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Results for “INTRAOCULAR PRESSURE”

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PubMed1982

[Variations of intraocular pressure during valsalva's maneuver in relation to body position and length of the bulbus in myopia (author's transl)].

Intraocular pressure was measured in 49 persons of either sex while carrying out Valsalva's maneuver in erect and recumbent position. 16 of the tested persons had myopia up to -8.0 D. The average intraocular pressure in recumbent position was 2 mm Hg higher when compared to the erect position. During Valsalva's maneuver the intraocular pressure was elevated in erect as well as in recumbent position. Three characteristic patterns of variation of intraocular pressure were seen after cessation of Valsalva's maneuver. The intraocular pressure in myopic persons was slightly higher than in those with emmetropia.

Adolescent↗

PubMed2004

Effects of 2-alkynyladenosine derivatives on intraocular pressure in rabbits.

We evaluated the activities of 2-alkynyladenosine derivatives, relatively selective adenosine A2 receptor agonists, in the intraocular pressure regulation in rabbits. An adenosine A2 receptor agonist 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680) decreased intraocular pressure, while another A2 receptor agonist 2-(phenylamino)adenosine transiently increased it. The first group of 2-alkynyladenosine derivatives (1-hexyn-1-yl derivatives) caused a transient increase followed by decrease in intraocular pressure, while the second group (1-octyn-1-yl and 6-cyano-1-hexyn-1-yl derivatives) only decreased it. The second group is also effective in the ocular hypertensive models induced by water-loading and alpha-chymotrypsin. The outflow facility was increased by a 1-octyn-1-yl derivative. Both increase and decrease in intraocular pressure induced by 2-alkynyladenosine derivatives were inhibited by an adenosine A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine, but not by an adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropyl xanthine. These findings suggest that 2-alkynyladenosine derivatives may affect intraocular pressure via adenosine A2 receptor, and 2-alkynyladenosine derivative-induced ocular hypotension is due to the increase of outflow facility.

Adenosine↗

PubMedDate not supplied

Development of a completely encapsulated intraocular pressure sensor.

A completely encapsulated intraocular pressure (IOP) sensor equipped with telemetric signal and energy transfer is introduced integrated into a silicone disc for implantation into the eye. After implantation into enucleated pig eyes and into rabbit eyes in vivo, the IOP was recorded and compared to established techniques of IOP measurement. Pressure chamber tests showed that the sensor functioned correctly after biocompatible encapsulation in polydimethylsiloxane. In vivo and in vitro tests in rabbit and pig eyes demonstrated that the implanted system worked with the same precision as established techniques for IOP determination. The correlation between the measurements with the implanted device and pneumotonometry in several experiments was between 0.9 and 0.99. This device serves as a functioning model for the realization of a telemetric IOP sensor for integration into an artificial intraocular lens. Such a device will open new perspectives, not only in the management of glaucoma, but also in basic research for mechanisms of glaucoma.

Animals↗

PubMed1981

The relationship between body temperature and intraocular pressure.

A comparison of the intraocular pressures of well-hydrated nonacclimatized and acclimatized subjects during submaximal work load in a hot environment was made. This comparison attempts to eliminate all possible influences on IOP, except body temperature. A direct relationship between the IOP and rectal temperature is postulated.

Acclimatization↗

PubMed2005

Discontinuing nasal steroids might lower intraocular pressure in glaucoma.

BACKGROUND: Topical, intraocular, oral, and parenteral steroids might increase intraocular pressure (IOP), but little is known regarding the effect of nasal steroid spray. OBJECTIVE: We sought to examine the effect of discontinuing nasal steroid sprays on IOP in patients with glaucoma. METHODS: A retrospective chart review of patients with glaucoma using nasal steroids was performed. Averaged IOP for each pair of eyes was determined for presteroid use, steroid use, and 2 consecutive poststeroid use (poststeroid 1 and poststeroid 2) examinations. RESULTS: Twenty-four eyes of 12 patients taking nasal steroids were identified. The mean IOP for each pair of eyes was 15.4 +/- 4.3 mm Hg (range, 9-23.5 mm Hg) for the presteroid use examination, 18.0 +/- 3.8 mm Hg (range, 12-24.5 mm Hg) for the steroid use examination, 14.5 +/- 3.3 mm Hg (range, 9.5-20 mm Hg) for poststeroid use examination 1, and 14.8 +/- 3.4 mm Hg (range, 95-22.0 mm Hg) for poststeroid use examination 2. Eleven patients experienced decreased averaged IOP at poststeroid use examination 1 after steroid discontinuation at a mean of 35 +/- 14 days and continued to maintain this decrease on the poststeroid use examination 2 visit at a mean of 191 +/- 150 days. A significant increase between presteroid and steroid use examination IOPs (P = .007) and a significant decrease between steroid use and both poststeroid use 1 (P < .001) and poststeroid use 2 (P = .011) examination IOPs were observed. No significant difference between presteroid use and either poststeroid use examination IOPs (P = 1.00) was found. Many patients met their target pressures and were able to avoid or delay additional glaucoma therapy. CONCLUSION: A significant reduction in IOP occurred with nasal steroid discontinuation in patients with glaucoma. Nasal steroids might contribute to IOP increase, and inquiry as to whether a patient has glaucoma before medication initiation is warranted.

Administration, Intranasal↗

PubMed1999

[The optic nerve disk in myopic children with elevated intraocular pressure].

The optic nerve disc of short-sighted children with elevated intraocular pressure was investigated to achieve early assessment of glaucoma and to detect signs which differentiate changes in the disc caused by short-sightedness from changes caused by glaucoma. The authors examined 16 eyes of 8 short-sighted children with elevated intraocular pressure. In addition to the basic ophthalmological examination they made a digital analysis of the optic nerve disc incl. planimetric evaluation of the dimensions of the disc, excavation and the neuroretinal rim. In two patients despite the higher intraocular pressure the area of the rim was supraliminal. In three patients the narrower area of the neuroretinal rim increased the probability of glaucoma In two patients with anisometropia on the eye with greater myopia the intraocular pressure was higher and the neuroretinal rim narrower as compared with the other eye. In one patient the area of the rim was very narrow and the diagnosis of glaucoma was confirmed also by arcuate scotoma in the lower part of the visual field corresponding to the narrow rim on top.

Adolescent↗

PubMed1982

[Further observations on the application of the campimetric method for measuring individually tolerated intraocular pressure in glaucoma].

The results of campimetric investigations performed in 127 eyes (83 patients) are presented. The vertical diameter of the blind spot and intraocular pressure were measured several times before and after oral intake of a dose of glycerol combined with ascorbic acid. The tonometric value obtained when the blind spot is smallest is considered the individually tolerated level of intraocular pressure. This tolerable pressure was determined in 105 eyes. In the overwhelming majority of the cases (95 eyes) the initial IOP values were within the standard (not exceeding 27 mmHg), according to the present glaucoma classification. However, in 64 eyes the IOP level approached the upper limit of the standard and only in 31 eyes was it between 18 and 22 mmHg. In contrast, the individually tolerated intraocular pressure in 99 eyes (94.3%) shifted to a level of between 18 and 22 mmHg and only in six cases. (5.7%) did the intraocular pressure also remain at the upper limit of the standard after intake of glycerol combined with ascorbic acid. These data show that the individually tolerable intraocular pressure, which does not interfere with the blood circulation in the retina and optic nerve, is in the 18-22 mmHg range in most patients. Under these conditions the vertical diameter of the blind spot (measured at a distance of 1 m with an object 2 mm in diameter) does not exceed 12 cm. This simple method of determining the individually tolerable method of determining the individually tolerable intraocular pressure can be used in any ophthalmological practice.

Glaucoma↗

PubMed1998

[Effect of mental and physical stress on intraocular pressure--a pilot study].

BACKGROUND: The aim of the present study was to examine the influence of phasic stressors on intraocular pressure (IOP). SUBJECTS AND METHODS: We exposed 15 ophthalmologically and systemically healthy non-smoking subjects (m:f = 8:7; mean age 25.4 years) to both bicycle ergometry physical stress and a computer-game psychological stress. IOP, blood pressure, and subjective stress were measured. To adjust for between-subject variance, we calculated intra-subject z-scores based on IOP values. Because of the habituation occurring during repeated tonometric measurements, we tested the significance of the difference between the observed and expected IOP z-values for each of the stressors. The expected IOP value was the mean of the pre- and post-stress relaxation-period values. Student's t-tests were used to assess the impact of the stressors on blood pressure. RESULTS: Both stressors increased the systolic blood pressure, but only under mental stress was the intraocular-pressure increase statistically significant (p = 0.048). DISCUSSION: The selective increase in intraocular pressure during mental stress by similar reaction of blood pressure to both stressors is a hint for possible different regulation circuits in the autonomic nerve system for intraocular- and blood pressure, respectively. Additionally, it was possible to demonstrate that mental stress could lead to a rise in intraocular pressure.

Adult↗

PubMed1977

Intraocular pressure and diabetic retinopathy.

Between intraocular pressure (I.O.P.) and the metabolic carbohydrate disturbance is a relationship: 1. diabetics frequently show primary open angle-galucoma; 2. as the diabetic retinopathy progresses towards stage III (Pr.), IOP decreases; 3. as diabetics exhibit dilatation of veins, increased blood viscosity, arteriolar narrowing and increased I.O.P. central retinal vessel disease with hemorrhages occurs redily; 4. capillary hemorrhages, periapaillary and macular oedema may be caused by increased oncotic pressure with acidosis of the blood; hyperglycemia with ketosis goes together with decreased I.O.P.; 5. only mild I.O.P.-rise may be considered as usefull to prevent hemorrhages by reducing retinal blood flow resulting subsequently from reduced uveal blood flow; 6. local application of glucocorticoids with permanent control of visual fields and I.O.P. should be a good additional treatment for diabetic retinopathy; unfortunately only very few cases are responsive to increase of I.O.P. by glucocorticoids; 7. it is important that prolactine levels in the blood are higher in the morning before the patient wakes up: this goes together with the morning I.O.P.-rise in glaucoma patients. Decreased activity of the hypophysis improves the diabetic retinopathy; this is contradictory to the beneficial effect of mild I.O.P.-rise.

Adult↗

PubMed1988

The electroretinogram and choroidal PO2 in the cat during elevated intraocular pressure.

The effects of elevated intraocular pressure (IOP) on the dark-adapted standing potential (SP), b- and c-waves of the electroretinogram (ERG) and choroidal PO2 of the intact cat eye were studied. During pressure elevation the SP increased, c-wave amplitude increased and the b-wave decreased, with the SP and c-wave being considerably more sensitive to pressure elevation. Inspiration of 100% O2 reversed the effects of elevated IOP on the c-wave and SP. ERG changes were found to be more consistent when related to perfusion pressure (PP = MAP - IOP) rather than absolute IOP. Initial increases in c-wave amplitudes and SP were observed at PPs as high as 105 mm Hg. The SP was most sensitive to IOP increases; the PP at which a change was first detected averaged 84.0 +/- 16.3 mm Hg (n = 7 cats). The PP at which the earliest c-wave change occurred was 78.7 +/- 16.7 mm Hg (n = 12 cats). The PP at which a b-wave change was first observed was 51.5 +/- 14.9 mm Hg (n = 11 cats). Choroidal PO2 was measured with an oxygen microelectrode and decreased with increasing IOP. A positive correlation was found (r = 0.78) between an increase in c-wave amplitude and decrease in choroidal PO2. From our results we can hypothesize that increased IOP led to decreased choroidal blood flow and outer retinal hypoxia measured as decreased choroidal PO2, and that this hypoxia was responsible for the c-wave and standing potential changes we observed.

Animals↗

PubMed2001

Clinical comparison of ocular blood flow tonometer, Tonopen, and Goldmann applanation tonometer for measuring intraocular pressure in postkeratoplasty eyes.

PURPOSE: Intraocular pressure (IOP) measurements vary with different tonometers in irregular corneas. The purpose of our study was to determine the comparability of the ocular blood flow tonometer (OBF) and Tonopen with the Goldmann applanation tonometer (GAT) in measuring IOP in post-keratoplasty eyes. METHODS: The IOP was measured using the OBF tonometer, GAT, and Tonopen in 69 post-keratoplasty eyes by two observers. The same instruments were used, and the sequence of measurements was randomized. Pachymetry to measure corneal thickness was done in all patients. RESULTS: Interobserver variation for IOP measured with GAT was statistically significant ( p = 0.039). Two-way analysis of variance (ANOVA), however, did not demonstrate any statistical difference between measurements with the three tonometers and two observers. Corneal thickness did not appear to have an effect on measurements with any of the tonometers. CONCLUSION: There was no significant difference in the overall accuracy of the OBF tonometer over the Tonopen versus the GAT. The OBF tonometer can be a useful alternative in measuring IOP in post-keratoplasty eyes.

Adolescent↗

PubMedDate not supplied

Effect of oral chloral hydrate sedation on the intraocular pressure measurement.

We measured the intraocular pressure (IOP) of 50 normal, cooperative, awake children below 6 years of age and 10 glaucoma patients with the Perkins' hand-held applanation tonometer (Perkins) and the Digilab pneumatonographer-tonometer (Pneuma). The measurements were repeated after oral chloral hydrate administration in the dose of 100 mg/kg body weight for the first 10 kg plus 50 mg/kg for every additional kg. There were no clinically or statistically significant changes in IOP measured before and after chloral hydrate in the 50 normal children (Pneuma: mean = 14.74 +/- 1.27 mm Hg vs 14.74 +/- 0.96 mm Hg; P > .05; Perkins: mean = 5.86 +/- 1.69 mm Hg vs 5.61 +/- 1.50 mm Hg; P > .05) or in the 15 glaucomatous eyes (Pneuma: mean = 28.93 +/- 5.26 vs 28.47 +/- 4.42 mm Hg; Perkins: mean = 20.27 +/- 5.36 vs 19.53 +/- 4.49 mm Hg; P > 0.05). Although some children did resist swallowing the bitter-tasting medicine, no significant side effects were encountered. The high-dose oral chloral hydrate protocol resulted in efficient sedation in children below the age of 6 years, without any alteration of the IOP levels in both normal and glaucomatous eyes.

Administration, Oral↗

PubMed1995

[The effect of an endothelin receptor antagonist, 97-139, on intraocular pressure in rabbits].

We studied intraocular pressure (IOP) response to an intravitreal injection of 10(-5)M (20 microliters) endothelin-1 (ET-1) in unanesthetized rabbits, and found a transient IOP rise followed by a prolonged IOP reduction. ET-1 (10(-6)M) caused a sustained IOP reduction without an initial IOP rise. The ETA receptor selective antagonist, 97-139 (10(-2)M, 20 microliters), had no effect when used alone; however, when used in combination with ET-1 (10(-5)M), 97-139 (10(-2)M) significantly blocked the ocular hypotensive response to ET-1. 97-139 (10(-3)M), when used with 10(-6)M ET-1, also suppressed the IOP reduction induced by ET-1. Aqueous prostaglandin (PG) E2, determined by radioimmunoassay, was significantly elevated following intravitreal injection of ET-1 (10(-5)M). Prior injection of 97-139 (10(-2)M) significantly suppressed the elevation of aqueous PGE2 concentration caused by ET-1 (10(-5)M). These results suggest that both the IOP response and the elevation of aqueous PGE2 following ET-1 injection are at least partially mediated by ETA receptor.

Animals↗

PubMed1998

The effects of anesthesia and gender on intraocular pressure in lions (Panthera leo).

Intraocular pressure (IOP) was measured in a pride of 22 (11 males, 11 females) lions (Panthera leo) using a Schiotz tonometer. Two anesthetic protocols were used in the study. Lions in group I (n = 14) were anesthetized using xylazine, atropine sulfate, and ketamine. Lions in group II (n = 8) were anesthetized using ketamine and diazepam. Five sequential readings were taken from each eye of every lion. There were no significant differences in IOP between the two anesthetic groups, between left and right eyes, or over the five readings. The IOP was significantly higher in males than in females, controlling for age and weight. The mean (+/-SD) tonometer reading in 22 eyes of 11 male lions was 2.9 (+/-0.5) mm; with a 95% confidence interval (CI) of 1.6-4.5 mm. The mean tonometer reading in 22 eyes of 11 female lions was 4.0 (+/-0.7) mm, with a 95% CI of 1.8-6.3 mm. Using the 1955 Friedenwald human calibration table, the estimated mean IOP in 22 eyes of 11 male lions was 24.9 (+/-2.0) mm Hg, with a 95% CI of 20.4-29.4 mm Hg. The estimated mean IOP in 22 eyes of 11 female lions was 20.9 (+/-2.4) mm Hg, with a 95% CI of 15.6-26.3 mm Hg.

Adjuvants, Anesthesia↗

PubMed2002

Randomized clinical trial of latanoprost and unoprostone in patients with elevated intraocular pressure.

PURPOSE: To compare the intraocular pressure (IOP)-lowering effect and safety of latanoprost 0.005% once daily with that of unoprostone 0.15% twice daily for patients with primary open-angle glaucoma or ocular hypertension. DESIGN: Randomized clinical trial. METHODS: In a prospective, 8-week, investigator-masked, parallel-group study conducted at numerous centers in the United States, 165 previously treated patients with IOP >or= 25 mm Hg in one or both eyes after washout were randomly assigned to receive either latanoprost 0.005% once daily in the evening or unoprostone 0.15% twice daily. Observations procedures were Goldmann applanation tonometry, best-corrected visual acuity, slit lamp biomicroscopy, and ophthalmoscopy. The main outcome measure was change in the mean of the IOPs measured at 8:00 AM, 12 noon, and 4:00 PM between baseline (before treatment) and after 8 weeks of treatment. RESULTS: The change in the mean +/- SD of the IOPs measured at 8:00 AM, 12 noon, and 4:00 PM was -7.2 +/- 3.2 mm Hg (28%) for latanoprost (25.3 +/- 2.8 mm Hg at baseline to 18.2 +/- 2.8 mm Hg at 8 weeks) and -3.9 +/- 2.6 mm Hg (15%) for unoprostone (25.5 +/- 3.3 mm Hg at baseline to 21.6 +/- 4.0 mm Hg; P <or=.001. No serious adverse event related to either medication was reported. CONCLUSIONS: Over an 8-week period, latanoprost 0.005% once daily lowered IOP more than unoprostone 0.15% twice daily in patients with elevated IOP. Both agents were safe and well tolerated.

Adult↗

PubMed1999

The effects of betaxolol hydrochloride ophthalmic solution on intraocular pressures during transient microgravity.

BACKGROUND: Intraocular pressure (IOP) has been found to increase during microgravity. After peaking in the first few hours of orbital flight, IOP slowly decreases to a level that is slightly elevated above baseline IOP's. These modest elevations in IOP do not require treatment. Just as in 1-G, a clinically significant elevation of IOP that occurred during spaceflight would require treatment. We are not aware of previous studies of the efficacy of IOP lowering agents under conditions of microgravity. METHODS: This double-masked, placebo-controlled study measured the IOP's of 11 adult subjects (22 eyes) at baseline, preflight, and zero-gravity aboard the NASA KC-135 aircraft, and postflight. One eye of each of the subjects was treated with betaxolol hydrochloride ophthalmic solution 0.5%, while the contralateral eye was treated with normal saline placebo, for 7 d prior to parabolic flight. IOP's were measured by the Tono-Pen 2, a gravity independent tonometer. RESULTS: A modest, but statistically significant reduction of 2.4 mmHg in mean IOP was noted in betaxolol treated eyes at the time of preflight measurement. During zero-G, the mean IOP's of both betaxolol treated eyes and placebo treated eyes increased approximately 20% over preflight levels. Postflight IOP's were similar to preflight IOP's. CONCLUSIONS: The effect of betaxolol on the IOP of eyes treated with for 1 wk prior to exposure to microgravity was statistically significant, but may lack clinical significance in normal eyes. Further research needs to be done to determine the efficacy during microgravity of betaxolol and other agents, in subjects who have upper normal to slightly elevated IOP's at 1 G.

Adaptation, Physiological↗

PubMed1993

Individual variability in the diurnal intraocular pressure curve.

BACKGROUND: Reduction of intraocular pressure (IOP) is a primary goal of most glaucoma treatments. However, because the IOP varies during the day, single measurements performed in an ophthalmologist's office do not necessarily provide information on the peak level and fluctuation of the IOP. METHODS: Home tonometry was performed to gain more information on the nature of the diurnal IOP curves and on their variability. One hundred seventy-six patients with open-angle glaucoma (OAG), 55 subjects with ocular hypertension (OHT), and 18 control individuals measured their IOP five times daily at home for 4 to 8 consecutive days using a self-tonometer. RESULTS: Well-defined diurnal IOP variations were observed in all three groups with a predominance of curves with morning or mid-day maxima. Erratic IOP curves without a diurnal rhythm were present in OHT (22%) and OAG (16%) patients but not in control subjects. Differences between the curves of the two eyes of an individual were frequent in OHT (33%) and OAG (36%) patients but not in control subjects (6%). Finally, the majority of OHT (72%) and OAG (66%) patients showed a difference in their diurnal curve patterns on repeat home tonometry performed months apart. CONCLUSION: The authors indicate that it is difficult to rely on one eye as a control for the other. They also indicate that changes in IOP observed in the office at different visits often may be due to a shift in the type of diurnal curve rather than to a true change in the mean IOP. Monitoring of the diurnal IOP may be necessary in some cases if the clinician relies, even partially, on the level of IOP when making a decision on patient management.

Circadian Rhythm↗

PubMed1975

[Intraocular pressure after changing the patient's position (author's transl)].

The influence of the patient's position (sitting or supine) on the intraocular pressure has been examined by means of Goldmann applanation-tonometry. The statistical analysis shows that the intraocular pressure decreases after the first measurement. This is the reason for measuring higher values in the first position, irrespective wether the first measurement is done in sitting or supine position. Analysing the values of steady state pressure i.e. 12 min after taking or changing position indicates a little higher mean value of intraocular pressure in the sitting position of the patient. The difference of mean valuse of sitting ans supine position of the patient is not significant. There are patients who have always higher others have always lower values of intraocular pressure in the supine position. These observations described earlier by Strobl and Follmann, have been confirmed by repeated measurements on 19 patients with differences in both directions of 2 to 4 mm Hg. For this reason it seems not feasible to use a statistical mean value of a population to correct the intraocular pressure of a particular case after changing position.

Elasticity↗