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Pattern of retinal nerve fiber layer damage in Korean eyes with normal-tension glaucoma and hemifield visual field
Michael S Kook1, Sang-Un Lee, Kyung-Rim Sung
1Department of Ophthalmology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnapdong, Songpa-gu, 138-736 Seoul, Korea. mskook@www.amc.seoul.kr
Purpose:
To evaluate quantitatively the pattern of retinal nerve fiber layer (RNFL) damage in eyes with normal-tension glaucoma (NTG) with hemifield dominant visual field defects using scanning laser polarimetry.
Methods:
Prospectively, 40 consecutive eyes from 40 patients with NTG and hemifield defect based on the findings of examination using the Humphrey Field Analyzer underwent RNFL thickness measurements. Twenty normal eyes from 20 subjects matched in age and refractive error formed a control group.
Results:
Symmetry, calculated as the ratio of superior to inferior RNFL thickness, showed no statistically significant difference between the study group and the control group ( P=0.50). Overall, 27.5% (11/40 eyes) showed an "abnormal" symmetry index that indicated focal RNFL change. The affected ratio, calculated as the ratio of RNFL thickness in the quadrant corresponding to the hemifield of visual field defect to that of the temporal quadrant was significantly lower in the study group than in the control group ( P<0.0001). A similar finding was noted for the unaffected ratio.
Conclusion:
Despite strict selection of the eyes with visual field defect confined to one hemifield, a mixture of both focal and diffuse RNFL damage was noted, with a common occurrence of symmetrical RNFL thinning in both upper and lower quadrants based on scanning laser polarimetry.