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Results for “INTRAOCULAR PRESSURE”

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PubMedDate not supplied

Effects of systemic administration of 0.5% tropicamide on intraocular pressure, pupillary diameter, blood pressure, and heart rate in normal cats.

OBJECTIVE: The objective of the study was to determine the effects of systemic 0.5% tropicamide on intraocular pressure (IOP), pupillary diameter (PD), blood pressure, and heart rate (HR) in normal felines with normotensive eyes. PROCEDURES: Intraocular pressure, PD, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and HR were measured in 18 clinically healthy cats. Each of the previously mentioned parameters was measured every 30 min during the trial period. At T(60), each cat was treated with one to two drops of 0.5% tropicamide ophthalmic solution placed on the dorsal aspect of the tongue. Changes in SBP, DBP, MBP, and HR were evaluated using one-way repeated measures analysis of variance, with time as the repeated factor. IOP and PD were evaluated using two-way repeated measures analysis of variance, with time and side (OD vs. OS) as the repeated factors. P values less than or equal to 0.05 were considered statistically significant. RESULTS: After lingual tropicamide administration, the mean PD at T(60) was 3.53 mm OD and 3.53 mm OS. The mean PD at T(90) was 6.36 mm OD and 6.31 mm OS. The mean PD at T(120) was 8.25 mm OD and 8.19 mm OS. This change in PD from T(60), T(90), and T(120) was statistically significant, demonstrating a linear increase in PD over time after tropicamide application on the tongue (P<0.0001). There was no statistically significant difference in PD when comparing the right to the left pupils (P=0.10). The mean IOP at T(60) was 14 mmHg OD and 12.94 mmHg OS. The mean IOP at T(90) was 14.5 mmHg OD and 14.23 mmHg OS. The mean IOP at T(120) was 14.94 mmHg OD and 14.89 mmHg OS. This change in IOP from T(60), T(90), and T(120) was statistically significant, demonstrating a linear increase in IOP over time after tropicamide application on the tongue (P=0.034). There was no statistically significant difference in IOP when comparing the right eye to the left eye (P=0.28). There were no statistically significant differences in SBP, DBP, MBP, and HR values over time for the duration of the study. CONCLUSIONS: We conclude that although lingual application of tropicamide appears to result in systemic absorption, causing significant pupillary dilation and elevations in IOP, systemic effects on SBP, DBP, MBP, and HR were not observed.

Administration, Sublingual↗

PubMedDate not supplied

Intraocular pressure measurement after hyperopic and myopic LASIK.

PURPOSE: To assess the effects of hyperopic and myopic laser in situ keratomileusis (LASIK) on the intraocular pressure (IOP) measurement by Goldmann applanation tonometry. METHODS: Intraocular pressure was measured by Goldmann applanation tonometry pre- and postoperatively in 48 hyperopic eyes (26 patients) and 56 myopic eyes (28 patients). RESULTS: The mean preoperative spherical equivalent refraction was +3.97 +/- 2.48 diopters (D) in the hyperopic group and -6.73 +/- 4.79 D in the myopic group. Attempted correction was equivalent to preoperative refraction in each group. Mean preoperative IOP was 14.22 +/- 2.56 mmHg and 13.70 +/- 2.09 mmHg in the hyperopic and myopic groups, respectively. Following LASIK, the mean IOP was 11.85 +/- 2.52 mmHg and 11.38 +/- 3.08 mmHg in the hyperopic and myopic groups, respectively. CONCLUSIONS: The IOP measurement was significantly reduced (P < .001) by 2.37-2.25 mmHg and 2.32 +/- 2.89 mmHg following hyperopic and myopic LASIK, respectively.

Adult↗

PubMed1982

[Fluorescein angiography of the choroid with elevated intraocular pressure (author's transl)].

Artificially induced increases in intraocular pressure slow the influx of dye during fluorescein angiography sufficiently to permit a sparation in time of the filling of the retina and the choroidea. During the filling of the choroidea segmental filling patterns appear in the form of lobules: the size of these wes determined. Interarterial anastomoses between ciliar arteries were also demonstrated. The clarity of the photographs was enhanced by computer-assisted image evaluation.

Adult↗

PubMed2003

Relationship between intraocular pressure and preservation of visual field in glaucoma.

Intraocular pressure (IOP) correlates with progressive loss of visual field in patients with glaucoma. Decreasing IOP has been proven to reduce progressive loss of the visual field. This is true both for glaucoma patients with IOPs above or within the normal range. For individuals with ocular hypertension (high IOP but no evidence of glaucomatous neuropathy), lowering IOP may reduce the risk of developing glaucoma. This article reviews scientific evidence that supports the importance of lowering IOP in patients with glaucoma or ocular hypertension.

Glaucoma↗

PubMed1989

Intraretinal and preretinal PO2 response to acutely raised intraocular pressure in cats.

The effect of acutely raised intraocular pressure (IOP) on retinal oxygenation has been determined using oxygen-sensitive microelectrodes preretinally and intraretinally. Anesthetized cats were ventilated alternately with one of two oxygen concentrations, 21 or 100%, while the IOP was manipulated via a hydrostatic pressure head connected to the anterior chamber. Preretinal and inner retinal oxygen tension remained stable over a broad range of IOP for air breathing. In contrast, the outer retina was severely affected, with the PO2 reducing as IOP was raised, resulting in some areas becoming anoxic. Outer retinal oxygen consumption was reduced for perfusion pressures less than 50 mmHg. It is postulated that under air-breathing conditions the preretinal and inner retinal oxygen tension was stabilized by the autoregulatory capacity of the retinal circulation. The inability of the choroidal circulation to autoregulate was reflected in the reduction of outer retinal oxygen tension with increasing IOP. With 100% oxygen breathing, increases in IOP caused a significant reduction in PO2 throughout the entire retina and preretinal vitreous. It is proposed that the effect of the autoregulatory capacity of the retinal circulation on retinal oxygenation is reduced in hyperoxia.

Animals↗

PubMed2003

[Glaucoma and ocular hypertension: the importance of intraocular pressure in treatment decisions in France].

PURPOSE: Several recent clinical studies have shown the benefit of lowering intraocular pressure in both ocular hypertensive and glaucoma patients. However, in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT), there is no consensus on the value of intraocular pressure (IOP) to be reached to prevent the progression of visual field defects. This IOP value, called target IOP, is defined by the ophthalmologist according to the patient and the progression of the disease, without a clear explicit justification of this decision. In France, ophthalmologists' education is mainly based on scientific meetings and the European Guidelines. This study was conducted to investigate the position of the IOP target in the treatment strategy for patients with glaucoma or OHT. MATERIAL: and methods: A cross-sectional descriptive survey was conducted in France among ophthalmologists in private practice. Patients with simple OHT or with OAG who required an initiation or a modification of treatment were included. RESULTS: We included 1735 patients (805 males, 46.4%) in the study. An OAG was diagnosed in 1338 patients (77.1%) and a simple OHT in 397 patients (22.9%). The patients with OAG were older than the OHT patients (65 years vs 61.7 years, p<0.0001). Most patients (73.5%) were included for treatment modification (77.5% of the patients with OAG and 59.9% of the patients with simple OHT; p<0.0001). The main reason for treatment change was an unsatisfactory IOP value. The main therapeutic objective was to reach a target IOP in 46.0% of the patients. The choice of the ocular hypotensive drugs depended on the IOP value in 51.9% of the patients. When the treatment was modified, monotherapy was preferred in 60.8% of the patients. CONCLUSION: Among ophthalmologists, the main objective for the treatment of patients with simple OHT or with OAG was to reach a target IOP. About half the participants were used to set up a target pressure for their patients. This fairly good ratio shows the comprehensiveness and the adaptation of our colleagues to relatively new concepts in treating and managing patients with ocular hypertension or chronic open-angle glaucoma. If a modification in the treatment was necessary, then monotherapy was preferred. This decision was motivated by the efficacy of the treatment but also by expected better patient compliance.

Adult↗

PubMed1998

Medical control of intraocular pressure after cataract surgery.

PURPOSE: To compare the effectiveness of 2 medications commonly used to prevent intraocular pressure (IOP) elevation in the early period after cataract surgery. SETTING: Palo Alto Veterans Affairs Health Care System, Palo Alto, California, USA. METHODS: This prospective study comprised 202 eyes of patients scheduled for cataract extraction who agreed to participate. Patients were randomized to receive oral acetazolamide, 500 mg 1 hour preoperatively; oral acetazolamide, 500 mg immediately postoperatively; apraclonidine hydrochloride 1%, 2 drops 1 hour preoperatively; or artificial tears (control group). Intraocular pressure was measured preoperatively and 4 to 6 and 24 hours postoperatively. RESULTS: Preoperative IOP was not significantly different among the 4 groups. At 4 to 6 hours postoperatively, only preoperative acetazolamide was significantly more effective than the control medication (P = .038); at 24 hours there were no significant differences among the 4 groups. Postoperative IOP elevation in excess of 35 mm Hg at 6 or 24 hours decreased significantly in the preoperative acetazolamide group (3/46 eyes) compared with the control group (14/54 eyes). There was no statistically significant difference in IOP elevation between eyes having extracapsular cataract extraction and those having phacoemulsification, independent of treatment group. CONCLUSION: The results favor preoperative acetazolamide to control postcataract IOP elevation. The method of cataract removal did not affect postoperative IOP elevation.

Acetazolamide↗

PubMed1997

The effect of an artificially-elevated intraocular pressure on corneal thickness in Chinese eye.

We measured the central corneal thickness and the applanation intraocular pressure (IOP) on 45 Hong Kong Chinese. There was no obvious relationship between these two parameters, as different from other literatures. It could be due to either a limited number of subjects with a high IOP level (only six subjects with IOP > or = 22 mmHg), or Chinese has a thicker central cornea in general. The mean central cornea of our subjects was thicker (566 +/- 36 microns) than some previous findings. Thirty subjects had their intraocular pressure further increased by adopting a 40 degrees head-down posture. Their IOP and topographic corneal thickness were measured again. There was no significant change in the central corneal thickness even though the IOP was elevated by 11.7 mmHg. However the nasal cornea demonstrated a thinning effect (by some 18 microns) during the IOP elevation but it returned to the pre-inverted level after returning to a sitting posture for 5 min. Further investigation with more corneal regions being measured would be valuable to evaluate the in vivo effect of IOP elevation from glaucoma attack on corneal thickness.

Cornea↗

PubMed1989

Tono-Pen estimation of intraocular pressure through bandage contact lenses.

The Tono-Pen was used to determine the reliability of intraocular pressure readings obtained through bandage contact lenses in 48 eyes of 24 healthy volunteers. The mean difference between readings obtained before lens insertion and readings obtained with the lens in place was 0.27 mm Hg and was not statistically significant (P greater than .2). The mean difference between readings obtained with the lens in place and readings obtained after lens removal was 0.85 mm Hg and was statistically significant (P less than .01). Ninety-five percent confidence intervals suggest that the true difference between mean Tono-Pen readings obtained with and without the lens in place ranges from -0.3 to +1.5 mm Hg. Our results suggest that the Tono-Pen is probably an effective way to estimate intraocular pressure through bandage contact lenses, with a probable true mean difference of less than 1.5 mm Hg and a standard deviation of about 2 mm Hg.

Adult↗

PubMed1993

Topical application of serotonin or the 5-HT1-agonist 5-CT intraocular pressure in rabbits.

PURPOSE: The effect of serotonin (5-hydroxytryptamine: 5-HT) and other agonists on rabbit intraocular pressure (IOP), pupil size, and the breakdown of blood-aqueous barrier were evaluated. METHODS: Serotonin and various other agonists were applied topically to the rabbit eye, and intraocular pressure was followed over the next 3 hours using a Digilab 30D pneumatometer. RESULTS: It was demonstrated immunohistochemically that topical 5-HT reached the anterior chamber within 1 hour. Serotonin raised the IOP in a dose-dependent manner over a period of up to 4 hours, with a maximum reached between 30 minutes and 1 hour. A similar effect was observed with the 5-HT1-agonist 5-carboxamidotryptamine (5-CT). Neither tryptamine, 5-hydroxytryptophan, melatonin, gepirone, nor 5,6/5,7-dihydroxytryptamine caused any changes in IOP. Serotonin did not cause a change in pupil size or a breakdown of the blood-aqueous barrier, nor did the aqueous cAMP change significantly after topical 5-HT administration. CONCLUSIONS: The data presented suggest a role for 5-HT in the control of IOP. Previously demonstrated receptors on the iris-ciliary body and the effect of the 5-HT1-agonist 5-CT suggest that the rise in IOP may be caused partly or entirely by an increase in aqueous secretion mediated by 5-HT1-like receptors. Whether or not 5-HT has a role in altering aqueous outflow resistance remains to be seen. An effect of serotonin on other aspects of aqueous dynamics or on the extraocular muscles to cause a change in IOP cannot be excluded.

Administration, Topical↗

PubMed1986

2-Substituted 1, 3, 4-thiadiazole-5-sulfonamides as carbonic anhydrase inhibitors: their effects on the transepithelial potential difference of the isolated rabbit ciliary body and on the intraocular pressure of the living rabbit eye.

In order to understand the pharmacology of carbonic anhydrase inhibitors in reduction of aqueous secretion, three sorts of studies were conducted using five 2-substituted 1, 3, 4-thiadiazole-5-sulfonamides: an inhibition study of carbonic anhydrase II, electrical measurements of the isolated ciliary body, and pharmacological study on intraocular pressure of living animals. The inhibitors of carbonic anhydrase employed here were 2-amino-1, 3, 4-thiadiazole-5-sulfonamide; 2-methylamino-1, 3, 4-thiadiazole-5-sulfonamide; 2-formylamino-1, 3, 4-thiadiazole-5-sulfonamide; 2-acetylamino-1, 3, 4-thiadiazole-5-sulfonamide (acetazolamide); and 2-propionylamino-1, 3, 4-thiadiazole-5-sulfonamide. All of these compounds showed significant inhibitory activity to carbonic anhydrase II which exists in the ciliary epithelium, but their potencies of inhibition varied relative to one another (I50S were 1.91 X 10(-7) to 3.3 X 10(-8) M). The effects of the five compounds on electrical phenomena were observed using isolated rabbit ciliary body mounted on an Ussing's chamber. Each compound decreased the negative electrical potential of the tissue (-0.70 mV as the average of the initial values) by 10- to 33%, and this effect was proportional to its inhibitory activity to carbonic anhydrase II. The effects of the five compounds on intraocular pressure were determined, and each compound decreased the intraocular pressure (18 mmHg as the average of the initial values) by 7- to 32%. This effect was also proportional to the inhibitory activity to the enzyme. Correlation between the two effects was studied, and good correlation was observed. This implies that both effects have a common basis which relates to the physiological role of carbonic anhydrase. The present study, therefore, shows the importance of the bicarbonate ion in the aqueous humor formation since it is both substrate and product of carbonic anhydrase II.

Acetazolamide↗

PubMed1985

Change in appearance of the optic disc associated with lowering of intraocular pressure.

This report provides additional documentation that the appearance of the optic disc may improve after intraocular pressure is lowered in patients with glaucoma. Photographic records of one of the authors (GLS) were reviewed retrospectively. Seven previously unreported cases showing apparent improvement of the optic disc were found, and the patients' charts were reviewed. In two cases the improvement was transient, and in five it was lasting. Patients with evidence of disc improvement had an age range of 5 to 55 years. In one case, the scleral ring decreased in size following the lowering of intraocular pressure. In the other cases, the disc appeared to "fill in" without change in the size of the scleral ring. When improvement is short-lived, it presumably represents edema. When of longer duration, it may be a response to anterior repositioning of a posteriorly displaced lamina cribrosa, a decrease in diameter of the scleral ring, hypertrophy and/or proliferation of glial cells, or return towards normal of axonal metabolism. Because apparent improvement in the appearance of the optic disc can be subtle, it is usually not sought and is probably often unrecognized. Its true incidence is still unknown but appears to be underestimated.

Adolescent↗

PubMed1994

Moderate exertion lasting only seconds reduces intraocular pressure.

Intense physical exertion is known to reduce intraocular pressure (IOP). However, the effect of physical exertion on IOP in the first few seconds after beginning exertion has not been studied previously. IOP was determined twice within 15 s in 32 healthy, young men. Seventeen performed six deep knee bends within 8-10 s preceding the second IOP measurement, while 15 did not. The mean reduction in IOP immediately after such brief and moderate exertion was 1.9 +/- 0.3 mmHg, compared with 0.8 +/- 0.2 mmHg in the control group. The difference between both groups was statistically significant. Thus, even moderate physical exertion may reduce IOP. As the relative decrease in IOP correlated with the relative increase in heart rate, the observed reduction in IOP after brief, moderate physical exertion may be due to sympathetic activity.

Adult↗

PubMed1978

Increased corneal thickness simulating elevated intraocular pressure.

A 17-year-old girl had intraocular pressure readings of 30 to 40 mm Hg in both eyes, with normal visual fields and optic nerve heads. Medical treatment was unsuccessful in lowering the IOP measurements substantially. The central corneal thickness was 0.90 mm in each eye in the absence of corneal edema. Cannulation of the left anterior chamber revealed an IOP of 11 mm Hg, while the Perkins' and Schiŏtz' tonometers gave readings of 35 and 34 mm Hg, respectively. Previously, elevated tonometry readings had been obtained by Goldmann's, Perkins', Schiŏtz', MacKay and Marg's, pneumatic tonometer and air puff tonometer. This suggested that measurement of central corneal thickness be performed in cases in which IOP recordings do not correspond to other clinical findings.

Adolescent↗

PubMed1979

Blockade of rapid axonal transport. Effect of intraocular pressure elevation in primate optic nerve.

After acute intraocular pressure (IOP) elevation, an induced disturbance of rapid axonal transport at the optic nerve head began within three hours at the IOP levels tested. The accumulation of radioactive label at the scleral lamina cribrosa increased with time of IOP elevation. There was a 60% decrease in the amount of transported material in the optic nerve, tract, and lateral geniculate body (LGN). Detailed analysis suggests that this decrease is not due to a simple slowdown of transport, but results from a total block of rapid transport in some axons, with no impairment in other axons. This total blockade of rapid transport by elevated IOP in involved axons differs from the apparent slowdown of transport in experimental papilledema, and the difference may explain the response of ganglion cells to the two conditions.

Animals↗

PubMed2006

Intraocular pressure changes and ocular biometry during Sirsasana (headstand posture) in yoga practitioners.

PURPOSE: To study the intraocular pressure (IOP) changes in Sirsasana (headstand posture) done by experienced yoga practitioners and correlate the ocular biometric parameters with the IOP changes, and to screen for the prevalence of ocular hypertension in this group of subjects. DESIGN: Prospective case observational series. PARTICIPANTS: Seventy-five subjects (50 Asian Indians and 25 Caucasians) from a yoga training institute volunteered for the study. METHODS: All participants underwent a detailed ophthalmic examination along with ocular biometry and corneal pachymetry. Intraocular pressure was recorded using a Tonopen before, during, and after the Sirsasana. Changes were compared using the paired t test. Age, axial length, anterior chamber depth, lens thickness, corneal curvature, corneal thickness, race, and the length of time for which the practitioner was performing yoga were correlated with the induced IOP difference in a randomly selected eye using Pearson's correlation coefficient with Bonferroni correction for multiple comparisons. MAIN OUTCOME MEASURES: Ocular biometry and induced IOP difference. RESULTS: The mean increase in IOP at baseline and immediately after assuming Sirsasana was 15.1+/-4.1 mmHg (R = 0.07; P = 0.999) and after 5 minutes was 15.8+/-4.6 mmHg (R = -0.25; P = 0.357). The induced increase in IOP during the posture was twice the baseline IOP. There was no correlation between age, ocular biometry, and ultrasound pachymetry when compared with the induced IOP difference. One subject (1.33%) was found to have baseline IOP of more than 21 mmHg. CONCLUSION: There was a uniform 2-fold increase in the IOP during Sirsasana, which was maintained during the posture in all age groups irrespective of the ocular biometry and ultrasound pachymetry. We did not demonstrate a higher prevalence of ocular hypertensives in this cohort of yoga practitioners nor did the risk factors contributing to glaucoma show any correlation with magnitude of IOP raise during the posture.

Adult↗

PubMed2005

Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses.

OBJECTIVE: To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry. DESIGN: Prospective study. ANIMALS: 100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses. PROCEDURES: In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applanation tonometry. RESULTS: For the enucleated dog and horse eyes, there was a strong (r2 = 0.99) linear relationship between pressures obtained by means of direct manometry and those obtained by means of rebound tonometry. Mean +/- SD IOPs obtained with the rebound tonometer were 10.8 +/- 3.1 mm Hg (range, 5 to 17 mm Hg) and 22.1 +/- 5.9 mm Hg (range, 10 to 34 mm Hg) for the dogs and horses, respectively. Mean IOPs obtained with the applanation tonometer were 12.9 +/- 2.7 mm Hg (range, 8 to 18 mm Hg) and 21.0 +/- 5.9 mm Hg (range, 9 to 33 mm Hg), respectively. Values obtained with the rebound tonometer were, on average, 2 mm Hg lower in the dogs and 1 mm Hg higher in the horses, compared with values obtained with the applanation tonometer. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the rebound tonometer provides accurate estimates of IOP in clinically normal eyes in dogs and horses.

Animals↗

PubMed1987

Intraocular pressure assessment in gas-filled eyes following vitrectomy.

The accuracy and precision of tonometric methods in measuring intraocular pressure (IOP) was assessed in 24 eye-bank eyes subjected to pars plana lensectomy/vitrectomy and air-fluid exchange. Intraocular pressure was measured in masked fashion with a Perkins' applanation tonometer, pneumatic applanation tonometer; a mercury manometer served as a reference standard. Pneumatic tonometry underestimated actual IOP by as much as 25%, and Schiotz' indentation tonometry underestimated actual IOP by as much as 79%. Perkins' applanation tonometry was significantly more accurate in estimating actual IOP in gas-filled eyes than pneumatic tonometry or Schiotz' indentation tonometry.

Humans↗