Comparison of ambulatory blood pressure values in patients with glaucoma and ocular hypertension

Meta-analysis of Timolol on Diurnal and Nighttime Intraocular Pressure and Blood Pressure

Purpose

To evaluate the nighttime intraocular pressure (IOP) and blood pressure (BP) response to timolol treatment in patients with ocular hypertension or primary open-angle glaucoma.

Methods

This was a meta-analysis of previously published studies that must have been randomized, prospective, crossover or parallel, single or double-masked trials. The treatment period must have been ≥2 weeks with ≥19 patients per treatment arm for a crossover, and ≥50 patients for a parallel designed trial. Studies must have included both baseline and treated 24-hour curves.

Results

For the IOP analysis, we included 8 articles with 340 patients. A reduction from baseline was observed for timolol at each time point and for the 24-hour curve (p≤0.009). When 2 studies, in which timolol was used adjunctively were removed, a similar difference was observed as above at each time point and for the 24-hour curve (p≤0.003). In 2 studies, there were small reductions from baseline for the mean diastolic and systolic BPs at most time points and for the 24-hour curve (3.9 and 4.2 mmHg, respectively) with timolol treatment. The ocular perfusion pressure did not show any difference between baseline and timolol treatment at any time point or for the 24-hour curve (p>0.05).

Conclusions

This meta-analysis suggests that topical timolol therapy provides an ocular hypotensive effect over the 24-hour curve, including the nighttime hours, and while small reductions in the systolic and diastolic pressures occur, the ocular perfusion pressure is not altered over 24 hours.

Glaucomatous Optic Neuropathy Associated with Nocturnal Dip in Blood Pressure: Findings from the Maracaibo Aging Study

PURPOSE

To determine which nocturnal blood pressure (BP) parameters (low levels or extreme dipper status) are associated with an increased risk of glaucomatous damage in Hispanics.

DESIGN

Observational cross-sectional study.

PARTICIPANTS

A subset (n = 93) of the participants from the Maracaibo Aging Study (MAS) who met the study eligibility criteria were included. These participants, who were at least 40 years of age, had measurements for optical tomography coherence, visual field (VF) tests, 24-hour BP, office BP, and intraocular pressure <22 mmHg.

METHODS

Univariate and multivariate logistic regression analyses under the generalized estimating equations (GEE) framework were used to examine the relationships between glaucomatous damage and BP parameters, with particular attention to decreases in nocturnal BP.

MAIN OUTCOME MEASURES

Glaucomatous optic neuropathy (GON) based on the presence of optic nerve damage and VF defects.

RESULTS

The mean age was 61.9 years, and 87.1% were women. Of 185 eyes evaluated, 19 (26.5%) had signs of GON. Individuals with GON had significantly lower 24-hour and nighttime diastolic BP levels than those without. However, results of the multivariate GEE models indicated that the glaucomatous damage was not related to the average systolic or diastolic BP levels measured over 24 hours, daytime, or nighttime. In contrast, extreme decreases in nighttime systolic and diastolic BP (>20% compared with daytime BP) were significant risk factors for glaucomatous damage (odds ratio, 19.78 and 5.55, respectively).

CONCLUSIONS

In this population, the link between nocturnal BP and GON is determined by extreme dipping effects rather than low nocturnal BP levels alone. Further studies considering extreme decreases in nocturnal BP in individuals at high risk of glaucoma are warranted.

Systemic and Ocular Hemodynamic Risk Factors in Glaucoma

Primary open angle glaucoma (POAG) is a multifactorial disease characterized by progressive retinal ganglion cell death and visual field loss. It is known that alterations in intraocular pressure (IOP), blood pressure (BP), and ocular perfusion pressure (OPP) can play a significant role in the pathogenesis of the disease. Impaired autoregulatory capacity of ocular blood vessels may render tissues vulnerable to OPP changes and potentially harmful tissue ischemia-reperfusion damage. Vascular risk factors should be considered more important in a subgroup of patients with POAG, and especially in patients with normal tension glaucoma (NTG) with evidence of unphysiological BP response. For example, reduction of BP during the nighttime has an influence on OPP, and increased circadian OPP fluctuation, which might stand for unstable ocular blood flow, has been found to be the consistent risk factor for NTG development and progression. Central visual field may be affected more severely than peripheral visual field in NTG patients with higher 24-hour fluctuation of OPP. This review will discuss the current understanding of allegedly major systemic and ocular hemodynamic risk factors for glaucoma including systemic hypertension, arterial stiffness, antihypertensive medication, exaggerated nocturnal hypotension, OPP, and autonomic dysregulation.

Relationship between daytime variability of blood pressure or ocular perfusion pressure and glaucomatous visual field progression

PURPOSE

To study daytime or nighttime variability of mean arterial pressure and ocular perfusion pressure in untreated normal-tension glaucoma (NTG) patients and determine whether increased short-term mean arterial pressure and/or ocular perfusion pressure variability are associated with greater risk of visual field (VF) progression.

DESIGN

Longitudinal, retrospective, observational study.

METHODS

This study enrolled 237 eyes of 237 untreated NTG patients who underwent 24-hour intraocular pressure and ambulatory blood pressure monitoring in the habitual position, and had ≥5 reliable VF tests during follow-up. Kaplan-Meier analyses were performed to compare outcomes with reference to the level of short-term mean arterial pressure and ocular perfusion pressure standard deviation for VF deterioration. Hazard ratios for the association between clinical factors, including short-term mean arterial pressure and ocular perfusion pressure standard deviation, and VF progression were obtained using Cox proportional hazards models.

RESULTS

Over-dipper NTG patients showed significantly larger daytime and nighttime mean arterial pressure and ocular perfusion pressure standard deviation than non-dippers or dippers. Both increased daytime and nighttime mean arterial pressure or ocular perfusion pressure standard deviation were associated with greater VF progression probabilities. Increased daytime mean arterial pressure or ocular perfusion pressure standard deviation was a significant predictor of subsequent VF progression (P = .023 and P < .001, respectively).

CONCLUSIONS

Over-dipper NTG eyes showed significantly higher daytime or nighttime mean arterial pressure and ocular perfusion pressure variabilities than non-dipper and dipper NTG eyes. Increased daytime mean arterial pressure and ocular perfusion pressure standard deviation at baseline were significant predictors of future VF progression in NTG.

24-hour intraocular pressure and blood pressure levels with latanoprost/timolol fixed combination versus timolol

PURPOSE

To evaluate 24-hr intraocular pressure (IOP) and blood pressure (BP) with timolol or latanoprost/timolol fixed combination (LTFC).

METHODS

Patients with primary open-angle glaucoma or ocular hypertension with normal blood pressure were randomized to LTFC, dosed each evening, or timolol dosed twice daily in a cross-over design for 8 weeks and the opposite medicine for 8 weeks. IOP was measured at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours in the sitting position with Goldmann applanation tonometry and BP monitoring every 30 min while awake and every hour while asleep at the end of each 8-week treatment period.

RESULTS

Twenty-nine patients had a 24-hr baseline IOP of 26.3 +/- 2.5 mmHg, systolic BP (SBP) of 121.4 +/- 12.4 mmHg, diastolic BP (DBP) 72.9 +/- 7.1 mmHg, and ocular perfusion pressure (OPP) of 33.9 +/- 5.7 mmHg. No statistical differences were found between untreated and treated 24-hr SBP, DBP, mean BP (MBP), heart rate, or nocturnal BP dipping status with either medication. LTFC lowered IOP more at each timepoint compared to timolol (difference between treatments 2.7 mmHg, p = 0.0002).

CONCLUSIONS

Neither timolol or evening-dosed LTFC reduced SBP, DBP, MBP, OPP, or increased nocturnal dipping. LTFC was more effective than timolol in decreasing IOP.

Twenty-four hour blood pressure pattern in patients with normal tension glaucoma in the habitual position

PURPOSE

To investigate the relationship between blood pressure (BP) parameters in the habitual position and glaucomatous damage at initial presentation in patients with untreated normal tension glaucoma (NTG).

METHODS

Fifty-four eyes from 54 subjects diagnosed with NTG were consecutively enrolled. BP was measured with an automated ambulatory monitoring device in the habitual position during 24-hour in-hospitalization. Patients were classified into three groups: non-dippers, dippers, and over-dippers. corresponded to the degree of reduction in their nocturnal mean arterial pressure (MAP) compared with their diurnal MAP. Regression models were used to evaluate potential risk factors, including: age, pre-admission office intraocular pressure (IOP), central corneal thickness (CCT), and BP parameters. Functional outcome variables for glaucomatous damage included mean deviation (MD) and pattern standard deviation (PSD) on a Humphrey field analyzer (HFA). Anatomic outcome variables were TSNIT score (temporal, superior, nasal, inferior, and temporal) average, superior average, inferior average, and nerve fiber indicator (NFI) score on scanning laser polarimetry with variable corneal compensation (SLP-VCC; GDx-VCC).

RESULTS

Marked systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP fluctuation were noted in the over-dipper group (p<0.05). A linear regression analysis model revealed that nocturnal trough DBP and MAP, average nocturnal SBP, and MAP were all significantly associated with a decreased average TSNIT score and an increased NFI score.

CONCLUSIONS

Nocturnal BP reduction estimated in the habitual position was associated with structural damage in eyes with NTG. This finding may suggest systemic vascular etiology of NTG development associated with nocturnal BP reduction.

Renal sodium handling in patients with normal pressure glaucoma

Low BP (blood pressure) is a recognized risk factor for some patients with NPG (normal pressure glaucoma). We have shown previously that patients with orthostasis have impaired circadian renal handling of sodium, which may contribute to the low BP. Therefore the aim of the present study was to examine the renal handling of sodium, the circadian variations in BP and the neurohormonal response to an orthostatic test in a selected subpopulation of 18 patients with NPG with vasospastic and orthostatic symptoms, and in 24 healthy control subjects. The variations in BP and renal tubular sodium handling were evaluated using 24 h ambulatory BP recordings, 24 h urine collections and determination of endogenous lithium clearance as a marker of proximal sodium reabsorption. The neurohormonal and BP responses to changes in posture were also determined in a 30 min orthostatic test. This selected group of patients with NPG had lower 24 h ambulatory BPs (P<0.001), and a more pronounced fall in BP when assuming an upright position (P<0.001) compared with controls. FE(Li) (fractional excretion of lithium) was higher in patients with NPG than controls during the day (36.6+/-21.8 compared with 20.4+/-8.7% respectively; P<0.01; values are means+/-S.D.) as well as during the night (38.8+/-41.9 compared with 19.7+/-10.8% respectively; P<0.02), suggesting a reduced reabsorption of sodium in the proximal tubule. This was compensated for by an increased distal reabsorption of sodium in patients with NPG (P<0.01). These data demonstrate that patients with vasospastic NPG have a high excretion of lithium, suggesting reduced sodium reabsorption in the proximal tubule, in spite of a low BP. The abnormal renal sodium handling might contribute to the maintenance of arterial hypotension and progression of the optic nerve damage in these patients.

Non-contact tonometry synchronized with cardiac rhythm and its relationship with blood pressure

PURPOSE

The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values.

METHODS

One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean +/- S.D., 29.93 +/- 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure.

RESULTS

The mean +/- S.D. values for the standard intraocular pressure (IOP_N: 14.76 +/- 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 +/- 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 +/- 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 +/- 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 +/- 14.22, diastolic 77.7 +/- 8.38 and MAP 93.64 +/- 9.44 mmHg. The pulse rate was 77.3 +/- 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate.

CONCLUSIONS

NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of +/-2.5 to +/- 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle.