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PubMed1980

[Anaesthesia and intraocular pressure (author's transl)].

Almost every modern anaesthetic has an impact on the complex physiology of the intraocular pressure. The different factors influencing the intraocular pressure are discussed. With the exception of succinylcholine and ketamine all other substances used in modern anaesthesia produce a more or less significant reduction of the intraocular pressure. Hence, the anaesthesiologist disposes in general of a great variety of drugs to conduct an anaesthesia that is well adapted to the physiological requirements of the eye. Yet, he may still encounter some difficulties in emergency-situations, like a perforating eye trauma in a patient with a full stomach. Fazadinium may be a usefull alternative to succinylcholine in these situations, as its rapid onset of action is not accompanied by a rise in the intraocular pressure. Some other measures to reduce the intraocular pressure intraoperatively are also mentioned, like controlled hypotension, osmotic diuresis and inhibition of the carbonic anhydrase.

Anesthesia, General↗

PubMed2002

[Evaluation of ophthalmic visicoelastic devices in rabbit penetrating keratoplasty--the protective effect for corneal endothelial cells after autokeratoplasty and the effect of intraocular pressure after aqueous exchange].

PURPOSE: To investigate the effect of sodium hyaluronate molecular weight on corneal endothelial cells and intraocular pressure after penetrating keratoplasty in rabbits. MATERIAL AND METHOD: Rotating autokeratoplasty was carried out on rabbits using six groups of sodium hyaluronate in which the molecular weight differed. Then the endothelial cell density, hexagonal cell rate, corneal thickness, and intraocular pressure were measured. The intraocular pressure in the rabbit eyes after aqueous exchange with six groups of sodium hyaluronate was also measured. RESULTS: The endothelial cell density and hexagonal cell rate in the hyaluronate group of molecular weight 1.53-2.13 million and 1.9-3.9 million were the same as in the eye groups receiving no manipulation. As for the intraocular pressure after aqueous exchange, the highest intraocular pressure was more than 40 mmHg in the group treated with hyaluronate over 1.9 million and the group treated with hyaluronate and chondroitin sulfate compounding agent. CONCLUSION: Endothelial protection was considered to be superior when hyaluronate with a molecular weight of 1.5-3.9 million was used in rabbits. However, it is grossible that leaving a large amount of hyaluronate with a molecular weight over 1.9 million in the eye may lead to a remarkable increase in the early postoperative intraocular pressure.

Animals↗

PubMed1999

Responses of intraocular pressure and the pupil of feline eyes to prostaglandin EP1 and FP receptor agonists.

PURPOSE: Previous studies suggested that FP receptors do not mediate the relaxation of the ciliary muscle and reduction of intraocular pressure in cats by prostaglandin (PG) F2alpha. The present study was undertaken to determine whether the reduction of intraocular pressure in cats induced by PGF2alpha is mediated by FP or other prostaglandin receptors. METHODS: One eye of each cat was treated topically with prostaglandin F2alpha, fluprostenol (FP receptor agonist), or 17-phenyl trinor PGE2 (EP1 receptor agonist) in a dose range of 12.5 to 50 microg. The effects of SC19220 and SC51089 (EP1 receptor antagonists), BWA868c, and SQ29548 (DP and TP receptor antagonists, respectively) on the intraocular response to PGF2alpha were also examined. At intervals up to 6 hours after treatment, intraocular pressure was measured with a pneumotonometer, and pupil diameters were measured with a millimeter ruler. RESULTS: In the dose ranges used, PGF2alpha and 17-phenyl trinor PGE2 decreased intraocular pressure and pupil diameter. The greatest reduction of intraocular pressure by 50.0 microg PGF2alpha was 5.0+/-1.4 mm Hg, whereas that by 50 microg 17-phenyl trinor PGE2 was 6.2+/-1.5 mm Hg. The isopropyl ester of PGF 2alpha at a dose of 1.25 microg reduced intraocular pressure by 3.75+/-0.25 mm Hg at 2 hours. At doses up to 100 microg, fluprostenol did not decrease intraocular pressure but did reduce pupil diameter. SC19220, a weak but selective EP1 receptor antagonist, inhibited the intraocular pressure response to both PGF2alpha and 17-phenyl trinor PGE2. The more potent EP1 receptor antagonist SC51089 had a greater inhibitory effect than SC19220 on the intraocular pressure response to PGF2alpha. Both of these antagonists had a small but non-dose dependent and statistically insignificant effect on the pupil response to PGF2alpha. These observations suggest that in cats, intraocular pressure and pupil responses to PGF2alpha, are mediated by EP1 and FP receptors, respectively. However, SC19220 significantly and dose-dependently inhibited the pupil response to 17-phenyl trinor PGE2alpha suggesting that EP1 receptors mediate pupil response to this agonist. DP and TP receptor antagonists at doses 5- to 20-fold greater than the IC50 values had no effect on the ocular hypotensive response to PGF2alpha. The concurrent administration of 12.5 microg of each of PGF2alpha and 17-phenyl trinor PGE2 did not produce an additive effect on intraocular pressure, indicating that in cats PGF2alpha and 17-phenyl trinor PGE2 act on the same receptor type. CONCLUSIONS: These results suggest that a significant proportion of the ocular hypotensive action of PGF2alpha in cats is mediated by EP1 but not by FP receptor. Evidence was also provided to show that 17-phenyl trinor PGE2 is an ocular hypotensive agent in cats.

Animals↗

PubMed1991

Chronic reversal of hemifield loss after intraocular pressure lowering in advanced glaucoma.

Lowering intraocular pressure in two cases of severe glaucoma was associated with a chronic reversal of hemifield loss, as documented by automated threshold perimetry. In the first case, a small central 10 degrees island of vision expanded to 40 degrees in both hemifields eight months after intraocular pressure lowering by filtration surgery. The mean deviation of the central 30 degrees field improved by more than 14dB or 1.4 log units. To our knowledge, this case represents the greatest degree of reversal of chronic visual field loss reported in the literature. In the second case, a small central 10 degrees island of vision slowly expanded to 40 degrees in the inferior hemifield over a three-year period.

Chronic Disease↗

PubMed1984

Diurnal and seasonal variations in intraocular pressure in the rabbit.

The diurnal variations in intraocular pressure in the rabbit were measured during a period of 12 months in a cross-sectional study. The average intraocular pressure of all the measurements taken during the year was 19.6 +/- 2.0 mmHg (mean +/- S.D.; n = 1957). The daily curve showed a continuous rise during the day from 18.2 +/- 1.7 mmHg (n = 175) at 0800 hr to 20.6 +/- 1.8 mmHg (n = 167) at 1700 hr. During the month of June, when the measurements were extended until midnight, this rise in intraocular pressure continued until 2200 hr, reached a level of 22.5 +/- 1.6 (n = 16), and started to decline. A similar daily pattern was observed throughout the year. The annual curve showed two peaks, during the summer and winter seasons, with a daily average of 20.2 +/- 2.1 (n = 404) and 20.2 +/- 2.0 (n = 638) respectively. The lowest average daily IOP value was obtained during the spring and was 18.8 +/- 2.0 (n = 509). An intermediate level between the summer/winter and the spring values was obtained during the autumn and was 19.4 +/- 1.7 (n = 406).

Animals↗

PubMed1981

Argon laser treatment of the anterior chamber angle for increased intraocular pressure.

Sixty-five eyes of 63 patients with increased intraocular pressure which was resistant to medical therapy were treated with argon laser and were then followed up for 3-12 months. From 70 to 110 burns were directed from 360 degrees around the chamber angle into or immediately posterior to the pigmented trabecular band. The power settings used were 1200-2200 mW, exposure time 0.1 seconds and beam diameter 50 microns. There was exfoliation syndrome in 35 eyes. Post-laser control of the intraocular pressure was achieved in 31 of these eyes. The average decrease in intraocular pressure was about 40%. Thirty eyes were without exfoliation syndrome. Twenty-six were controlled post-laser. The average intraocular pressure decreased by about 35%. The outflow measured tonographically improved in both groups. The final pressure drop did not emerge in some of the patients until several weeks after the laser therapy. The treatment caused no essential complications.

Adult↗

PubMed1996

Continuous measurement of intraocular pressure in rabbits by telemetry.

PURPOSE: Intraocular pressure (IOP) is dynamic and can be influenced by the use of tonometers. The authors developed a technique to implant a telemetric pressure transducer to measure IOP continuously in unrestrained rabbits. METHODS: A commercial telemetric pressure transducer was implanted subcutaneously on the dorsal neck, between the scapulae, of pigmented rabbits. A fluid-filled catheter that conducts pressure to the transducer was routed to the orbit subcutaneously and implanted in the anterior chamber through a limbal opening. The transducer measured pressure and broadcast this information by amplitude modulation radio to a receiver in the animal's cage. Data were recorded at a rate of 50 or 100 samples per second for 60 seconds to study transient changes in IOP to tonometry, or for 15 seconds every 2.5 minutes to study circadian behavior of IOP. RESULTS: Intraocular pressure was recorded from seven rabbits for 180 to 370 days. Within 3 to 8 days of implant surgery, IOP began to follow a circadian rhythm: IOP decreased after room lights were turned on at 00:00 CT and increased after they were turned off at 12:00 CT. (The term CT refers to circadian time and begins at 00:00 CT when lights are turned on.) The maximum difference in IOP between light and dark phases ranged from 6.4 mm Hg to 16.6 mm Hg. When the lighting cycle was advanced by 6 hours, the time of nocturnal rise in IOP also advanced, but it did so gradually over 10 to 14 days. CONCLUSIONS: The implanted pressure transducer provides a convenient, preinvasive method to measure and study IOP in unrestrained experimental animals. This technique will be used to study circadian variations in IOP, the effects of environmental stimuli, and the oculohypotensive effects of therapeutic agents.

Animals↗

PubMed1980

The effect of H1-blocking antihistamines on intraocular pressure in rabbits.

H1-blocking antihistamines were administered topically to rabbits to determine their effects on intraocular pressure. Chlorcyclizine which is in the piperazine class of H1-inhibitors was found to elevate intraocular pressure. This effect was prevented by the systemic administration of indomethacin and is probably a prostaglandin induced change. Of the other agents tested, antazoline which is in the ethylenediamine class, was the only drug found to lower intraocular pressure. The antazoline-induced lowering of intraocular pressure was associated with no changes in outflow facility, episcleral venous pressure, systemic blood pressure, or ocular blood flow. Tonographic and aqueous humor ascorbate humor ascorbate data suggested a decreased (41% and 33% respectively) rate of aqueous flow as the mechanism for the decrease in intraocular pressure. The systemic administration of the alpha-adrenergic blocker phentolamine prevented the decrease in intraocular pressure but systemically administered blockers of cholinergic (atropine) or beta-adrenergic (propranolol) activity had no effect.

Animals↗

PubMed1989

Effects of carbachol and acetylcholine on intraocular pressure after cataract extraction.

We compared the effect of carbachol and acetylcholine on intraocular pressure 24 hours after extracapsular cataract extraction. All agents were administered intracamerally at the time of surgery. Sixty patients scheduled for routine extracapsular cataract extraction and intraocular lens implantation were randomly assigned into one of three treatment groups: (1) carbachol, (2) acetylcholine, or (3) 0.5% balanced salt solution (placebo). Baseline intraocular pressures were determined the day before surgery, and postoperative pressures were measured approximately 24 hours after surgery. The group intraocular pressures averaged over preoperative and postoperative values were 21.06 mm Hg in the acetylcholine group, 19.36 mm Hg in the control group, and 17.30 mm Hg in the carbachol group. The average difference between preoperative and postoperative intraocular pressure measurements for the three groups were 7.33 mm Hg for the acetylcholine group, 8.73 mm Hg for the control group, and 2.20 mm Hg for the carbachol group. Only carbachol was significantly different from placebo on statistical subsequent testing. Carbachol is suggested as the agent of choice both for achieving intrasurgical miosis and prophylaxis of increasing intraocular pressure after cataract surgery.

Acetylcholine↗

PubMed1985

Influence of picosecond and nanosecond YAG laser capsulotomy on intraocular pressure.

To evaluate laser-induced intraocular pressure rise with three YAG lasers, I performed posterior capsulotomies on three groups of patients. Each group contained 100 nonglaucomatous patients who had extracapsular cataract extraction with and without lens implantation. In each group 50 patients were treated with prophylactic medications. The three YAG lasers were (1) a picosecond TEMoo, mode locked, ten-degree cone angle; (2) a nanosecond TEMoo, Q-switched, 16-degree cone angle, delivering the energy in five nanoseconds per pulse; and (3) a Q-switched, 15-degree cone angle, closer to multimode than TEMoo, delivering energy in 14 nanoseconds seconds per pulse. The energy delivered per pulse, the thickness of the lens material, the shape (mode) of the pulse, the optical delivery system, and the width of the shock wave appear to act on intraocular pressure and to be factors influencing the possibility of marking the lens.

Adolescent↗

PubMed2003

Open-angle glaucoma: variations in the intraocular pressure after visual field examination.

PURPOSE: To evaluate intraocular pressure (IOP) variations after automated visual field examination in patients with primary open-angle glaucoma and in healthy subjects. PATIENTS AND METHODS: Intraocular pressure was measured in 49 patients (94 eyes) with primary open-angle glaucoma and in 13 healthy subjects (26 eyes) before and immediately after automated visual field examination. All patients had stable IOP and were using local medication to treat glaucoma. The visual field test was performed with a Humphrey 630 VF analyzer and the Central 30-2 full-threshold program. RESULTS: Mean IOP increased significantly in glaucomatous patients immediately after automated visual field examination (P < 0.01), and returned to pretest values after 1 hour (P = 0.2). Mean IOP variation was 2.38 (range, -6-11) mm Hg. In 42 (44.68%) glaucomatous eyes, IOP increased more than 2 mm Hg, with a mean increase of 5.5 mm Hg. Elderly glaucoma patients showed a significantly higher IOP rise than younger patients. No significant IOP variation was detected in healthy subjects. CONCLUSION: Intraocular pressure varied significantly and tended to increase immediately after automated visual field examination in patients with primary open-angle glaucoma. Age seemed to contribute to these IOP changes, but other factors could be involved.

Adult↗

PubMed1995

Enzymatic histochemistry of retina with experimental intraocular pressure elevation in rabbits.

To investigate the pathogenesis of retina lesions caused by intraocular pressure elevation, activities and distribution of enzymes in retina including lactic dehydrogenase (LDH), succinate dehydrogenase (SDH), adenosinetriphosphatase (AT-Pase), acid phosphatase (ACP), cholinesterase (ChE), cytochrome oxidase (CCO), nucleotidase (5'-Nase) and glucose-6-phosphatase (G6Pase) were determined histochemically in 30 rabbits. It was found that 1) in the early stage of intraocular pressure elevation, the activities of LDH, SDH, ATPase, ACP, and ChE in retina were increased, while the activities of CCO, 5'-Nase decreased; 2) in the late stage of intraocular pressure elevation, the activities of all these enzymes but ACP, which showed a reduced activity, were close to the normal level; 3) in superoxide dismutase.(SOD-CCE) treated group, except the slight increase of LDH and G6Pase activities, the activities of the remaining enzymes were near to normal. Our results suggest that the various histochemical changes in retina induced by intraocular pressure elevation were compensatory in the early stage and were beneficial to the supply of energy needed in retinal tissue and cellular metabolism; while in the late stage, the lesion of retina cells developed due to decompensation. SOD-CCE could alleviate the retinal lesions caused by intraocular pressure elevation, and can be used as auxiliary drug for the treatment of intraocular pressure elevation.

Animals↗

PubMed1978

Application of intraocular pressure reduction and regulation system.

In some patients undergoing intraocular procedures, the intraocular pressure may remain dangerously high immediately before surgical penetration of the anterior chamber despite all available measures. A mechanical device, called an "Intraocular Pressure Reduction and Regulation System," has been devised as a means of reducing and regulating intraocular pressure immediately before and during intraocular procedures. The system has been used in selected glaucoma patients with satisfactory results.

Adult↗

PubMed1997

Intraocular pressure and pregnancy: a comparison between normal and ocular hypertensive subjects.

Decrease in intraocular pressure (IOP) during pregnancy has been reported by previous studies, but these studies have concentrated on the last trimester of pregnancy or one reading per trimester. Moreover, IOP changes during pregnancy in ocular hypertensive subjects have never been described. Therefore, the present study was planned to determine IOP throughout the pregnancy, in both normal and ocular hypertensive subjects. Intraocular pressure was measured at six-week intervals throughout the pregnancy in 44 normal and 32 ocular hypertensive women. Intraocular pressure was also measured in 44 normal and 32 ocular hypertensive non-pregnant controls of the same age group. IOP measurements were taken with the Goldmann applanation tonometer. In normal subjects, IOP decreased significantly at the 18th week (p < 0.05). The IOP differences between first and second (p < 0.05) and second and third (p < 0.01) trimesters of pregnancy were significant. In these subjects, pregnancy decreased IOP by 19.6%. About 35% of total decrease occurred between 12th and 18th weeks of pregnancy. In ocular hypertensive subjects, IOP decreased significantly at the 24th week (p < 0.05). The IOP differences between second and third (p < 0.001) trimesters of pregnancy were significant. In these subjects, pregnancy decreased IOP by 24.4%. About 61% of total decrease occurred between 24th and 30th weeks of pregnancy. In both groups, decreases in IOP were independent of systolic and diastolic blood pressures, body weight, height, and number of previous pregnancies. With advancing pregnancy, intraocular pressure decreases. The higher decrease in ocular hypertensive subjects may be due to their higher level of ocular pressure. In ocular hypertensive subjects, pregnancy can decrease intraocular pressure up to a level of normal limit.

Adult↗

PubMed2002

Unilateral nostril breathing in intraocular pressure of right-handed healthy subjects.

The effects of unilateral forced nostril breathing on the intraocular pressures of right and left eyes was studied in 24 male and 26 female right-handed adults. In men, the forced breathing through both the right and left nostrils significantly decreased the intraocular pressures of both right and left eyes. For women, the forced breathing through right nostril did not affect the intraocular pressures of right and left eyes, and the forced breathing through left nostril also had no effect on the intraocular pressure of right eye, although it decreased the intraocular pressure of left eye significantly. These results show that unilateral forced nostril breathing decreases intraocular pressure especially in men, perhaps increasing sympathetic nervous system activity.

Adult↗

PubMed2005

[Intraocular pressure difference in Goldmann applanation tonometry versus a transpalpebral tonometer TGDc-01"PRA" in glaucoma patients].

PURPOSE: The object of this study was to compare intraocular pressure measurements obtained with the TGDc-01"PRA", a new, transpalpebral indentation tonometer, with those from Goldmann applanation tonometry in normal and glaucomatous eyes. METHODS AND PATIENTS: Forty healthy eyes and 185 eyes suffering from glaucoma were included in the study. For Goldmann tonometry three measurements and for the TGDc-01 ten measurements were performed in a random order. All participants were placed in an upright position for all measurements. RESULTS: In both groups a systematic increase of intraocular pressure was found within the TGDc-01-measurements. Therefore, the first 3 measurements of each device were used for further statistical analysis. No learning curve could be demonstrated for the TGDc-01-measurement with normal eyes. Within the group of normal eyes the mean IOD obtained with the TGDc-01 was 1.84 mmHg lower than the mean IOD obtained with Goldmann tonometry (two-sided Student's t-test; P = 0.003). In the group of glaucomatous eyes, the mean intraocular pressure obtained with the Goldmann tonometry was 19.7 +/- 10.1 mmHg, with the TGDC-01 18.1 +/- 7.1 mmHg (coefficient of correlation r = 0.64, P < 0.001). The mean standard deviation of intraocular pressure measurements with Goldmann tonometry was 1.2 +/- 0.9 mmHg, with the TGDc-01 3.1 +/- 2.1 mmHg. TGDc-01-measurements overestimated intraocular pressure compared to Goldmann tonometry up to values of 16 mmHg and underestimated intraocular pressure at values over 16 mmHg. The difference increased by 5.5 mmHg per 10 mmHg Goldmann tonometry. The probability of success, defined as TGDc-01-recordings within +/- 3 mmHg of the Goldmann tonometry recordings, was less than 53 % between 5 and 20 mmHg and less than 30 % between 20 and 30 mmHg. Intraocular pressure (Goldmann tonometry) over 30 mmHg was always accompanied by TGDc-01-measurements lower than 3 mmHg. CONCLUSION: In eyes with elevated intraocular pressure, the TGDc-01"PRA" significantly underestimated the intraocular pressure measurement when compared to the gold standard, Goldmann tonometry. At present, measurement of the intraocular pressure with the TGDc-01 should not be used for clinical management of patients with glaucoma.

Adult↗

PubMed2002

Reproducibility and agreement between three methods of intraocular pressure measurement.

OBJECTIVE: The aim of the present study was to establish reproducibility between consecutive intraocular pressure measurements using the same method of tonometry as well as to assess agreement between 3 different methods of tonometry. MATERIALS AND METHODS: The study included 55 patients. Intraocular pressure of 94 eyes was measured, using Goldman applanation tonometry, Maklakoff applanation tonometry and indentation tonometry according to Schioetz method. The mean values and the differences in intraocular pressure measurements were calculated (using Bland and Altman method) in order to assess agreement between Goldman and Maklakoff applanation tonometry and Goldman and Schioetz tonometry. Reproducibility of the methods was assessed based on three consecutive intraocular pressure measurements on three groups of 20 eyes at 5-minute intervals. RESULTS: The mean intraocular pressure (Po) measured by Goldman method was 23.26 +/- 0.78 mmHg, the mean pressure estimates (Po) according to Maklakoff method were 19.4 +/- 0.64 mmHg and it (Po) was 21.18 +/- 0.74 mmHg using Schioetz tonometry. The correlation (Pearson) between Goldman Po and Maklakoff Po was 0.74 and between Goldman and Schioetz Po - 0.93. Mean differences were 4.12 +/- 0.53 and 2.08 +/- 0.3 mmHg respectively. Variation coefficients between consecutive measurements were: for Goldman tonometry - 2.00%, for Maklakoff - 7.90% and for Schioetz - 5.72%. CONCLUSIONS: According to Bland and Altman method there is low agreement between intraocular pressure estimates obtained by Goldman and Maklakoff tonometry, i.e. these methods are not interchangeable. This fact might be explained by the high variation coefficient of Maklakoff method. The low variation coefficient of Goldman tonometry makes it the most accurate of the three methods.

Humans↗

PubMed1978

[The influence of changes in body position on intraocular pressure, episcleral venous pressure, and blood pressure (author's transl)].

The intraocular pressure, the ophthalmic artery pressure, and the episcleral venous pressure increased after changes from sitting to recumbent body position, whereas the subclavian artery pressure remained unchanged or decreased slightly. Changing from recumbent to sitting position was followed by a decrease in IOP, ophthalmic pressure, and subclavian artery pressure. Comparing the last measurement in the first position to the first value after change, it was found that the IOP alters by about 20%, the ophthalmic artery pressure by 15%, and the episcleral venous pressure by 50%. In all series a decrease in subclavian artery pressure was observed during the first 15 min. The mean pressure in the ophthalmic artery diminished in the series that changed from sitting to recumbent position, whereas it increased in the other series during the first 15 min. The episcleral venous pressure increased more than the corresponding IOP after changing to the recumbent position.

Blood Pressure↗