Abstract
Purpose :
To describe a method that provides simultaneous visualization of functional and structural change in a 2D space.
Methods :
Subjects were arranged into two cohorts. Cohort one was used to create structural and functional scores. Cohort two was used to apply those scores for analysis of structure-function progression with a combined vector. The first cohort included eyes with mild glaucoma (abnormal GHT, PSD<0.05 on 2 exams, MD>-5dB) and normal controls. The second cohort included all stages of OAG with ≥5 OCT-RNFL scans and ≥5 reliable VFs and follow-up ≥ 4 years. The scores were created as follows: one of each pair of highly correlated OCT and VF variables (p2>0.5) were removed. The remaining parameters were subjected to LASSO regression and selected variables were used in the logistic model. The functional and structural scores were normalized from 0 (worst) to 100 (best).
Vectors were created for each eye to represent the trajectory of glaucoma progression over time. Each vector was defined by structural (x) and functional (y) components. The structural component was calculated with a linear model of OCT scores over time (Fig 1c). The functional component was calculated with a linear model of VF measurements over time (Fig1d). The resultant vector and its confidence interval were plotted in 2D structural-functional space (Fig1e). Eyes were divided into severity stages based on baseline MD. A mean vector was calculated for each severity stage.
Results :
64 normal and 121 glaucomatous eyes were used in the first cohort. Two OCT and 5 VF parameters were selected for the model. Diagnostic precision of the logistic function for these parameters was 93% and 97% for the structural and functional scores.
799 2D vectors (799 eyes of 463 OAG patients) were calculated. The mean follow-up period was 6.7(±1.1) years. Mean baseline MD was -4(±5.0dB). Preperimetric, mild, moderate and severe groups included 146, 224, 221 and 208 eyes, respectively. Mean baseline MDs were 1.0, -0.95, -3.6, and -11.0 dB, respectively, and mean vector slopes were 0.7, 1.2, 2.9 and 2.4(Fig2).
Conclusions :
We present a method that facilitates simultaneous visualization of glaucoma progression in a 2D structural/functional space. It provides the clinician with a rapid and intuitive summary of the patient’s glaucoma trajectory over time. The relative ratio of structural/functional change decreases with the severity of glaucoma.
This is a 2020 ARVO Annual Meeting abstract.