CHANGES IN INTRAOCULAR PRESSURE DURING HEMODIALYSIS.
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Target intraocular pressure in the management of glaucoma.
Achievement of target intraocular pressure is the goal of every efficient antiglaucoma therapy. Target intraocular pressure is the level of intraocular pressure which is associated with minimal likelihood of visual field or optic nerve lesion, or an existing lesion progression due to elevated intraocular pressure. Results of large clinical studies which have offered some new concepts on target intraocular pressure in the management of glaucoma are reviewed. An association between the curve of intraocular pressure decrease and glaucoma progression was demonstrated in these studies. Generally, a lower value of target intraocular pressure implies better protection from the loss of vision and visual field impairment in glaucoma patients. In advanced glaucoma, the greatest possible reduction from the initial intraocular pressure should be attempted. A 20% reduction from the initial intraocular pressure or decrease to < 18 mmHg in advanced glaucoma has been recognized as a favorable strategy to reach target intraocular pressure. In normal tension glaucoma, a lower value of target intraocular pressure is associated with a slower disease progression. In patients with initial glaucoma, 25% reduction from the initial intraocular pressure will slow down the disease progression by 45%. The value of target intraocular pressure depends on the pretreatment level of intraocular pressure, optic nerve condition, glaucoma disease state, rate of glaucoma progression, patient's age, and other risk factors for the development of glaucoma.
Disease Progression↗
Aqueous humor messengers in the transient decrease of intraocular pressure after ganglionectomy.
Intraocular pressure (IOP) decreases in rabbits 1 day after superior cervical ganglionectomy. It was hypothesized that this IOP decrease was caused by an accumulation of norepinephrine (NE) released from the iris-ciliary body into the aqueous humor during nerve degeneration. Direct measurement of aqueous humor NE concentration, however, was not successful because of the technical difficulty. In the current study, aqueous humor NE after superior cervical ganglionectomy was extracted and quantified using high-performance liquid chromatography-electrochemical detection. Twelve New Zealand albino rabbits were maintained in a daily 12-hr light-12-hr dark environment. Unilateral ganglionectomy was done on these rabbits during the light phase under halothane anesthesia. Twenty-two hours after the procedure, a significant IOP decrease occurred. The IOP was 16.1 +/- 0.6 mmHg (mean +/- the standard error of the mean) in the operated eye and 20.9 +/- 0.6 mmHg in the contralateral eye (P < 0.01). Aqueous humor NE concentration in the operated eye (475 +/- 81 pg/ml) was not different from that in the contralateral eye (469 +/- 58 pg/ml). However, the concentration of aqueous humor cyclic adenosine monophosphate (cAMP) in the operated eye (29.8 +/- 6.8 pmol/ml) was significantly higher (P < 0.05) than that in the contralateral eye (11.7 +/- 0.8 pmol/ml). These data indicate that aqueous humor NE per se does not cause the transient IOP decrease after superior cervical ganglionectomy and cAMP-mediated ocular activities may be involved in this change in IOP.
Animals↗
Effect of sodium thiopentone and midazolam on intraocular pressure, pulse rate and blood pressure--a comparative study.
A programmed study on the effect of sodium thiopentone and midazolam on systemic blood pressure, pulse rate and intraocular pressure was done on sixty patients. A significant increase of all parameters was found after one minute. These values became less increased after three minutes. After five minutes a significant decrease of systolic and diastolic pressure, and intraocular pressure, as well normalization of pulse rate was found for both groups. A comparison between the results of both groups show that the systolic pressure was more significantly increased under the effects of midazolam than thiopentone. In contrast to this, pulse rate and introcular pressure showed similar changes in both groups.
Adult↗
Intraocular pressure trends in pregnancy and in the third trimester hypertensive patients.
BACKGROUND: Systemic blood pressure is positively related to intraocular pressure. During the third trimester of pregnancy decreased intraocular pressure while increased blood pressure has been reported. After taking into account all those factors that can affect intraocular pressure, the present study investigated whether or not the high blood pressure found in late pregnancy influences the known ocular hypotensive effect of late pregnancy. SUBJECTS AND METHODS: Normotensive subjects in all trimesters of pregnancy and non-pregnant control groups along with third trimester hypertensive subjects were studied. Intraocular pressure was measured with the Goldmann applanation tonometer. RESULTS: In the second and third trimester subjects, the mean intraocular pressure was significantly lower than in the non-pregnant control group. The differences between first and second, first and third, and second and third trimesters of pregnancy were (mean +/- s.d.) -0.5 +/- 1.2 (p < 0.05), -1.5 +/- 1.7 (p < 0.001), and -1.0 +/- 2.1 (p < 0.01) mmHg respectively. The mean difference between third trimester hypertensive and third trimester normotensive pregnant women was 0.53 +/- 1.5 mmHg (p < 0.05). CONCLUSIONS: With advancing pregnancy, intraocular pressure decreases. The mean intraocular pressures of third trimester hypertensive pregnant women were significantly higher from that of third trimester non-hypertensives. Knowledge of the normal level of intraocular pressure in various stages of pregnancy may help glaucoma screeners.
Adult↗
The effect of intravenous diazepam on rise of intraocular pressure following succinylcholine.
Because succinylcholine raised intraocular pressure, its use to facilitate tracheal intubation for ocular surgery, especially in emergency open-eye cases, has been a controversial topic among anaesthetists for more than two decades. In recent years, intravenous diazepam pretreatment before succinylcholine has been reported to reduce the untoward side effects of myalgia, and elevation of serum potassium and creatine phosphokinase. This study was designed to assess the effect of pretreatment with intravenous diazepam 0.1 mg kg-1 on control (base-line) intraocular pressure and to determine if such pretreatment diminished the rise in intraocular pressure following the standard anaesthesia induction sequence of thiopentone 3 - 5 mg kg-1., followed by tracheal intubation. Such diazepam pretreatment was shown to reduce the intraocular pressure from control levels and to diminish the rise of intraocular pressure following succinylcholine and tracheal intubation. Because succinylcholine produces rapid onset of neuromuscular block for tracheal intubation and since only minor intraocular pressure elevation occurs following thiopentone and succinylcholine in patients pretreated with diazepam, its use in ocular surgery, including emergency open-eye cases, can be rationally advocated. The addition of 0.6 mg kg-1 d-tubocurarine to the diazepam pretreatment did not produce a further reduction of the increase of intraocular pressure following succinylcholine.
Adult↗
Intraretinal analysis of electroretinogram with K+ microelectrodes during acute intraocular pressure elevation.
We examined the effects of acute intraocular pressure elevation on the intraretinal electroretinogram in the cat dark-adapted eye. Perfusion pressure of the eye (mean arterial pressure minus intraocular pressure) was regulated within the range of 25-75 mm Hg by increasing the intraocular pressure, which was adjusted by changing the height of the reservoir of balanced salt solution perfused into the eye through a needle placed in the anterior chamber. The vitreal electroretinogram, transepithelial c-wave, slow PIII and light-evoked decrease in extracellular K+ concentration were recorded during intraocular pressure elevation in the dark-adapted retina. The c-wave increased in amplitude between 40 and 75 mm Hg of perfusion pressure and decreased below 40 mm Hg in some cases. These changes were unrelated to the standing potential. The transepithelial c-wave, slow PIII and light-evoked decrease in extracellular K+ concentration were larger in the range of perfusion pressure examined. These suggest that some factor induces electroretinographic changes that are not readily explained by hypoxia or pH changes alone.
Animals↗
Intraocular pressure and axial length in children.
The intraocular pressure and the anteroposterior length of the eye are of great clinical importance for the diagnosis and management, before and after surgery, of congenital glaucoma. It is well-known that normal intraocular pressure in children is different from the normal levels in adults. We performed measurements of intraocular pressure and axial length in 141 children who had been admitted for eye problems other than glaucoma. The intraocular pressures were measured with the Perkins hand-held applanation tonometer at the beginning of general anesthesia. Simultaneously, A-scan ultra-sound measurements of the axial lengths of the eyes were made. In 10 children under the age of two years, the intraocular pressure was 11.85 +/- 1.35 mmHg. In 79 children from two to seven years, the intraocular pressure was 12.80 +/- 1.73 mmHg. In 52 children from seven to 15 years, the intraocular pressure was 13.31 +/- 1.79 mmHg. The axial lengths of the eyes in children under the age of two years, from two to seven years, and from seven to 15 years, were 21.31 +/- 0.97 mm, 22.04 +/- 0.92 mm, and 23.22 +/- 1.00 mm, respectively. These results were considered to be guidelines for measuring intraocular pressure and axial length in children suspected of having congenital glaucoma. The differences of intraocular pressures stated by other authors are due to early measurement of the intraocular pressure at the beginning of general anesthesia.
Adolescent↗
[Circadian variations in intraocular pressure and their clinical implications].
Intraocular pressure follows a circadian rhythm like many of the body's parameters. These fluctuations in intraocular pressure were recently identified as a risk factor for visual field loss, in addition to intraocular pressure itself. Furthermore, the pressure curve seems to have a different profile in glaucomatous patients: the peak occurs later compared with normal subjects. Better knowledge of pressure fluctuations and their physiological mechanisms is essential for optimal management of glaucomatous patients not only to interpret the single ocular tension recordings, but also to use the available treatments rationally, both drugs and surgery. The authors review different studies that have contributed to the current knowledge on the circadian rhythm of intraocular pressure, aquous humor flow regulation, and the effects of topical hypotensive drugs on the pressure curve.
Adult↗
The effect of midazolam maleate and diazepam on intraocular pressure in adults.
The effect on intraocular pressure of induction of anesthesia with 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazol[1,5-a][1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum) as maleate or 7-chloro-1,3-dihydro-1-methyl-5-phenyl-(2H)-1,4-benzodiazepin-2-one (diazepam) has not previously been reported. We induced anesthesia in 30 patients, free of ophthalmologic disease and in good general health, with either midazolam maleate, diazepam or 5-ethyl-5-(1-methylbutyl)-2-thiobarbituric acid (thiopental). Ten patients were treated with each agent for induction. Intraocular pressure was measured with a hand-held Perkins applanation tonometer before induction, 1 and 3 min after induction, 1 min after succinylcholine, 1 mg/kg, and 1 min after tracheal intubation. A significant (p less than 0.001) decrease in intraocular pressure occurred after each induction agent both 1 and 3 min after induction. Also, after each agent, a significant rise in intraocular pressure compared with control occurred after succinylcholine and tracheal intubation. We conclude that midazolam maleate and diazepam reduce intraocular pressure to the same degree as thiopental and would be safe for procedures in which a fall in intraocular pressure is desirable; however, none of these drugs will protect against the rise in intraocular pressure seen following the administration of succinylcholine or tracheal intubation during a rapid sequence induction of general anesthesia.
Adult↗
Effect of inverted body position on intraocular pressure.
We evaluated changes in intraocular pressure in eyes with primary open-angle glaucoma after inversion into a totally dependent position with the head down and compared them with the changes intraocular pressure in healthy nonglaucomatous eyes. Five minutes after inversion, intraocular pressure increased from 16.8 mm Hg +/- 2.8 (sitting) to 32.9 mm Hg +/- 7.9 in normal eyes and from 21.3 mm Hg +/- 2.3 (sitting) to 37.6 mm Hg +/- 5.0 in glaucomatous eyes. Although visual fields were unchanged after inversion, glaucomatous eyes may be particularly susceptible to such changes and unable to withstand the transient but significant increase in intraocular pressure that occurs after assuming an inverted position. We recommend that patients with ocular hypertension or glaucoma refrain from this activity.
Adult↗
Intraocular pressure after optic nerve transection.
Intraocular pressure response to systemically administered osmotic agents was studied in albino rabbits with one optic nerve transected and the fellow optic nerve left intact. There eas a significant increase in intraocular pressure of both eyes following water ingestion but no significant difference in the pressure rise of the two eyes. There was a significant decrease in intraocular pressure of both eyes following glycerol ingestion but no significant difference in the pressure fall of two eyes. These results do not support the hypothesis that the optic nerve carries fibers which are part of the control system for intraocular pressure.
Animals↗
Effects of opiates and opioids on intraocular pressure of rabbits and humans.
Acute intraocular injection of morphine or D-Ala-met-enkephalinamide (D-Ala-E) in rabbits caused a sustained decrease in intraocular pressure. Conjunctival instillation of naloxone solution prevented the lowering effect of morphine or D-Ala-E on intraocular pressure. Aqueous outflow facility appeared to be significantly higher in patients addicted to morphine or heroin than in healthy volunteers. Intraocular pressure was significantly lower in addicted patients than in control subjects. Conjunctival instillation of naloxone solution decreased aqueous outflow facility and increased intraocular pressure in addicted patients. Patients with chronic open angle glaucoma showed a significant decrease in intraocular pressure after conjunctival instillation of morphine solution. It is concluded that intraocular opiate receptors are involved in the regulation of intraocular pressure in animals and humans.
Adult↗
Comparative effects of laryngeal mask airway and endotracheal tube insertion on intraocular pressure in children.
Intraocular pressure (IOP) measurements in children are frequently performed under halothane-nitrous oxide anesthesia; however, anesthesia face masks may limit access to the eyes, and tracheal intubation is associated with transient increases in IOP. Use of the laryngeal mask airway (LMA) permits the maintenance of a patent airway without the need for laryngoscopy and tracheal intubation. In a randomized study of 41 children, we compared the IOP, hemoglobin oxygen saturation, and hemodynamic responses to the insertion of an LMA or tracheal tube during a standardized steady-state anesthetic technique consisting of 1 MAC halothane and 66% nitrous oxide. Baseline measurements of IOP, hemoglobin oxygen saturation, heart rate, and arterial blood pressure were recorded and repeated within 15-30 s after insertion of the airway device and at 1-min intervals for 5 min. Insertion of the LMA required significantly less time (26 +/- 16 vs 39 +/- 17 s [mean +/- SD]) and was associated with higher hemoglobin oxygen saturation values compared with the tracheal intubation. The LMA did not increase IOP, heart rate, or arterial blood pressure above baseline values. In contrast, tracheal intubation was associated with significant increases of IOP, heart rate, and arterial blood pressure. We concluded that the laryngeal mask offers advantages over tracheal intubation and the face mask for airway management in patients undergoing IOP measurements.
Anesthesia↗
On the short-term variability of measurements of intraocular pressure.
Measurement of intraocular pressure (IOP) (tonometry) is conducted routinely in the eye clinic for the diagnosis and management of primary open-angle glaucoma. Mean IOP may be influenced by a number of factors including ocular accommodation, spontaneous pulsations of IOP, and the effect of repeated applanation. A review of some of the factors that influence IOP should help us gain a perspective on the reliability of diurnal tonometry in the diagnosis of primary open-angle glaucoma.
Accommodation, Ocular↗
M-7 lowers rabbit intraocular pressure.
Changes in intraocular pressure (IOP) and pupil diameter were studied in albino rabbits following topical administration of TL-99, M-7 (N,N-dimethyl analogues of 2-aminotetralin), DiPr-5,6-ADTN, DiPr-6,7-ADTN (dipropyl analogues of aminotetralin) and DPDA (N,N-di-n-propyl-dopamine), known as mixed alpha-adrenoceptor/dopamine receptor agonists with variable alpha 1/alpha 2-adrenoceptor/selectivity. The potencies of those compounds to decrease IOP were compared with each other. We found that M-7 has the most potent IOP-lowering properties, caused minimal ocular discomfort and is of interest as a potential antiglaucoma agent. The ocular hypotension was completely inhibited by rauwolscine and slightly antagonized by various other blocking agents. The results strongly suggest that the IOP-lowering effect of M-7 is mediated by the stimulation of alpha 2-adrenoceptors.
Animals↗
[Clinical approach to normal intraocular pressure glaucoma].
Normal intraocular pressure (IOP) glaucoma is a clinical condition characterized by pathologic optic nerve excavation and visual field impairment, defined as optic neuropathy with certain features of a disease known as glaucoma. Glaucomatous optic nerve lesion is characterized by optic disk excavation or depression, however, this feature may greatly vary. The level of IOP is considered only one of the multiple risk factors involved in the disease development. In normal IOP glaucoma, papillary lesions and visual field impairments may differ from those occurring in primary open-angle glaucoma. In modern ophthalmology, the terminology has been modified, so the term low IOP glaucoma has been replaced by the term normal IOP glaucoma. It is now believed that various factors play a role in the development of glaucomatous optic neuropathy in normal IOP glaucoma and show variable interference depending on IOP level. Additional studies are needed to define these interactions and their impact on the mechanism of glaucomatous excavation. This will hopefully pave the way to new therapeutic approaches and help in clinical decisions concerning the prognosis and treatment of individual patients.
Glaucoma↗
Effects of intracameral injection of viscoelastic solutions on intraocular pressure in dogs.
Intraocular pressure (IOP) was determined in right eyes of 20 healthy dogs after sodium hyaluronate (1%, n = 5), sodium chondroitin sulfate (4%) and sodium hyaluronate (3%, n = 5), hydroxypropyl methylcellulose (2%, n = 5), or balanced salt solution (control, n = 5) was injected into the anterior chamber. Applanation tonometry was used to measure IOP in both eyes of each dog for up to 168 hours. The 3 viscoelastic solutions resulted in an increased mean IOP by postinjection hours (PIH) 2; from PIH 12 until PIH 72, the IOP was significantly (P less than 0.001) lower than baseline. The control group did not have an increase in IOP at PIH 2; mean IOP decreased below baseline measurements within 2 hours and remained lower until PIH 72. Mean differences in IOP were not found among treated eyes (P = 0.50), and a significant interaction of any treated eyes in a group was not detected (P = 0.21). By PIH 168, the IOP approached baseline values in all groups.
Analysis of Variance↗