Using the arteriolar Pressure Attenuation Index to predict ocular hypertension progression to open-angle glaucoma.
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.
Cohen
Shawn L
SL
Department of Ophthalmology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada. v.cohen@sympatico.ca
Lee
Paul P
PP
Herndon
Leon W
LW
Challa
Pratap
P
Overbury
Olga
O
Allingham
R Rand
RR
D000328:Adult; D001160:Arterioles; D001794:Blood Pressure / Q000502:physiology; D018450:Disease Progression; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure; D009798:Ocular Hypertension / Q000175:diagnosis / Q000503:physiopathology*; D009898:Optic Disk / Q000098:blood supply; D010781:Photography; D012161:Retinal Artery / Q000502:physiology*; D014794:Visual Fields