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M. V. Boland, A. T. Broman, H. A. Quigley; Evaluation of Structure-Function Relationships in Eyes With Open Angle and Angle Closure Glaucoma Using a Scanning Laser Ophthalmoscope. Invest. Ophthalmol. Vis. Sci. 2007;48(13):494.
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To compare the topography of the optic nerve head as measured by scanning laser ophthalmoscopy using the HRT in angle closure glaucoma (ACG) and open angle glaucoma (OAG).
In a university glaucoma clinic, 166 persons with OAG and 51 persons with ACG underwent standard automated perimetry (SAP), optical coherence tomography (OCT) of the optic disc and circumpapillary nerve fiber layer (NFL), and topographical optic disc analysis using the HRT. Characteristics of the eyes enrolled in the study were compared using generalized estimating equations (GEE) to compensate for having two eyes from some subjects. GEEs were also used to assess the difference between HRT parameters for the two groups when controlling for total nerve damage, disc area, gender, and age. Total nerve damage was defined as the SAP mean deviation (MD) or OCT average NFL thickness.
OAG and ACG subjects showed no differences for age, ethnicity or laterality of eye. The ACG group had a higher proportion of women. In the analysis of the individual eyes in the study, there was no difference in IOP at the time of exam, corneal thickness, visual acuity, history of surgery, or prevalence of pseudophakia. The highest IOP ever recorded was higher in ACG eyes, axial length was shorter in ACG, ACG eyes were more hyperopic, and fewer ACG eyes were using eyedrops. Interestingly, the disc area measured by the HRT was larger in the ACG group (p<0.001). Average MD on SAP was the same for the two groups, but the average pattern standard deviation (PSD) was lower for the ACG group (p<0.001). The average NFL thickness by OCT was greater in the ACG group (p<0.01). In the multivariate analysis of HRT parameters there were differences in cup area, rim area, and cup-disc area ratio when controlling for total damage, disc area, age, and gender. These differences were consistent between the models using HFA MD and OCT NFL thickness as measures of damage. They were not significant after correcting for analysis of multiple models, however.
After controlling for variables including disc area and total nerve damage, none of the HRT parameters were clearly different between OAG and ACG eyes. Nerve damage in ACG eyes, as judged by the PSD, was more diffuse than in OAG eyes. Taken together, these results support the hypothesis that the optic nerve changes in OAG and ACG are similar but that the uniformity of damage may differ.
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