Abstract
Purpose :
While progressive ONH deformation and VF loss define glaucoma, their temporal relationship is poorly understood. It remains obscure what levels of IOP would impact ONH deformation and whether ONH deformation predicts VF change. We investigate the effect of IOP on the rates of change of anterior LC surface depth (ALCSD) and ONH surface depth (ONHSD) and examine if these rates of change are predictive of VF progression in glaucoma.
Methods :
146 eyes of 95 glaucoma patients (age: 50.3±14.5 years) were followed for OCT measurements of ALCSD and ONHSD (with reference to BMO in 6 evenly spaced radial scans for each eye in each visit) and perimetry every 4 months for ≥5 years (range: 5.0-7.4 years). The influence of IOP and other covariates on the rates of change of ALCSD/ONHSD was evaluated with linear mixed models with adjustment of correlation between fellow eyes. A joint longitudinal survival model was applied to determine the impact of the rates of change of ALCSD/ONHSD on prediction of VF progression (defined as “likely progression” by the EMGT criteria).
Results :
2519 follow-up visit measurements were analyzed (each eye had ~17 visits). 43 and 41 eyes showed progressive posterior deformation whereas 34 and 35 eyes showed progressive anterior deformation of the LC surface and ONH surface, respectively (as determined by linear regression analyses between ALCSD/ONHSD and time for individual eyes). The mean rates of change of ALCSD/ONHSD were 5.3µm/year/4.2µm/year (posterior deformation); and -5.9µm/year/-4.4µm/year (anterior deformation), respectively. IOP (p≤0.044) was positively whereas age (p<0.001) and baseline ALCSD/ONHSD (p≤0.002) were negatively associated with the rates of change of ALCSD/ONHSD. Each 5µm/year increase in the rate of change of ALCSD/ONSHD (i.e. posterior deformation) was associated with a 3.19-fold (95% CI: 1.28-9.92)/8.46-fold (95% CI: 1.37-52.5) increase in risk of VF progression after controlling for IOP, age and baseline ALCSD/ONHSD. An example is shown in Figure.
Conclusions :
The rates of change of LC and ONH surface deformation, which are subject to the influence of IOP, age and baseline ALCSD/ONHSD, are predictive of VF progression.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.