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Seth J Bricel, Elizabeth Cretara, Steven L Mansberger, Stuart Keith Gardiner; Contributions of structural vs. functional data when grading the rate of glaucomatous progression. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1993.
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© ARVO (1962-2015); The Authors (2016-present)
In treating patients with glaucoma, it is critical for the clinician to determine not just if their disease is "progressing", but also the rate of progression, and if a change in treatment is warranted. We sought to discover the relative contributions of functional and structural testing of the optic nerve in informing clinicians' assessment of glaucomatous progression.
A sample set of 40 eyes from 20 patients with ocular hypertension or glaucoma were selected from the Portland Progression Project (P3). Patients were excluded if they underwent glaucoma surgery during the study period, had other coexisting severe eye disease, had more than 2 unreliable visual fields, or had significant optic nerve anomaly precluding reliable OCT monitoring. Patients underwent bilateral Humphrey SITA standard 24-2 visual fields and Spectralis OCT scans every 6 months for an average of 3.45 years (6.9 visits). Series were reviewed by two physicians in glaucoma fellowship, who graded the rate of progression for each eye on a Likert scale of 1 to 7, where 1= no significant progression, 4= a rate that would trigger a change in treatment, and 7= an eye expected to rapidly progress to blindness without intervention. Each series was assigned grades based on function only, structure only, and combined data from both. Generalized estimating equation models were used to predict the overall grade (averaged between physicians) based on the function-only and structure-only scores, and to determine whether the contribution of functional vs. structural information differed by disease severity.
Inter-grader correlations were 0.89 for function-only, 0.73 for structure-only, and 0.87 for combined scores. The average combined score was better-correlated with the function-only score than the structure-only score (r=0.98 vs. r=0.67, p=0.0003). However, when plotted against most recent visual field mean deviation (MD), the contribution of the structure-only score increased with MD (p=0.029) while the contribution of the function-only score decreased (p=0.050). The overall score was closely related to function but not structure in more damaged eyes, but was related to both in less damaged eyes.
In early stages of glaucoma, clinicians rely on both structure and function when making judgements about the rate of progression. In more severe glaucoma, clinicians rely almost entirely on functional data.
This is a 2020 ARVO Annual Meeting abstract.
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