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Results for “INTRAOCULAR PRESSURE”

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PubMed1995

Correlation of intraocular pressures in pairs of monozygotic and dizygotic twins.

PURPOSE: Studies of twins may help to establish the importance of hereditary and environmental determinants of chronic diseases. Intraocular pressure (IOP) is a risk factor for glaucoma. The authors hypothesized that IOPs would be more highly correlated between monozygotic (MZ) than between dizygotic (DZ) twins. METHODS: This was a concurrent, case-control study. Volunteer pairs of twins were recruited at a twins' festival. Zygosity was determined by a questionnaire that correlates well with blood-typing classification. Intraocular pressure was measured with a Tonopen six times within 5 minutes (3 times per eye) and averaged. RESULTS: Mean IOP was 14.4 +/- 2.7 mmHg for 61 pairs of MZ twins and 13.9 +/- 2.6 mmHg for 32 pairs of DZ twins. The difference in IOP between the members of a pair was abbreviated delta IOP. The authors found a significant difference in median delta IOP between the MZ and DZ groups (1.2 versus 2.3 mmHg; P = 0.0014). Intraocular pressures were more highly correlated when considering right versus left eyes (intraclass correlation, r1 = 0.853; P < 0.001) than when considering the members of pairs of MZ twins (r1 = 0.735; P < 0.001), which in turn were more highly correlated than pressures of the members of pairs of DZ twins (r1 = 0.407; P = 0.006). CONCLUSIONS: The intraclass correlation for IOP was greater for MZ than for DZ twins. In addition, the median intrapair difference (median delta IOP) was less for MZ than for DZ twins. These results suggest that hereditary factors may play some role in the determination of IOP.

Adolescent↗

PubMed1996

Comparison of three tonometers for measuring intraocular pressure in rabbits.

PURPOSE: Rabbits are used commonly for the evaluation of drugs and surgery to lower intraocular pressure (IOP). The authors compared the accuracy and variability of three tonometers for measuring IOP in rabbits. METHODS: The anterior chamber of adult rabbits was cannulated with a 25-gauge needle connected to an elevated bottle of balanced salt solution. The bottle was raised and lowered to control IOP. A fluid-filled pressure transducer also was placed in the anterior chamber. Intraocular pressure was decreased in increments of 5 to 10 cm H2O from 50 to 0 mm Hg and was recorded with each of these instruments: the hand-held applanation tonometer, the Tono-pen XL, and the pneumatonometer. RESULTS: The Tono-pen XL and the hand-held applanation tonometer underestimated the IOP, whereas the pneumatonometer slightly overestimated IOP. Under close stopcock conditions, at IOPs between 3 and 30 mm Hg, the Tono-pen XL was as accurate as the pneumatonometer but had a smaller variance; the hand-held applanation tonometer had lower accuracy and higher variability. CONCLUSIONS: The Tono-pen XL is the tonometer of choice for measuring IOP in rabbits within the range of IOP 3 to 30 mm Hg. All tonometers were less accurate when the IOP was elevated markedly.

Animals↗

PubMed1998

The rarity of clinically significant rise in intraocular pressure after laser peripheral iridotomy with apraclonidine.

OBJECTIVE: To determine the incidence of intraocular pressure (IOP) rise of varying degrees after laser peripheral iridotomy (LPI) in patients with and without glaucoma treated perioperatively with pilocarpine and apraclonidine. DESIGN: A retrospective chart review. PARTICIPANTS: A total of 289 eyes in 179 patients with narrow occludable angles (NOA) (N = 148), open-angle glaucoma or ocular hypertension (OAG) (N = 115), or chronic-angle closure glaucoma (CACG) (N = 26) were reviewed. MAIN OUTCOME MEASURES: The difference between preoperative and postoperative IOP, absolute postoperative IOP, and the need for acute IOP-lowering treatment was noted. RESULTS: Only 1.1% (95% confidence interval [CI], 0.03%-5.8%; 1 of 94) of patients and 0.7% (95% CI, 0.02%-3.7%; 1 of 148) of eyes with NOA experienced a rise of more than 10 mmHg 1 to 2 hours after LPI. The incidence of postoperative IOP greater than 25 mmHg and acute postoperative IOP-lowering management was 0% (95% CI, 0%-3.8%). Intraocular pressure in 1 of 115 eyes (0.9%, 95% CI, 0.02%-4.7%) with OAG rose more than 10 mmHg, requiring acute treatment. None of the 26 CACG eyes experienced a rise of more than 10 mmHg (95% CI, 0%-13.2%). CONCLUSION: The IOP rise that requires further intervention after LPI with the perioperative use of pilocarpine and apraclonidine is very uncommon. In patients with NOA, routine postiridotomy IOP monitoring may not be required.

Adrenergic alpha-Agonists↗

PubMed1989

The time-course of intraocular pressure in timolol-treated and untreated glaucoma suspects.

We studied the behavior of intraocular pressure in glaucoma suspects randomly selected to receive either topical timolol or no treatment over the course of a long-term prospective follow-up study. All patients who after six years of follow-up showed no localized field defects or disk changes, or whose pressures were not dangerously increased (24 treated and 22 untreated patients), were included in the present study. Overall, the two groups showed an increase in pressure followed by a gentle leveling off and a decrease toward the end of the follow-up period. The pressure-time curves of the two groups were parallel and vertically separated by 4.94 mm Hg. When pressure-time relationships were determined in individual patients, the categorical group differences were not statistically significant. Our results suggest that most glaucoma suspects did not exhibit a random time-course of intraocular pressure and that the effect of treatment was simply to lower the pressure-time curve of the treated group by a fixed level throughout the six-year follow-up period.

Drug Evaluation↗

PubMed1986

Intraocular pressure reduction after argon laser trabeculoplasty in open-angle glaucoma. A two-year follow-up.

One hundred and twenty-eight eyes of 113 pre-surgical patients with open-angle glaucoma, treated with 360-degree orgon laser trabeculoplasty, were followed up for 24 months. Success was defined as an intraocular pressure below 23 mmHg as well as an intraocular pressure reduction of at least 20% with the same medical therapy as given before laser treatment, or less. The total success rate was 64%. In 79 eyes with capsular glaucoma the success rate was 76%, whereas in 49 eyes with simple glaucoma it was 45%. The success rate increased in groups with higher degrees of trabecular pigmentation, probably an effect of a higher proportion of eyes with capsular glaucoma in these groups. Baseline intraocular pressure had no influence on the success rate. No correlation was found between the amount of laser energy delivered and the degree of pressure reduction after 6 months. Neither was there any significant difference in laser energy levels between eyes showing successful results and those regarded as failures at the end of the 2-year follow-up period.

Aged↗

PubMed1993

Postoperative intraocular pressure abnormalities in the Silicone Study. Silicone Study Report 4.

BACKGROUND: Chronically abnormal intraocular pressure (IOP) may follow surgery for proliferative vitreoretinopathy (PVR), using either long-acting gas or silicone oil tamponade. Its prevalence and clinical significance are unclear. METHODS: In the Silicone Study, 241 eyes with severe (> or = C-3) PVR were treated with vitrectomy, randomized to perfluoropropane gas (C3F8) or silicone oil, and followed for 6 months or longer. Chronic IOP abnormalities, based on findings at two consecutive or any three postoperative visits, were defined as (1) low IOP (hypotony), 5 mmHg or less, or (2) elevated IOP, more than 25 mmHg. RESULTS: Eleven (5%) eyes had chronically elevated IOP and 58 (24%) had chronic hypotony. Chronically elevated IOP was more prevalent in eyes randomized to silicone oil than in those randomized to C3F8 gas (8% versus 2%; P < 0.05). Chronic hypotony was (1) more prevalent in eyes randomized to C3F8 gas than in those randomized to silicone oil (31% versus 18%; P < 0.05); (2) more prevalent in eyes with anatomic failure (48% versus 16%; P < 0.01); and (3) correlated with poor postoperative vision (P < 0.0001), corneal opacity (P < 0.001), and retinal detachment (P < 0.001). Factors prognostic of chronic hyotony included preoperative hypotony (P < 0.01), diffuse contraction of the retina anterior to the equator (P < 0.01), rubeosis (P = 0.02), and large retinal breaks (P = 0.02). In a multivariate analysis, diffuse contraction of the retina anterior to the equator remained an independent factor prognostic of chronic hypotony (odds ratio = 4.2), regardless of whether the retina was attached postoperatively. CONCLUSION: Intraocular pressure abnormalities are a common postoperative complication in eyes with PVR, and may occur with either C3F8 gas or with silicone oil. The presence of diffuse contraction of the retina anterior to the equator should alert the vitrectomy surgeon that the eye is likely to be hypotonus postoperatively.

Chronic Disease↗

PubMed1981

Study of the additive effect of timolol and epinephrine in lowering intraocular pressure.

A randomised, double-masked clinical study was conducted in patients with primary open-angle glaucoma to determine if timolol and epinephrine have an additive effect in lowering intraocular pressure. Sixteen patients were randomly assigned to one of 2 treatment sequences (timolol alone, supplemented after 2 weeks with epinephrine, and vice versa). An initial additive effect in lowering intraocular pressure was found in both sequences. However, after several weeks of combined therapy complete loss of additive effect was found. Patients who were treated first with epinephrine for 2 weeks and then supplemented with timolol had significantly lower intraocular pressures for at least 2 weeks than patients in the reverse treatment sequence. Epinephrine treatment alone caused a significant increase in facility of outflow, but this effect did not occur with simultaneous timolol treatment. The results are discussed in terms of possible fundamental beta and alpha adrenergic influences on aqueous dynamics and their potential clinical relevance.

Adult↗

PubMed1982

The effects of oversize donor buttons on postoperative intraocular pressure and corneal curvature in aphakic penetrating keratoplasty.

Forty-one consecutive aphakic corneal transplants performed by the same surgeon were studied in order to determine the effects on intraocular pressure and corneal curvature of using 8.0-mm donor buttons in 7.5-mm recipient openings. One half of the grafts had oversize donor buttons, and all were followed for 13 months. The intraocular pressure in the oversize donor group was statistically significantly less during the first five days after keratoplasty, but not subsequently. Eliminating eyes with preoperative glaucoma, more transplants in the same size donor group (P = 0.08) needed glaucoma therapy 13 months after operation. The anterior corneal curvature (mean keratometry reading) was statistically significantly greater in the oversize donor group throughout the postoperative period. Concurrently, the oversize donor group was less hyperopic after all sutures were removed. There was no difference in keratometric astigmatism or corneal thickness between the two groups. Thus, the use of 0.5-mm oversize donor tissue in aphakic corneal transplants reduced the intraocular pressure and increased the central corneal curvature after keratoplasty.

Aphakia↗

PubMed2005

Comparison of the effect of two viscoelastic agents on an early postoperative intraocular pressure.

This prospective study compares the effect of two viscoelastic agents (Viscoat and Provisc) on an early postoperative intraocular pressure after phacoemulsification and intraocular lens implantation. The study compares 36 patients with senile cataract. Intraocular pressure (IOP) was measured by standard Goldmann aplanation tonometry preoperatively as well as on the first postoperative day, after 24 hours and 1 week postoperatively. The mean postoperative IOP at first postoperative day in the Viscoat group was 24.2 mmHg and in the Provisc group was 21.2 mmHg. The increase was significantly higher in the Viscoat group than in the Provisc group but after 24 hours and 1 week postoperatively the mean IOP was not statisticaly different. The two viscoelastic agents cause equivalent pressure elevation postoperatively.

Chondroitin Sulfates↗

PubMed1997

Autoregulation of human optic nerve head circulation in response to increased intraocular pressure.

The following experiments were undertaken to determine if blood flow is maintained by autoregulation in the human optic nerve head when circulation is challenged by elevated intraocular pressure, and to determine if the presence or absence of autoregulation is universal. Laser Doppler flowmetry was used to determine the average velocity, the number of moving erythrocytes, and the volume of flow in the capillary bed of the optic disc. These parameters were measured in 10 subjects at spontaneous levels of intraocular pressure (IOP), and at pressures artificially elevated to 25, 35, 45 and 55 mm Hg with a scleral suction cup. Four subjects (two who showed autoregulation and two who did not) were studied on six additional occasions to determine consistency of the findings. In these same four subjects a second location on the disc was also measured on six occasions to determine if the IOP-effect on blood flow varied by location. Of the 10 subjects initially studied, seven maintained the baseline level of blood flow over the lower part of the range of elevated intraocular pressure (evidence of autoregulation), but showed a decline in flow by the time IOP reached 45 or 55 mm Hg. Two subjects showed a linear decline in blood flow beginning with the smallest increment of elevation of IOP (no autoregulation), and one showed an uninterpretable result. The two individuals who showed the linear decline and two of those who showed efficient autoregulation were remeasured, and each showed consistently the same pattern as before when restudied on six different occasions each. However, at a different location on their discs, autoregulation was manifest in all of these four individuals. When challenged by elevated IOP, the optic nerve head typically maintains a steady-blood flow over a range of IOP, but fails to maintain the same flow by the time IOP reaches 45 or 55 mm Hg. Some disc locations, at least in some individuals, do not show this autoregulation, but exhibit a decline in blood flow linearly related to IOP, even with the modest elevation of IOP.

Adult↗

PubMed2001

The effect on intraocular pressure of tracheal intubation or laryngeal mask insertion during sevoflurane anaesthesia in children without the use of muscle relaxants.

BACKGROUND: We studied the effects of sevoflurane on intraocular pressure after induction in children undergoing either tracheal tube (TT) or laryngeal mask airway (LMA) insertion without a muscle relaxant METHODS: The study included 38 children. Anaesthesia was induced (8%) and maintained (3-4%) with sevoflurane in 100% O2. No muscle relaxant was used. A TT was inserted in group I (n=20), and an LMA in group II (n=18). IOPs were measured after induction, insertion of TT or LMA and at 1, 2 and 3 min thereafter. The heart rate, mean arterial pressures were also recorded. RESULTS: Intraocular pressures increased significantly in group I after TT (P < 0.01) and remained high until after 3 min. The pressures were similar in the LMA group at all measurements. CONCLUSION: Sevoflurane does not prevent the increase in IOP after intubation without muscle relaxants. LMA does not increase IOP in children after sevoflurane induction.

Anesthesia, Inhalation↗

PubMed2005

[Influence of prostaglandins on aqueous humour dynamics and intraocular pressure].

In the glaucoma disease the disturbed trabecular outflow results not only in an increase in the intraocular pressure (IOP) level, but also in an increase in the intraocular pressure fluctuations in the majority of patients. This induces a biomechanical stress that may damage the optic nerve head over time and may result in the typical glaucomatous excavation. Prostaglandin analogues show positive effects on both risk factors. They enhance the uveoscleral outflow of the aqueous humour, improve the trabecular outflow facility and probably the regulatory capacity of the trabecular meshwork itself. This dual mechanism might explain the strong IOP-lowering efficacy of the prostaglandins and their additional property to reduce IOP fluctuations leading to a general improvement of the aqueous humour dynamics. Therefore, it makes sense pharmacologically to combine prostaglandins with those medications that also reduce aqueous humour production.

Animals↗

PubMed2004

Pattern of intraocular pressure in epidemic dropsy in India.

This study was conducted to report on the intraocular pressure (IOP) pattern in patients with epidemic dropsy. Two hundred and thirty proven cases of epidemic dropsy were sent for ocular examination. We measured IOP by applanation tonometry at different intervals. Patients were followed up until 24 weeks. Intraocular pressure of more than 22 mm of Hg was detected in 10.86% patients at the start of the study. However, at 12 weeks only 0.43% patients needed medication for control of IOP. None required medication for IOP control after 20 weeks. The rise of IOP in this case series of epidemic dropsy appeared to be a transient phenomenon and drugs needed to be titrated on a weekly basis.

Adult↗

PubMed1988

Topical prostaglandin E2 effects on normal human intraocular pressure.

This was a double-masked, randomized, paired comparison with vehicle trial of a topically administered prostaglandin (PG)E2 in healthy human volunteers. A statistically significant decrease of the intraocular pressure in these non-glaucomatous volunteers occurred at six hours following one drop of 0.02% solution that persisted to the last measurement of IOP at the 24 hour examination. Significant elevation in the intraocular pressure was present at one and two hours following the eye drop instillation. All volunteers reported transient ocular side effects related to drug administration, including mild eye ache and intermittent photophobia for a duration of 2 to 4 hours. These symptoms were associated with a transient conjunctival vasodilation, but with no evidence of anterior chamber cells and flare or ciliary flush as determined by slit lamp examination. The results of this study suggest that PGE2, or a derivative, may offer a new class of topically effective ocular hypotensive agents useful in lowering the intraocular pressure of glaucoma patients.

Administration, Topical↗

PubMed2006

[Long-term effects of isopropyl unoprostone monotherapy on intraocular pressure and visual field for normal-tension glaucoma and primary open-angle glaucoma patients].

We retrospectively investigated the long-term effects of isopropyl unoprostone monotherapy on intraocular pressure and visual field for normal-tension glaucoma and primary open-angle glaucoma patients. Among 80 eyes of 49 subjects receiving isopropyl unoprostone monotherapy for 2 years or more, 32 eyes of 32 subjects were analyzed because of the good reliability of their visual acuity and visual field (age, 68.1 +/- 10.1 yrs, follow-up period 47.8 +/- 14.7 months). The mean values of intraocular pressure and visual field indices were compared with baseline data before medication. The visual field changes were also analyzed using the Kaplan-Meier life-table method. The mean intraocular pressure decreased for 4 years from 14.7 +/- 4.3 mmHg (mean +/- SD) at baseline, to 12.7 +/- 4.4mmHg at 4 years. The global index of visual field (mean defect, loss variance) did not change significantly during the 4 years. The accumulative probability of survival was 80.7 +/- 8.0% after 4 years when the endpoint was defined as 3dB progression in mean defect. Isopropyl unoprostone might have the possibility of stabilizing the visual field for a long period of time.

Aged↗

PubMed2006

Relationship of progression of visual field damage to postural changes in intraocular pressure in patients with normal-tension glaucoma.

PURPOSE: To evaluate whether postural changes of intraocular pressure (IOP) are associated with progression of visual field damage in patients with normal-tension glaucoma (NTG). DESIGN: Prospective, noncomparative, nonrandomized study. PARTICIPANTS: Sixty eyes of 33 patients with NTG. METHODS: Intraocular pressure, blood pressure (BP), and pulse rate (PR) were measured in both sitting and supine positions. Visual fields were examined using Humphrey Field Analyzer (HFA; Zeiss-Humphrey Instruments, Inc., San Leandro, CA). Changes in mean deviation (MD) per year (dB/year), that is, MD slope, were calculated by linear regression analysis of the HFA Statpac 2 program. MAIN OUTCOME MEASURES: The relationship between postural changes of IOP and MD slope was analyzed. The correlation between postural changes of IOP and cardiovascular parameters such as BP and PR also was analyzed. RESULTS: The IOP in the supine position was significantly higher than that in the sitting position (P<0.001, paired t test). There was no significant correlation between MD slope and sitting IOP (Pearson r = 0.172; P = 0.188), but a significant correlation was found between MD slope and supine IOP (r = -0.261; P = 0.043). The MD slope significantly correlated with IOP elevation caused by the postural change (r = -0.682; P<0.001). The systolic BP in the supine position correlated with postural changes of IOP (r = 0.364; P = 0.004), but other cardiovascular parameters did not correlate with IOP parameters. CONCLUSIONS: The progression of visual field damage in NTG is associated with IOP in the supine position and the magnitude of IOP elevation accompanying postural changes. These results suggest that deterioration in NTG may occur when patients are lying flat during sleep.

Aged↗

PubMed1990

Techniques of intraocular pressure determination.

A variety of indentation or applanation tonometers are available for the measurement of intraocular pressure in conscious or anesthetized animals. The Schiøtz tonometer is a simple indentation tonometer, but unless used properly can give misleading values. Applanation tonometers include the air tonometer, pneumatonograph, and the Goldmann type (either slit-lamp or hand-held models). These flatten a small, fixed area of cornea and measure the resultant pressure. In anesthetized animals anterior chamber cannulation may be performed, although breakdown of the blood-aqueous barrier can ensue together with an alteration of intraocular pressure. Of importance is that all tonometers be calibrated for each species since scleral rigidity, ocular curvature, pressure/volume relationships, etc. all vary between species.

Humans↗

PubMedDate not supplied

[Proxodolol, a new domestic preparation for lowering intraocular pressure in glaucoma].

Effects of a Russian b-a-adrenoblocker proxodolol on the intraocular pressure, ocular hemodynamics, pupil diameter, ocular functions, arterial pressure, and heart rate were studied in 105 patients (163 eyes) with primary open-angle glaucoma. A manifest hypotensive effect of proxodolol was due to depression of aqueous humor production and improvement of its outflow. Comparative study of the efficacies of proxodolol and timolol maleate by the blind test and randomization demonstrated the identity of these drugs. A synergic effect on intraocular pressure was observed when proxodolol was combined with pilocarpine and/or klofelin.

Adrenergic alpha-Antagonists↗