Evaluation Of The Structure And Function Relationship In Primary Open Angle Glaucoma

Part ⅠComparison of macular and peripapillary retinal nerve fiber layer parameters in glaucomaPurposeTo evaluate the macular ganglion cell complex (mGCC) and peripapillary retinal nerve fiber layer parameters (ppRNFL) in POAG patients measured with fourier-domain optical coherence tomography (FD-OCT).Methods1. The macular GCC thickness and peripapillary RNFL thickness of40eyes of40non-glaucoma subjects,30eyes of30preperimetric glaucoma,30eyes of30early POAG patients,32eyes of32moderate-advanced POAG patients were measured using FD-OCT (RTVue OCT). The mean RNFL and mean mGCC were compared within the four groups. The study also investigated whether there was any correlation between the temporal RNFL and mGCC thicknesses.2. The area under the receive operating characteristic curve (AROC) of the mGCC thickness and ppRNFL thickness were calculated and compared. The study also explored factors affecting the glaucoma diagnostic capability.Results1. There were significant differences of ppRNFL and mGCC thickness measurements between early, moderate-advanced glaucoma or preperimetric glaucoma patients and non-glaucoma subjects (P<0.001). The ppRNFL and mGCC thickness decreased with the severity of glaucoma, while the measurements of GCC-FLV and GCC-GLV increased with significant difference (P<0.001).2. Correlations were seen for the average, superior, inferior mGCC and corresponding RNFL sectors in all glaucoma group (r=0.524-0.762). We also evaluated correlations for each of the supero-temporal sectors and the superior mGCC (r=0.564-0.849), in addition to each of the infero-temporal sectors and inferior mGCC in the glaucoma group(r=0.517-0.643). With the exception of the papillomacular bundle (r=0.336), correlations were also analyzed in each of the preperimetric glaucoma mGCC and temporal RNFL sectors (r=0.522-0.725).3. The AROC of all ppRNFL and mGCC parameters were large (0.810-0.999). There were no significant differences of the AROC between the GCC and RNFL thickness parameters.4. Optic disc area, presence of central scotoma could affect the diagnostic performance. ppRNFL parameters were generally superior to mGCC measurements in the diagnosis of glaucoma. mGCC parameters were of greater value in eyes with larger optic discs and presence of central scotoma.ConclusionsThe mGCC and ppRNFL thickness measured using FD-OCT decreased with the severity of glaucoma, and a high correlation existed between the two. Like RNFL, mGCC can potentially be used to detect glaucoma.Part ⅡComparison of multi-focal visual evoked potential and standard automated perimetry in glaucomaPurpose1. To investigate the amplitude of Multi-focal visual evoked potential (mfVEP) in primary open-angel glaucoma patients.2. To evaluate the relationship between mfVEP and Humphrey visual field (HVF) and the agreement of mfVEP and HVF in diagnosis of glaucoma.Methods1.30early POAG patients,32moderate-advanced POAG patients and30normal volunteers were enrolled in the study. Multi-focal visual evoked potential and Humphrey visual field were performed in all the participants. One eye per individual was included in the study.2. The relationship between mfVEP and subjective Humphrey visual field was analyzed. The agreement of these two tests was assessed using Kappa statistical method.Results1. There was highly significant reduction of MD and mean mfVEP amplitude in all three regions in glaucoma patients。2. A high level of correlation was detected between MD and amplitude of the mfVEP for each of the three sectors. Correlations were seen between MD and amplitude of the mfVEP in the early glaucoma group (r=0.454-0.638) and moderate-advanced glaucoma group (r=0.623-0.804).3. We demonstrated strong topographical associations between the two functional damages in patients with glaucoma. The agreement between the mfVEP and the HVF results was89%(Kappa=0.767). The mfVEP detected substantially more abnormality than HVF.ConclusionsThe mfVEP test is a powerful tool for the detection, management and study of glaucoma. Both have their own advantages in detecting glaucomatous damage. When the mfVEP has a large SNR and the damage is unilateral, it will often be superior to the HVF in detecting damage. On the other hand, when the mfVEP has a small SNR and the damage is bilateral, the HVF will probably be superior. The mfVEP offers a valuable alternative to the HVF for those patients who produce questionable HVFs.Part ⅢEvaluation of the relationship between structural and functional damage in glaucomaPurposeTo investigate topographical relationship between amplitude of multifocal visual evoked potential, standard automated perimetry and optical coherence tomography in glaucoma.Methods1.30early POAG patients,32moderate-advanced POAG patients and30normal volunteers were enrolled in the study. Macular GCC thickness and peripapillary RNFL thickness were measured using FD-OCT, mean deviation(MD) of visual field was examined using Humphrey VF analyzer, and the amplitude of mfVEP were measured. The associations between the GCC or RNFL thickness and MD or amplitude of mfVEP were evaluated with linear and curvilinear regression models.2. The agreement of these three tests was assessed using Kappa statistical method.Results1. The ppRNFL thickness was correlated well with the multifocal VEP amplitude and MD value of the corresponding regions. Correlations were seen in ppRNFL thickness and MD value of the corresponding regions (r=0.418-0.626). Correlations were also analyzed for the ppRNFL thickness and multifocal VEP amplitude of the corresponding regions (r=0.454-0.632).2. The mGCC thickness was correlated well with the multifocal VEP amplitude and MD value of the corresponding regions. Correlations were seen in mGCC thickness and MD value of the corresponding regions (r=0.389-0.571). Correlations were also analyzed for the mGCC thickness and multifocal VEP amplitude of the corresponding regions (r=0.431-0.0.614).3. The curvilinear regression model could well describe the relationship between GCC, ppRNFL thickness and MD value. The linear regression model could well describe the relationship between GCC, ppRNFL thickness and amplitude of mfVEP.4. We demonstrated strong topographical associations between structural and functional damage in patients with glaucoma. The agreement between the OCT results and the HVF was89%(Kappa=0.764). The agreement between the OCT results and the mfVEP was91%(Kappa=0.808).ConclusionsBoth of the mGCC thickness and ppRNFL thickness showed a curvilinear relationship with MD and a linear relationship with amplitude of mfVEP. The mfVEP, HVF and OCT provide complementary information in detecting glaucoma.