Abstract
Purpose :
To test whether higher systemic vascular resistance, as indicated by higher pulsatility index (PI) and resistive index (RI), is associated with more rapid functional and structural loss in glaucoma.
Methods :
313 eyes of 164 subjects in the longitudinal Portland Progression Project were tested every six months for 4 – 11 visits. On each visit, a continuous 200Hz plethysmography recording was made via a finger cuff to obtain a blood pressure pulse waveform. Hemodynamic parameters associated with vascular resistance were extracted using custom software: resistive index RI = (Max – Min) / Max; and pulsatility index PI = (Max – Min) / Mean. These were averaged across the series, and compared against rates of change of retinal nerve fiber layer thickness (RNFLT, from a 6 degree radius peripapillary OCT scan) and linearized Mean Deviation (MDlin = 10(MD/10), from standard automated perimetry) over the series. Eyes were classified as “glaucoma suspect” vs. “glaucoma” eyes, based on the presence of functional loss on the first visit.
Results :
For all eyes together, we found that higher systemic vascular resistance (Both RI and PI) predicted faster functional loss, after adjusting for the mean MDlin (p<0.001, generalized estimating equation linear regression) (Figure). Among 199 “glaucoma suspect” eyes (average MD -0.635 dB), higher systemic vascular resistance was associated with faster functional loss (RI p=0.012; PI p=0.041). Among 114 “glaucoma” eyes (average MD -4.566 dB), higher vascular resistance was not significantly associated with the rate of functional loss (RI p=0.110; PI p=0.079). The relationship with RNFL thinning were not significant for RI or PI respectively, (GLS: p=0.140 and 0.199; GL: p=0.930 and 1.000).
Conclusions :
Higher systematic vascular resistance, and by implication stiffer vasculature systemically, were associated with more rapid functional loss in eyes without significant existing loss at baseline. Our results are consistent with our recent findings (PMID: 37335567) whereby higher retinal vascular resistance was also associated with more rapid functional loss in glaucoma suspect eyes. This indicates that systemic hemodynamics may play a role in the disease process of glaucoma.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.