Morphologic And Functional Evaluating Of Optic Disk And Early Glaucoma Diagnosis

Glaucoma is one of the main diseases causing blindness in China, which is related to the elevated intraocular pressure (IOP) and results in optic nerve damage and visual function loss. Hitherto, the neural cell of optic nerve is irreversible. The blindness causing by glaucoma cannot be cured. Therefore, early diagnosis and early treatment is very important.The current situations are: 1) Modern laser and computer technologies supply new detecting approach for measuring optic nerve. HRT (Heidelberg Retinal Tomography) was considered as one of the most efficient facility in quantitatively evaluating optic nerve head. But its accuracy needs to be supported by various clinical researches. 2) Conventional automatic staticperimetry is nonspecific in stimulation of various types of ganglion cells and therefore is not able to detect the earlier glaucomatous function loss until the disease has damaged 20-40% of the optic nerve fibers. Frequency-doubling perimetry (FDP) is a new kind of perimetric test, which is designed to selectively examine the functions of retinal ganglion cells. However, this important function needs to be further clinical identification. 3) One of the common question in glaucoma diagnosis and management is: patients with NTG have glaucomatous optic nerve head damage and visual field defect in spite of normal IOP. Several authors reported that central cornea thickness (CCT) was significantly thinner in NTG patients than in POAG or normal subjects. The applanation IOP of normal tension glaucoma (NTG) may be likely to be underestimated for their thinner cornea and NTG actually is POAG. NTG is the same disease as POAG, or not? This is an important question. Opposite to NTG, Patients with ocular hypertension (OH) have elevated IOP but do not have apparently optic nerve head damage. Is it related to the overestimated applanation IOP because of the thicker cornea?Based on above situations, we have questions: 1) Be HRT able to detect the optic disk damage? Are optic disk changes detected by HRT correlated to glaucomatous visual field defects? 2) How is about the sensitivity and specialty of FDP test? Be FDP really able to detect glaucomatous visual field defect earlier than conventional perimetry? 3) NTG has normal IOP but with glaucomatous optic nerve head damage and visual field defect. Is it related to its thinner corner? OH have elevated IOP but without apparently optic nerve head damage. Is it related to its thicker corner? How does thecornea thickness affect the glaucoma diagnosis?In order to answer these questions, we carried out a serious of researches: \). Evaluating of optic disc of early open-angle glaucoma with only hemifield defect by Heidelberg Retinal Tomography; 2). Frequency-doubling perimetry in open-angle glaucoma eyes with hemifield defect - combining Heidelberg Retinal Tomography study; 3 ). The influence of corneal thickness on glaucoma diagnosis.1 Evaluating of optic disc of early open-angle glaucoma with only hemifield defect by Heidelberg Retinal TomographyObject: to investigative whether the glaucomatous optic disc change demonstrated by Heidelberg Retinal Tomography (HRT) is consistent to the distribution of the visual field defects and whether HRT parameters in primary open angle glaucoma (POAG) and normal tension glaucoma (NTG) are different.Method: 64 eyes of 64 open angle glaucoma patients (27 of POAG, 37 of NTG) with only hemifield defect detected by Humphery Field Analyzer (HFA) were tested on HRT. The HRT parameters and the visual field results were divided into two parts ( 0° - 180° and 180° -360° ) for the corresponding analysis.Results: Comparing with the half discs corresponding to the intact hemifield, the half discs corresponding to the defect hemifield have significantly higher value of cup/disc area ratio and cup shape measure , significantly lower value of rim area, retinal nerve fiber layer thickness andretinal nerve fiber layer cross-section area. No significant differences were founded between NTG eyes and POAG eyes in the...