Twenty-four-hour intraocular pressure and ocular perfusion pressure characteristics in newly diagnosed patients with normal tension glaucoma

Abstract

Purpose To determine the mean 24-h intraocular pressure (IOP) and mean ocular perfusion pressure (MOPP) characteristics of newly diagnosed, previously untreated, Caucasian, normal tension glaucoma (NTG) patients and to identify relationships between these features and visual field (VF) loss at diagnosis. Methods Consecutive newly diagnosed NTG patients underwent 24-h habitual IOP and blood pressure (BP) monitoring. Parameters from pooled measurements obtained in the sitting (0800-2200 hours) and supine (1200-0600 hours) positions were compared and associations were sought with VF mean deviation (MD) and pattern standard deviation (PSD). Results Sixty-two Caucasian NTG patients (24 men and 38 women) successfully completed circadian IOP and BP monitoring. In habitual position, 8 subjects (12.9%) exhibited a diurnal acrophase, 42 subjects (67.7%) demonstrated a nocturnal acrophase, one subject (1.6%) showed a flat rhythm and 11 patients (17.7%) revealed a biphasic/ polyphasic rhythm. Nighttime MOPP values (supine position) were significantly greater than diurnal values (sitting position); (Po0.001). No association could be demonstrated between glaucomatous damage, as indicated by VF parameters, and either mean habitual 24-h IOP (P = 0.20 and P = 0.12 for MD and PSD, respectively), or habitual 24-h MOPP (P = 0.96 and 0.29, for MD and PSD, respectively).

Low nocturnal diastolic ocular perfusion pressure as a risk factor for NTG progression: a 5-year prospective study

“…In a separate retrospective study, Sung et al [4] also found that greater 24-h MOPP fluctuation is associated with the increased rate of NTG progression. In contrast, Quaranta et al found no association between 24 h MOPP and VF damage in Caucasian NTG patients [10].…”

Diurnal Cycle of Translaminar Pressure in Nonhuman Primates Quantified With Continuous Wireless Telemetry

“…Evidence suggests that glaucoma is a multifactorial disease, and so an individual's susceptibility is likely related to a combination of factors, including the eye's optic nerve head (ONH) structure and biomechanical properties, 1,2 tissue and cellular responses to IOP and cerebrospinal fluid pressure (CSFP), [3][4][5][6][7][8][9][10] and ocular perfusion pressure (OPP). [11][12][13][14] Complicating things even further, racial differences 15,16 and changes with age 15,17,18 or exposure to chronic IOP elevation/glaucoma [18][19][20] likely influence these factors as well. 2,21 CSFP has been hypothesized as a driving factor in glaucoma, as it provides a counter-pressure to IOP, but only at the ONH.…”

IOP, IOP Transient Impulse, Ocular Perfusion Pressure, and Mean Arterial Pressure Relationships in Nonhuman Primates Instrumented With Telemetry

“…One possible explanation for this finding is that OPP is much lower at night with less variability, which may explain why the relationship was significant for waking hours, but not for sleeping hours. In addition, past studies have suggested that ocular blood flow is related to the level of visual stimuli, 5 , 8 , 23 , 24 and pulsatile ocular blood flow is an important factor in the ocular pulse amplitude (OPA). Hence, we might expect that IOP transient impulse and OPP will be larger during periods of intense activity, when visual system is stimulated, blood flow (and OPA) are high, and blinks and saccades are frequent.…”

“… 1 Intraocular pressure (IOP) is a known risk factor for both the development and progression of glaucoma. 2 , 3 Lowering IOP is the only clinically proven method to prevent glaucoma and slow disease progression, although some patients develop glaucoma at statistically normal IOP levels, 4 , 5 and others continue to progress even after IOP is lowered. 6 Diurnal IOP fluctuations, measured hourly, have been reported as higher in glaucoma patients in some studies 7 and may be predictive of disease progression.…”

“…There have been conflicting reports as to whether mean arterial pressure (MAP) and ocular perfusion pressure (OPP) contribute to glaucoma or whether they have an influence on IOP. 5 , 8 – 13 Most studies have suggested that IOP and OPP are not strongly correlated despite IOP being a factor in the calculation of OPP (OPP = BP − IOP). 5 , 10 – 12 When interpreting these findings, it is important to consider that most previous studies have either used applanation tonometry, which cannot measure IOP continuously, or contact lens sensors, which can only measure circumferential corneal stretch presumably due to IOP fluctuations and not IOP itself.…”