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PubMed1995

Suprachiasmatic nucleus in the neural circuitry for the circadian elevation of intraocular pressure in rabbits.

Intraocular pressure (IOP) in light-dark entrained rabbits changes in a circadian pattern. Previous studies indicate that signals for the circadian IOP elevation in the early dark phase come from the central nervous system (CNS) via the ocular sympathetic nerves. Its neural circuitry in the CNS was totally unclear. In the present study, the role of the suprachiasmatic nucleus in the circuitry was investigated. Adult New Zealand albino rabbits were entrained in a daily 12 hr/12 hr light-dark cycle, and their circadian IOP elevations around the onset of dark were determined. Bilateral lesions of the suprachiasmatic nuclei were made by heat probe and verified by histology. Change in the circadian IOP elevation was monitored for up to 3 months. After the lesion, there was a significant reduction of the circadian IOP elevation for 2 weeks. Elevations in the plasma concentration of melatonin and the aqueous humor concentration of norepinephrine (NE) in the early dark phase were significantly reduced. When exposed to constant light, the residual circadian IOP elevation in the postoperative rabbits was further reduced to the level seen in intact rabbits exposed to constant light. In postoperative weeks 6-10, the circadian IOP elevation returned to the initial value. A full, inhibitory effect of constant light on the circadian IOP elevation was observed. In postoperative months 2-3, concentrations of plasma melatonin and aqueous humor NE regained the circadian pattern. These results indicate that the suprachiasmatic nucleus is in the neural circuitry which propagates the circadian elevation of IOP in rabbits.

Animals↗
PubMed2026

Nonuniform Association of Genetic Risk Scores for Intraocular Pressure.

IMPORTANCE: Elevated intraocular pressure (IOP) is a risk factor for primary open-angle glaucoma, and genetic risk scores hold promise as a tool for screening for ocular hypertension. However, genetic risk scores for IOP have a nonuniform association across the range of IOP, which reduces their accuracy. OBJECTIVE: To test the hypothesis that nonuniform behavior of genetic risk scores for IOP is associated with a specific type of genetic interaction. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional, post hoc genetic association studies were performed using linear and quantile regression in a sample of UK Biobank participants. Data were analyzed from January to September 2025. EXPOSURES: Ninety-eight genetic variants associated with IOP. MAIN OUTCOMES AND MEASURES: Tests were carried out for 98 genetic variants associated with IOP (P&#x2009;<&#x2009;5.0&#x2009;&#xd7;10-8) to examine (1) dominant or recessive genetic effects, (2) genotype&#x2009;&#xd7;&#x2009;genotype interactions, (3) genotype&#x2009;&#xd7;&#x2009;age interactions, and (4) genotype&#x2009;&#xd7;&#x2009;sex interactions. RESULTS: A total of 98&#x202f;235 participants (mean [SD] age, 58.1 [7.9] years; 52&#x202f;168 female [53.1%]) were included in this analysis. More variants exhibited genotype&#x2009;&#xd7;&#x2009;age interactions than expected by chance (14 of the 98 variants associated with IOP had at least nominal evidence of an interaction with age; P&#x2009;=&#x2009;3.76&#x2009;&#xd7;10-4). For 12 of these 14 variants, age increased rather than decreased the magnitude of the IOP vs genotype association. However, integrating age interactions into the genetic risk score construction process did not yield improved accuracy (incremental noninteraction model, R2&#x2009;=&#x2009;4.05; 95% CI, 3.82-4.31 and interaction model, R2&#x2009;=&#x2009;4.04; 95% CI, 3.80-4.27). There was little support for other types of genetic interaction. CONCLUSIONS AND RELEVANCE: In the current work, findings show minimal evidence that nonadditive allelic effects, genotype&#x2009;&#xd7;&#x2009;genotype interactions, and genotype&#x2009;&#xd7;&#x2009;sex interactions contributed to the nonuniform association of genetic variants with IOP across quantiles of IOP. Although a genetic risk score for IOP was more accurate in older vs younger individuals, efforts to account for genotype&#x2009;&#xd7;&#x2009;age interactions in genetic risk score construction did not improve accuracy. These findings suggest other factors, such as gene-environment interactions, contribute to the nonuniform relationship of genetic variants with IOP.

Humans↗
PubMed1988

[Modification in amplitude of nycthemeral changes in intraocular pressure under timolol].

Diurnal variations of intraocular pressure are probably related to indolamines, prostaglandins, and the sensory nervous system. Because timolol maleate is able to block beta-1, beta-2, and dopaminergic receptors, as well as to act like an antagonist of serotonin, we evaluated its effect on diurnal variations of intraocular pressure. Eighty-eight intraocular pressure curves were established in 22 normal young volunteers. Intraocular pressures were measured in both eyes before and one week after the beginning of monolateral treatment with timolol 0.5% twice daily. The results showed a decrease in amplitude of diurnal variations of 24% (P = 0.07 in paired t-test) in timolol-treated eyes and no significant change in the contralateral eyes. The difference between both eyes was statistically significant in paired t-test (P = 0.01). Knowing the type of receptors on which timolol is susceptible to act, and furthermore, the type of neuro-transmitter which may be involved in the regulatory mechanisms of diurnal variations of intraocular pressure, we suggest that timolol could reduce the amplitude of these variations by means of interactions with indolamines.

Adult↗
PubMed1985

The effect of prophylactic acetazolamide on the intraocular pressure rise associated with Healon-aided intraocular lens surgery.

Sixteen consecutive patients undergoing primary posterior chamber lens insertion with Healon were followed closely for any postoperative rise in intraocular pressure. Patients were divided into an experimental group (who received acetazolamide) and a control group (no acetazolamide). Careful attention was given to the same operative technique and the amount of Healon left in the eye. The treated group showed a mean intraocular pressure of 14.7 mm Hg, whereas the pressure in the control group was 22.6 mm Hg on the first postoperative day. These findings support the rationale for the use of prophylactic acetazolamide as an adjunct to Healon-aided cataract surgery.

Acetazolamide↗
PubMed1987

Effect of body position on intraocular pressure and aqueous flow.

The relationship between intraocular pressure and the rate of aqueous humor formation was studied in human subjects. Intraocular pressure was altered by changing the subject's gravity-dependent body position. Aqueous humor flow was measured fluorophotometrically. An average change of intraocular pressure of 2.4 +/- 1.2 mmHg and 11.2 +/- 2.7 mmHg was recorded in subjects whose body position was alternated +/- 15 degrees from horizontal and +/- 50 degrees from horizontal. No change of the rate of fluorescein clearance was observed for the milder change of position. A small change of fluorescein clearance was noted in response to the steeper change of position. Changing intraocular pressure seems not to induce compensatory changes in aqueous flow. Therefore we conclude that aqueous formation is relatively pressure-insensitive, a conclusion one would draw from clinical instances of angle-closure glaucoma or as in other systems of secretion, such as the toad bladder or the cerebrospinal fluid, where alterations in pressure do not necessarily influence flow. If there is a regulator of aqueous flow it is not responsive to the changes in intraocular pressure brought about in this study. If aqueous flow regulates intraocular pressure or compensates for changes in intraocular pressure, the signal is not small changes in pressure.

Adolescent↗
PubMed2002

Subtenon's depot corticosteroid injections in patients with a history of corticosteroid-induced intraocular pressure elevation.

PURPOSE: To determine whether a history of intraocular pressure elevation from local corticosteroid administration could predict subsequent intraocular pressure elevation after posterior subtenon's corticosteroid injection. METHODS: A retrospective review was performed of 64 consecutive patients (64 eyes) receiving posterior subtenon's corticosteroid injection. Patients were categorized as either historical corticosteroid responders or nonresponders based on intraocular pressure response to topical corticosteroid drops in the same eye or to previous posterior subtenon's corticosteroid injection of the fellow eye. Historical responders were defined as having a relative intraocular pressure increase of 5 mm Hg and absolute intraocular pressure greater than 24 mm Hg with an anatomically open angle. Relative risk of intraocular pressure elevation was evaluated based on historical response and presenting diagnosis. RESULTS: Nine eyes were historical responders, and 55 eyes were historical nonresponders. A higher rate of recurrent intraocular pressure elevation developed in historical responder eyes (4 of 9, 44%) compared with nonresponders (7 of 55, 13%) after posterior subtenon's injection (P = .04, Fisher's test; P = .07, Kaplan-Meier analysis). Historical responders with uveitis were at significantly higher risk of intraocular pressure elevation than nonresponders without uveitis (hazard ratio = 10.8, P = .04, Cox proportional hazards). All but one eye that developed intraocular pressure elevation from posterior subtenon's injection was adequately controlled with topical antiglaucoma therapy. CONCLUSION: In nonglaucomatous eyes, a previous history of corticosteroid-induced intraocular pressure elevation is a relative, not absolute, contraindication to posterior subtenon's corticosteroid injection, because the risk of intraocular pressure elevation is not absolute, and because it can usually be well controlled with topical antiglaucoma therapy.

Adult↗
PubMed1994

Effect on intraocular pressure of local anaesthesia in eyes undergoing intraocular surgery.

A total of 104 eyes undergoing intraocular surgery were studied to investigate the effect on intraocular pressure (IOP) of peribulbar and retrobulbar anaesthesia in eyes with and without glaucoma. Forty eyes had glaucoma. Intraocular pressure was measured before, immediately after, and 5 minutes after injection of local anaesthetic. Mean IOP rose by 5.8 mm Hg at 1 minute (p < 0.01) and 0.7 mm Hg at 5 minutes (p > 0.05). However, in eyes not receiving external ocular compression after the 1 minute measurement (n = 70, 67%), IOP was still 3.6 mm Hg higher than baseline (p < 0.01), compared with 5.2 mm Hg lower than baseline (p < 0.01) where compression was used. Patients with glaucoma experienced higher and more persistent increases in IOP than those without glaucoma. The increase in IOP varied greatly between patients: the maximum rise was 25 mm Hg, and in one glaucoma patient an IOP of 50 mm Hg occurred, persisting for 5 minutes. At 1 minute, 14 of the glaucoma subjects (35%) had experienced an IOP rise of > or = 10 mm Hg, and four (10%) a rise of > or = 20 mm Hg. These results suggest that the changes in IOP in patients with glaucoma, with an acute increase in IOP being succeeded by an acute decrease on entry into the anterior chamber, may be hazardous. The implications for clinical practice are discussed.

Anesthesia, Local↗
PubMed1998

Changes in anterior chamber depth and intraocular pressure after phacoemulsification and posterior chamber intraocular lens implantation.

BACKGROUND AND OBJECTIVE: To determine anterior chamber depth (ACD) and intraocular pressure (IOP) following uncomplicated cataract extraction with phacoemulsification and posterior chamber intraocular lens (IOL) implantation. PATIENTS AND METHODS: The ACDs and IOPs of 56 patients were prospectively evaluated after phacoemulsification and IOL implantation. Measurements of ACD were performed using ultrasonography and measurements of IOP were performed using a Goldmann applanation tonometer preoperatively and at 1 week and 1, 3, 6, and 9 months postoperatively. RESULTS: The mean IOP had decreased and the mean ACD had increased significantly by 1 month postoperatively (P < .03 and P < .01, respectively). Between 1 and 3 months, a significant increase in ACD (P < .05) and decrease in IOP (P < .01) was also observed. The ACD peaked (3.51 +/- 0.45 mm) and the IOP reached its lowest value (10.05 +/- 2.23 mm Hg) at 3 months postoperatively. The reduction in IOP and increase in ACD remained significant during the follow-up period, compared with the preoperative values. CONCLUSION: These results suggest that increases in ACD and decreases in IOP occur in selected patients after uncomplicated cataract extraction by phacoemulsification with IOL implantation.

Adult↗
PubMed1994

Reduction of intraocular pressure after phacoemulsification and aspiration with intraocular lens implantation.

We prospectively evaluated the pre- and postoperative intraocular pressures (IOP) of 1,118 cataract patients. All surgical procedures were performed by the same skilled surgeon using the same method of phacoemulsification and aspiration with intraocular lens implantation. The mean +/- SE preoperative IOP was 13.29 +/- 0.12 mm Hg, while the mean IOP values were 10.87 +/- 0.12, 9.94 +/- 0.09, and 10.43 +/- 0.14 mm Hg 1, 3, and 6 months, respectively, after surgery. When the preoperative IOP was in the low 20 s, a decrease of approximately 40% was achieved. The present study shows that the IOP decreased postoperatively to a greater extent than previously considered, and the rate of decrease was dependent on the initial measurement.

Aged↗
PubMed2003

Which endpoint: mean intraocular pressure or proportion of successful patients?

A reduction in intraocular pressure in clinical trials can be determined through the mean intraocular pressure, through the proportion of patients who have the intraocular pressure reduced to a specific target intraocular pressure, or both. Since both these possible endpoints measure the shift of 2 intraocular pressure distributions, we recommend that only one of them be tested. In general, testing the difference between mean-values is much more efficient than testing the difference between proportions. However, proportions of successful patients are valuable in showing the clinical implication of a reduction in mean intraocular pressure, particularly when evaluating a moderate pressure reduction. The effect of a small mean intraocular pressure reduction on the probability to reach the target intraocular pressure is pointed out, particularly the fact that it can be substantial even if the mean reduction is smaller than the measurement error.

Data Interpretation, Statistical↗
PubMed1984

Intraocular pressure in retinal vein occlusion.

The intraocular pressure of 59 patients with retinal vein occlusion was studied. Central retinal vein occlusion (CVO) was diagnosed in 24 patients and branch retinal vein occlusion (BVO) was diagnosed in the rest. The intraocular pressure of a sex and age matched group of controls was also studied for comparison. The intraocular pressure in the CVO group were significantly different from those of the matched controls (p less than 0.001). A statistically significant difference of a lesser degree (p less than 0.05) was also found in a comparison of the intraocular pressures of the BVO group with those of their sex and age matched group of controls. These findings may indicate the possible role of increased intraocular pressure in the pathogenesis of CVO and BVO.

Constriction, Pathologic↗
PubMed2006

[What do we know about intraocular pressure in the Togolese population?].

BACKGROUND: Intraocular pressure is a major ocular risk factor of chronic open angle glaucoma. This study aimed to describe characteristics of intraocular pressure in a defined black African population. METHODS: Hospital outpatients were recruited for this study, and all measures were taken with a pulse air tonometer between 8 AM and 12 AM; some participants were glaucoma patients under medical treatment. On the whole, 7,042 participants (13,831 eyes) were included in this study. RESULTS: The mean age of all participants was 41 +/- 18 years: 9.9% were under 16 years of age; 21.2% were between 35 and 44 years old. The average intraocular pressure was 17.05+/-5.93 mmHg; for the subgroup under 16 years of age. Girls had higher pressure than boys: 16.01 vs 16.32 mmHg in the right eye. For those over 16 years of age, pressures were higher in men, with an average of 17.45 mmHg vs 16.67 mmHg in the right eye. High intraocular pressure was found in 22.28% of the participants, with values ranging from 20 to 29 mmHg in 86.8% of cases. The relative prevalence of hypertony seems to increase with age, reaching 30% for those aged 55-64 years. CONCLUSION: There is a high rate of hypertony in our findings, which seems to correlate with the increased glaucoma prevalence already described in the Togolese population. We concluded that in our setting, the prevention of glaucoma in isolated hypertonies and the management of glaucomatous cases warrant a thorough assessment of intraocular pressure at all ages.

Adolescent↗
PubMed1989

[The blood flow in post-laminar optic nerve in monkeys was dependent on intraocular pressure level].

The effects of artificial elevation of intraocular pressure on the blood flow in the 1mm post-laminar portion of the optic nerve was evaluated in 9 monkeys (Macaca fuscata). The intraocular pressure of one eye was elevated while the fellow eye served as control. The intraocular pressure of the control was maintained at 15 mmHg. We used the hydrogen clearance method in quantitating the blood flow. Anesthesia was maintained with injection of pentobarbital sodium into the femoral vein. In each experiment, the intraocular pressure was raised from 15 mmHg to 30, 50 or 70 mmHg in a stepwise fashion. At the intraocular pressure level of 15 mmHg, the blood flow measured 120.0 +/- 19.4 ml/min/100g (mean +/- standard deviation). The blood flow decreased linearly along with the rise of intraocular pressure up to 70 mmHg. The blood flow at 70 mmHg was 37% of the initial value. At each level of raised intraocular pressure, the blood flow remained constant for at least 60 minutes. The decreased blood flow promptly returned to the initial level when the raised intraocular pressure was restored to the initial value of 15 mmHg. We concluded from the above findings that the blood flow in the immediate post-laminar portion of the optic nerve is dependent on the level of intraocular pressure up to 70 mmHg.

Animals↗
PubMed1997

Ten-year follow-up of intraocular pressure after phacoemulsification and aspiration with intraocular lens implantation performed by the same surgeon.

We evaluated the pre- and postoperative intraocular pressure (IOP) levels of 498 patients, to determine whether IOPs are affected over a 10-year period. All surgeries were performed by the same surgeon using phacoemulsification and aspiration (PEA) with posterior chamber intraocular lens (PCIOL) implantation. The mean preoperative IOP was 12.2 +/- 4.0 mm Hg, and the mean postoperative IOPs were not affected for 10 years. However, when the preoperative IOP was over 20 mm Hg, a significant decrease was achieved without glaucoma surgery. When the preoperative IOP was under 10 mm Hg, the IOP significantly increased. PEA with implantation of a PCIOL provides an excellent chance for improved intraocular tension control, providing that the surgery is properly performed.

Aged↗
PubMed1990

Intraocular pressure in school myopia.

The relationship between intraocular pressure and ocular refraction and axial length were studied in a follow-up of myopic children and in a cross-section sample of school children. In the follow-up group intraocular pressure significantly decreased with age. Mean intraocular pressure at the mean age of 10.9 years was 17.4 mmHg, and three years later 16.1 mmHg. Intraocular pressure above 20 mmHg was recorded in 7.6% of total measurements in the follow-up group and in 8.7% of cases in the cross-section sample. There was a significant correlation between mean intraocular pressure and the spherical equivalent both at the beginning and at the end of the study in the follow-up group and in the cross-section sample among the boys only. There was also a significant positive correlation between intraocular pressure and axial length at the end of the follow-up among the boys but not among the girls.

Adolescent↗
PubMedDate not supplied

Comparative evaluation of intraocular pressure changes subsequent to insertion of laryngeal mask airway and endotracheal tube.

AIMS: To evaluate the intraocular pressure and haemodynamic changes subsequent to insertion of laryngeal mask airway and endotracheal tube. SUBJECTS AND METHODS: The study was conducted in 50 adult patients. A standard general anaesthesia was administered to all the patients. After 3 minutes of induction of anaesthesia baseline measurements of heart rate, non-invasive blood pressure and intraocular pressure were taken following which patients were divided into two groups: laryngeal mask airway was inserted in group 1 and tracheal tube in group 2. These measurements were repeated at 15-30 second, every minute thereafter up to 5 minutes after airway instrumentation. RESULTS: A statistically significant rise in heart rate, systolic blood pressure, diastolic blood pressure and intraocular pressure was seen in both the groups subsequent to insertion of laryngeal mask airway or endotracheal tube. Mean maximum increase was statistically more after endotracheal intubation than after laryngeal mask airway insertion. The duration of statistically significant pressure responses was also longer after endotracheal intubation. CONCLUSION: Laryngeal mask airway is an acceptable alternative technique for ocular surgeries, offering advantages in terms of intraocular pressure and cardiovascular stability compared to tracheal intubation.

Adult↗