Study Of Spectral Domain OCT And MfEGR In The Early Diagnosis Of Primary Open Angle Glaucoma

Objective: Glaucoma is one of the major cause of blindness, primary open angleglaucoma (POAG) is a common type of glaucoma, it occurs insidiously,most of thepatients already suffered serious damage of visual function when they are found comingdown with glaucoma. Although in the clinical practice，visual field examination as the"gold standard ", but before abnormal visual field，it already had damage of retinalstructure and function. For example: the changes of retinal nerve fiber layer (RNFL)thickness and the optic disc morphology, and the changes of retinal ganglion cells(RGC) function.Only using visual field examination can not meet the current needs ofearly diagnosis of POAG. Combined with one even more examinations to assist thediagnosis of early POAG is the urgent demand of clinic, as well as current researchfocus. The purpose of this research is using spectral domain optical coherencetomography (SDOCT) and multifocal electroretinogram (mfERG) to detect the retinalstructure and function changes in early POAG group and normal group, exploring theapplication value of early diagnosis of POAG.Methods: We collected20eyes of15early POAG patients diagnosed in TheSecond Affiliated Hospital of Dalian Medical University from September2013toFebruary2014as experimental group, and chose20eyes of10healthy volunteers in the same period as normal control group.we use the two groups for a comparative study. Allsubjects were conducted routine eye examinations (such as visual acuity, intraocularpressure, anterior segment examination, angle examination, and fundus examination)and special inspection (vision, spectral domain OCT, and mfERG). The subjects withserious systemic disease, intolerant to any examination or allergic to sodium fluoresceinwere excluded. The consent of included subjects was obtained before experiment. Allinspections were performed by trained surveyors. Application SPSS17.0software wasused for data processing, and measurement data was presented as mean±standarddeviation. Independent sample t test was used to compare normal and early POAGgroup data, and statistically significant (P <0.05) measurement parameters were selectedto draw the curve of receiver operating characteristic (ROC curve). The area under theROC curve of each parameter was compared, appraise the diagnostic value of eachparameter.Results:1.General information: The age and diopter (after the equivalent sphericaltransform) of subjects between early POAG group and the control group showed nosignificant difference (P>0.05).2. Spectral domain OCT examination: The average and four quadrants RNFLthickness of early POAG group were thinner than normal control group, and thedifference of average, superior and inferior quadrants was statistically significant (P<0.05), while nasal and temporal quadrants showed no statistically significant (P>0.05).The area under the ROC curve of RNFL thickness was (from high to low) average(0.907)>superior quadrant (0.885)>inferior quadrant (0.880), and the diagnostic valuewas average>superior quadrant>inferior quadrant RNFL thickness.3.mfERG: In early POAG group, the amplitude density of1to6ring in P1waveand the supertemporal, infratemporal, supernasal and infranasal quadrants decreasedcompared with normal control group, and the difference was statistically significant (P<0.05). The amplitude density decreased mostly in the central area of macula (1ring),followed by2ring. The amplitude density decreased less when it approached to thesurrounding. However, the difference of amplitude density of P1wave in four quadrants between two groups showed no significant regularity. The area under the ROC curve ofP1wave amplitude density was greater than0.7, indicating that there was a certainvalue in the diagnosis. The area under the ROC curve of central macular region (1ring)was maximum (0.851), with the greatest diagnostic value. The latencies of P1wave in1to6ring and four quadrants between two groups was no significant difference (P>0.05).Conclusion:1. Spectral domain OCT and mfERG can evaluate the characteristicsof structure and function impairments of the retina from different aspects, and both ofthem have diagnostic value of POAG and are beneficial to clinical diagnosis of POAG.2. The average, superior and inferior quadrant RNFL thickness of early POAGpatients were significantly thinner than the normal control group. These threeparameters measured by spectral domain OCT are helpful to detect structural damagesof retina in early POAG patients, which provide the basis for early diagnosis of POAG.3. The amplitude density of1to6ring in mfERG P1wave in early POAG patientsdecreased, especially in the central area of the macula (1ring), conjecturing earlyPOAG patients suffered more serious damages in macular area.4. In the aspect of diagnosing early POAG, among the measurement parameters inthe spectral domain OCT, the order of diagnostic value from high to low isaverage>superior quadrant>inferior quadrant RNFL thickness. The P1wave amplitudedensity in central macular region (1ring) has the highest diagnostic value in the mfERGparameters.