9.04 micrometer, superior maximum 83.52 +/- 12.38 micrometer, and inferior maximum 82.64 +/- 12.70 micrometer. The parameters which showed a difference between men and women were superior average and superior and inferior maximum average RNFLT. The superior RNFLT was thicker than the inferior ones. RNFLT was not statistically different in each decade of age. CONCLUSIONS: We can make good use of the normal parameters of GDx VCC in Koreans for early diagnosis and follow-up of glaucoma.

The Relationship between the Capillary Nonperfusion Area and the Retinal Nerve Fiber Layer Defects in Branch Retinal Vein Occlusion Patients

PURPOSE: To determine the relationship between the capillary nonperfusion area and the retinal nerve fiber layer (RNFL) defects in branch retinal vein occlusion (BRVO) patients. METHODS: We compared the difference between the RNFL thickness of both eyes in unilateral BRVO patients using the scanning laser polarimeter (GDx R ). The mean RNFL thickness was calculated for each quadrant. Fluorescein angiography was done to determine the retinal capillary nonperfusion area and we evaluated the relationship between the retinal capillary nonperfusion area and the right-left difference of RNFL thickness. RESULTS: In left superior temporal BRVO group, the Average of RNFL was thinner (p=0.015) and the Integral was smaller (p=0.045) in the left BRVO eye than in the right normal eye in the superior temporal sector. In patients with the other sector BRVO, there was no significant difference of RNFL thickness between both eyes. As the retinal capillary nonperfusion area increased, the right-left difference of Average increased in the superior temporal sector in patients with left superior temporal BRVO (p=0.042). CONCLUSIONS: The scanning laser polarimeter allowed the quantification of RNFL defect in patients with BRVO, and it may help to evaluate the quantification of retinal ischemia.