24-hour Intraocular Pressure Pattern Research Articles

Twenty-Four-Hour Intraocular Pressure in Chronic Primary Angle-Closure Disease.

Primary angle closure and primary angle closure glaucoma may exhibit normal intraocular pressure. Twenty-four-hour intraocular pressure fluctuation is highest in primary angle closure glaucoma. The degree of peripheral anterior synechiae was associated with a 24-hour intraocular pressure pattern in primary angle-closure disease without laser iridotomy. The purpose of this study was to study 24-hour intraocular pressure (IOP) patterns in eyes with chronic primary angle-closure disease and evaluate associations between peripheral anterior synechiae (PAS) and 24-hour IOP pattern. In this prospective cohort study, 59 eyes of 35 Asian patients with chronic primary angle-closure disease underwent complete ocular examinations at Ramathibodi Hospital, Mahidol University. Twenty-four-hour IOP records were obtained using Goldmann applanation tonometry at 2-hour intervals. Peak, mean, and trough 24-hour IOP values and 24-hour IOP fluctuation (difference between peak and trough values) were compared among groups. None of the participants received any treatment before complete data collection. Even univariable analysis demonstrated a significant difference in peak, mean, and trough IOP and 24-hour IOP fluctuation between the 3 groups; the magnitude of trough IOP was not higher than 21mmHg in all groups. In multivariable analysis, PAC and PACG eyes showed significantly higher peak IOP ( P =0.020 and 0.006, respectively) and 24-hour IOP fluctuation ( P =0.048 and 0.001, respectively) compared with PACS eyes. In comparison between combined PACS and PAC eyes versus PACG eyes, PACG eyes revealed significantly higher 24-hour IOP fluctuation. The degree of PAS was associated with peak and mean IOP values and with 24-hour IOP fluctuation in PAC and PACG eyes. Twenty-four-hour IOP fluctuation was highest in PACG eyes. Although PAC and PACG eyes showed higher peak IOP and 24-hour IOP fluctuation values, compared with PACS eyes, trough IOP in PAC and PACG eyes were mostly below 21mmHg. In addition, the degree of PAS was associated with a 24-hour IOP pattern in either PAC or PACG eyes.

Role of 24-Hour Intraocular Pressure Monitoring in Glaucoma Management.

Glaucoma is the leading cause of irreversible blindness worldwide and the prevalence is on the rising trend. Intraocular pressure (IOP) reduction is the mainstay of treatment. The current practice of IOP monitoring is based on spot measurements during clinic visits during office hours. However, there are up to 50% of glaucoma patients who had normal initial IOP, while some treated patients continued to have progressive glaucomatous optic nerve damage even with a low IOP. Recent studies have shown that the IOP of glaucoma patients fluctuated during the day with different patterns, and some of them had peak IOP outside office hours. These findings provided us with new insights on the role of 24-hour IOP monitoring in managing normal tension glaucoma and patients with progressive deterioration despite apparently well-controlled IOP. Nevertheless, results to date are rather inconsistent, and there is no consensus yet. In this review, we briefly highlighted the current modalities of 24-hour IOP monitoring and summarized the characteristic 24-hour IOP pattern and the clinical relevance of IOP parameters in predicting glaucomatous progression in different glaucoma subtypes. We also discussed the therapeutic efficacy of current glaucoma treatment modalities with respect to the mentioned 24-hour IOP profiles, so as to strengthen the role of 24-hour IOP monitoring in identifying and stratifying the risks of progression in glaucoma patients, as well as optimizing treatments according to their IOP profiles.

24-Hour Intraocular Pressure Rhythm in Patients With Untreated Primary Open Angle Glaucoma and Effects of Selective Laser Trabeculoplasty.

The purpose of the study was to evaluate the 24-hour nyctohemeral rhythm of intraocular pressure (IOP) in patients with untreated primary open angle glaucoma using a contact lens sensor. To evaluate the effect of selective laser trabeculoplasty (SLT) on the 24-hour rhythm of IOP. Prospective study conducted in a chronobiology center. Fourteen patients with primary open angle glaucoma underwent three 24-hour IOP measurement sessions after a complete wash-out of the medical treatment: before SLT and 1 and 6 months after, using the contact lens sensor Triggerfish (SENSIMED, Lausanne, Switzerland). IOP and the main parameters of nyctohemeral rhythm (existence of a rhythm, acrophase, bathyphase, midline estimating statistic of rhythm, amplitude, and range) before SLT were compared with the same parameters measured 1 and 6 months later. IOP increased from 16.3±3.7 to 22.1±8.4 mm Hg (5.8 mm Hg; 95% confidence interval (CI), 2.41-12.71; P=0.009) after the wash-out procedure. After SLT, IOP significantly decreased by 3.4 mm Hg (95% CI, 0.09-7.89; P=0.041) (14.9%) at 1 month and 1.9 mm Hg (95% CI 0.10-3.84; P=0.044) (8.1%) at 6 months. After medication wash-out, 100% of the subjects had a nyctohemeral IOP rhythm with nocturnal acrophase (01:57±3:32 AM, 01:22±3:01 AM, and 03:17±2:12 AM at inclusion, 1 and 6 mo, respectively). SLT did not significantly change the characteristics of the 24-hour IOP pattern, notably the amplitude and the type of rhythm (persistence of nocturnal acrophase). After medical treatment wash-out, patients with open angle glaucoma consistently had a significant 24-hour IOP rhythm with nocturnal acrophase. SLT reduces the absolute IOP value but does not modify the nyctohemeral IOP rhythm.

Hourly Awakening vs Continuous Contact Lens Sensor Measurements of 24-Hour Intraocular Pressure

All studies of 24-hour intraocular pressure (IOP) rhythm conducted to date have used repeated IOP measurements requiring nocturnal awakenings, potentially disturbing sleep macrostructure. To evaluate the effects on sleep architecture and IOP rhythm of hourly awakening vs a contact lens sensor (CLS) to continuously monitor IOP without awakening. Cross-sectional study at a referral center of chronobiology among 12 young healthy volunteers, with a mean (SD) age of 22.3 (2.3) years. Volunteers underwent two 24-hour IOP measurement sessions during a 2-month period. The eye order and session order were randomized. During one session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was measured hourly using a portable noncontact tonometer (session with nocturnal hourly awakening). During the other session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was not measured (session without nocturnal awakening). Overnight polysomnography was performed during the 2 sessions. A nonlinear least squares, dual-harmonic regression analysis was used to model the 24-hour IOP rhythm from the CLS data. Comparisons of acrophase, bathyphase, amplitude, and the midline estimating statistic of rhythm were used to evaluate the effect of hourly awakening on IOP rhythm. To evaluate the effects of hourly awakening on sleep architecture, comparisons of sleep structure were used, including total sleep period, rapid eye movement, wake after sleep onset, absolute and relative total sleep time, and non-rapid eye movement sleep (N1, N2, and N3). A 24-hour IOP rhythm was found in all individuals for the sessions with and without awakening (P < .05). Hourly awakening for nocturnal IOP measurements increased wake after sleep onset (P = .04) but did not seem to change total sleep time, total sleep period, sleep efficiency, or slow-wave and rapid eye movement sleep stage duration (P > .30). Hourly awakening during noncontact tonometer IOP measurements did not seem to alter the mean variables of the 24-hour IOP pattern evaluated using CLS, including signal, maximum signal, minimum signal, acrophase, and bathyphase (P > .15). The 24-hour IOP rhythms seem to be unaffected by hourly nocturnal awakening for IOP measurements in young healthy individuals.

24-Hour Intraocular Pressure Rhythm in Young Healthy Subjects Evaluated With Continuous Monitoring Using a Contact Lens Sensor

This study evaluates a new device that has been proposed to continuously monitor intraocular pressure (IOP) over 24 hours. To evaluate 24-hour IOP rhythm reproducibility during repeated continuous 24-hour IOP monitoring with noncontact tonometry (NCT) and a contact lens sensor (CLS) in healthy participants. Cross-sectional study of 12 young healthy volunteers at a referral center of chronobiology. Participants were housed in a sleep laboratory and underwent four 24-hour sessions of IOP measurements over a 6-month period. After initial randomized attribution, the IOP of the first eye was continuously monitored using a CLS and the IOP of the fellow eye was measured hourly using NCT. Two sessions with NCT measurements in 1 eye and CLS measurements in the fellow eye, 1 session with CLS measurements in only 1 eye, and 1 session with NCT measurements in both eyes were performed. A nonlinear least squares, dual-harmonic regression analysis was used to model the 24-hour IOP rhythm. Comparison of acrophase, bathyphase, amplitude, midline estimating statistic of rhythm, IOP values, IOP changes, and agreement were evaluated in the 3 tonometry methods. A significant nyctohemeral IOP rhythm was found in 31 of 36 sessions (86%) using NCT and in all sessions (100%) using CLS. Hourly awakening during NCT IOP measurements did not significantly change the mean phases of the 24-hour IOP pattern evaluated using CLS in the contralateral eye. Throughout the sessions, intraclass correlation coefficients of the CLS acrophase (0.6 [95% CI, 0.0 to 0.9]; P = .03), CLS bathyphase (0.7 [95% CI, 0.1 to 0.9]; P = .01), NCT amplitude (0.7 [95% CI, 0.1 to 0.9]; P = .01), and NCT midline estimating statistic of rhythm (0.9 [95% CI, 0.9 to 1.0]; P < .01) were significant. When performing NCT measurements in 1 eye and CLS measurements in the contralateral eye, the IOP change at each point normalized from the first measurement (9 am) was not symmetric individually or within the population. The CLS is an accurate and reproducible method to characterize the nyctohemeral IOP rhythm in healthy participants but does not allow for estimating the IOP value in millimeters of mercury corresponding to the relative variation of the electrical signal measured.

Twenty-Four–Hour Pattern of Intraocular Pressure in Untreated Patients with Ocular Hypertension

To characterize the 24-hour pattern of intraocular pressure (IOP) in untreated ocular hypertensive (OHTN) patients. IOP measurements were taken every 2 hours during a 24-hour period from 15 untreated OHTN patients (ages 41-77 years). Measurements were both sitting and supine (diurnal) and supine only (nocturnal). Mean diurnal and nocturnal IOPs in the OHTN group were compared to previously reported values in age-matched healthy and glaucomatous eyes. Post hoc analysis compared the 24-hour IOP pattern of the OHTN patients who converted to glaucoma and those who did not with that in the same healthy and glaucomatous eyes. Mean sitting and supine IOPs were significantly higher in the OHTN group than in the healthy control but not the glaucoma group. Similar to the glaucoma group, the OHTN group demonstrated significant differences from healthy controls in diurnal IOP variation and IOP changes upon awakening in habitual and supine positions. The 24-hour IOP curve acrophases and amplitudes for OHTNs were closer to those of the glaucoma than the healthy control group in the habitual position. Thirty-three percent of OHTNs developed glaucoma during a mean follow-up period of 4.3 ± 3.8 years. Similar to findings in the glaucoma group, habitual IOP curve phase delay, habitual IOP variation, diurnal-to-nocturnal IOP changes, and IOP changes upon awakening of the converters were significantly different from those in healthy controls. There were no differences between nonconverters and other groups. Baseline 24-hour IOP pattern in OHTN patients is similar to that in glaucomatous patients. In contrast to nonconverters, OHTN patients who converted to glaucoma are significantly different from healthy controls.

Effects of Aging on 24-Hour Intraocular Pressure Measurements in Sitting and Supine Body Positions

To evaluate how aging alters 24-hour measurements of intraocular pressure (IOP) in the sitting and supine body positions. Fifteen older volunteers with healthy eyes (ages, 53-71 years) were each housed for 1 day in a sleep laboratory. An 8-hour accustomed sleep period was assigned to each subject. Every 2 hours, measurements of IOP were taken in the sitting and supine positions. Sitting and supine patterns of 24-hour IOP were compared. Simulated 24-hour IOP rhythms in the same body position were determined using cosine fitting of individual 24-hour data. The average postural IOP effects during the diurnal/wake period and the nocturnal/sleep period were compared. Data from this group of older subjects were compared with previously collected data from 16 healthy younger subjects (ages, 18-25 years) under the same experimental conditions. Within each age group, sitting and supine patterns of 24-hour IOP were similar and parallel. Compared to the younger subjects, the phase timing (simulated peak) of 24-hour IOP was significantly delayed for the older subjects in both body positions. The postural IOP effect for the older subjects was 4.7 ± 0.8 and 4.8 ± 0.8 mm Hg during the diurnal and nocturnal periods, respectively. These postural IOP effects were not significantly different from the postural effects in the younger subjects. Although aging can significantly delay the phase timing of the 24-hour IOP pattern toward the diurnal/awake period, it may not affect the postural IOP effect during the diurnal and the nocturnal periods.

Relationship of the 24-Hour Pattern of Intraocular Pressure with Optic Disc Appearance in Primary Open-Angle Glaucoma

To study the relationship between the 24-hour pattern of intraocular pressure (IOP) with optic disc appearance in primary open-angle glaucoma (POAG) patients. Observational clinical study. Seventy-five eyes of 45 POAG patients. Patients underwent 24-hour IOP assessment in a sleep laboratory. Two observers classified the optic disc appearance for each eye as either concentric or nonconcentric. The IOP measurements were obtained with the subjects in the supine and sitting positions during the diurnal period and in the supine position during the nocturnal period. The mean, peak, and trough IOP and IOP range (peak through trough) were calculated for the office-hour period (9 am to 4 pm), the diurnal period (7 am to 11 pm), the nocturnal period (11 pm to 7 am), and the 24-hour period. Further, the difference in supine and sitting IOP during the diurnal periods was calculated, and generalized estimating equations were used to compare IOP measurements in both groups. Diurnal and nocturnal IOP measurements. Forty eyes were classified as having concentric optic disc appearance and 35 eyes as having nonconcentric optic disc appearance. The mean nocturnal IOP was significantly greater in the concentric group (mean+/-standard deviation [SD], 24.0+/-3.8 mmHg) compared with the nonconcentric group (mean+/-SD, 21.9+/-1.9 mmHg; P = 0.004). Most IOP peaks of patients with the concentric optic disc appearance occurred during the nocturnal period, as opposed to the diurnal period of patients with the nonconcentric optic disc appearance. Concentric optic disc appearance may be associated with higher nocturnal IOP compared with nonconcentric optic disc appearance. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Effects of Aging on Corneal Biomechanical Properties and Their Impact on 24-hour Measurement of Intraocular Pressure

To study the effects of aging on corneal biomechanical properties and their impact on 24-hour measurement of intraocular pressure (IOP). Experimental study. Fifteen older volunteers with healthy eyes (age range, 50 to 80 years) were housed for one day in a sleep laboratory with a 16-hour diurnal or wake period and an eight-hour nocturnal or sleep period. Every two hours, sitting corneal hysteresis, corneal resistance factor, and IOP were measured. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. Data were compared with previous observations in 15 healthy younger volunteers (age range, 20 to 25 years). Variations in 24-hour corneal hysteresis and corneal resistance factor were not significant in the older subjects, but there were time-dependent variations in CCT and IOP. The nocturnal CCT was thicker than the diurnal CCT, but the IOP difference between the diurnal and nocturnal periods was not significant. Cosine-fits of CCT and IOP showed synchronized 24-hour rhythms. The phase timing of CCT rhythm appeared significantly earlier than the phase timing of IOP rhythm. Compared with younger subjects, older subjects had a lower mean 24-hour corneal hysteresis and corneal resistance factor, but not a lower CCT. Phase timings of 24-hour rhythms of CCT and IOP were significantly delayed by aging. Aging may lower corneal hysteresis and corneal resistance factor, but neither parameter shows a significant 24-hour variation. Aging may not change CCT significantly, but can shift its 24-hour rhythm. The 24-hour IOP pattern in this group of older subjects is not an artifact resulting from a variation in corneal hysteresis, corneal resistance factor, or CCT.

The Effect of Sympathectomy on Circardian Rhythm of Intraocular Pressure in Rat

Purpose: The present study was undertaken to determine the 24-hour pattern of intraocular pressure (IOP), and to reveal the effect of unilateral decentralization on circardian rhythm of IOP in eyes of rats. Methods: Nine male Sprague-Dawley rats were exposed to a 12-hour light/dark cycle for 3 weeks. 24-hours IOP pattern was measured at six time points (8, 12, 16, 20, 24, and 4 circardian time) by Tonopen XL tonometer in awake state. After unilateral sympathectomy (cervical ganglionectomy), IOP measurements were performed at the same time points on post-operation 1, 2, 3, and 4 weeks. Results: 24-hour IOP pattern of rats showed a rhythmic pattern that appeared to be sinusoidal with 12-hour light/dark cycle. IOPs were low during the light phase and high during dark phase. After unilateral sympathectomy, the circardian rhythm of IOP was maintained in control eyes. But in sympathecotmized eyes, the circardian thythm of IOP was loss. Conclusions: These results show that sympathetic nervous systems contribute to the circardian rhythm of IOP in rats.

Effect of Light Cycle on 24-hour Pattern of Mouse Intraocular Pressure

The present study was undertaken to determine the magnitude, dynamic pattern, and synchrony of the 24-hour pattern of intraocular pressure (IOP), and to clarify the effect of light cycle on 24-hour pattern of IOP in ddY albino mice. Three groups of ddY albino mice were exposed to a 12-hour light/dark cycle (control group), to constant light and, to constant dark, respectively. Every group was exposed to each condition for 4 weeks before IOP measurements. IOP was measured every 3 hours using a microneedle method. Mice were measured repeatedly at 1-week interval. The 24-hour IOP pattern of the control group showed a rhythmic pattern that appeared to be sinusoidal. This IOP declined in the morning until 9:00, and then increased in the early evening until 21:00. In contrast, IOP of the constant light and dark groups were asynchronous exhibiting multiple peaks and troughs during the 24-hour period. The mean IOP of the constant light group was almost equal to that of control group. The mean IOP measured at the daytime of the constant dark group (light time of control group), was significantly higher than that of the control group, and was almost equal to the mean IOP measurements at the dark time of the control group. These results show that 24-hour IOP pattern in mouse eyes is biphasic and that extended exposure to constant light or dark disrupts this 24-hour IOP pattern.

Twenty-four-hour intraocular pressure pattern associated with early glaucomatous changes.

To characterize the 24-hour pattern of intraocular pressure (IOP) in untreated patients with newly diagnosed early glaucomatous changes. Measurements of IOP, blood pressure, and heart rate were taken every 2 hours during a 24-hour period from a group of 24 untreated patients (ages 40-78 years) with newly diagnosed abnormal optic discs and/or abnormal visual fields. In the 16-hour diurnal awake period, IOP was measured sitting and supine, and blood pressure and heart rate were measured supine. In the 8-hour nocturnal sleep period, all measurements were taken in the supine position. Mean diurnal and nocturnal IOP, blood pressure, and heart rate in the glaucoma group were compared with data obtained from an age-matched control group of 24 individuals with healthy eyes. Mean diurnal IOP, either sitting or supine, was significantly higher in the glaucoma group than in the control group. For both subject groups, nocturnal supine IOP was higher than diurnal sitting IOP. However, this diurnal-to-nocturnal increase in IOP was significantly smaller in the glaucoma group. When compared with the diurnal supine IOP, the nocturnal supine IOP was lower in the glaucoma group but higher in the control group. Around normal awakening time, the supine IOP increased in the glaucoma group and did not change in the control group. There was a diurnal-to-nocturnal decrease in mean blood pressure only in the glaucoma group. Compared with healthy eyes, the diurnal IOP is higher, the diurnal-to-nocturnal change of habitual IOP is less, and the posture-independent IOP pattern around normal awakening time is different in eyes with early glaucomatous changes.