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PubMed1985

Cervical ganglionectomy alters the circadian rhythm of intraocular pressure in New Zealand White rabbits.

A circadian rhythm of intraocular pressure in rabbits could provide a useful model for understanding the daily rhythm of intraocular pressure in humans and for studying mechanisms which regulate intraocular pressure. Our results confirm earlier work showing that New Zealand White rabbits housed in an environment with a lighting cycle of 12 hours light and 12 hours dark have a rhythm of intraocular pressure, and that this rhythm persists in constant dark. We show further that the cycle of light and dark is the zeitgeber for entrainment of the rhythm of intraocular pressure, and therefore persistence of this rhythm in constant dark establishes it as a circadian rhythm. Cervical ganglionectomy demonstrated that intact sympathetic innervation to the eye is required for maintenance of the normal circadian rhythm of intraocular pressure in rabbits. Intraocular pressure in sympathectomized eyes is no different from control eyes during the light, but is significantly reduced during the dark.

Animals↗
PubMed1980

Characteristics of reduction of intraocular pressure after trabeculectomy.

The change in intraocular pressure achieved after 98 trabeculectomy operations performed on 70 patients with primary open-angle glaucoma was analysed. The reduction was proportional to the untreated preoperative pressure, and the results indicated that a first trabeculectomy reduced the intraocular pressure to between 16 and 20 mmHg irrespective of its initial level. Cases which required medical therapy for final pressure control after surgery showed a distribution of initial intraocular pressure similar to those not requiring such therapy. In addition, these cases were reduced to a level of pressure only slightly above the arbitrary figure of 20 mmHg before medical therapy was added, and were therefore considered almost to have reached the normal physiological range. Cases submitted to a second trabeculectomy are discussed, including 2 cases with unexplained acute open-angle glaucoma some months after the first operation.

Female↗
PubMed2004

A randomized, investigator-masked comparison of diurnal responder rates with bimatoprost and latanoprost in the lowering of intraocular pressure.

In glaucoma and ocular hypertension, clinically relevant intraocular pressure lowering due to a new medication is frequently defined as at least a 15% or 20% reduction from baseline intraocular pressure. This report compares the percentages of treated patients achieving such reductions in intraocular pressure after 6 months of treatment with bimatoprost or latanoprost. In the previously published study (Noecker et al: A six-month randomized clinical trial comparing the intraocular pressure-lowering efficacy of bimatoprost and latanoprost in patients with ocular hypertension or glaucoma. Am J Ophthalmol 135:55-63, 2003), patients with glaucoma or ocular hypertension were randomly assigned to once-daily treatment with bimatoprost 0.03% (n=133) or latanoprost 0.005% (n=136), after washout of any previous glaucoma medications. The primary outcome measure of that study was mean change from baseline intraocular pressure. The secondary, post hoc analysis presented here compares the diurnal and long-term responder rates observed with bimatoprost and latanoprost patients. Diurnal responders were defined as patients who achieved at least a 15% or 20% reduction from baseline intraocular pressure at each of the three timepoints (8 am, 12 pm, and 4 pm) on a given visit. At week 1 and months 1, 3, and 6, in the bimatoprost group, 70.7-81.2% of patients achieved at least a 15% reduction in IOP at each timepoint, and 57.9-68.4% achieved at least a 20% reduction. Significantly fewer patients receiving latanoprost achieved a 15% or a 20% decrease in IOP at each timepoint: 48.5-61.8% of patients achieved at least a 15% decrease and 36.0-47.1% achieved at least a 20% decrease. (P< or =.007). The data presented here suggest that patients using bimatoprost are more likely than patients using latanoprost to achieve intraocular pressure reductions of at least 15% or 20% from baseline throughout the day.

Adult↗
PubMed1996

[Effect of local administration of mitomycin C on intraocular pressure].

BACKGROUND: Animal studies suggest that the decrease of intraocular pressure after application of mitomycin C is particularly mediated by toxic effects on the substance of ciliary body. Moreover it has been shown that the concentration of mitomycin C after topical application in the aqueous humour is as high when performing fistulating surgery. In this prospective study we wanted to investigate whether the topical application of mitomycin C would result in a significant decrease of intraocular pressure. PATIENTS AND METHODS: Forty-one eyes of 41 patients underwent pterygium surgery using a bare sclera technique. Afterwards phototherapeutic keratectomy with the excimer laser (193 nm) was performed in the area of the excision. In hospital mitomycin C eye drops (0.02%) were given twice daily for four days. The intraocular pressure of treated and untreated eyes was measured with applanation tonometry at least three times per day preoperatively, postoperatively at the fourteenth day and after 6 month. RESULTS: Mean intraocular pressure of the treated eyes was preoperatively 15.73 +/- 2.35 mm Hg, 14 days postoperatively 15.92 +/- 2.79 mm Hg and at the last examination 15.86 +/- 2.39 mm Hg. For untreated eyes the mean intraocular pressure was preoperatively 15.70 +/- 2.04 mm Hg, after 14 days 15.76 +/- 2.96 mm Hg and at the last examination 15.89 +/- 2.67 mm Hg. Consequently there was no statistically significant change of intraocular pressure in the eyes treated with mitomycin C. Furthermore there were no significant differences of intraocular pressure between treated and untreated eyes at any time of postoperative check-up. CONCLUSION: The short-term local application of mitomycin C did not result in a detectable change of intraocular pressure and is therefore probably an alternative to intraoperative application during filtration surgery.

Adult↗
PubMed1998

Mechanism of intraocular pressure elevation during hemodialysis.

PURPOSE: To detect the mechanism of intraocular pressure elevation during hemodialysis. METHODS: We measured intraocular pressure, as well as serum osmolality and plasma CO2 pressure, every 30 min during hemodialysis, in 5 eyes with severely compromised aqueous outflow facility (Group A) from 4 renal failure patients. The same measurements were repeated on the same eyes using intravenous hyperosmotic Glyceol to prevent a rapid change in serum osmolality. We also measured the same parameters on 8 eyes with normal aqueous outflow facility (Group B) from 5 patients. The mean +/- SE of percent changes in each parameter was used for the statistical analysis. RESULTS: In Group A, the mean percent change of intraocular pressure increased significantly after 90 min, with the exception of the change at 180 min. The mean percent change of serum osmolality decreased significantly after starting dialysis. A negative correlation in the mean percent change of intraocular pressure with serum osmolality was detected (r = -0.759, r < 0.0001). The administration of intravenous hyperosmotic agent prevented significant changes in not only serum osmolality but also intraocular pressure. In Group B, the mean percent change in intraocular pressure showed no significant difference at any time, although the change in serum osmolality decreased significantly. CONCLUSION: A remarkable rise in intraocular pressure occurs during hemodialysis in eyes with an impaired aqueous outflow, when serum osmolality decreases rapidly.

Aged↗
PubMed1988

Intraocular pressure response after pneumatic retinopexy.

We measured intraocular pressure over a five-day period in ten consecutive patients undergoing pneumatic retinopexy to determine the effect of an expanding gas bubble. During treatment, all eyes received 0.3 ml perfluoropropane gas. All eyes had an immediate rise in intraocular pressure, which in four eyes was associated with absence of central retinal artery perfusion for three minutes. Once intraocular pressure fell toward baseline (30 to 60 minutes after gas injection), we did not find a high intraocular pressure during the subsequent five-day period. We conclude that intraocular pressure-reducing medication is not routinely indicated in these eyes.

Cryosurgery↗
PubMed1982

The effect of metocurine and metocurine-pancuronium combination on intraocular pressure.

Maintenance of a normal to low intraocular pressure during ocular surgery is of critical importance. The prime considerations for anaesthetic management include adequate depth of anaesthesia, normal carbon dioxide and arterial oxygen tensions, stable cardiovascular status and avoidance of stimuli likely to raise central venous pressure. Non-depolarizing muscle relaxants are associated with a reduction in intraocular pressure. Metocurine, a non-depolarizing relaxant, formerly known as dimethyltubocurarine, has been recently reintroduced into clinical practice. Metocurine has been reported to be 1.8 times more potent than d-tubocurarine and has the clinically advantageous cardiovascular effects of stable heart rate and mean blood pressure with minimal associated histamine release. When combined with pancuronium, metocurine potentiates the neuromuscular blocking properties, so that small doses of both drugs in combination produce effective neuromuscular block. This study was designed to assess the suitability of metocurine 0.3 mg.kg-1 and metocurine 0.08 mg.kg-1 plus pancuronium 0.02 mg.kg-1 as muscle relaxants for ocular surgery. The results demonstrated that metocurine and metocurine-pancuronium combination in the above doses combined with sodium thiopentone 5 mg.kg-1 produced ideal conditions for intubation of the trachea in 4.45 (+/- 0.19 SE) minutes and 4.35 (+/- 0.16 SE) minutes respectively. In both treatment groups intraocular pressure was reduced below control values and a pattern of intraocular pressure stability ideal for ocular surgery was obtained during the 10 minutes observation period. The delayed onset of sufficient paralysis for tracheal intubation - 4.45 (+/- 0.19 SE) minutes for metocurine and 4.35 (+/- 0.16 SE) minutes for the combination - makes these techniques unsuitable for emergency ocular surgery because of the long interval when the airway is unprotected.

Adolescent↗
PubMed2004

The relationship of intraocular pressure to intracranial pressure.

STUDY OBJECTIVE: The early detection of intracranial hypertension can lead to timely medical and neurosurgical intervention, preventing brain herniation and death. In this investigation, we hypothesize that an increase in intracranial pressure can be detected by an increase in intraocular pressure using noninvasive existing technology, the handheld tonometer. METHODS: This was a prospective observational pilot study conducted at a community hospital. Admitted patients with an invasive intracranial pressure monitor were solicited for participation. Patients were excluded if they had known glaucoma or had sufficient ocular or facial trauma that precluded intraocular pressure determination. Simultaneous measurements of intracranial and intraocular pressure were recorded. RESULTS: Twenty-seven patients were enrolled, and 76 individual measurements were performed. All patients with an abnormal intracranial pressure had an abnormal intraocular pressure; similarly, all patients with a normal intracranial pressure had a normal intraocular pressure (sensitivity 1.00, 95% confidence interval 0.86 to 1.0; specificity 1.0, 95% confidence interval 0.93 to 1.0) CONCLUSION: Abnormal intraocular pressure as measured with the handheld tonometer is an excellent indicator of abnormal intracranial pressure in patients with known intracranial pathology.

Female↗
PubMed2001

Acute primary angle-closure: long-term intraocular pressure outcome in Asian eyes.

PURPOSE: To report the long-term outcome of intraocular pressure after laser peripheral iridotomy in Asian eyes with acute primary angle-closure. METHODS: Retrospective study of 111 eyes of 96 consecutive patients with acute primary angle-closure, presenting at the National University Hospital, Singapore, from 1990 to 1994. The presenting features of the affected eye and the treatment instituted were recorded. The subsequent long-term intraocular pressure outcome was analyzed. An increase in intraocular pressure on follow-up was defined as increase in intraocular pressure greater than 21 mm Hg and requiring treatment by medication or surgery. RESULTS: The mean follow-up period was 50.3 months (range, 9 to 107 months). The mean presenting intraocular pressure was 52.8 mm Hg (range, 28 to 80 mm Hg). One hundred ten eyes were treated with laser peripheral iridotomy, with resolution of the acute episode and intraocular pressure less than 21 mm Hg in all eyes after laser peripheral iridotomy. Of these, only 46 eyes (41.8%) were successfully treated with laser peripheral iridotomy alone in the long term. Sixty-four eyes (58.1%) developed an increase in intraocular pressure (requiring treatment) on follow-up, of which 49 eyes developed an increase in intraocular pressure within the first 6 months after acute primary angle-closure. Thirty-six eyes (32.7%) eventually underwent trabeculectomy because of uncontrolled intraocular pressure despite laser and medical therapy. CONCLUSIONS: In this study of Asian eyes, a high proportion (58.1%) of eyes with acute primary angle-closure developed an increase in intraocular pressure on long-term follow-up after resolution of the acute attack, despite the presence of a patent laser peripheral iridotomy. These results suggest a racial difference in the outcome of laser peripheral iridotomy after acute primary angle-closure in Asians, compared with Caucasians. Because a majority of eyes that develop an increase in intraocular pressure do so within the first 6 months of presentation, close monitoring of intraocular pressure is advised in the follow-up of patients with acute primary angle-closure.

Acute Disease↗
PubMed1976

Effect of intraocular gas on intraocular pressure.

The problems encountered in measuring intraocular pressure in eyes containing a compressible gas and the problem of determining the effect of changes in ambient atmospheric pressure on such eyes have been studied experimentally in enucleated human eyes and living rabbit eyes, and studied theoretically using the Friedenwald pressure-volume relationship, Boyle law, and the Goldmann equation of aqueous humor inflow and outflow. It has been concluded that high displacement tonometry, such as Schiötz tonometry will give false low measurements of intraocular pressure under these circumstances, and that there is no reliable way to correct these erroneous measurements other than to carry out tonometry with a low displacement instrument such as the Goldmann tonometer, the Perkins tonometer, or the Mackay-Marg tonometer. It was noted that large changes in intraocular pressure occur during rapid changes in ambient atmospheric pressure. It was concluded from theoretical considerations that persons with an eye containing 1 cu cm or more of a compressible gas should be advised to avoid air travel.

Aerospace Medicine↗
PubMed1991

[The effect of trabeculotomy on the day-time variation of intraocular pressure of the primary open-angle glaucoma].

We selected 34 eyes with primary open-angle glaucoma cases having glaucomatous visual field loss, but with relatively low base-line intraocular pressure (average intraocular pressure at normal office hour, below 20mmHg) and with one or more episodes of intraocular pressure over 21mmHg in a diurnal fluctuation estimated at 8:30, 9:30, 11:30, 13:30, 15:00 and 17:00. They were treated with trabeculotomy ab externo and we compared the pre- and postoperative diurnal fluctuation pattern of the intraocular pressure. The mean of the base-line intraocular pressure decreased from 18.4 to 16.3mmHg. The mean values of the maximal pressure of the diurnal estimation and of the diurnal difference (maximum minus minimum) also decreased, from 23.4 to 17.9 and from 7.4 to 3.9mmHg, respectively. In 31 eyes (91%) the individual maximal value did not exceed 20mmHg postoperatively. From these findings, it was speculated that trabeculotomy can be effective on primary open-angle glaucoma with relatively low intraocular pressure.

Circadian Rhythm↗
PubMed1981

Changes in intraocular pressure during acute exercise.

The effect of vigorous physical activity on intraocular pressure has been well documented. Other studies have only focused on pretest and posttest measurements of intraocular pressure. This study presents a continuous evaluation of intraocular pressure during exercise and correlates changes in intraocular pressure with changes in heart rate through time. A total of 17 adult male and female subjects were submaximally tested on a bicycle ergometer using the Astrand-Rhyming protocol. The results of this test were used to design an individualized four-stage workload that would proportionally take each subject to 85% of a predicted maximum heart rate. During this test, intraocular pressure was measured at the end of each stage and through 15 min of recovery with an American Optical non-contact tonometer. A statistically significant decrease (p less than 0.05) in intraocular pressure was noted at the end of the fourth stage and during 1, 5, and 10 min of recovery; however, no trend was found to indicate a significant correlation between heart rate and intraocular pressure.

Adolescent↗
PubMed1984

Intraocular pressure response to inversion.

Intraocular pressure (IOP) response to hanging completely head-down (inversion) was measured in 26 healthy young subjects. Systolic and diastolic blood pressure (BP) were also recorded. From the standing position, subjects were rotated 180 degrees and suspended by the ankles from a gravity inversion device. IOP and BP were measured in the standing position, immediately upon inverting, 3 min after inverting, immediately on return to the standing position and 3 min later. Subjects remained at rest during the test. Mean standing right eye IOP of 16.4 mm Hg and left eye IOP of 15.9 mm Hg increased to 34 and 31 mm Hg, respectively. Mean standing BP of 110/77 mm Hg increased to 130/90 mm Hg. Both IOP and BP remained elevated during inversion and decreased to near original values on return to the standing position. IOP significantly increases when the posture changes from standing to hanging completely head-down.

Adult↗
PubMed2006

Change in intraocular pressure within 1 week of phacoemulsification and intraocular lens implantation using Adatocel.

PURPOSE: To examine the change in intraocular pressure (IOP) within 1 week of phacoemulsification and foldable posterior chamber intraocular lens (PC IOL) implantation using Adatocel (hydroxypropyl methylcellulose 2% [HPMC]). SETTING: Department of Ophthalmology, University of Sciences, Faculty of Medicine, Pécs, Hungary. METHODS: In this prospective study, the IOP in 118 eyes of 118 patients (57 men, 61 women, mean age 68 years +/- 7.8 [SD]) with no history of glaucoma was assessed by Goldmann applanation tonometry 2 to 3, 6 to 8, and 22 to 24 hours and 1 week after uneventful phacoemulsification and PC IOL implantation. The effect of the removal of Adatocel ("partial removal" from the anterior chamber [AC] only versus "complete removal" from behind of the IOL as well), the lens type (Medicontur 601 HP versus Bausch & Lomb Hydroview), and the type of anesthesia (topical versus parabulbar) were compared. Statistical analysis was performed using the Student t test, and P< or =.05 was considered statistically significant. RESULTS: The mean preoperative IOP was 13.83 +/- 2.5 mmHg. There were no significant differences at any time in postoperative IOP measurements between the 2 IOL types and the 2 modes of anesthesia. At 2 to 3 hours, 6 to 8 hours, and 22 to 24 hours, the IOP was significantly higher in the 30 eyes in which the Adatocel was partially removed (from the AC only) than in the 88 eyes in which it was completely removed (from behind the PC IOL as well) (P< or =.05, P< or =.01, and P< or =.001, respectively). CONCLUSION: Severe postoperative IOP spikes in nonglaucomatous patients after uneventful phacoemulsification cataract surgery are rare. The type of implanted PC IOL and the mode of anesthesia had no significant effect on postoperative IOP. Total removal of the ophthalmic viscosurgical device, even when using HPMCs such as Adatocel, is necessary to prevent postoperative IOP spikes.

Adult↗
PubMed2003

Intraocular pressure in a Somali population living in the United States.

PURPOSE: Intraocular pressure is a risk factor for the development of glaucomatous optic neuropathy. With few exceptions, higher mean intraocular pressure and greater prevalences of glaucoma have been reported for individuals of African origin. This study was performed to compare the mean intraocular pressure of a group of ethnic East Africans living in the United States with that of Caucasians living in the same community. PATIENTS AND METHODS: Retrospective comparison of Somali patients 30 years of age or greater with age- and gender-matched Caucasian control subjects. All patients were seen in the same clinic in Seattle, Washington, between July 1996 and March 1998. Patients were excluded for conditions or medications affecting intraocular pressure and for a diagnosis of glaucoma. Mean intraocular pressure of the two populations was compared using an independent sample two-tailed t test. RESULTS: Following exclusions and defined age limits, 57 Somali patients and 57 Caucasian control subjects were included in the final analysis. Mean age of Somalis was 48.5 +/- 12.2 years versus 48.1 +/- 11.3 years for control subjects (P = 0.84). The mean intraocular pressure of Somalis was 13.76 +/- 3.63 mm Hg versus 13.94 +/- 2.78 mm Hg for control subjects (P = 0.77). CONCLUSION: Some populations of African origin may not have higher mean intraocular pressures compared with non-African populations. Consideration of ethnic and racial origins more specific than "African" should be given when evaluating intraocular pressure in individual patients.

Adult↗
PubMed2004

[Role of adenosine in intraocular pressure].

Adenosine is thought to participate in the regulation of intraocular pressure since adenosine and several adenosine derivatives increase and/or decrease intraocular pressure. This article reviews the involvement of adenosine receptors in the regulation of intraocular pressure and the possible application of relatively selective adenosine A(2)-receptor agonists, 2-alkynyladenosine derivatives (2-AAs), as novel drugs for treatment of glaucoma. We found that some 2-AAs decreased intraocular pressure in normotensive rabbits. Moreover, these 2-AAs are also effective in the ocular hypertensive models induced by water-loading and alpha-chymotrypsin. In addition, the ocular hypotension induced by 2-(1-octyn-1-yl) derivative was inhibited by an adenosine A(2)-receptor antagonist 3,7-dimethyl-1-propargylxanthine, but not by an adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropyl xanthine. Moreover, the outflow facility was increased by the 2-(1-octyn-1-yl) derivative. These findings suggest that 2-AAs may affect intraocular pressure via adenosine A(2)-receptor, and 2-AAs-induced ocular hypotension is due to the increase in outflow facility. Some 2-AAs may be novel drugs against ocular hypertension and/or glaucoma, although additional studies are required to characterize the effects of 2-AAs on regulation of intraocular pressure in detail.

Adenosine↗
PubMed1985

Comparison of the effects of Viscoat and Healon on postoperative intraocular pressure.

We compared the effects of Viscoat and Healon on postoperative increases in intraocular pressure in patients undergoing uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens implantation in a prospective, randomized, single-masked study. Eleven eyes received Viscoat and 13 received Healon. The Viscoat or Healon was aspirated from the anterior chamber with the irrigation-aspiration tip of an automated irrigation-aspiration system at the end of the procedure. No prophylactic intraoperative or postoperative ocular hypotensive agents were used. Intraocular pressure was measured at three, six, 12, and 24 hours postoperatively. Compared with preoperative intraocular pressure, postoperative intraocular pressure was significantly increased in both the Viscoat group and the Healon group. Some postoperative intraocular pressures were as high as 50 to 60 mm Hg, despite removal of the viscoelastic substance at the end of surgery. There was no significant difference in the postoperative intraocular pressures of the Viscoat group and the Healon group.

Aged↗
PubMed2003

Correlation between hand preference and intraocular pressure from right- and left-eyes in right- and left-handers.

To test whether there is a relationship between handedness and the intraocular pressure and there is a lateralization in the intraocular pressure, the intraocular pressures of the right- and left-eyes were compared in right- and left-handed students. The intraocular pressures were higher in the right-eye than in the left-eye in men, right-handers, and right-eyed subjects; there was no right-left difference in females, left-handers, left-eyed, and both-eyed subjects. The intraocular pressure of right- and left-eyes was higher in left-handers than right-handers. And there were significant negative correlations between hand preference and the intraocular pressure of both right- and left-eyes. We have concluded that the dominant eye has higher intraocular pressure compared to the nondominant one, and there is a relationship between hand preference and the intraocular pressure.

Adolescent↗