Abstract
Purpose: :
To evaluate the association between structural optic nerve damage (OND), standard automated perimetry (SAP) and Frequency doubling technology (FDT) screening mode in a population-based glaucoma cohort.
Methods: :
A population-based sample of Latinos aged 40 years and older underwent a detailed ophthalmic examination including stereoscopic optic disc photography and visual field testing with the FDT screening mode 20-1 and Humphrey Field Analyzer Swedish Interactive Threshold Algorithm (HFA SITA) standard C 24. Three masked observers examined the optic disc photographs stereoscopically and assessed the vertical and horizontal cup-disc ratios (VCDR, HCDR). Mean deviation (MD), pattern standard deviation (PSD) for each eye was obtained from the HFA SITA visual field. An FDT score was calculated for each eye by weighting denser defects and those closer to fixation more than the milder or no defects and those further away from fixation. FDT scores ranged from 0 (normal) to 87 (complete loss). A person was diagnosed as having open-angle glaucoma (OAG) if they had evidence of either glaucomatous optic nerve changes or visual field loss in either eye. A minimum consensus of two out of three glaucoma specialists was required for diagnosis. One eye (eye with the greater MD) was analyzed for each person. Spearman’s correlation coefficients (SCC) and regression slopes were calculated to examine the relationship between VCDR, HCDR and MD, PSD and FDT scores.
Results: :
Of the 6357 participants who completed an ophthalmic examination,290 were diagnosed with OAG. Over ¾ of these 290 participants were previously untreated. The mean age of persons with OAG was 65 years and 52% were women. The mean intraocular pressure, HCDR, MD, PSD, and FDT score was 17m Hg, 0.7, -10dB, 5.77 and 16. The overall SCC for VCDR and MD, PSD, and FDT score was 0.35, 0.31, 0.33(all p<0.001). The overall SCC for HCDR and MD, PSD, and FDT score was 0.27, 0.24, 0.37 (all p<0.001). However, the regression slopes between VCDR /HCDR and all visual function parameters were minimal (slopes ranged from 0.003-0.008) until a HCDR/VCDR of 0.8. In persons with an HCDR/VCDR of 0.8 or higher, the regression slopes ranged from 0.001-0.07.
Keywords: optic nerve • perimetry