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Using the Arteriolar Pressure Attenuation Index to Predict Ocular Hypertension Progression to Open-angle Glaucoma
Shawn L. Cohen, MD;
Paul P. Lee, MD, JD;
Leon W. Herndon, MD;
Pratap Challa, MD;
Olga Overbury, PhD;
R. Rand Allingham, MD
Arch Ophthalmol. 2003;121:33-38.
Background Vascular phenomena are considered important to optic nerve and visual field progression in open-angle glaucoma (OAG). A recently described formulation, the Pressure Attenuation Index (PAI), links arteriolar caliber variations to pressure loss along the retinal arteriolar system.
Objective To examine whether the PAI could predict ocular hypertension (OHT) progression to OAG.
Methods The PAI was calculated for 27 eyes of 14 patients with OHT using initial and final digitized optic disc photographs taken during a follow-up interval of 5 to 18 years. Serial stereo color disc photographs and visual fields were analyzed to determine progression.
Results At baseline, the arteriolar tree of 8 subjects with OHT that progressed to OAG (n = 8 eyes) demonstrated a 45.8% greater mean PAI value than that of 7 subjects who did not progress (n = 7 eyes) (mean ± SEM, 5.31 ± 0.93 vs 3.64 ± 0.34; r = 0.83). Progression was independent of baseline cup-disc ratio. The PAI values of subjects with stable OHT remained stable after a median follow-up interval of 12.0 years. The PAI values of subjects with OHT that progressed demonstrated a further increase of 19.97% ± 11.24% during a median follow-up period of 6.0 years.
Conclusions The results support the hypothesis that low end-arteriolar pressure predicts the progression from OHT to OAG. The PAI provides a new, early, reproducible, and physiological method to study vascular phenomena in glaucoma.
From the Department of Ophthalmology, Royal Victoria Hospital (Dr Cohen), and the Department of Ophthalmology, Jewish General Hospital (Drs Cohen and Overbury), McGill University, Montreal, Quebec; and the Duke University Eye Center, Durham, NC (Drs Lee, Challa, Herndon, and Allingham).
The authors have no financial interest in the subject matter or materials discussed in this article.
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