Increase In IOP Research Articles

The amount of intraocular pressure rise during pharmacological pupillary dilatation is an indicator of the likelihood of future progression of glaucoma

Aim:To determine if there is a relationship between the amount of increase in IOP following dilatation with a cycloplegic agent and the future course of glaucoma.Method:A retrospective chart review of...

Melanopsin-Expressing Retinal Ganglion Cells Are More Injury-Resistant in a Chronic Ocular Hypertension Model

To investigate the survival of melanopsin-expressing retinal ganglion cells (mRGCs) after the induction of chronic ocular hypertension. Intraocular pressure (IOP) was elevated in adult Sprague-Dawley rats using an argon laser to photocoagulate the episcleral and limbal veins. IOP was measured with a calibrated tonometer and monitored for a period. Seven days before the animals were killed, a piece of sterile foam soaked with gold fluorescent dye was placed onto the superior colliculus (SC) to label the SC-projecting retinal ganglion cells (scRGCs) retrogradely. mRGCs were visualized by free floating immunohistochemistry on whole-mounted retinas. The number of surviving scRGCs and mRGCs were counted on flatmounted retinas. The branching pattern of dendrites and soma size of mRGCs were examined. An approximately 1.7-fold increase of IOP and a significant loss of scRGCs were found in experimental eyes after laser photocoagulation. However, no significant cell loss or morphologic changes on mRGCs and their dendrites after the induction of chronic ocular hypertension are noticed over a 12-week period. Although the degeneration of retinal ganglion cells (RGCs) is a major concern in glaucomatous damage, the findings show that mRGCs are less susceptible to death after the induction of chronic ocular hypertension. This result indicates that mRGCs carry some unique properties that are different from those of other subpopulations of RGCs. The immunohistochemistry approach can be used to distinguish easily these mRGCs from other subtypes. This method provides a useful tool to investigate their injury-resistant properties that are informative for the development of effective neuroprotective treatment for glaucoma.

A Cellular Solid Model of the Lamina Cribrosa: Mechanical Dependence on Morphology

The biomechanics of the optic nerve head (ONH) may underlie many of the potential mechanisms that initiate the characteristic vision loss associated with primary open angle glaucoma. Therefore, it is important to characterize the physiological levels of stress and strain in the ONH and how they may change in relation to material properties, geometry, and microstructure of the tissue. An idealized, analytical microstructural model of the ONH load bearing tissues was developed based on an octagonal cellular solid that matched the porosity and pore area of morphological data from the lamina cribrosa (LC). A complex variable method for plane stress was applied to relate the geometrically dependent macroscale loads in the sclera to the microstructure of the LC, and the effect of different geometric parameters, including scleral canal eccentricity and laminar and scleral thickness, was examined. The transmission of macroscale load in the LC to the laminar microstructure resulted in stress amplifications between 2.8 and 24.5xIOP. The most important determinants of the LC strain were those properties pertaining to the sclera and included Young's modulus, thickness, and scleral canal eccentricity. Much larger strains were developed perpendicular to the major axis of an elliptical canal than in a circular canal. Average strain levels as high as 5% were obtained for an increase in IOP from 15 to 50 mm Hg.

Macular oedema in central retinal vein occlusion treated with intravitreal triamcinolone

To investigate the efficacy of intravitreal triamcinolone as treatment for macular oedema in central retinal vein occlusion (CRVO). We conducted a retrospective comparative case series of nine patients with macular oedema associated with CRVO (six non-ischaemic and three ischaemic) treated with an intravitreal injection of 4 mg triamcinolone acetonide, compared with 10 control (observation) patients (six non-ischaemic and four ischaemic). Examination included visual acuity (VA) tests and complete ophthalmic examinations at baseline, 1, 2 and 6 months postoperatively. The mean baseline VA was 20/161 for CRVO treatment group patients and 20/75 for observation group patients (p = 0.15). No significant difference in VA between CRVO treatment group patients (20/99) and controls (20/282) was observed at the final 6-month visit (p = 0.33). Subgroup analysis of the non-ischaemic CRVO treatment patients compared with the non-ischaemic controls also showed no significant difference at the 6-month visit (20/59 and 20/100, respectively; p = 0.20). At 6 months, five of the six non-ischaemic treated patients had VA >or= 20/100, compared with five of the six non-ischaemic control patients. All patients tolerated the procedure well, but there was a significant increase in intraocular pressure by the 2-month visit (p = 0.015). Intravitreal injection of triamcinolone may not be effective for treatment of macular oedema in all CRVO patients or all non-ischaemic CRVO patients. A trend towards VA improvement was noted but was not statistically significant. Although our treatment was not hindered by severe complications, there was a significant increase in IOP in the 2 months following treatment.

Ocular Hypertensive Response to Topical Dexamethasone Ointment in Children

PurposeTo investigate the rate and the degree of the ocular hypertensive response to dexamethasone ointment in children undergoing eyelid surgery.MethodsDexamethasone ointment (Dexcosil®) was applied three times a day for the first week and twice a day for the second to third week postoperatively to children undergoing epiblepharon surgery. Intraocular pressure (IOP) was measured on the day before surgery, postoperative day 1, 7, 14, 21, 28 and 2 weeks thereafter until the IOP reached preoperative levels. Peak IOP, IOP net increase and time to reach a peak IOP were analyzed. Dexamethasone ointment was discontinued if the IOP was 25 mmHg or more.ResultsA total of 96 children (mean age, 6.5±2.7 years) were included. Preoperative mean IOP was 13.6±2.9 mmHg (range 7-19). After dexamethasone ointment treatment, the children showed a significant rise in IOP as compared with the preoperative values. The peak IOP was 20.6±4.9 mmHg (range 11-39) and the time to reach peak IOP was 8.5±5.9 days. The low responders (delta IOP ≤5 mmHg) of our group comprised 35.4% (34/96) of patients, intermediate responders (delta IOP 6-15 mmHg) comprised 56.3% (54/96) of patients and high responders (delta IOP≥16) comprised 8.3% (8/96) of patients. A net increase in IOP was significantly higher in children 5 years old or less as compared with those older than 5 years (age ≤5, 9.4±7.5 mmHg vs age >5, 6.3±4.4 mmHg; p=0.015, unpaired t-test).ConclusionsOcular hypertensive response after dexamethasone ointment to the eyelids occurred frequently in children, especially those 5 years old or younger.

Intraocular pressure rise after phacoemulsification surgery in glaucoma patients

Reply: Drs. Liu and coauthors raise an important question about the short-term changes in IOP after phacoemulsification surgery in eyes with OAG.1 Our study demonstrated that the IOP increased transiently from 1 to 3 days after phacoemulsification surgery, but then gradually decreased. Furthermore, a marked rise in IOP to 30 mm Hg or more occurred the day after surgery in approximately 13% of OAG eyes. Liu and coauthors suggest that the increase in IOP shortly after surgery might be due to withdrawal of antiglaucoma drugs. However, several previous studies show that the IOP gradually decreases for several weeks after cataract surgery2–4; more recent studies report a transient rise in IOP in the early postoperative days in glaucomatous eyes as well as in eyes without glaucoma.5,6 Furthermore, it is well known that an early IOP elevation occurs in a certain percentage of glaucoma patients,7 so our results are consistent with those in previous studies. The transient increase in IOP does not appear to be due to the withdrawal of antiglaucoma medications. The IOP-reducing effect of ß-blockers is known to last for 2 weeks after cessation,8 and in the article by Linden and coauthors9 cited by Liu and coauthors, the effect of latanoprost is shown to be substantial for at least 1 week after cessation. Based on these studies, it is improbable that the IOP increases suddenly the day after withdrawal. We believe the IOP elevation immediately after surgery is related to deterioration of the outflow facility due to minimum residual cortex, inflammatory cells, and, possibly, residual ophthalmic viscosurgical device. When we examine the IOP in the patients who received and those who did not receive antiglaucoma drugs before surgery, we find no significant difference in the mean IOP throughout the period of follow-up (Table 1). In addition, the mean decrease in IOP from the preoperative level was similar in the 2 groups. Furthermore, the marked increase in IOP occurred in 3 (12%) of the 25 eyes that received antiglaucoma drugs and in 1 (14.2%) of the 7 eyes that did not; this occurrence was not significantly different using the survival analysis (P=.8736). These results indicate that the increase in IOP seen in the early postoperative period was not related to withdrawal of antiglaucoma medications.Table 1: Comparison of mean IOP and decrease in IOP between the group that received antiglaucoma medications before surgery and the group that did not.Hitoshi Yasutani MD Ken Hayashi MD Hideyuki Hayashi MD Fumihiko Hayashi MD

Short-Term Increase of Intraocular Pressure Does Not Alter the Response of Retinal and Optic Nerve Head Blood Flow to Flicker Stimulation

It has been shown that stimulation with diffuse luminance flicker induces vasodilatation in the human retina and increases optic nerve head (ONH) blood flow. The present study was designed to investigate the influence of a short-term increase in intraocular pressure on flicker-induced changes in ONH blood flow and retinal vessel diameters. In a group of 15 healthy volunteers, IOP was increased by the episcleral suction cup technique. ONH blood flow was assessed with a laser Doppler flowmeter, and retinal vessel diameters were measured with the retinal vessel analyzer. Flicker responses of retinal vessel diameters and ONH blood flow were determined at baseline conditions and during suction of 70 and 140 mm Hg. Flicker light consisted of 8-Hz square-wave flashes at a wavelength below 550 nm and produced a retinal irradiance of 140 muW/cm(2). Suction increased IOP from 12 +/- 2 to 27 +/- 4 mm Hg and 43 +/- 4 mm Hg. Stimulation with diffuse luminance flicker induced an increase in ONH blood flow of +24.0% +/- 20.7%. Increased IOP did not significantly change the flicker response in the ONH (+19.3% +/- 26.6% and +22.1% +/- 25.1%). In retinal veins, flicker induced an increase in vessel diameter of +3.0% +/- 2.0%. Flicker responses in retinal veins were not significantly altered after the IOP was increased, compared with those recorded at baseline IOP (+2.8% +/- 2.5% and +3.2% +/- 2.2%). The flicker response in retinal arteries at baseline IOP was +3.5% +/- 2.0%. Again, the increase in IOP did not significantly alter this flicker response (+2.8% +/- 1.6% and +3.1% +/- 2.4%). A short-term increase in IOP does not alter the response of retinal vessel diameters and ONH blood flow to diffuse luminance flicker, which indicates that increased IOP does not alter retinal or ONH regulation during neuronal stimulation.

Effect of Latanoprost 0.005% and Brimonidine 0.2% on Intraocular Pressure After Phacoemulsification and Intraocular Lens Implantation Surgery

patients). IOP was measured 6, 12, and 24h postoperatively with the Goldmann applanation tonometer. The preoperative IOP assessment was taken at 0900 hours and 1700 hours on the day before surgery. The baseline IOP was determined by calculating the mean value of both IOP measurements. Surgery was performed with peribulbar anesthesia. The changes from baseline at each time within each of the treatment groups were evaluated statistically with Wilcoxon signed rank tests, while the Mann-Whitney U test of the group median was used for comparing the three groups. Table 1 shows preoperative and postoperative IOP for the latanoprost, brimonidine, and control groups. There were no significant differences in preoperative IOP among the three groups. In the latanoprost and brimonidine groups, there was no statistically significant increase in mean IOP at 6, 12, or 24h postoperatively (P 0.05). However, there were statistically significant increases in mean IOP at 6, 12, and 24h postoperatively in the control group compared with the preoperative mean IOP (P 0.01). At 6, 12, and 24h postoperatively, IOPs were significantly higher in the control group than in the latanoprost and brimonidine groups (P 0.05). We did not see any ocular or systemic complications.

Efeitos da injeção subtenoniana posterior de corticóide em pacientes com uveíte

PURPOSE: To determine the effects of posterior subtenon steroid injection (PSSI) according to intraocular pressure and visual acuity, in patients with uveitis. METHODS: Eighteen patients with diagnosis of uveitis were analized and submitted to posterior subtenon steroid injection of triancinolone acetonide (Kenalog® 40mg - 9 patients, 14 injections) or of methyl- prednisolone acetate (Depomedrol® 40mg - 9 patients, 15 in- jections) for the treatment of chronic eye inflammation or cystoid macular edema. RESULTS: Final visual acuity improved in 92% of the patients after the first injection; 50% improved one line, and 42% improved at least three lines. The mean time for improvement was three weeks. Increase of IOP occurred in 44% of the patients (8 patients), who showed a mean intraocular pressure of 31 mmHg and a range of 21 to 38 mmHg. It was more frequent among young patients, and in the Kenalog® group, with onset after 2.5 weeks on average. CONCLUSION: A subtenoninjection of corticosteroids appears to be an effective treatment for decreased vision associated with some types of uveitis, such as intermediate uveitis, Behcet's disease, Vogt-Koyanagi-Harada syndrome, retinal vasculitis and rheumatoid arthritis. However, it may contribute to increase in intraocular pressure in some cases, specially in children and young patients.

Optimal Dosage of Propofol for Prevention of Increase in IOP during Rapid Sequence Induction with Endotracheal Intubation

Optimal Dosage of Propofol for Prevention of Increase in IOP during Rapid Sequence Induction with Endotracheal Intubation

Relevance of long-term follow-up of cyclocryocoagulation

In spite of the availability of cyclocryodestructive laser therapy there still appears to be an indication for cyclocryotherapy in different kinds of glaucoma. Cyclocryotherapy very often appears to be the operation of choice in cases of progressive functional visual loss if a patient is not sufficiently helped with the maximum tolerated medical therapy. We investigated long-term IOP effects and possible complications in our group of patients undergoing cyclocryotherapy. Cyclocryotherapy was performed on 109 eyes of 97 patients from 1988 to 1994. Cyclocryotherapy was performed as follows: 67 of 109 eyes were controlled for IOP for an average of 10 months (3-41 months). We applied cryotherapy six times 3-4 mm behind the limbus for an average duration of 50 to 60 s over half of the circumference. We achieved satisfactory IOP control (IOP < or = 22 mm Hg) in 40 eyes, however, with 30 additional operations. One eye developed phthisis bulbi, and 3 other eyes became blind because of complications in neovascular glaucomas. Neovascular glaucoma cases responded the least. Cyclocryotherapy produced a statistically significant IOP reduction in eyes with primary open-angle glaucoma or secondary glaucoma. Close long-term follow-up appears advisable in order to check the eyes for possible increase in IOP or complications of surgery.

Circadian intraocular pressure variation with beta-blockers.

To investigate circadian intraocular pressure variation in patients treated with topical beta-blockers as monotherapy. Circadian IOP curves were measured on 25 patients (47 eyes) treated with topical beta-blockers. IOP was recorded 4 times during the day and twice at night. All IOP measurements were taken using a non-contact tonometer. IOP at night was significantly higher than IOP during the day. Thirty-four percent exhibited an increase in IOP of more than 5 mmHg at night, and 15% exhibited an increase of 10-18 mmHg at night. The median range of circadian IOP variation was 7 mmHg. Determined separately by day, the range of IOP variation was 4 mmHg. Patients treated with beta-blockers as monotherapy may experience greater variations in IOP than can be detected by conventional daytime IOP measurements.

On the relevance of the long-time follow-up of the cyclocryotherapy

In spite of the availability of cyclocryodestructive laser therapy there still appears to be an indication for cyclocryotherapy in different kinds of glaucoma. Cyclocryotherapy very often appears to be the operation of choice in cases of progressive functional visual loss if a patient is not sufficiently helped with the maximum tolerated medical therapy. We investigated long-term IOP effects and possible complications in our group of patients undergoing cyclocryotherapy. Cyclocryotherapy was performed on 109 eyes of 97 patients from 1988 to 1994. Cyclocryotherapy was performed as follows: 67 of 109 eyes were controlled for IOP for an average of 10 months (3-41 months). We applied cryotherapy six times 3-4 mm behind the limbus for an average duration of 50 to 60 s over half of the circumference. We achieved satisfactory IOP control (IOP K 22 mm Hg) in 40 eyes, however, with 30 additional operations. One eye developed phthisis bulbi, and 3 other eyes became blind because of complications in neovascular glaucomas. Neovascular glaucoma cases responded the least. Cyclocryotherapy produced a statistically significant IOP reduction in eyes with primary open-angle glaucoma or secondary glaucoma. Close long-term follow-up appears advisable in order to check the eyes for possible increase in IOP or complications of surgery.

Combined phacoemulsification and goniotrepanation in primary chronic open angle glaucoma and classical pseudoexfoliation glaucoma

Combined glaucoma and cataract operation has been demonstrated to be effective in controlling IOP and increasing visual acuity. Because of the differences between patients with primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXEG), for cataract and glaucoma surgery alone we evaluated the effects and complications for simultanous surgical management. In a retrospective study 103 patients were examined who underwent a combined phacoemulsification and goniotrephination between January 1993 and January 1997 and had no surgery before (110 eyes with POWG, 22 eyes with PXEG). The average age in the POAG group (75.1 +/- 8.7 years) was significantly less than in the PXEG group (79.3 +/- 5.9 years) (P < 0.05). The mean preoperative IOP in PXEG (31.8 +/- 10.3 mmHG) was significantly higher than in POAG (25.0 +/- 6.4 mmHg) (P < 0.0005). Due to the combined surgery the mean intraocular pressure decreased in both groups < 10 mmHg (days 1 and 7). PXEG had a significantly higher IOP at day 3 than POAG (12.3 +/- 8.4 mmHg versus 8.5 +/- 5.7 mmHg) (P < 0.05) and developed after combined operation IOP peaks > 25 mmHg into a significantly higher level (P < 0.05). Moreover, zonulolysis, rupture of the posterior capsule, vitreous loss and persistence of inflammatory response occurred more often in PXEG, but there was no significant difference compared to POAG. PXEG has an higher incidence of typical problems of phacoemulsification, a temporary increase of IOP and prolonged inflammation after combined cataract and glaucoma surgery than POAG, but there is a similar risk compared to a single procedure.

Peak pulse blood volume in controlled modification of local perfusion parameters

Choroidal autoregulation is discussed controversially. The present study was designed to investigate for the effect of standardized manipulation of local perfusion parameters on choroidal hemodynamics in cynomolgus monkey eyes with lasersurgically induced glaucoma (CMG; German abbreviation: RA-LHDG). CMG unilaterally received 2-3 laser treatments so as to develop the lasered-eye glaucoma model. Intraocular pressure (IOP; German abbreviation: IOD) and Ocular Pulse Amplitude (OPA) were measured and Peak Pulse Blood Volume (PPBV; German abbreviation: PGBV) was determined. In CMG PPBV was not significantly (sig., p > 0.05) altered in laser-treated eyes--despite a sig. (p < 0.05) increase in IOP. Untreated contralateral control eyes of monkeys with an IOP-increase > 5 mm Hg in laser-treated eyes showed a sig. (p < 0.05) increase in PPBV. Unchanged PPBV in laser-treated eyes of CMG and an increase in PPBV in control eyes point at a bilateral autoregulatory compensatory mechanism, which is more manifest in eyes with IOPs in the normal range.

Initial clinical experience with the picosecond Nd:YLF laser for intraocular therapeutic applications

AIMS/BACKGROUNDCompared with nanosecond (ns) pulses of conventional Nd-YAG lasers, picosecond (ps) laser pulses allow intraocular surgery at considerably lower pulse energy. The authors report initial clinical experiences using a Nd:YLF...

Continuous intraocular pressure measurement by telemetry in alpha-chymotrypsin-induced glaucoma model in the rabbit: Effects of timolol, dorzolamide, and epinephrine

The aim of this study was to set-up and validate the use of a radio-telemetry system in order to record IOP in chronic ocular hypertensive animals. The transmitter of a miniaturized radio-telemetry system was implanted in rabbits, and its catheter was tunnelled subcutaneously to the superior conjunctival sac and inserted into the midvitreous. Implantation was performed in chronic ocular hypertensive rabbits induced by an injection of alpha-chymotrypsin into the posterior chamber of the eye. The effects of 0.5% timolol maleate, 2% dorzolamide hydrochloride and 1% epinephrine were assessed and compared after topical administration in this model. Implanted radio-telemetric system into the vitreous allowed IOP measurement for more than 6 months. In this study, circadian IOP kinetic profiles were monitored in all animals over 24 h for 3 weeks. Timolol maleate was found significantly potent in reducing IOP, while changes depended on the nyctemeral period. Dorzolamide hydrochloride induced a very large IOP reduction and was found to be also well effective at night. We evidenced a biphasic time-dependent effect after topical epinephrine, with a long lasting IOP increase occurring after the administration. This change was found to be related to side effects resulting from a poor ocular tolerance of this drug in the rabbit, leading to either a complete eye closure or a higher blinking rate. By using our method, we confirmed the pressure pulses and undershoots occurring during blinking. Radio-telemetry in chronic glaucoma rabbits appears as a refined method to assess anti-glaucoma drug activity, 24 hours a day, for long-term periods in unrestrained animals, while also providing information on the ocular side effects of eye drops.

The effectiveness of dapiprazole in preventing exercise-induced IOP increase in patients with pigmentary dispersion syndrome

The authors investigated the use of dapiprazole, an alpha-adrenergic blocking agent, in preventing pigment release and IOP increase after exercise in patients affected with PDS. Three young myopic males (31, 34 and 35 years old) affected with pigmentary dispersion syndrome performed 30 minutes of jogging on a computerized treadmill. Telemetric heartbeat measurement was performed to obtain constant pulse rate training. Computerized tonography and IOP measurement were performed 10 minutes after the exercise. After one month the patients repeated the same exercise after pre-treatment with dapiprazole 0.5% eyedrops (one drop 30, 20 and 10 minutes before the exercise). Ten minutes after the exercise IOP measurements and computerized tonography were repeated. After 30 minutes of exercise IOP measurements showed values ranging from 19 to 45 mmHg (mean 30.33; SD 8.73). Computerized tonography C values after exercise ranged from 0.04 to 0.16 (mean 0.09; SD 0.04). After pre-treatment with dapiprazole 0.5% eyedrops, IOP values ranged from 18 to 28 mmHg (mean 23.33; SD 3.44) and tonography C values ranged from 0.10 to 0.20 (mean 0.14; SD 0.03). The study supports the concept that exercise-induced pigment release temporarily obstructs the acqueous outflow channels, causing IOP increase in some patients with PDS. Pre-treatment with dapiprazole was useful in reducing IOP spikes and in increasing tonographic total outflow facility after exercise. The absence of induced myopia and the lack of dangerous vitreoretinal tractions on retinal periphery make dapiprazole a safe method to reduce exercise-induced pigment dispersion.

Prevalence of glaucoma and distribution of intraocular pressure in a population. The Casteldaccia Eye Study.

IOP was measured in 1062 middle-aged and elderly subjects of a small Sicilian town, enrolled in a population based survey. The mean IOP was 15.1 +/- 3.7 mmHg without interocular or sex differences. A small but significant age-dependent increase of IOP was found. Circadian and seasonal influences were recorded: IOP was higher in the morning and in winter. The prevalence of chronic open-angle glaucoma was 1.2%, but it grew to 3.6 if only subjects aged 70 years or more were considered. IOP of 24 mmHg or more was found in 2.7%, while 4.3% of subjects showed IOP of 21 mmHg or more. This survey shows that mean IOP of the Mediterranean population studied is similar to the IOP found in other epidemiologic investigations; the prevalence of glaucoma, however, seems to be rather high.

Intraocular pressure and blood flow of the optic disk: A fluorescent blood cell angiography study

The damage to disk microcirculation in glaucoma and ocular hypertension is correlated with the damage to the neuronal tissue. However, it is not clear whether the primary damage is vascular or neurogenic. We have developed a new method which allows in vivo observation of the retinal capillary blood cell flow and the plasma flow, separately. The method was used to examine the blood cell flow in the optic disks of cats' eyes. The ber. It was found that blood cell flow became stagnant in a few capillaries at the optic disk with an intraocular pressure of 30–45% of the systemic mean blood pressure. When an induced IOP increase to 45% of systemic mean blood pressure was sustained for 30 minutes, microcirculatory blood flow recovery was complete two hours later. When this pressure was sustained for 120 minutes, the recovery was incomplete two hours later. This work represents a new tool in the research of retinal and disk hemodynamics and microvascular pathologies. The results presented in this paper support the hypothesis that early ischemic microdamage might be the basis of the pathogenesis of the chronic glaucomas.