Suitability of the Visual Field Index according to Glaucoma Severity.

Syril Dorairaj,Mauro T Leite,Tiago S Prata,Jessica S Maslin,Luis G Biteli,Marina Cc Sousa

doi:10.5005/jp-journals-10008-1186

Syril Dorairaj, Mauro T Leite + Show 4 more

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https://doi.org/10.5005/jp-journals-10008-1186

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Abstract

ABSTRACTPurpose: To investigate the suitability of the visual field index (VFI) in different degrees of disease severity in glaucoma patients.Methods: In this cross-sectional study, we consecutively enrolled patients with primary open-angle glaucoma and glaucoma suspects (ocular hypertension). All eyes required a reliable standard automated perimetry (SAP) test to be included. Subjects were categorized into five groups based on glaucoma severity using SAP’s mean deviation (MD). To evaluate the correlation among VFI, MD and pattern standard deviation (PSD), a linear regression model was built. To evaluate the nature of the correlation (i.e. linear vs nonlinear), results were plotted in a scatterplot graph.Results: One hundred and twenty-two eyes of 81 patients (mean age, 59.8 ± 14.5 years) were included. A strong, positive association was found between MD and VFI values (R2 = 0.98, p < 0.001), showing a 3.2% reduction in the VFI for each dB loss in the MD index. It was noticed that 15% of eyes with mild glaucoma (average MD of -3.1 dB) had VFI > 99%. Considering only the eyes with mild and moderate damage in the regression, we found a weaker (nonlinear) correlation than the one we found using all eyes (R2 = 0.85, p < 0.001). There was also a significant, nonlinear correlation between VFI and PSD (R2 = 0.85, p < 0.001). Although higher PSD values were found with increasing visual field damage, this initial trend was reversed when VFI became smaller than 50%, approximately.Conclusion: Visual field index had a strong correlation with MD; however, this correlation was weaker in mild disease, as some patients with early disease had very high VFI values (ceiling effect). Therefore, initial deterioration in visual field status (as assessed by MD values) in patients with early disease may not be detectable using the VFI alone.How to cite this article: Sousa MCC, Biteli LG, Dorairaj S, Maslin JS, Leite M, Prata TS. Suitability of the Visual Field Index according to Glaucoma Severity. J Curr Glaucoma Pract 2015;9(3):65-68.

Highlights

Glaucomatous optic neuropathy is characterized by loss of retinal ganglion cells with characteristic changes of the optic nerve head and visual field
Suitability of the Visual Field Index according to Glaucoma Severity
Bengtsson and Heijl introduced the visual field index (VFI), which is less affected by media opacity and takes into consideration the functional loss corrected for age spots identified as changed in the probability map of the pattern standard deviation (PSD).[3]

Summary

Introduction

Glaucomatous optic neuropathy is characterized by loss of retinal ganglion cells with characteristic changes of the optic nerve head and visual field. The most traditional are: the mean deviation (MD), usually related to generalized loss of function; the pattern standard deviation (PSD), more related to localized functional loss, and glaucoma hemifield test, which compare the functional loss in lower and upper hemifields.[2] Bengtsson and Heijl introduced the visual field index (VFI), which is less affected by media opacity (as cataract) and takes into consideration the functional loss corrected for age spots identified as changed in the probability map of the PSD.[3] These indices should be interpreted together in the evaluation of glaucomatous patients and may vary according to the type of field defect and the stage of disease. We investigated the suitability of the VFI and its correlations with the other available indices in different stages of primary open-angle glaucoma (POAG)

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