Significant Differences In Intraocular Pressure Values Research Articles

Comparison of Tonovet® and Tonovet plus® tonometers for measuring intraocular pressure in dogs, cats, horses, cattle, and sheep.

Reference ranges for intraocular pressure (IOP) in healthy animals are device-specific; therefore, it is strongly recommended to use appropriate reference values according to the device. Therefore, our aim was to compare IOP readings made by TonoVet® and TonoVet Plus® in healthy dogs, cats, sheep, cattle, and horses. We compared IOP values measured by TonoVet® and TonoVet Plus® tonometers in clinically normal eyes of dogs, cats, horses, cattle, and sheep. Five groups comprising 20 animals each of dogs (various breeds, 9 months-10 years old, 14 females, 6 males), cats (various breeds, 6 months-12 years old, 8 females, 12 males), horses (various breeds, 5-12 years old, 12 females, 8 males), cattle (Holstein, 1-7 lactation, female), and sheep (Latvian Darkhead ewes, 1-8 years old) were included in the study. Both eyes of all animals were subjected to ophthalmic examination, including evaluation of IOP by rebound tonometry using TonoVet® and TonoVet Plus® devices. Normality was determined using the Shapiro-Wilk test. The independent t-test was used to determine differences between IOP values in the right and left eyes and between both tonometers. This study was approved by the Ethical Commission of the Latvia University of Life Sciences and Technologies (Nr. LLU_Dzaep_2022-2-4). No differences in IOP between the right and left eyes were found in all cases (p > 0.05). The mean IOP ± standard deviation values in both eyes for TonoVet® and TonoVet Plus® tonometers were as follows: for dogs, 15.25 ± 2.73 mmHg and 19.65 ± 3.46 mmHg; and in cats, 18.88 ± 3.98 mmHg and 18.78 ± 4.26 mmHg, respectively. In horses, mean IOP was 22.15 ± 3.74 mmHg and 24.28 ± 3.00 mmHg; in cattle, 24.73 ± 2.89 mmHg and 23.28 ± 2.97 mmHg; and in sheep, 18.05 ± 3.54 mmHg and 22.49 ± 4.66 mmHg, respectively. Significant differences in IOP values were observed between the tonometers in sheep, dog, and horse groups (mean difference -4.40, -4.48, and 2.13, respectively). This study showed significantly higher IOP values measured by the TonoVet Plus® tonometer in dogs and sheep.

Tonometry and pachymetry to evaluate fluctuations of intraocular pressure in the context of SCUBA diving

It is currently still not clarified whether diving using aself-contained breathing apparatus (SCUBA) is associated with intraocular pressure (IOP) fluctuations of clinical relevance and whether intensive diving could exacerbate the damage in glaucoma patients. This study aimed to evaluate the effect of SCUBA diving on IOP in healthy volunteers without prior eye injuries or surgery. recreational diving does not lead to significant increases or fluctuations of the IOP. The study included 16divers (5female) who performed atotal of 96dives with air or nitrox32 to adepth of 20-30 m for an average of 50 min. The central cornea thickness was measured using ultrasonic pachymetry Pocket IITM (Quantel Medical Pocket II™, Quantel Medical, Clermont-Ferrand, France), and the IOP was measured using an Icare® PRO (Icare® PRO, Icare Finland Oy, Espoo, Finland) directly before the dive and 10 min after surfacing. All data refer to the right eye. Average IOP values ranged from 15.6 to 19.2 mm Hg pre-dive and 16.8 to 18.2 mm Hg post-dive. The range of IOP values was 2.2-11.5 mm Hg pre-dive (∆ = 9.3 mm Hg) and 2.7-14.8 mm Hg post-dive (∆ = 12.1 mm Hg). Of the divers 11.5% vs. 18.8% had increased IOP values > 21 mm Hg (pre-dive vs. post-dive). This study found no significant differences in IOP values between pre-dive and post-dive measurements in healthy SCUBA divers. Therefore, recreational SCUBA diving is unlikely to affect the IOP in healthy individuals.

The impact of obesity on ocular hemodynamics and choroidal thickness.

Obesity affects microvascular structures. The effect of obesity on the ocular vascular system can be evaluated by changes in the choroidal thickness (CT) and retrobulbar blood flow (RBF). To evaluate the CT and RBF parameters in obese patients with various body mass index (BMI) values and compare these parameters with normal weight, healthy subjects. A prospective study. The study included 102 eyes of 102 female patients. Patients were divided into three groups according to BMI as group 1 with a BMI of 18.5-24.99 (n = 32), normal weight group; group 2 with a BMI of 30-34.99 (n = 35), as obese class I; and group 3 with a BMI of 35-39.99 (n = 35), as obese class II. The peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index, and pulsatility index values of the central retinal artery (CRA) and ophthalmic artery (OA) were evaluated with color Doppler ultrasonography. CT was measured at the subfoveal area and at 500-µm intervals nasal and temporal to the fovea up to a distance of 1500 µm by using the enhanced depth imaging technique of optical coherence tomography. Intraocular pressure (IOP) was measured with a Goldmann applanation tonometry. There was a significant difference in IOP values within the groups with the highest values in group 3 (17.6 ± 2.1 mmHg) and the lowest in group 1 (12.4 ± 1.7 mmHg). The CT in groups 2 and 3 was found to be statistically significantly lower than that in group 1 at all measurement points (p < 0.001). There was a statistically significant negative correlation between CT at all measurement points and BMI (p < 0.001). The mean CRA PSV, EDV, and OA EDV values were statistically significantly lower in each obese group than those values in group 1 (p < 0.001). The OA PSV values were significantly lower in group 3 (36.5 ± 5.9 cm/s) than those in group 2 (43.8 ± 4 cm/s) and group 1 (44.6 ± 5.2 cm/s) (p < 0.001). Also, significant associations were found between BMI and CRA PSV, CRA EDV, and OA PSV values (p < 0.001). Obesity may predispose to eye pathologies by changing the ocular vascular circulation.

Effects of topical administration of tafluprost and combination of tafluprost and timolol or tafluprost and betaxolol on Schirmer tear test, intraocular pressure, and pupil size in clinically healthy dogs.

The aim of this study was to evaluate the effects of 0.0015% preservative-free (PF) tafluprost alone and in combination with 0.5% timolol maleate or0.5% betaxolol HCl on Schirmer tear test (STT), intraocular pressure (IOP), and pupil diameter (PD) in clinically normal dogs. Twenty-one healthy adult castrated male cross-bred dogs were used in this study. Dogs were randomly divided into three groups. The first group received one drop of (PF) tafluprost (Taf), in a randomly selected eye. The second group received one drop of (PF) tafluprost plus one drop of timolol maleate (Taf-Tim), and the last group received one drop of (PF) tafluprost plus one drop of betaxolol HCl, (Taf-Bet). In all groups, the fellow eyes were served as control and received one drop of saline as a placebo. IOP, STT, and PD measurements were performed at the baseline and every 30min for the first 2h, every 2 h for the next 10 h, and at 24h and 36h post-instillation (PI). In all groups, significant differences in IOP values were observed between treated and untreated eyes (Taf: p < 0.001, Taf-Tim: p = 0.014, Taf-Bet: p = 0.008). The maximum reduction in mean IOP after unilateral administration of Taf, Taf-Tim, and Taf-Bet was 8.3mmHg, 10.7mmHg, and 13mmHg, respectively. No significant differences in STT values were observed between treated and untreated eyes at any time points. In all groups, significant differences in PD values were observed between treated and untreated eyes in all time points except the baseline and 36h post-drug instillation (p < 0.001). Tafluprost alone or in combination with timolol and betaxolol was able to reduce intraocular pressure. The greatest effect of the drugs occurred 6 and 8h PI. The present study revealed that the combination of tafluprost/betaxolol is more potent in decreasing IOP than tafluprost alone or a combination of tafluprost/timolol in healthy dogs.

The Effect of Increased Intraocular Pressure During Steep Trendelenburg Positioning in Robotic Prostatectomy and Hysterectomy on Structural and Functional Ocular Parameters.

Robotic prostatectomy and robotic hysterectomy require steep Trendelenburg positioning. Many authors documented significant increases in intraocular pressure (IOP) during steep Trendelenburg. However, the long-term biological effect of a significant increase in IOP on the structural and functional ocular system is unknown. This study examines the effect of a significant increase in IOP on the visual acuity, retinal nerve fiber layer thickness (RNFLT), and ganglion cell complex (GCC) thickness in 52 patients without preexisting ocular disease of both genders before and 3 months after their procedures. This was a prospective cohort study. The total number of patients included was 56, then 3 females and 1 male case were excluded, totaling 28 robotic hysterectomies and 24 robotic prostatectomies were performed. Patients underwent complete eye examination before the procedure and 3 months after, measuring the main outcome of RNFLT and the secondary outcomes of GCC thickness, foveal threshold (FT), mean deviation (MD), and pattern standard deviation (PSD). These outcomes were analyzed using linear mixed-effects models. On the day of surgery, we examined the IOP after induction of anesthesia, at the end of steep Trendelenburg, and in the recovery room. There were significant differences in IOP values at the end of steep Trendelenburg versus after induction and 45-60 minutes post-awakening (P < .001 for both groups). No difference between IOP 45 and 60 minutes post-awakening and IOP after induction was observed in either group. The highest IOPs occurred at the end of the steep Trendelenburg time point for both groups. The mean duration of steep Trendelenburg in robotic prostatectomy was 184.6 minutes (standard deviation [SD] = 30.8), while the mean duration in robotic hysterectomy was 123.0 minutes (SD = 29.8). All ophthalmologic examinations were normal preoperatively and 3 months postoperatively. The ocular parameters in the retina and optic disk did not differ significantly before surgery and 3 months after. There is a significant increase in IOP during steep Trendelenburg positioning. There was no significant difference in the ocular parameters examined 3 months after the procedure in this cohort.

Schirmer’s Test I and Determination of Intraocular Pressure in Healthy Common Buzzards (Buteo buteo)

Background: The structure of the eye in wild birds is 45% larger than that in humans, which provides excellent visual capacity but also makes them vulnerable to eye trauma. Trauma, neoplasia, infectious diseases of the ocular surface, uveitis, glaucoma, and corneal diseases in wild birds, but mainly trauma, can cause a reduction in their tear production; therefore, determining the amount of tear production in the wild birds is very important. Studies have shown that the results of the Schirmer’s tear test (STT) and intraocular pressure (IOP) values differ among wild bird species, and that both anesthesia and sedation affects these parameters. The main objective of the present study was to determined IOP and STT I values in healthy common buzzards (Buteo buteo).Materials, Methods &amp; Results: Thirty healthy common buzzards were selected for the study following clinical and ophthalmic examinations. Following physical and clinical examinations of all subjects, routine ophthalmologic examinations were conducted, including reflex examinations (pupillary, palpebral, menace, dazzle) and direct ophthalmoscopy for the eyelids, conjunctiva, cornea, iris, lens, and fundus. All examinations were conducted without anesthesia or sedation while the birds were in the dorsal recumbent position, and the results of STT I and IOP were recorded. Both tests were repeated for the right and left eyes. The mean ± SE STT I values for the right and left eyes were 12.63 ± 0.51 and 12.43 ± 0.54 mm/min, respectively. A comparison between STT I values of the right and left eyes revealed no statistically significant differences (P &gt; 0.620). The means and ranges of the TonoVet® IOP results for the right and left eyes were 32.06 ± 1.58 and 32.60 ± 1.51 mmHg, respectively. There was no statistically significant difference between the results of the test on the two eyes (P &gt; 0.05).Discussion: Tear production is either increased or decreased in wild birds as a result of several types of eye diseases or trauma (1, 6). The most common method by which to determine tear production is either STT I (3), which is conducted without topical anesthesia, or STT II, which is conducted with topical anesthesia. As in our study, previous studies have used STT I as their method by which to determine tear production of wild birds. In a study conducted on 20 common buzzards, STT I values were 12.47 ± 2.66 mm/min. In our study using 30 common buzzards, the STT I value was 12.63 ± 0.51 mm/min for the right eye and 12.43 ± 0.54 mm/min for the left eye. There was no statistically significant difference between the results of the tests on the two eyes. In previous study with 25 common buzzards, IOP measured rebound tonometry was 5-30 (35-60). In our study, rebound tonometry results for IOP of 30 common buzzards were 32.06 ± 1.58 mmHg (16-47) for the right eye and 32.60 ± 1.51 mmHg (17-50) for the left eye. There was no statistically significant difference in IOP values between right and left eyes. Given that there are few studies on tear production and IOP in common buzzard, we believe that the results of this study will provide valuable new information to the literature.

Intraocular pressure changes in the intensive care unit: The effect of spontaneous respiration, mechanical ventilation, non-invasive cpap and medical treatments

Aim: The aim of this study was to investigate the intraocular pressure (IOP) changes in patients in intensive care unit (ICU) and the parameters that cause these changes.Material and Methods: In total, 304 eyes of 152 patients were examined. IOP and central corneal thickness (CCT) were measured. Age, sex, hospitalization (surgical/non-surgical causes), type of ventilation (spontaneous, intubated, non-invasive continuous positive airway pressure (CPAP), Glasgow coma scale, use of hypertonic solution and sedation status were evaluated.Results: The mean age was 63.52±21.47 (range: 18–96) years, and the male/female ratio was 73/79. The mean hospitalization time was 30.91±47.80 (8-297) days, and the mean Glasgow coma scale score was 9.61±4.42. While 33 patients (21.7%) had hypertonic solution, 28 (18.4%) were sedated. The mean IOP was measured as 13.81±3.58 (6–28) mmHg. In 5 patients, the IOP was more than 20 mmHg, and in 14 patients, it was less than 10 mmHg. It was observed that gender and hospitalization diagnosis had no effect on the IOP change (p=0.97, p=0.814, respectively). When the patients were evaluated according to their respiration types, there was no statistically significant difference in IOP values between patients with spontaneous respiration and intubated patients (p=0.261), but non-invasive CPAP patients were significantly different from patients with spontaneous breathing (p=0.035) and intubated patients (p0.001). In addition, the use of hypertonic solution and sedation significantly decreased IOP (p0.001 in both groups).Conclusion: Some changes in IOP were observed due to some applications in the ICU. These changes are often not significant in patients with no eye problems. However, patients with a glaucoma diagnosis or susceptibility to glaucoma, as well as patients with simultaneous IOP reduction, should be carefully monitored for IOP changes.

Antibacterial effects of ER: YAG-PIPS, ER, CR: YSGG laser and conventional irrigation on enterococcus faecalis and candida albicans

Aim: The aim of this study was to investigate the intraocular pressure (IOP) changes in patients in intensive care unit (ICU) and the parameters that cause these changes.Material and Methods: In total, 304 eyes of 152 patients were examined. IOP and central corneal thickness (CCT) were measured. Age, sex, hospitalization (surgical/non-surgical causes), type of ventilation (spontaneous, intubated, non-invasive continuous positive airway pressure (CPAP), Glasgow coma scale, use of hypertonic solution and sedation status were evaluated.Results: The mean age was 63.52±21.47 (range: 18–96) years, and the male/female ratio was 73/79. The mean hospitalization time was 30.91±47.80 (8-297) days, and the mean Glasgow coma scale score was 9.61±4.42. While 33 patients (21.7%) had hypertonic solution, 28 (18.4%) were sedated. The mean IOP was measured as 13.81±3.58 (6–28) mmHg. In 5 patients, the IOP was more than 20 mmHg, and in 14 patients, it was less than 10 mmHg. It was observed that gender and hospitalization diagnosis had no effect on the IOP change (p=0.97, p=0.814, respectively). When the patients were evaluated according to their respiration types, there was no statistically significant difference in IOP values between patients with spontaneous respiration and intubated patients (p=0.261), but non-invasive CPAP patients were significantly different from patients with spontaneous breathing (p=0.035) and intubated patients (p0.001). In addition, the use of hypertonic solution and sedation significantly decreased IOP (p0.001 in both groups).Conclusion: Some changes in IOP were observed due to some applications in the ICU. These changes are often not significant in patients with no eye problems. However, patients with a glaucoma diagnosis or susceptibility to glaucoma, as well as patients with simultaneous IOP reduction, should be carefully monitored for IOP changes.

Comparison of goldmann applanation tonometry measurements with and without fluorescein among adult sudanese glaucomatous and nonglaucomatous population 2018

Background: Goldman applanation tonometry (GAT) is still the most accurate for measuring intraocular pressure (IOP). Usually, fluorescein eye drops are used in additional to topical anesthesia to gain the best visualization result. Objective: The main objective of the study is to compare the GAT values with and without fluorescein in adult Sudanese glaucomatous and nonglaucomatous population. Materials and Methods: In a cross-sectional hospital-based study, 400 patients were recruited from out patient's and glaucoma clinics at Makkah Eye Complex, Khartoum, in the period from December 2017 to January 2018. Different ages were classified into three groups, patients also classified into glaucoma (n = 200) and nonglaucoma (n = 200) patients, another classification according to gender. Then, IOP measurements with and without topical fluorescein were done by GAT. Results: Two hundred and sixteen (n = 216; 54%) were male and 184 (46%) were female, with an average age of 54.76 ± 24.5 years. Two hundred (50%) were glaucomatous, and the other 200 (50%) were nonglaucomatous. The average IOP with fluorescein was higher than without fluorescein by 13.1% (2.08 mmHg) and still was higher in comparison between non-Glaucomatous and glaucomatous with and without fluorescein up to 3. 41 mmHg (17.86%). Both results ± fluorescein and ± glaucoma were statistically significant (P = 0.000). There was a significant correlation between age and IOP values with fluorescein and between having glaucoma and IOP with fluorescein (P = 0.000), while there was nonsignificant correlation between sex and IOP measurements with fluorescein. Conclusion: There are statistically significant differences in IOP values by GAT either ± fluorescein or ± glaucoma. A significant correlation between age and IOP values either ± fluorescein or ± glaucoma were detected, but not to sex.

Reproducibility of the water-drinking test in patients with exfoliation syndrome and exfoliative glaucoma.

To evaluate the reproducibility of intraocular pressure (IOP) peaks and fluctuations detected during the water-drinking test (WDT) in patients with exfoliation syndrome (XFS) and exfoliative glaucoma (XFG). This prospective study included 34 XFS and 30 XFG patients. Each patient was evaluated twice, with the two WDTs performed on a 30-day interval. We recorded IOP peak (highest IOP during the WDT) and IOP fluctuation (IOP peak minus IOP before the test). Bland-Altman analysis was applied to assess the agreement of IOP peaks and fluctuations between the two consecutive visits. We defined reproducible as within 4 mmHg for IOP peak and within 2 mmHg for IOP fluctuation. There were no significant differences in IOP values, IOP peaks and IOP fluctuations between the two visits for both XFS and XFG patients (p>0.05, for all). The coefficient of repeatability for IOP peak was 2.5mmHg and 3.5mmHg in XFS and XFG patients respectively and for IOP fluctuation, it was 2.1mmHg and 2.2mmHg. None of the XFS or XFG patients had an IOP peak difference higher than 4mmHg. Intraocular pressure (IOP) fluctuation differences above 2.0mmHg were found in 8.8% of XFS patients and 16.6% of XFG patients. Intraocular pressure (IOP) peak and IOP fluctuation have a reproducibility, both in XFS and in XFG.

Efficiency, safety, and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog.

BackgroundWe investigated the efficiency, safety and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog.MethodsWe initially enrolled 44 eyes from 44 primary open angle glaucoma patients, and a total of 42 patients completed the study. All patients were under treatment with various prostaglandin F2α analogs and dorzolamide 1%/timolol 0.5%. While maintaining the prostaglandin F2α analog, dorzolamide 1%/timolol 0.5% was switched to brinzolamide 1%/timolol 0.5%. Conjunctival hyperemia, superficial punctate keratopathy, and intraocular pressure (IOP) were evaluated at baseline and at 4, 12, and 24 weeks. Adverse events and patient preferences, measured using a questionnaire at study initiation and at 24 weeks, were also noted.ResultsThe IOP was 17.7±1.7, 16.8±2.6, 16.7±2.2, and 16.7±2.4 mmHg at baseline and at 4, 12, and 24 weeks, respectively, with no significant differences in IOP values at any time point (P=0.117, one-way analysis of variance). In addition, no significant differences were found in the incidence of conjunctival hyperemia or SPK score at any time point (all P>0.5, by Kruskal–Wallis test). Based on the evaluation of side effects using the questionnaire, stinging/burning was less common (P=0.042), while blurred vision was more common (P=0.003), after switching to brinzolamide 1%/timolol 0.5%. Regarding patient preferences, 13 patients (31%) preferred dorzolamide 1%/timolol 0.5%, 12 patients (29%) preferred brinzolamide 1%/timolol 0.5%, and 17 patients (40%) preferred neither.ConclusionWhen switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5%, the IOP values and incidence of superficial punctate keratopathy and conjunctival hyperemia were sustained throughout the 24-week observation period, and the patient preferences were similar for the two regimens. However, differences were observed in the ocular sensations of stinging/burning with dorzolamide 1%/timolol 0.5% and blurred vision with brinzolamide 1%/timolol 0.5%.

The Effect of Corneal Biomechanical Properties on Rebound Tonometer in Patients With Normal-Tension Glaucoma

To evaluate the effects of corneal biomechanical properties on intraocular pressure (IOP) measured with the ICare, and to compare IOP readings obtained with ICare, Ocular Response Analyzer (ORA), and Goldmann applanation tonometry (GAT) in normal-tension glaucoma (NTG) and normal subjects. Prospective, cross-sectional, comparative study. IOP was measured with ICare, ORA, and GAT. All subjects had corneal hysteresis (CH) and corneal resistance factor (CRF), which were measured with ORA; and central corneal thickness (CCT), axial length, spherical equivalent, and keratometry. This study enrolled 97 eyes of 97 NTG patients and 89 eyes of 89 normal subjects. CCT, CH, and CRF in NTG patients were significantly lower than those in normal subjects (P = .033, P = .006, and P = .003). The difference in IOP between techniques was highly significant in NTG patients (P < .001), while there was no significant difference in IOP values between techniques in normal controls (P = .931). ICare readings were significantly lower than corneal-compensated IOP in NTG patients (P = .014). CH and CRF were significantly associated with IOP measurements with ICare in NTG and normal subjects (P < .001). The greater difference between IOPcc and ICare in NTG patients was significantly influenced by the lower CH (P < .001). Since ICare is a convenient way to measure IOP, ICare is a reasonable option as an alternative tonometer in NTG patients. However, the clinician must consider that the corneal biomechanical characteristics in NTG can cause ICare to underestimate IOP.

Effect of medetomidine-butorphanol and dexmedetomidine-butorphanol combinations on intraocular pressure in healthy dogs

ObjectiveTo assess the effects of intravenous (IV) medetomidine-butorphanol and IV dexmedetomidine-butorphanol on intraocular pressure (IOP). Study designProspective, randomized, blinded clinical study. AnimalsForty healthy dogs. Mean ± SD body mass 37.6 ± 6.6 kg and age 1.9 ± 1.3 years. MethodsDogs were allocated randomly to receive an IV combination of dexmedetomidine, 0.3 mg m−2, combined with butorphanol, 6 mg m−2, (group DEX) or medetomidine 0.3 mg m−2, combined with butorphanol 6 mg m−2, (group MED). IOP and pulse (PR) and respiratory (fR) rates were measured prior to (baseline) and at 10 (T10), 20 (T20), 30 (T30) and 40 (T40) minutes after drug administration. Oxygen saturation of hemoglobin (SpO2) was monitored following sedation. Data were analyzed by anova followed by Dunnett's tests for multiple comparisons. Changes were considered significant when p < 0.05. ResultsFollowing drug administration, PR and fR were decreased significantly at all time points but did not differ significantly between groups. Baseline IOP in mmHg was 14 ± 2 for DEX and 13 ± 2 for MED. With both treatments, at T10, IOP increased significantly (p < 0.001), reaching 20 ± 3 and 17 ± 2 for DEX and MED respectively. This value for DEX was significantly higher than for MED. There were no significant differences in IOP values between groups at any other time points. At T30 and T40, IOP in both groups was below baseline (DEX, 12 ± 2 and 11 ± 2: MED 12 ± 2 and 11 ± 2) and this was statistically significant, for DEX. Conclusions and clinical relevanceAt the documented doses, both sedative combinations induced a transient increase and subsequent decrease of IOP relative to baseline, which must be taken into consideration when planning sedation of animals in which marked changes in IOP would be undesirable.

Changes in Intraocular Pressure During Prone Spine Surgery Under Propofol and Sevoflurane Anesthesia

Intraocular pressure (IOP) has been shown to increase during prone spine surgery. Although propofol and sevoflurane have been widely used during such surgery, there have been no data to compare the IOP changes under propofol and sevoflurane anesthesia. The present study was therefore conducted to investigate IOP changes under propofol and sevoflurane anesthesia during prone spine surgery. After institutional approval and informed consent, 24 patients undergoing prone spine surgery were studied. Patients were randomly allocated to 1 of 2 groups: the propofol or sevoflurane group. Propofol or sevoflurane was administered to maintain the bispectral index between 40 and 60. The IOP was measured using a Tonopen XL hand-held tonometer 10 minutes after induction of anesthesia in the supine position (baseline), 10, 60, and 120 minutes after positioning in the prone position, and 10 minutes after returning to the supine position. There were no significant differences in IOP values at baseline between the 2 groups. IOP values after positioning in the prone position were significantly higher than those at baseline in both groups (propofol group: from 8.9±3.5 to 21.9±5.0 mm Hg; sevoflurane group: from 11.6±3.9 to 24.8±3.4 mm Hg; P<0.05). Although IOP values were higher in the sevoflurane group than in the propofol group, the differences in IOP values were not statistically significant. The results indicated that the choice of anesthetic agent, sevoflurane or propofol, did not have significant effects on IOP changes during a relatively short interval of prone spine surgery.

Rebound tonometry for the measurement of intraocular pressure and its relation with gender and refractive errors in Mozambique

Aim: To evaluate the intraocular pressure (IOP) in the university student population in an urban region in Mozambique using rebound tonometry. Methods: A cross-sectional study with a random selection of students was conducted. IOP was measured after an optometric examination that included uncorrected visual acuity testing, static retinoscopy and subjective refraction without cycloplegia. Refractive error data were converted into spherical equivalent. IOP of the participants was assessed with the Icare® rebound tonometer (Tiolat Oy, Helsinki, Finland). Results: A total of 422 subjects (197 men and 225 women) between 17 and 26 years of age were examined. The mean value of IOP of the whole sample was 14.32 ± 3.30 mmHg. Statistically significant differences in IOP values were not found between men and women (p = 0.564) nor among refractive groups (p = 0.725). Conclusion: Rebound tonometry has been demonstrated to be a convenient and effective method for measuring IOP in this population. Icare can be considere...

Intraocular pressure, corneal thickness, and corneal hysteresis in Steinert's myotonic dystrophy

Low intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT) is one of the ocular manifestations of Steinert's myotonic dystrophy. The goal of this study was to evaluate the corneal-compensated IOP as well as corneal properties (central corneal thickness and corneal hysteresis) in patients with myotonic dystrophy. A total of 12 eyes of 6 patients with Steinert's myotonic dystrophy (dystrophy group) and 12 eyes of 6 age-, race-, and gender-matched healthy volunteers (control group) were included in the study. GAT, Dynamic Contour Tonometry (DCT-Pascal) and Ocular Response Analyzer (ORA) were used to assess the IOP. Central corneal thickness was obtained by ultrasound pachymetry, and corneal hysteresis was analyzed using the ORA device. In light of the multiplicity of tests performed, the significance level was set at 0.01 rather than 0.05. The mean (standard deviation [SD]) GAT, DCT, and corneal-compensated ORA IOP in the dystrophy group were 5.4 (1.4) mmHg, 9.7 (1.5) mmHg, and 10.1 (2.6) mmHg, respectively. The mean (SD) GAT, DCT, and corneal-compensated ORA IOP in the control group was 12.6 (2.9) mmHg, 15.5 (2.7) mmHg, and 15.8 (3.4) mmHg, respectively. There were significant differences in IOP values between dystrophy and control groups obtained by GAT (mean, -7.2 mmHg; 99% confidence interval [CI], -10.5 to -3.9 mmHg; P<0.001), DCT (mean, -5.9 mmHg; 99% CI, -8.9 to -2.8 mmHg; P<0.001), and corneal-compensated ORA measurements (mean, -5.7 mmHg; 99% CI, -10.4 to -1.0 mmHg; P=0.003). The mean (SD) central corneal thickness was similar in the dystrophy (542 [31] µm) and control (537 [11] µm) groups (P=0.65). The mean (SD) corneal hysteresis in the dystrophy and control groups were 11.2 (1.5) mmHg and 9.7 (1.2) mmHg, respectively (P=0.04). Patients with Steinert's myotonic dystrophy showed lower Goldmann and corneal-compensated IOP in comparison with healthy individuals. Since central corneal thickness and corneal hysteresis did not differ significantly between groups, the lower IOP readings documented in this dystrophy seem not to be related to changes in corneal properties.

In Vitro and In Vivo Comparison of Applanation Tonometry and Rebound Tonometry in Dogs

Intraocular pressure (IOP) evaluated by applanation tonometry via TONO-PEN XL (TP), and rebound tonometry via TonoVet (TV) were compared in enucleated canine eyes with varied pressure of the anterior chamber (AC) and in clinical cases. TV measured IOP values were lower than IOP measurements of TP in the enucleated eyes with 5-10 mmHg of AC (P<0.0001), though there was no significant difference in IOP values obtained with TP and TV on the pressure ranges of 15-20 mmHg. However, TP detected IOP values were lower than IOP measurements of TV in the eyes with over 25 mmHg of AC (P<0.0001). The results of clinical cases were similar to the enucleated eye model. There was no significant difference in IOP values obtained from TP and TV in dogs with normotensive eyes. IOP measurements of TP were lower than those of TV in glaucomatous eyes (P<0.0001). TV was a reliable tonometer for measurement of IOP in hypertensive eyes, whereas it was less accurate than TP in hypotensive eyes. The characteristics of TP and TV should be considered in the evaluation of IOP in practice.