| Objectives: To observe the morphological changes of visual pathways inpatients with suspected glaucoma, and to explore the early diagnosis ofglaucoma, through the application of optical coherence tomography （OCT）combined with diffusion tensor imaging （DTI）, associated with the changes ofvisual field examination.It is well known that glaucoma is a group of diseases characteristic ofoptic nerve atrophy and visual field defect. It is a serious irreversible conditionthat ranks the second leading cause of blindness in the world and poses a greatthreat to human visual health. Its main pathological defect characterized byloss of retinal ganglion cells, which in turn leads to optic atrophy. Highintraocular pressure is among the risk factors in spite of the fact that its precisemechanism is still unknown and is under the research of medical workers. Itshould be noted that the course of chronic open-angle glaucoma is slow, andmost patients have no apparent symptoms, which makes it hard for earlydetection. Once diagnosed, the patients’ optic functions have been irreversiblydamaged. As a result, it is more risky than other types of glaucoma, and actsas hidden killers of visual function. Among the patients, some have thefollowing characteristics: their intraocular pressure is above the normal upperlimit statistically, but they have no substantial glaucoma impairment anddevelop from the open-angle glaucoma group. The conditions are stronglylatent at early stage, and are more easily overlooked and missed clinically.Consequently, the best timing for treatment tends to be missed. Therefore, toprevent suspected glaucoma from development into chronic open-angleglaucoma, early diagnosis is particularly important. With the advancement ofscience and technology, further research has been carried out in the field. Anew measuring method has been developed, through which in vivo non-invasive detection of subtle changes of retinal nerve fiber layers（RNFL）and the structure of brain proteins can be achieved. The technology can detectthe subtle changes in the visual pathway quantitatively, providing materialguarantee for clinical research. In short, this study aims to measure themorphological changes of visual pathways in patients with suspectedglaucoma quantitatively, combined with changes in visual field through OTCcombined with DTI, to explore changes in early stage and provide clinicalbasis for early diagnosis and early treatment, and help to improve theprognosis of patients.Methods: Subjects are selected from outpatients of the Department ofOphthalmology, the Second Hospital of Hebei Medical University, fromOctober2011to December2012. Among them,20eyes of20cases ofsuspected glaucoma patients（12males,8females, ranging from22to48）,20eyes of20cases of diagnosed for primary open angle glaucoma（POAG）（13males,7females, ranging from26to53）,20eyes of20cases of normalpeople （10males,10females, ranging from26to45） are selected. Thesubjects are divided into three groups: the suspected glaucoma group, theprimary open-angle glaucoma group and the normal control group. TheDepartment of Glaucoma in the Second Hospital of Hebei Medical Universityis responsible for the clinical examination and data collection: visual fieldexamination by fully automated threshold perimetry Octopus101made inSwitzerland to test mean defect（MD） and mean sensitivity（MS）; retinal nervefiber layer thickness（RNFLT） testing by OTC SPECTRAUS, made inHeidelberg, Germany; visual pathway examination by DTI GE3.0ZOOM-EPI, made in the United States. data are obtained and analyzed by thesoftware attached to the devices. Comparisons of the following indexes aremade among different groups: optic nerves, optic tracts, fractionalanisotropy（FA） of the radioactive diffusion capacity, apparent diffusioncoefficient （ADC）, and the sizes of lateral geniculate bodies, combined withmeasurements of RNFLT through OCT, MS and MD through visual fieldexamination, subtle changes of defects are to be detected, which will provide effective evidence for early diagnosis and treatment of suspected glaucoma.Results: The subjects are divided into three groups and twenty eyes fromeach group are chosen respectively. Analysis of variance and rank varianceanalysis of conversion are made about the following indexes among threegroups of subjects---RNFLT, MS, MD of the selected eyes; comparisons aremade about the corresponding optic nerves, optic tracts, FA and DC of visualradioactivity, sizes of geniculate bodies. The results are as follows: the indexesof RNFLT among the suspected glaucoma group, the primary open-angleglaucoma group and the normal control groups are statistically significant,with suspected glaucoma group（76.13±3.12） μm and the primary open angleglaucoma group（47.35±6.48） μm, showing RNFL thickness of thinningcompared with that of control group（104.43±9.2） μm.The comparisons of the suspected glaucoma group, the primaryopen-angle glaucoma group with the control group in MS and MD throughvisual field examination are as follows:①MS: there is no significantdifference between the suspected glaucoma group and the control group; thereis significant difference between the POAG group and the control group; thereis significant difference between the suspected glaucoma group and the POAGgroup, with POAG showing lower.②MD: the differences among thesuspected glaucoma group（3.37±1.43）dB, the primary open-angle glaucomagroup（18.54±5.38dB） and the normal control group（1.92±1.15） dB arestatistically significant, with the former two groups showing rise in MD.The indexes of diffusion characteristics of optic fibers of suspectedglaucoma group and primary open-angle glaucoma are as follows,①FAvalues of different groups are significantly different（p<0.05）, with thesuspected glaucoma group（0.56±0.05）×10-3mm2/s, the primary open angleglaucoma group（0.46±0.06）×10-3mm2/s, and the normal control group（0.61±0.05）×10-3mm2/s, with the former two groups showing lower FA values;②DC also increases, but there is no significant difference between the normalcontrol group（1.21±0.45）×10-3mm2/s and the suspected glaucomagroup（1.28±0.35）; whereas there is significant difference （p<0.05） between the normal control group（1.21±0.45）×10-3mm2/s and the open angleglaucoma group（1.72±0.30）×10-3mm2/s, between the suspected glaucomagroup（1.28±0.35）×10-3mm2/s and the angle glaucoma group（1.28±0.35）×10-3mm2/s.The indexes of diffusion characteristics of optic tracts of the suspectedglaucoma group and the primary open-angle glaucoma are as follows,①FAvalues of different groups are significantly different（p<0.05）, with suspectedglaucoma group（0.52±0.09）×10-3mm2/s, primary open angle glaucomagroup（0.39±0.06）×10-3mm2/s, and normal control group（0.57±0.01）×10-3mm2/s, with the former two groups showing lower FA values;②DC alsoincreases, but there is no significant difference between the normal controlgroup（1.11±0.40）×10-3mm2/s and the suspected glaucoma group（1.23±0.19）×10-3mm2/s; whereas there is significant difference （p<0.05） between thenormal control group（1.11±0.40）×10-3mm2/s and the open angle glaucomagroup（1.39±0.18）×10-3mm2/s, between the suspected glaucoma group（1.23±0.19）×10-3mm2/s and the angle glaucoma group（1.39±0.18）×10-3mm2/s.The relationships of diffusion characteristics of optic radioactivity of thesuspected glaucoma group, the primary open angle glaucoma group andnormal control group are as follows:①FA values of different groups aresignificantly different, with the suspected glaucoma group（0.32±0.07）×10-3mm2/s, the primary open angle glaucoma（0.19±0.09）×10-3mm2/s, and thenormal control group（0.40±0.06）×10-3mm2/s, with the former two groupsshowing lower FA values;②compared with the normal control group, DCvalues of the other two groups also increases, there is significant differencebetween the normal control group and the suspected glaucoma group, betweenthe normal control group and the open angle glaucoma group（p<0.05）,whereas there is no significant difference between the suspected glaucomagroup and the open angle glaucoma groups.Comparisons of sizes of geniculate bodies of the three groups are madeand are processed by rank conversion analysis of variance as follows: there isno significant difference between the normal control group（120.42±31.3） mm3and the suspected glaucoma group（108.48±21.03） mm3, whereas there issignificant difference （p<0.05） between the normal control group（120.42±31.3） mm3and the open angle glaucoma group（63.17±19.27） mm3, betweenthe suspected glaucoma group（108.48±21.03） mm3and the open angleglaucoma group（63.17±19.27） mm3, characterized by reductions of lateralgeniculate body size with the worsening of optic nerve atrophy.Conclusions: OCT combined with DTI can be applied to detect thesubtle changes of nerve fibers of visual pathways at early stage and providethe basis for early diagnosis of suspected glaucoma; it can be found throughthe study that there exists the central nervous system damage of nerve fibers inspite of the fact that there is no visual function defect at the early stage forsuspected glaucoma patients. Thus it can be boldly concluded that glaucoma isa progressive disease that will compromise central nervous system and impairthe visual function. |
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