Diurnal Variation Of Intraocular Pressure Research Articles

Diurnal Pattern of Intraocular Pressure is Affected by Microgravity When Measured in Space With the Pressure Phosphene Tonometer (PPT)

This study was designed to evaluate the effect of microgravity on the diurnal variation of intraocular pressure (IOP). IOPs were measured with the pressure phosphene tonometer in 1 subject (the first Korean astronaut) during spaceflight. IOPs were measured every 3 hours during day time (6 times per day) at 2 separate days in space with 3 repeated measurements at each time on both eyes. A total of 72 measurements were obtained during spaceflight. To obtain control IOP data, IOP was measured using the same protocol on ground before spaceflight. Mean IOP increased by 26.3% during spaceflight compared with that on ground [16.47 ± 0.60 (SD) mm Hg vs. 13.04 ± 0.74 mm Hg, P<0.001). The IOP elevation was maintained until Launch+8 days. There was no significant difference in IOP increase between right and left eyes (16.4 2 ± 0.65 mm Hg right eye vs. 16.53 ± 0.56 mm Hg left eye). There was a different pattern of diurnal variation of IOP during spaceflight compared with that on ground. The IOP at 7 AM was the lowest under microgravity, whereas it was the highest on ground. The slope of the best fit line for diurnal IOP measures was 0.0349 mm Hg/h (95% confidence interval: 0.0082-0.0616) under microgravity and -0.0294 mm Hg/h (95% confidence interval: -0.0063-0.0041) on ground. The study showed a different diurnal pattern of IOP under microgravity compared with that on ground. This result suggests that gravity and subsequent body fluid shift is one of the determining factors of IOP diurnal variation.

Diurnal Variations in Axial Length, Choroidal Thickness, Intraocular Pressure, and Ocular Biometrics

To investigate the pattern of diurnal variations in axial length (AL), choroidal thickness, intraocular pressure (IOP), and ocular biometrics over 2 consecutive days. Measurements of ocular biometrics and IOP were collected for 30 young adult subjects (15 myopes, 15 emmetropes) at 10 different times over 2 consecutive days. Five sets of measurements were collected each day at approximately 3-hour intervals, with the first measurement taken at ~9 AM and final measurement at ~9 PM. AL underwent significant diurnal variation (P < 0.0001) that was consistently observed across the 2 measurement days. The longest AL was typically observed at the second measurement session (mean time, 12:26) and the shortest AL at the final session of each day (mean time, 21:06). The mean diurnal change in AL was 0.032 ± 0.018 mm. Choroidal thickness underwent significant diurnal variation (mean change, 0.029 ± 0.016 mm; P < 0.001) and varied approximately in antiphase to the AL changes. Significant diurnal variations were also found in vitreous chamber depth (VCD; mean change, 0.06 ± 0.029 mm; P < 0.0001) and IOP (mean change, 3.54 ± 0.84 mm Hg; P < 0.0001). A positive association was found between the variations of AL and IOP (r(2) = 0.17, P < 0.0001) and AL and VCD (r(2) = 0.31, P < 0.0001) and a negative association between AL and choroidal thickness (r(2) = 0.13, P < 0.0001). There were no significant differences in the magnitude and timing of diurnal variations associated with refractive error. Significant diurnal variations in AL, choroidal thickness, and IOP were consistently observed over 2 consecutive days of testing.

The Association Between Diurnal Variation of Optic Nerve Head Topography and Intraocular Pressure and Ocular Perfusion Pressure in Untreated Primary Open-angle Glaucoma

To investigate the hypotheses that the topography of the optic nerve head (ONH) significantly changes during the day in untreated primary open-angle glaucoma (uPOAG) and healthy volunteers; and that there is a significant association with diurnal variations of intraocular pressure (IOP) and mean ocular perfusion pressure (MOPP). Fourteen uPOAG and 14 age-matched normals were included. IOP, blood pressure, and ONH topography were measured between 7:00 AM and 10:00 PM. MOPP was calculated. A mixed-effect repeated measures analysis was done. Variance component analysis was done for glaucoma and normal groups separately based on the mixed-effect models. The cup volume, rim volume, and cup shape measure in the temporal (T) and temporal-inferior (TI) sectors were significantly different between the 2 groups (P<0.05). The highest variance component was owing to "patients" whereas "time" had the smallest contributed percentage. Cup volume (T and TI) and reference height (RH) showed a significant (P<0.001) diurnal change in uPOAG. Rim volume (T and TI) showed a significant diurnal change in normals (P≤0.01). There was no significant (P>0.05) association between the change in IOP, MOPP, and ONH topography in either group. There was a significant association between cup volume and RH in both groups (P<0.001, global and T). There was a significant association between MOPP and RH in both groups (P<0.001). The ONH topography significantly changed during the day in both groups. The change in ONH topography was associated with the change in reference height, which in turn was associated with MOPP. These findings suggest that the time of the day and the level of perfusion pressure should be considered when evaluating ONH topography using the HRT. Repeated measures are recommended when evaluating ONH topography.

Effects of unoprostone on diurnal variation of intraocular pressure in healthy volunteers

PurposeTo prospectively evaluate the diurnal variation of intraocular pressure (IOP) during unoprostone treatment in 13 healthy volunteers.MethodIOP was measured by Goldmann applanation tonometry by the same observer every 3 hours from 9 am to 9 am the next morning. Unoprostone was then instilled at 9 am and 9 pm daily for 1 month. After 1 month, IOP was measured again with unoprostone instilled at 9 am and 9 pm during IOP measurement. We then compared the average daily IOP before and after the treatment (paired t-test).ResultsAfter 1 month of treatment, the average IOP decreased at every time point but one (12 pm, 3 pm, 6 pm, 9 pm, 12 am, 3 am, and 9 am, but not at 6 am). There were no adverse reactions and none of the subjects discontinued unoprostone.ConclusionThe hypotensive effects of unoprostone persist throughout the day, but this study suggests that the effects may be weaker at nighttime and early in the morning.

Adherence with brimonidine in patients with glaucoma aware and not aware of electronic monitoring

To assess the impact of open versus masked adherence monitoring on adherence with topical brimonidine using two different dosing schedules. Thirty-seven patients with glaucoma or ocular hypertension were enrolled in a prospective, observational cohort study. Patients were randomly assigned to open or masked adherence monitoring and to brimonidine twice daily (BID) or three times daily (TID). Patients received conventional brimonidine eye drops with attached electronic monitoring devices for 4 weeks with weekly intraocular pressure measurements. Adherence calculations comprised dosing intervals, adherence rate and time covered. Subgroup analysis with anova included the factors masking, regimen, diagnosis and age. Among 36 individually analysed patients, 12 (33%) had adherence rates above 75%, therein two (5%)>90%. The mean adherence rate in 19 patients aware of adherence measurements was 70 ± 17% for brimonidine BID and 65 ± 14% for TID, not significantly different to the rates of 17 patients not informed about adherence measurements (77 ± 6% BID, 62 ± 9% TID, p = 0.24). On average, patients with brimonidine TID achieved significantly lower adherence rates (64 ± 12%) than patients on BID (73 ± 13%, p = 0.02). Still, patients on TID applied brimonidine more often (TID 1.9 ± 0.3, BID 1.5 ± 0.1 mean applications per day). The median coverage was 70% and showed no statistically significant difference between patients on BID and TID (p = 0.36). The study findings suggest that adherence measurements are not significantly altered by open adherence monitoring, which may simplify future adherence studies. Adherence with brimonidine eye drops was insufficient for most patients. These results demonstrate the necessity to develop new strategies to improve compliance in glaucoma therapy.

The diurnal variation of intraocular pressure—the most important symptom for early detection and follow-up of the glaucomas

Hans Goldmann in 1958 emphasized the importance of the diurnal curve of intraocular pressure for very early detection of glaucoma. He stressed from the investigations of Leydhecker (1959) that there is a 10-year interval between early detection of chronic glaucoma and the first signs of neuronal defects or even later, functional problems. Roberto Sampaolesi (1974) finally has proven the important innovation from his great number of diurnal curves. Of course, a precise diurnal curve (Sampaolesi asked for eight measurements) is almost impossible by the ophthalmologist's office or even within the hospital. We need the cooperation of the patient (like we do this in blood pressure measurement or even diabetes control). This requires an easy-to-handle "self-tonometer", which allows measurement at any time of the day, even in different positions of the patient's body. Due to some difficult technical problems to be solved, it took until 1988 before the "automatic self-tonometer" was available. This was first tried in three space missions (Spacelab D1, 1985; Spacelab D2, 1993; German-Russian MIR-Mission 1992) allowing for the first time to register the enormous increase of intraocular and intracranial pressure after entering into microgravity. Some years later, the first instrument for clinical application was available, allowing a large series of dense diurnal curves, confirming Goldmann's and Sampaolesi's hypothesis. The technical solution, application, and results with this new instrument are described.

Diurnal Variation of Corneal Biomechanics and Intraocular Pressure in Normal Subjects

To assess and investigate the relationship between diurnal variations in intraocular pressure (IOP) and biomechanical properties of cornea. Sixty-two healthy volunteers were recruited. Corneal compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal resistance factor (CRF), and corneal hysteresis (CH) parameters were recorded by the Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured using an ultrasonic pachymeter. Three consecutive measurements of IOPcc, IOPg, CRF, CH, and CCT were recorded at 8:00 am, 11:00 am, 2:00 pm, and 5:00 pm. One-way analysis of variance and Pearson correlation tests were used for statistical analysis. Intra device repeatability was evaluated using Scheffe multiple comparison. IOPcc, IOPg, CRF, CH, and CCT measurements displayed a stable profile during daytime acquisitions and no statistically significant variation was noted (p>0.05). All measurements of IOPcc, IOPg, CRF, and CH recorded by ORA at 8:00 am, 11:00 am, 2:00 pm, and 5:00 pm were all found to be highly repeatable (p>0.05). There was a statistically significant and inverse correlation between IOPcc and CH (p=0.001), and a positive correlation was detected between IOPcc and CRF (p=0.001). CRF and CH were both found to be positively correlated to CCT (p=0.001). IOPcc readings and recordings of corneal biomechanics were constant throughout the day in healthy eyes. CRF and CH seem to exert different effects on IOPcc as diverse correlations were detected between CRF, CH, and IOPcc. Assessment of IOP and corneal biomechanics using ORA was found to be a highly repeatable.

Correlation between diurnal variation of intraocular pressure, ocular pulse amplitude and corneal structural properties

The purpose of this study was to evaluate the fluctuation of intraocular pressure measurements obtained by Goldmann applanation tonometry, dynamic contour tonometry, and corneal compensated non-contact tonometry during office hours in glaucoma and healthy participants. This study also aims at correlating the intraocular pressure fluctuations with fluctuations of corneal hysteresis, central corneal thickness, mean central corneal curvature and ocular pulse amplitude. A total of 12 controls (24 eyes) and 21 patients (38 eyes) with open-angle glaucoma were recruited. Intraocular pressure measured by Goldmann applanation tonometry, dynamic contour tonometry and corneal compensated non-contact tonometry, ocular pulse amplitude, central corneal curvature and thickness, corneal hysteresis, and resistance factor were obtained at intervals of 2 hours, between 9 AM and 5 PM. Intraocular pressure fluctuated significantly throughout the day in controls and glaucoma individuals with all tonometers (P<0.001). There was no statistically significant variation in mean corneal curvature (P=0.048 in controls; P=0.04 in glaucomatous) or hysteresis over time (P=0.12 in controls; P=0.36 in glaucomatous). The ocular pulse amplitude showed a significant diurnal fluctuation in both groups (P<0.001). There was a significant correlation between the intraocular pressure measured by dynamic contour tonometry and ocular pulse amplitude (P<0.001). There was significant intraocular pressure fluctuation over office hours on measurements performed by Goldmann applanation tonometry, dynamic contour tonometry, and corneal compensated non-contact tonometry in normal and glaucoma individuals. Intraocular pressure varied independently of corneal hysteresis, central corneal thickness, and central curvature variation. However, there was significant correlation between ocular pulse amplitude and intraocular pressure measurements performed by dynamic contour tonometry.

Intraoffice Variability of Corneal Biomechanical Parameters and Intraocular Pressure (IOP)

To evaluate the intraoffice hour variability of intraocular pressure (IOP) and in vivo biomechanical properties of the cornea, as measured with the Ocular Response Analyzer (ORA). The right eye of each of 58 young healthy subjects (14 men, 44 women) was measured at 1-hour intervals from 9.00 a.m. until 7.00 p.m. with the ORA. Subjects' age ranged from 19 to 45 years (average +/- standard deviation, 25 +/- 6 years). Average intraoffice hour variability of IOP and corneal biomechanical parameters were not statistically significant, showing a stable profile during the hours of the day studied. An interesting finding was that although there were no significant diurnal variations in any of the parameters, minor changes in corneal-compensated IOP and a Goldmann-equivalent IOP were significantly correlated with the intraoffice hour variability of corneal biomechanical parameters corneal hysteresis (CH) and the corneal resistance factor (CRF). Corneal-compensated IOP changes were the most strongly associated with intraoffice hour variability in CH for all measurement times (r = 0.598; p < 0.001). Changes of Goldmann-equivalent IOP were strongly correlated with intraoffice hour variability of corneal resistance factor (r = 0.849; p < 0.001). The present study confirms that intraoffice hour values of CH and corneal resistance factor are quite stable among a population of young healthy adults. However, average changes in these parameters over time correlate well with the changes in IOP values obtained with the same instrument, suggesting that diurnal variations of IOP could be at least in part related with changes in the biomechanical behavior of the cornea against the mechanical stimuli used by current non-contact tonometers. The most stable period to measure IOP and biomechanical parameters with ORA was in the afternoon.

Effect on Diurnal Intraocular Pressure Variation of Eliminating the α-2 Adrenergic Receptor Subtypes in the Mouse

To investigate the effect on circadian variation of intraocular pressure (IOP) of eliminating the alpha2A-, alpha2B-, or the alpha2C-adrenergic receptor subtypes in the mouse. A microneedle method was used to measure IOP in knockout mice lacking the alpha2A-, alpha2B-, or the alpha2C-receptor (alpha2A-R(-/-), alpha2B-R(-/-), alpha2C-R(-/-)), in wild-type mice of the alpha2B knockout strain (alpha2B-R(+/+)), and in the background strain mice, C57BL/6. All mice were maintained in a 12-hour light-dark cycle commencing at 0600 hours. IOP was measured at 0900 and 2100 hours in the five groups: C57BL/6 (n = 8), alpha2A-R(-/-) (n = 10), alpha2B-R(-/-) (n = 8), alpha2B-R(+/+) (n = 8), and alpha2C-R(-/-) (n = 10). In parallel experiments, eyes from the alpha2A-R(-/-), alpha2B-R(-/-), alpha2C-R(-/-), and C57BL/6 mice were embedded in epoxy resin, and semithin sections were stained with toluidine blue. IOP at 0900 hours in B6, alpha2A-R(-/-), alpha2B-R(-/-), alpha2B-R(+/+), and alpha2C-R(-/-) mice was 17.1 +/- 1.8, 17.7 +/- 1.4, 17.1 +/- 2.1, 17.6 +/- 1.3, and 17.3 +/- 0.9 mm Hg, respectively (mean +/- SD). IOP at 2100 hours in the same eyes was 19.6 +/- 1.9, 19.2 +/- 2.2, 20.5 +/- 1.5, 19.7 +/- 0.8, and 21.3 +/- 2.7 mm Hg, respectively. There was no significant difference among these genotypes in IOP measured at either time point (P > 0.05, ANOVA). Within each genotype, IOP at 2100 hours was significantly higher than IOP at 0900 hours (C57BL/6, alpha2B-R(-/-), alpha2B-R(+/+), and alpha2C-R(-/-): P < 0.01; alpha2A-R(-/-): P < 0.05, paired t-test). Differences in the diurnal IOP change among the different genotypes were insignificant (P > 0.05, ANOVA). Histopathologic assessment found minimal differences in the structural organization of the anterior segment among the alpha2A-R(-/-), alpha2B-R(-/-),alpha2C-R(-/-), or C57BL/6 mice. These results indicate that IOP magnitude and circadian variation are minimally altered by the absence of the alpha2A-, alpha2B-, or alpha2C-receptor subtypes in transgenic mice.

The Efficacy of TonoLab in Detecting Physiological and Pharmacological Changes of Mouse Intraocular Pressure—Comparison with TonoPen and Microneedle Manometery

Purpose: The efficacy of two non-invasive tonometers, TonoLab and TonoPen XL, in detecting physiological or pharmacological changes of intraocular pressure (IOP) in mouse eyes, was assessed by comparison with a microneedle method. Material and Methods: C57BL6 mice, bred under the 12-hr light and dark cycle over 2 weeks, were used. Under systemic anesthesia, mouse eyes were cannulated by a microneedle connected to a transducer and a water reservoir. We manipulated the intracameral pressure by changing the reservoir height, and obtained tonometer readings at each pressure (n = 39) with TonoLab and TonoPen XL. The correlation between each tonometer and the manometer was analyzed. Then the diurnal variation of IOP in the light and dark phases, and the IOP-lowering effect at 2 hr after latanoprost instillation, were measured with TonoLab, TonoPen XL, and a microneedle tonometer (n = 8). Results: In mouse eyes, TonoPen XL could not show reliable scores, but TonoLab readings showed a strong correlation with manometer readings (y = 0.87x – 0.27, r2 = 0.917). Nocturnal elevation of IOP in mouse eyes was significantly indicated with TonoLab and a microneedle tonometer (p < 0.001), but not with TonoPen XL. Latanoprost significantly reduced IOP by 2.1 ± 2.8 and 2.0 ± 1.0 mmHg with TonoLab and a microneedle tonometer, but not with TonoPen XL. Conclusion: TonoLab provides similar readings to a microneedle tonometer, and diurnal variation and drug effect were detectable in mouse eyes. TonoLab promises to be a non-invasive and useful method to evaluate physiological and pharmacological studies in mouse eyes.

Variabilidad diurna de la presión intraocular

To assess whether there are variations in the intraocular pressure (IOP) between the morning and afternoon in healthy subjects. This study was carried out in a Primary Care Health Center among usual patients of general practitioners. Two measurements of the intraocular pressure were assessed on the same day (between 8 and 9 a.m. and between 5 and 6 p.m.) using a Perkins applanation tonometer. The subjects (119 females and 101 males) had a mean age of 46.3 years, with ages ranging between 14 and 83 years. They were proportionally distributed among 4 age groups (14-24, 25-44, 45-64 and >65 years). The IOP mean values were: right eye, morning time and afternoon, 13.29 and 11.81 mm Hg, respectively (p<0.001); left eye, morning time and afternoon, 13.48 and 12.04 mm Hg (p<0.001). The IOP was significantly higher in males than in females, and showed a weak association with age. We found a diurnal variation of IOP of approximately 1.5 mm Hg. The time of day when the IOP is measured needs to be considered as a variable in research in ocular hypertension and glaucoma.

Relationship Between Intraocular Pressure and Obesity in Children

To establish the relationship between intraocular pressure (IOP) and obesity in children. Seventy-two obese children (body mass index in the 95th percentile or greater) were compared with 72 age-matched and sex-matched controls (body mass index <95th percentile). Both groups underwent Goldmann applanation tonometry (3 times), blood pressure measurement (3 times), and Hertel exophthalmometry. Paired and unpaired t tests and the Cochran-Mantel-Haenzel statistics were used for statistical analysis. The mean IOP between the obese children and controls were significantly different (P<0.0001), even after adjusting for systolic and diastolic blood pressure (P<0.001). Diurnal variation of IOP was higher in obese children (P<0.001). Obese children had higher Hertel values (P<0.001). Sex did not significantly effect IOP in either group (P>0.05). In addition to its indirect effect on IOP via blood pressure change, obesity is also an independent risk factor for increased IOP.

Diurnal variation of intraocular pressure in suspected glaucoma patients and their outcome

A case-controlled prospective study was conducted to evaluate the diurnal variation of intraocular pressure (IOP); the mean, the amplitude of variation and the peak and trough times of pressure readings in the suspected open-angle glaucoma patients as compared with a control group. We also looked at the outcome of these suspects after diurnal variation of IOP measurements. Diurnal variation of intraocular pressure was measured in 202 eyes of suspected open-angle glaucoma patients and 100 control eyes, at 4-hourly intervals for 24 hours (phasing). Based on the phasing results, optic disc changes and visual field defects, the patients were diagnosed as primary open angle glaucoma (POAG), normal tension glaucoma (NTG), ocular hypertension (OHT), or physiologic cup (PC), or still remained as glaucoma suspects due to inconclusive diagnosis. The last group (glaucoma suspects) was then followed up 6-monthly for their eventual outcome. The highest percentage of suspected glaucoma patients had peak (maximum) readings in the mid-morning (10-11 A.M.) and trough (minimum) readings after midnight (2-3 A.M.); the highest percentage of control group had peak readings in the late evening (6-7 P.M.) and trough readings after midnight (2-3 A.M.). The mean amplitude of variance was 6 mm Hg in suspected glaucoma group and 4 mm Hg in the control group. After 'phasing', 18.8% of the suspected glaucoma patients were diagnosed as POAG, 16.8% as NTG, 5% as OHT, and 28.7% as physiologic cup; 30.9% remained as glaucoma suspects. After 4 years follow-up, 70% of the glaucoma suspects still remained as glaucoma suspects, 6.7% developed NTG and another 6.7% POAG; 16.6% were normal. Serial measurement of IOP ( phasing) in a 24-hour period is still needed, in order not to miss the peak and the trough IOP readings in suspected open-angle glaucoma patients, which helps in better management of glaucoma. Among 30.9% of patients who remained as glaucoma suspects after the initial phasing, 13.4% developed NTG/POAG over a period of 4 years.

Large intraocular pressure fluctuations: a risk factor for glaucoma progression

Abstract Purpose: We are aware of the detrimental effects of peaks of intraocular pressure (IOP) above the normal range. However, we have observed that many of our patients continue to experience glaucomatous progression despite their mean IOP being below what the physician considers an adequate target IOP for that individual. We studied the risk associated with diurnal IOP variations in open angle glaucoma. Methods: The patients who were enrolled in the study used the Zeimer self‐tonometer to measure IOP over a period of 5 days. The readings were taken upon waking, noon, mid‐afternoon, dinnertime and bedtime. Visual fields over the 10‐year duration of the study were reviewed for progression. We performed statistical analyses on these readings to study the relative risk of disease progression. Results: Baseline office IOP had no predictive value (relative hazard: 0.98). The IOP range over multiple days was a significant risk factor for progression even after adjusting for office IOP, age, race and visual field damage at baseline (relative hazard ratio 5.76). 88% of patients in the upper 25 percentile of IOP fluctuation, and 57% of patients in the lower 25th percentile of IOP fluctuation, progressed within 8 years Conclusions: In this presentation, corroborating studies, common IOP fluctuations and proposed mechanisms for IOP fluctuations will be presented. Ways to control IOP spikes will be discussed and pharmacotherapy options will be explored.Diurnal fluctuations in IOP present a greater risk of visual‐field loss to the patient with glaucoma compared to mean IOP. By monitoring IOP more closely and by prescribing medication that offers the best control of IOP with the least amount of fluctuation, ophthalmologists can offer their patients the best therapy for glaucoma.

Diurnal Fluctuation and Concordance of Intraocular Pressure in Glaucoma Suspects and Normal Tension Glaucoma Patients

The study objective was to determine the concordance of intraocular pressure (IOP) in glaucoma suspects (GS) and normal tension glaucoma (NTG) patients. This was a retrospective review of diurnal curves of untreated GS and NTG patients. No subject had IOP greater than 21 mm Hg. We defined GS patients as having suspicious optic nerves with normal visual fields, and NTG patients as having glaucomatous optic nerves with associated visual field loss. Goldmann applanation tonometry was performed at 10:00, 13:00, 16:00, 19:00, 22:00, and 07:00. Linear association of OD and OS IOP was estimated using Pearson correlation coefficient (r). The diurnal period was divided into 7 time intervals of 3, 6, 9, 12, 15, 18, and 21 hours, and the absolute difference in change in IOP between fellow eyes and probability that it was within 3 mm Hg were calculated. The study included 68 GS and 95 NTG subjects. The diurnal curves of the OD and OS showed a parallel course in both groups. The average correlations (r) of OD and OS IOP over the 6 time points were 0.78 and 0.81 for GS and NTG, respectively. The mean absolute difference in IOP change between OD and OS over the 6 time intervals ranged between 1.4 and 1.9 mm Hg for GS, and 1.3 and 1.5 mm Hg for NTG subjects. The probability that this difference was within 3 mm Hg ranged between 87% and 94% for GS, and 86% and 93% for NTG subjects. The diurnal variation in IOP between the 2 eyes in GS and NTG is largely concordant in approximately 90% of the time.

Concordance of Diurnal Intraocular Pressure between Fellow Eyes in Primary Open-Angle Glaucoma

To study the concordance of diurnal intraocular pressure (IOP) between fellow eyes in primary open-angle glaucoma (POAG). Retrospective chart review. Ninety-three POAG patients. Patients who met the definition of POAG and underwent diurnal curve measurement were included. Subjects were excluded if there was a history of surgery, trauma, ocular vascular disease, incomplete diurnal curve, or asymmetric ocular medication use. Patients on symmetric ocular medication were included and analyzed separately. Goldmann applanation tonometry was performed at 10 am, 1 pm, 4 pm, 7 pm, 10 pm, and 7 am (the next day). The following statistical analyses were performed: (1) average Pearson correlation coefficient (r) from individual correlations of right and left eye IOP over the 6 time points for each subject; (2) linear mixed model analysis for repeated measures, with eye (right and left) and time as the within-subject fixed effects, and (3) absolute difference in change in IOP between fellow eyes over each time interval and probability that the difference was within 2 or 3 mmHg. The concordance of the IOP between fellow eyes as measured by absolute difference in change in IOP between fellow eyes and probability of the difference being within 2 or 3 mmHg. Thirty-seven patients were untreated and 56 were treated on symmetric IOP-lowering medications. The diurnal curves of fellow eyes exhibited parallel profiles according to the linear mixed model. The average difference in the change of IOP between fellow eyes over given time intervals ranged from 1.6 to 2.0 mmHg. The estimated probability that the absolute change in IOP between fellow eyes was within 2 mmHg was 68% to 90%, and within 3 mmHg was 78% to 95% for all time intervals. The diurnal variation of IOP in POAG is largely concordant between fellow eyes. For any given time interval, the fellow eye IOPs may fluctuate asymmetrically a minority of the time. Clinicians who utilize the uniocular trial should be aware of the limit of the IOP concordance.

Large Diurnal Variation of Intraocular Pressure Despite Maximal Medical Treatment in Juvenile Open Angle Glaucoma

To report the clinical significance of large fluctuations in intraocular pressure (IOP) and the effect of trabeculectomy on diurnal IOP variations in 2 cases of maximally medically treated juvenile open angle glaucoma (JOAG). A 24-hour IOP monitoring was performed before and after trabeculectomy on both eyes of 2 JOAG patients-one with transiently blurred vision early in the morning, the other with progression of visual field defect despite apparently well-controlled IOP. The patients' optic discs were scanned with Heidelberg retina tomograph (HRT) during peak and trough IOPs before trabeculectomy. Preoperatively, diurnal IOP varied widely up to 20/19 (OD/OS) mm Hg in case 1 and up to 16/22 (OD/OS) mm Hg in case 2, even though both patients were using 4 different types of antiglaucoma eye drops. Peak IOP was associated with temporary blurring of vision and mild corneal edema in 1 patient (case 1). Heidelberg retina tomograph revealed a deepening of the optic cup and a resultant narrowing of the neuroretinal rim at peak IOP in this patient; this was not detected in the second patient who had tilted optic discs. After trabeculectomy, diurnal IOP fluctuations were reduced to 4-6/2-4 (OD/OS) mm Hg in case 1 and to 6-7/3-7 (OD/OS) mm Hg in case 2, with a decrease in peak IOPs as well. Wide diurnal variation should be suspected in JOAG patients, even when receiving maximal medical treatment; this is especially important in cases with temporary blurred vision and/or progression of visual field defect despite apparently well-controlled IOP. Trabeculectomy was more effective in reducing diurnal IOP variation than medical treatment.

Comparison of Methods for Parameter Estimation in a Circular Linear Mixed Effect Model Incorporating the Diurnal Variation for Evaluating the Treatment Effects of Glaucoma Therapy

Glaucoma is the primary cause of vision loss in Japan. The most important glaucoma therapy is to decrease intraocular pressure (IOP) for preventing visual field defects in the pre-stage of vision loss. Considering a systematic diurnal variation of IOP, Kuwayama et al. (2006) proposed to use a circular linear mixed effect (CLME) model for evaluating the efficacy of therapy on IOP decrease for patients with normal tension glaucoma (NTG) and applied it to the data analysis in a clinical trial (Nipradilol trial) with 28 NTG patients. In this application, there occurred an issue that the parameter estimates were different depending on the method of estimation and the best method was not identified. We, therefore, compared six methods for parameter estimation (standard two-stage (STS) method, global two-stage (GTS) method, first order approximation (FOA) method, Laplacian approximation (LAP) method, Monte Carlo integration (MCI) method and Gaussian quadrature (GAUS) method) through a simulation experiment with the bias and square root of mean squared error as the criteria for evaluation. The GAUS method proved to be superior to others in realizing least bias and mean squared error under various simulation conditions, although it was most time consuming.

Effect of Latanoprost on the Diurnal Variations in the Intraocular and Ocular Perfusion Pressure in Normal Tension Glaucoma

To evaluate the effects of latanoprost on the diurnal variations in the intraocular pressure (IOP) combined with the ocular perfusion pressure (OPP) in patients with normal tension glaucoma (NTG). Twenty-two eyes from 22 patients with NTG were used for the study. The diurnal variations in the IOP and blood pressure (BP) were measured every 3 hours without therapy, and then the patients were treated with latanoprost (0.005%) once daily for more than 12 weeks. The diurnal variations in the IOP and BP under medication were again measured every 6 hours. The diurnal variation of IOP for 24 hours, mean diurnal IOP, maximum IOP, minimum IOP, range of variation in IOP, OPP, and BP were compared between the baseline and after treatment by means of a paired t test. At 3 months after the start of the latanoprost treatment regimen, the IOP showed a statistically significant decrease at every assessed time point over 24 hours (P<0.001). Latanoprost significantly reduced the mean diurnal IOP, maximum IOP, minimum IOP, and mean range of variation in the IOP values from baseline (P<0.001, <0.001, <0.001, and 0.009, respectively). OPP after treatment showed no significant difference at any assessed time points from the baseline (P>0.1). Latanoprost did not significantly alter the mean diurnal OPP (P>0.1), and BP (P>0.5) from the baseline. Latanoprost was thus found to significantly reduce IOP over 24 hours, whereas it does not affect OPP and BP in NTG patients. Therefore, it may be a useful medication for NTG.