Intraocular Pressure Assessment Research Articles

Impact of Acute Short-term Hypobaric Hypoxia on Anterior Chamber Geometry

Précis: Hypobaric hypoxia, the major environmental factor at high altitudes, has been observed to induce pupil miosis and widening of the anterior chamber angle. This environment may be safe for individuals with narrow angle and deserves further study. Purpose: This study aimed to quantify anterior chamber biometric parameters before and after acute short-term, effortless exposure to hypobaric hypoxia (HH) in healthy lowlanders using swept-source anterior segment optical coherence tomography (SS AS-OCT). Methods: This prospective study included 25 healthy young lowlanders (50 eyes) who underwent SS AS-OCT measurements and intraocular pressure (IOP) assessments under baseline sea-level conditions (T1).They were then passively exposed to simulated 4000 m above sea level for 3 hours and underwent Acute mountain sickness (AMS) symptoms evaluation and IOP measurement after 2-hours exposure to HH (T2).Repeat SS AS-OCT measurements and IOP assessments were taken within 15 minutes after leaving the hypobaric chamber (T3). Anterior segment parameters including anterior chamber depth (ACD),lens vault (LV),angle opening distance (AOD500), trabecular-iris space area (TISA500), angle recess area (ARA500) at 500 μm from the scleral spur, iris curvature (IC), iris volume (IV), pupil diameter (PD), and central corneal thickness (CCT) were obtained through SS AS-OCT. These repeated measurements were compared using linear mixed model analysis. Results: In comparison to sea level, both IOP (16.4±3.4 vs. 14.9±2.4 mm Hg, P=0.029) and PD (5.36±0.77 vs. 4.78±0.89 mm, P=0.001) significantly decreased after exposure to HH. Significant post-HH changes (Mean difference (95% CI)) were observed in AOD500 (0.129 (0.006, 0.252), P=0.04), TISA500 (0.059 (0.008, 0.11), P=0.025), ARA500 (0.074 (0.008, 0.141), P=0.029), IV (1.623 (0.092, 3.154), P=0.038), and IC (−0.073 (−0.146, 0.001), P=0.047), while CCT, ACD, and LV remained stable. After adjusting for age, post-HH variations in AOD500 (Beta=0.553, 95% CI: 0.001, 1.105, P=0.048) and TISA500 (Beta=0.256, 95% CI: 0.02, 0.492, P=0.034) were associated with decreased IC but were not related to lowered arterial oxygen pressure or IV increase per millimeter of pupil miosis (IV/PD). These differences in anterior segment parameters were neither correlated with differences in IOP nor AMS. Conclusion: After short-term, effortless exposure to hypobaric hypoxia, pupil miosis occurred with widening of the anterior chamber angle and decreased IC. These changes in anterior chamber angle parameters were associated with decreased IC but did not correlate with the post-hypobaric variations in IV/PD, IOP, or AMS.

A study on intraocular pressure variation in primigravida and multigravida in trimesters of pregnancy and puerperium

To study intraocular pressure variation in primigravida and multigravida in trimesters of pregnancy and puerperium.This is a cross sectional and hospital based study of intraocular pressure (IOP) assessment of 693 female patients of non-pregnant, 1 trimester, 2nd trimester and 3 trimesters of pregnancy and puerperium during routine ocular examination. This study carried out in nine groups of 77 in each group.In primigravida the mean IOP was 14.31 ± 1.78 mmHg, 14.82 ± 2.09 mmHg, 12.86 ± 1.75 mmHg in first, second and third trimesters respectively. In multigravida the mean IOP was 14.38 ±1.97 mmHg, 14.36 ± 2.01 mmHg, 12.71 ± 1.63 mmHg in first, second and third trimesters respectively. In primigravida puerperal period the mean IOP was 14.55 ± 1.88 mmHg and in multigravida puerperal period the mean IOP was 14.04 ± 2.52 mmHg. Mean IOP during whole period of pregnancy was 14.00 ± 1.87 mmHg and 13.81 ± 1.08 mmHg in primigravida and multigravida respectively. Control group IOP was 15.92 ± 2.11 mmHg.There is a trend of decrease of intraocular pressure during pregnancy and comes towards no pregnant level during puerperal period both in primigravida and multigravida. IOP decreased more towards second and third trimester of pregnancy. There was variation of IOP in primigravida and multigravida during pregnancy and puerperium. IOP was significantly low in multigravida than primigravida. The higher IOP in primigravida could be due to antenatal and postnatal anxiety and stress and sleeplessness. Pregnancy related effect on IOP is usual phenomenon and temporary.

Prospective assessment of corneal biomechanical properties and intraocular pressure during scleral lens wear

Prospective assessment of corneal biomechanical properties and intraocular pressure during scleral lens wear

Effectiveness of pars plana Ahmed® valve implantation in patients with refractory glaucoma

PurposeTo evaluate the success rate and complications of the Ahmed FP7 valve implanted via Pars Plana in a group of vitrectomized patients with refractory glaucoma and anterior segment abnormalities from January 2018 to June 2023. MethodsQuasi-experimental, prospective study. Eleven eyes with refractory glaucoma were included. Participants underwent a comprehensive ophthalmic examination, including assessment of intraocular pressure (IOP) reduction, visual acuity, characterization of glaucoma type, and number of antiglaucoma medications. ResultsThe mean baseline IOP was 37.3 ± 11 mmHg, which decreased to 13.5 ± 3.0 mmHg after one year. The qualified success rate was 63.7%, while the complete success rate was 36.3%. The most common diagnosis was neovascular glaucoma in 36.4% of cases. The most frequent postoperative complications were choroidal detachment and hypotony. ConclusionsOur data suggest that implantation of the Ahmed FP7 valve via pars plana is an effective and safe option for patients with refractory secondary glaucoma.

Efectividad de la válvula de Ahmed® implantada vía pars plana en pacientes con glaucoma refractario

PurposeTo evaluate the success rate and complications of the Ahmed® FP7 valve implanted via Pars Plana in a group of vitrectomized patients with refractory glaucoma and anterior segment abnormalities from January 2018 to June 2023. MethodsQuasi-experimental, prospective study. Eleven eyes with refractory glaucoma were included. Participants underwent a comprehensive ophthalmic examination, including assessment of intraocular pressure (IOP) reduction, visual acuity, characterization of glaucoma type, and number of antiglaucoma medications. ResultsThe mean baseline IOP was 37.3±11mmHg, which decreased to 13.5±3.0mmHg after one year. The qualified success rate was 63.7%, while the complete success rate was 36.3%. The most common diagnosis was neovascular glaucoma in 36.4% of cases. The most frequent postoperative complications were choroidal detachment and hypotony. ConclusionsOur data suggest that implantation of the Ahmed FP7 valve via pars plana is an effective and safe option for patients with refractory secondary glaucoma.

An Enigmatic Fluid Accumulation Following Descemet Membrane Endothelial Keratoplasty After Prior Laser In Situ Keratomileusis

Purpose: To report a case of interface fluid syndrome (IFS) following Descemet membrane endothelial keratoplasty (DMEK) 13 years after laser in situ keratomileusis (LASIK). Methods: A 79-year-old patient with bullous keratopathy underwent uneventful DMEK. Thirteen years prior, he had undergone LASIK. After DMEK, he developed an IFS, which was confirmed by a fluid accumulation in the flap interface, visible in the anterior segment optical coherence tomography (AS-OCT). In this case, IFS is presumed to have been triggered by the corticosteroid eye drops administered postoperatively. Measurements of the intraocular pressure (IOP) via applanation tonometry yielded erroneously low results. Results: The discontinuation of the corticosteroid eye drops, along with the initiation of IOP-lowering therapy, led to an improvement in fluid accumulation and a decrease in IOP. Regular ophthalmic examinations with a palpatory assessment of IOP and monitoring of fluid via AS-OCT are recommended. In this case, no more fluid could be detected in the flap interface after 14 months, and IOP was normal. Conclusions: IFS can occur many years after LASIK treatment. Corticosteroids should be discontinued, and IOP-lowering therapy should be initiated to prevent irreversible damage to the optic nerve. Applanation tonometry leads to inaccurately low IOP measurements; therefore, a palpatory assessment of IOP is recommended. AS-OCT is a crucial imaging modality that should be employed for monitoring.

Test-Retest Reliability of Intraocular Pressure Measurements With Office-Based Versus Home-Based Rebound Tonometers.

Intraocular pressure (IOP) measurements obtained with the HOME2 rebound tonometer are interchangeable with measurements obtained using the office-based IC100 and IC200 rebound tonometers, making characterization of circadian IOP achievable with no inter-device sources of variability. To evaluate test-retest reliability between IOP measurements obtained with a home rebound tonometer operated by patients and those obtained with office rebound tonometers operated by experienced clinical staff. After training and practice with a home rebound tonometer (iCare HOME2) in a randomly selected eye, patients with established or suspected open angle glaucoma underwent IOP measurement in the fellow eye as follows in randomized order: 3 good quality measurements with the iCare IC100 operated by experienced clinical staff, 3 good quality measurements with the iCare IC200 operated by experienced clinical staff, and 3 good quality measurements with the HOME2 operated by the patient. The Shrout-Fleisch intraclass correlation coefficient (ICC; 2,1) was the measure of reliability utilized based on the model using 2-way random effects, absolute agreement, and single measurement. Thirty eyes of 30 patients were evaluated. The Pearson correlation coefficient ( r ) for IOP measurements taken with the IC100 and HOME2 was 0.97, with the IC200 and HOME2 was 0.96, and with the IC100 and IC200 was 0.97. Test-retest reliability between HOME2 and IC100 (ICC: 0.90), HOME2 and IC200 (ICC: 0.92), and IC100 and IC200 (ICC: 0.94) all reflected excellent test-retest reliability. The test-retest reliability of IOP measurements taken by patients using the iCare HOME2 self-tonometer compared with IOP measurements taken by trained operators using the iCare IC100 and IC200 tonometers was uniformly excellent (ICCs all ≥0.9). These findings indicate that these three devices should be considered interchangeable for the clinical assessment of circadian IOP.

A study of clinical profile in patients of cataracts with pseudoexfoliation in rural populations of central India

Background Ophthalmologists deal with daily pseudoexfoliation (PXF) due to severe secondary glaucoma, which arises after cataract surgery. Cataracts with pseudoexfoliation are age-related and are associated with open-angle glaucoma. Therefore, pseudoexfoliation is expected to occur more frequently. Pseudoexfoliation is occasionally associated with the development of thick nuclear cataracts, which may make surgery challenging. risks of cataract extraction in patients with pseudoexfoliation include zonular weakness and inadequate pupillary dilation. This may cause vitreous loss, and intraoperative or postoperative lens displacement. It could also lead to a rise in postoperative intraocular pressure (IOP), progressing to long-term inflammation, phimosis of the capsular tissue, glaucoma, and surgical corneal decompensation. Recurrent secondary cataracts are typically caused by some remaining cortical tissue and decreased zonular support, which may lead to lens epithelial cell migration. Surgery for glaucoma and cataracts is complicated by the presence of pseudoexfoliative debris. Objectives To determine the prevalence of pseudoexfoliation in cataract patients visiting the ophthalmic OPD, AVBRH hospital, to locate patients with pseudoexfoliative cataracts, to evaluate their likelihood of progressing to open-angle glaucoma, and to examine the various ocular characteristics of these patients. Methodology The study participants will undergo ophthalmological examination after considering the inclusion and exclusion criteria. This examination will include sac syringing on the lacrimal gland, estimation of the highest corrected visual acuity, slit-lamp examination, application tonometer assessment of intraocular pressure (IOP), and fundus examination using an indirect ophthalmoscope. All individuals with cataracts visiting the ophthalmology department of AVBRH will be examined under a slit-lamp to determine the presence of pseudoexfoliation in the operating eye. Expected Results Hospital statistics from India indicated that the percentage of patients with pseudoexfoliation, in addition to cataracts, ranges from 1.87% to 13.5%.

TGFβ Signaling Dysregulation May Contribute to COL4A1-Related Glaucomatous Optic Nerve Damage.

Mutations in the genes encoding type IV collagen alpha 1 (COL4A1) and alpha 2 (COL4A2) cause a multisystem disorder that includes ocular anterior segment dysgenesis (ASD) and glaucoma. We previously showed that transforming growth factor beta (TGFβ) signaling was elevated in developing anterior segments from Col4a1 mutant mice and that reducing TGFβ signaling ameliorated ASD, supporting a role for the TGFβ pathway in disease pathogenesis. Here, we tested whether altered TGFβ signaling also contributes to glaucoma-related phenotypes in Col4a1 mutant mice. To test the role of TGFβ signaling in glaucoma-relevant phenotypes, we genetically reduced TGFβ signaling using mice with mutated Tgfbr2, which encodes the common receptor for all TGFβ ligands in Col4a1+/G1344D mice. We performed slit-lamp biomicroscopy and optical coherence tomography for qualitative and quantitative analyses of anterior and posterior ocular segments, histological analyses of ocular tissues and optic nerves, and intraocular pressure assessments using rebound tonometry. Col4a1+/G1344D mice showed defects of the ocular drainage structures, including iridocorneal adhesions, and phenotypes consistent with glaucomatous neurodegeneration, including thinning of the nerve fiber layer, retinal ganglion cell loss, optic nerve head excavation, and optic nerve degeneration. We found that reducing TGFβ receptor 2 (TGFBR2) was protective for ASD, ameliorated ocular drainage structure defects, and protected against glaucomatous neurodegeneration in Col4a1+/G1344D mice. Our results suggest that elevated TGFβ signaling contributes to glaucomatous neurodegeneration in Col4a1 mutant mice.

In Vivo Optical Coherence Elastography Unveils Spatial Variation of Human Corneal Stiffness.

The mechanical properties of corneal tissues play a crucial role in determining corneal shape and have significant implications in vision care. This study aimed to address the challenge of obtaining accurate in vivo data for the human cornea. We have developed a high-frequency optical coherence elastography (OCE) technique using shear-like antisymmetric (A0)-mode Lamb waves at frequencies above 10 kHz. By incorporating an anisotropic, nonlinear constitutive model and utilizing the acoustoelastic theory, we gained quantitative insights into the influence of corneal tension on wave speeds and elastic moduli. Our study revealed significant spatial variations in the shear modulus of the corneal stroma on healthy subjects for the first time. Over an age span from 21 to 34 (N = 6), the central corneas exhibited a mean shear modulus of 87 kPa, while the corneal periphery showed a significant decrease to 44 kPa. The central cornea's shear modulus decreases with age with a slope of -19 +/- 8 kPa per decade, whereas the periphery showed non-significant age dependence. The limbus demonstrated an increased shear modulus exceeding 100 kPa. We obtained wave displacement profiles that are consistent with highly anisotropic corneal tissues. Our approach enabled precise measurement of corneal tissue elastic moduli in situ with high precision (<7%) and high spatial resolution (<1 mm). Our results revealed significant stiffness variation from the central to peripheral corneas. The high-frequency OCE technique holds promise for biomechanical evaluation in clinical settings, providing valuable information for refractive surgeries, degenerative disorder diagnoses, and intraocular pressure assessments.

Comparing 0.75% Ropivacaine and 0.5% Levobupivacaine For Peribulbar Blockade In Vitrectomy Surgery Towards Intraocular Pressure

Peribulbar blockade is a regional anesthetic technique that can be used for vitrectomy surgery. Ropivacaine and levobupivacaine are local anesthetics that have the advantage of a long duration of action and a lower complication rate than bupivacaine. This study aims to find the effect of intraocular pressure from ropivacaine and levobupivacaine. The study design was a double-blind randomized controlled trial on 60 patients underwent vitrectomy at Netra Ophthalmic Clinic Bandung with peribulbar blockade. Twenty-nine subjects received 0.75% ropivacaine and thirty-one subjects received 0.5% levobupivacaine for peribulbar blockade. Assessment of eye intraocular pressure was assessed before the block, 5 minutes, 10 minutes, and 15 minutes. The 0.75% ropivacaine group obtained an average of 4.42mmHg at 15 minutes, while the 0.5% levobupivacaine group averaged 2.33mmHg after 15 minutes after injection. Statistical results obtained p value &lt;0.05 which means significant intraocular pressure of the two drugs. Intraocular pressure of ropivacaine 0.75% lower than levobupivacaine 0.5% in peribulbar blockade in vitrectomy surgery.

Measurement of Tear Production and Intraocular Pressure in Clinically Conscious Normal Captive Red Deer (Cervus elaphus).

Normal values of tear production (STT) and intraocular pressure (IOP) have not been reported in conscious red deer to date. The objective was to determine the normal range of STT and IOP in clinically healthy, conscious red deer (Cervus elaphus) by utilizing a chute restraint. A total of 60 red deer were examined in this study. Both eyes of all red deer underwent a complete ophthalmic examination, including evaluation of tear production with the Schirmer tear test (STT) and assessment of intraocular pressure (IOP) with rebound tonometry, employing the TonoVet® device. The mean ± standard deviation of STT values were 18.35 ± 4.54 mm/30 s in the right eye and 17.87 ± 4.12 mm/30 s in the left; for both eyes, 18.11 ± 4.33 mm/30 s, with a reference range of 17.33-18.89 mm/30 s. IOP was as follows: 26.96 ± 4.42 mmHg in the right eye and 26.67 ± 3.80 mmHg in the left; for both eyes, it was 26.81 ± 4.11 mmHg, with a reference range of 26.07-27.55 mm/30 s. No statistically significant differences were observed between the IOP and STT values of the right and left eyes. This study provides a reference range for the STT and IOP in healthy red deer, showing that STT determination of tear production, and rebound tonometry to evaluate the IOP methods, are practical methods for ophthalmic examination in deer.

Silicone Oil and Intraocular Pressure: Unraveling the Post-Vitrectomy Relationship

Aim of the Study: To assess the potential influence of silicone oil tamponade following vitrectomy on the early elevation of intraocular pressure (IOP), a critical factor associated with the emergence of secondary glaucoma in individuals with proliferative changes in the vitreous and retina.  Subjects and Methodology: This study was carried out in a prospective manner within the Department of Ophthalmology at Katuri Medical College and Hospital from January 2023 to January 2024, lasting for a duration of 1 year. The research involved 110 participants categorized into three groups based on their medical histories. The control cohort, comprising 40 patients, went through vitrectomy with either air or saline solution as a tamponade. The second group, consisting of 40 patients with retinal detachment and proliferative retinopathy changes, have undergone vitrectomy with silicone oil tamponade. The third group, comprising 30 patients diagnosed with diabetic retinopathy, underwent vitrectomy with silicone oil tamponade. This study encompassed the assessment of intraocular pressure’s (IOP) and gonioscopic findings one month before and after vitrectomy for all the participants. The primary focus of the analysis was the comparison of IOP values across the different groups.  Conclusion: The results indicated that there was no statistically notable contrast in intraocular pressure (IOP) values prior to and following the vitrectomy procedure within the control group (p=0.104). Additionally, there was no substantial difference in preoperative IOP values among the three groups of patients. However, a noteworthy distinction in IOP values was observed during one-month post-vitrectomy, particularly in patients who underwent silicone oil tamponade. This suggests that the use of silicone oil tamponade had a notable impact on intraocular pressure in these patients after the surgical procedure. The study observed that, a month Following vitrectomy, the mean intraocular pressure (IOP) values in individuals with silicone oil tamponade were notably elevated in comparison to the control group (p&lt;0.05). However, when examining individuals with retinal detachment and individuals with diabetic retinopathy changes, did not exhibit a statistically notable variance in IOP one-month post-vitrectomy (p=0.331). Nevertheless, the qualitative examination exposed a 2 mmHg increase in intraocular pressure (IOP) in the diabetic retinopathy cohort. This study indicates that there exists no significant variance in angle width prior to and following vitrectomy among various groups included. Silicone oil in emulsified form was identified in 18% of the individuals with retinal detachment and in 17% of those with diabetic retinopathy, found in the chamber angle. Moreover, within the cohort of individuals with diabetic retinopathy, 10% of patients demonstrated this attribute of angle neovascularization one-month post-vitrectomy. The rise in intraocular pressure (IOP) in the initial postoperative phase can be linked to the introduction of silicone oil into the vitreous cavity following vitrectomy. The emulsification of silicone oil might be a factor in the early elevation of intraocular pressure (IOP), particularly in individuals with diabetes exhibiting angle neovascularization, potentially hastening the development of secondary glaucoma.

A Suspicious Cup Disc with High Intraocular Pressure (IOP) and Normal Perimetry: A Rare Self Case Report

Background: Intraocular pressure (IOP) assessment involves evaluating the force exerted by aqueous humor on the internal surface of the anterior eye. Elevated IOP poses a substantial risk for glaucomatous optic neuropathy and is a key modifiable clinical risk factor. This study aims to explore cases of ocular hypertension coupled with optic nerve cupping, suspected to be glaucoma, providing comprehensive details of examination results, diagnosis, and subsequent management.&#x0D; Case presentation: A 23-year-old Asian male underwent an ocular examination, revealing average IOP levels measured using non-contact tonometry. Despite no complaints, consecutive measurements noted 28 mmHg for the right eye and 26 mmHg for the left eye. Initial assessments by a glaucoma specialist indicated open-angle anterior chambers. Optical coherence tomography revealed cup disc ratios of 0.7 to 0.8 for both eyes. Medication (Timol) was prescribed, adjusting with oral citicoline and brinzolamide. The diagnosis evolved to juvenile open-angle glaucoma (JOAG). Visual field testing showed normal results. Discontinuation of treatment led to reclassifying the diagnosis as ocular hypertension and scheduling follow-up OCT examinations for five years.&#x0D; Conclusion: The patient exhibited corneal thickness ≥610 μm, CDR ≥0.7 μm, IOP &gt;25 mmHg, and maintained good visual field conditions. Additional research is essential to understand the correlation between corneal thickness and other eye conditions. Recognizing potential overdiagnosis due to high IOP and large CDR emphasizes the need for meticulous clinical assessment and advanced diagnostic examinations to distinguish physiological and pathological conditions.

The Effects of Bevacizumab in Augmenting Trabeculectomy for Glaucoma : Systematic Review and Meta-Analysis

Introduction &amp; Objectives : Anti-vascular endothelial growth factor (VEGF) agents have been used to slow the healing response and postoperative scar tissue formation. To determine the effectiveness of adding Anti VEGF bevacizumab to the results of trabeculectomy in glaucoma.&#x0D; Methods : Searches were conducted in a structured way using keywords across several data sources, including Pubmed, Proquest and Cochrane library. The keywords used for searching were “Bevacizumab”, “Trabeculectomy” and “Glaucoma”. The reviewed articles are Randomized Control Trial in english, conducted on humans in the last 15 years. The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.&#x0D; Results : From a total of 353 articles, there were 6 studies with 362 eyes of 352 patients been evaluated for the effectiveness of bevacizumab addition to trabeculectomy. The primary outcome of all articles was the assessment of Intra Ocular Pressure (IOP). No significant difference in IOP was found between the subconjunctival bevacizumab + Mytomycin-c group and mytomycin-c alone group (MD 0.11 ; 95% CI -0.10 to 0.33), as well as subconjunctival comparison with mytomycin-c (MD 0.11 ; 95% CI -0.29 to 0.50). Similar results were also found in the intracameral and placebo groups (MD 0.08 ; -0.22 to 0.38). However, 3 articles reported significant differences in peripheral vascularity of the bleb both by the Moorfields Bleb Grading System and by the Indiana Bleb Appearance System.&#x0D; Conclusion : The addition of bevacizumab to trabeculectomy did not show any benefit in reducing IOP when compared with MMC. But it gives better peripheral vascularity of the bleb.

Displacement-pressure biparametrically regulated softness sensory system for intraocular pressure monitoring.

High intraocular pressure (IOP) is one of the high-risk pathogenic factors of glaucoma. Existing methods of IOP measurement are based on the direct interaction with the cornea. Commercial ophthalmic tonometers based on snapshot measurements are expensive, bulky, and their operation requires trained personnel. Theranostic contact lenses are easy to use, but they may block vision and cause infection. Here, we report a sensory system for IOP assessment that uses a soft indentor with two asymmetrically deployed iontronic flexible pressure sensors to interact with the eyelid-eyeball in an eye-closed situation. Inspired by human fingertip assessment of softness, the sensory system extracts displacement-pressure information for soft evaluation, achieving high accuracy IOP monitoring (>96%). We further design and custom-make a portable and wearable ophthalmic tonometer based on the sensory system and demonstrate its high efficacy in IOP screening. This sensory system paves a way towards cost-effective, robust, and reliable IOP monitoring.

Investigation into the usefulness of cynomolgus monkeys with spontaneously elevated intraocular pressure as a model for glaucoma treatment research

Many glaucoma treatments focus on lowering intraocular pressure (IOP), with novel drugs continuing to be developed. One widely used model involves raising IOP by applying a laser to the trabecular iris angle (TIA) of cynomolgus monkeys to damage the trabecular meshwork. This model, however, presents challenges such as varying IOP values, potential trabecular meshwork damage, and risk of animal distress. This study investigated whether animals with naturally high IOP (>25 mmHg) could be used to effectively evaluate IOP-lowering drugs, thereby possibly replacing laser-induced models. Relationships between TIA size, IOP, and pupil diameter were also examined. Three representative IOP-lowering drugs (latanoprost, timolol, ripasudil) were administered, followed by multiple IOP measurements and assessment of corneal thickness, TIA, and pupil diameter via anterior segment optical coherence tomography (AS-OCT). There was a positive correlation was noted between IOP and corneal thickness before instillation, and a negative correlation between IOP and TIA before instillation. Our findings suggest animals with naturally high IOP could be beneficial for glaucoma research and development as a viable replacement for the laser-induced model and that measuring TIA using AS-OCT along with IOP yields a more detailed evaluation.

Intraocular pressure assessment after dorzolamide and travoprost administration in a cat with bilateral posterior lens subluxation

Lens subluxation is mainly produced by the interruption, damage or degeneration of the suspension system of the zonules. In the case of felines, the primary etiology responsible for the appearance of this pathology is represented by anterior uveitis preceding the moment of diagnosis, often complicated by secondary glaucoma.

Assessing Agreement and Variability Among Alternative Devices for Intraocular Pressure Measurement: A Comparative Study.

Intraocular pressure (IOP) measurement is critical in diagnosing and managing eye conditions. This study aims to assess the comparability of three alternative devices for measuring IOP: Noncontact tonometer, Icare rebound tonometer, and Tono-Pen. A cross-sectional study included 172 adult participants (87 males and 85 females) who underwent IOP and central corneal thickness (CCT) assessments. IOP was measured using Noncontact (Canon TX-20), Icare (Icare TA01i), and Tono-Pen (Tonopen XL). CCT was measured with the built-in pachymetry of the Noncontact tonometer. Correlation coefficients and Bland-Altman analyses were conducted to assess the relationships and agreements between these tonometers. Participants were grouped based on IOP and CCT levels. The mean of the standard deviation of the three tonometer results was calculated to evaluate measurement result variability. One-way analysis of variance was conducted for comparing between the groups. IOP measurements among the three devices were not significantly different, indicating their comparability. Correlation analysis revealed strong correlations between the tonometers. Bland-Altman analysis showed good agreement, with the Icare rebound tonometer and Tono-Pen exhibiting narrower limits of agreement. Furthermore, IOP levels influenced measurement result variability, with higher IOP levels associated with greater variance. This study demonstrates that the alternative devices examined can provide reliable IOP measurements. It highlights the potential of these alternative devices for IOP measurement. These findings have implications for clinical practice, offering practitioners additional tools for accurate IOP assessment.

Influence of unilateral eyelid spasms and botulinum toxin treatment on intraocular pressure measured by transpalpebral tonometer.

Eyelid spasms might be associated with elevated intraocular pressure (IOP) in hemifacial spasm (HFS) patients. IOP assessment using a Goldmann applanation tonometer (GAT) is often compromised by eyelid spasms. This study aimed to assess the effect of HFS on IOP measurements using the transpalpebral tonometer Diaton® before and after treatment with botulinum toxin type A (BTX-A) and compared Diaton® and GAT measurements after treatment with BTX-A. IOP measurements were obtained with Diaton® in 27 patients with moderate-to-severe HFS before and after treatment with BTX-A. After treatment, the IOP was also measured using GAT and the results were compared with the ones measured with a Diaton®. The patients underwent automated perimetry, OCT, and pachymetry for screening to glaucoma. Mean IOP with Diaton® was 11 ± 3.42mmHg before treatment in the affected eye and 9 ± 2.98mmHg in the contralateral eye. This difference was statistically significant (P = 0.012). However, after treatment with BTX-A, no interocular difference was found in IOP obtained with Diaton® (P = 0.204) or GAT (P = 0.971). Comparison between GAT and Diaton® measurements showed no significant differences after BTX-A treatment between the affected (P = 0.212) and contralateral eye (P = 0.971). A significant reduction in IOP measurements on the affected side of HFS patients was observed after treatment with BTX-A, demonstrating that eyelid spasms may increase the IOP. No significant difference was observed between Diaton® and GAT measurements after the application of BTX-A. No differences were found in automated perimetry, OCT, and CCT when comparing affected eyes with contralateral eyes.