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Noya-Padin V, Garcia-Queiruga J, Sabucedo-Villamarin B, Nores-Palmas N, Taboada-Mecias R, Yebra-Pimentel E. Intraocular Pressure Fluctuation Throughout the Day. Cureus 2023; 15:e48826. [PMID: 38106705 PMCID: PMC10722343 DOI: 10.7759/cureus.48826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2023] [Indexed: 12/19/2023] Open
Abstract
Purpose To compare intraocular pressure (IOP) values at different time points, both in the total sample and according to iridocorneal angle aperture, to assess whether IOP fluctuations were constant throughout the day, and to examine correlations with other factors. Methods Over a single day, the IOP of 34 volunteers was measured at three-hour intervals from 9:00 a.m. to 6:00 p.m. To avoid any IOP value being affected by other measurements, anamnesis, slit-lamp evaluation (with iridocorneal angle measurement), and refractive status were performed after the final measurement. The differences between IOP values at different time points and IOP fluctuation at three-hour intervals were compared by ANOVA and Friedman test, respectively, both for the total group and according to iridocorneal angle aperture. For relationships, Pearson's correlation was performed for parametric variables and Spearman's correlation for nonparametric variables. Results Significant differences were observed in IOP between time points for the total sample (p < 0.001), but not for a narrow-angle group (p = 0.058). No significant differences were found in IOP fluctuations at three-hour intervals either in the total sample or according to angle aperture (all p ≥ 0.332). There was a positive correlation of IOP at different time points (all r ≥ 0.646, all p < 0.001) but no relationship with spherical equivalent, age, or sleep duration (all p ≥ 0.057). IOP at 12:00 p.m. was correlated with a 12:00 p.m. to 3:00 p.m. fluctuation (r = 0.428, p = 0.012); and IOP fluctuation between 9:00 a.m. and 12:00 p.m. was correlated with age (r = 0.485, p = 0.004). Conclusion As IOP decreases from morning until at least 6:00 p.m., measuring these two values during clinical evaluation is essential for the effective monitoring and prevention of IOP-related diseases.
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Affiliation(s)
- Veronica Noya-Padin
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
- Department of Optometry, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, ESP
| | - Jacobo Garcia-Queiruga
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
- Department of Optometry, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, ESP
| | - Belen Sabucedo-Villamarin
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
| | - Noelia Nores-Palmas
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
| | - Ricardo Taboada-Mecias
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
| | - Eva Yebra-Pimentel
- Department of Applied Physics (Optometry Area), Universidade de Santiago de Compostela, Santiago de Compostela, ESP
- Department of Optometry, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, ESP
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Campigotto A, Campbell RJ, Lai Y. Correlation between corneal and contact lens deformation with changes in intraocular pressure for wearable monitoring systems. Eye (Lond) 2023; 37:2055-2060. [PMID: 36302975 PMCID: PMC10333185 DOI: 10.1038/s41433-022-02285-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 09/11/2022] [Accepted: 10/07/2022] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVE The aim of this work is to evaluate the extent to which the eye's curvature deformation, due to changes in the intraocular pressure (IOP), can be directly tracked by an overlying contact lens. METHOD In this experimental study, using 12 cadaveric eyes, the IOP was increased from 10 to 36 mmHg, while video imaging was used to capture the three experimental variations. The deformation of the bare eye was used as a control, while the deformation of an overlying silicone grided contact lens and an overlying microfluidic IOP-sensing contact lens were examined and compared. RESULTS The relation between the slope of the radius of corneal curvature versus the IOP for both the bare eye and the marker contact lens yielded a linear relationship with a R2 value of 0.83. The microfluidic contact lens resulted in an average performance of 0.40 mm indicator movement/mmHg (SD 0.006). Comparing the slope of the marker contact lens deformation, to the performance of the microfluidic contact lens resulted in a R2 value of 0.78. The strain map of the overlaying grided contact lens showed most deformation occurring along the outer edge of the lens with increased deformation as increase IOP occurs; as well as with some negative, compressive movement near the central points. CONCLUSION The deformation from the curvature of the eye is significant enough from 10 to 36 mmHg that a silicone contact lens can capture and mimic those changes. The results show promise for optimization in contact lens-based IOP monitoring.
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Affiliation(s)
- Angelica Campigotto
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada
| | - Robert J Campbell
- Department of Ophthalmology, Queen's University, Kingston, ON, Canada
- Department of Ophthalmology, Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Yongjun Lai
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada.
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Schmidt I, Plange N, Walter P, Koutsonas A. Telemetric non-contact intraocular pressure monitoring with an implanted sensor in patients with glaucoma: long-term safety report and monitoring data. Br J Ophthalmol 2022:bjophthalmol-2021-319786. [PMID: 35314512 DOI: 10.1136/bjophthalmol-2021-319786] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 03/08/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND/AIMS Glaucoma is a chronic disease that requires lifelong monitoring and treatment. However, its control is limited due to discontinuous intraocular pressure (IOP) monitoring related to the practitioners' office hours. Implantable telemetric IOP sensors have made self-measurements possible and provide important information regarding the IOP profiles of patients. However, limited long-term monitoring data are currently available. METHODS In the ARGOS-01 study, a telemetric IOP sensor was implanted in the ciliary sulcus of six patients with open-angle glaucoma during cataract surgery between 2011 and 2012. This study reports telemetric monitoring data collected by self-tonometry and automated measurements and during outpatient visits, including an analysis of one active patient with several years of follow-up. The long-term safety, tolerability and functionality were assessed in the remaining patients during the last visit. RESULTS The follow-up period was up to 10 years, in which almost 25 000 IOP measurements were performed. The patients had excellent tolerance of the implanted sensor and did not experience sensor-related discomfort or complications. The active patient reported easy handling of self-tonometry and did not experience long-term restrictions in activities of daily living due to the implanted sensor. Telemetric data provide an insight into patients' measurement routines and IOP fluctuations. CONCLUSION So far, our data suggest good long-term safety, tolerability and functionality of the implanted sensors up to almost ten years. Such sensors may help facilitate patients' self-measurements of IOP. This disease monitoring method should be investigated further to determine if it helps improve wider patient experience, engagement and visual prognosis for those being treated for complex glaucoma.
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Affiliation(s)
- Ilka Schmidt
- Department of Ophthalmology, University Hospital Aachen, Aachen, Germany
| | - Niklas Plange
- Department of Ophthalmology, University Hospital Aachen, Aachen, Germany
| | - Peter Walter
- Department of Ophthalmology, University Hospital Aachen, Aachen, Germany
| | - Antonis Koutsonas
- Department of Ophthalmology, University Hospital Aachen, Aachen, Germany
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Murthy GJ, Ariga M, Singh M, George R, Sarma P, Dubey S, Choudhry RM, Parikh R, Panday M. A deep dive into the latest European Glaucoma Society and Asia-Pacific Glaucoma Society guidelines and their relevance to India. Indian J Ophthalmol 2022; 70:24-35. [PMID: 34937204 PMCID: PMC8917547 DOI: 10.4103/ijo.ijo_1762_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Glaucoma is the second leading cause of blindness in India. Despite advances in diagnosing and managing glaucoma, there is a lack of India-specific clinical guidelines on glaucoma. Ophthalmologists often refer to the European Glaucoma Society (EGS) and Asia-Pacific Glaucoma Society (APGS) guidelines. A group of glaucoma experts was convened to review the recently released EGS guideline (fifth edition) and the APGS guideline and explore their relevance to the Indian context. This review provides the salient features of EGS and APGS guidelines and their utility in Indian scenario. Glaucoma diagnosis should be based on visual acuity and refractive errors, slit-lamp examination, gonioscopy, tonometry, visual field (VF) testing, and clinical assessment of optic nerve head, retinal nerve fiber layer (RNFL), and macula. The intraocular pressure target must be individualized to the eye and revised at every visit. Prostaglandin analogues are the most effective medications and are recommended as the first choice in open-angle glaucoma (OAG). In patients with cataract and primary angle-closure glaucoma (PACG), phacoemulsification alone or combined phacoemulsification and glaucoma surgery are recommended. Trabeculectomy augmented with antifibrotic agents is recommended as the initial surgical treatment for OAG. Laser peripheral iridotomy and surgery in combination with medical treatment should be considered in high-risk individuals aged <50 years. In patients with phakic and PACG, phacoemulsification alone or combined phacoemulsification and glaucoma surgery are recommended. Visual acuity, VF testing, clinical assessment of the optic disc and RNFL, and tonometry are strongly recommended for monitoring glaucoma progression.
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Affiliation(s)
- Gowri J Murthy
- Glaucoma Service, Prabha Eye Clinic and Research Centre, Bangalore, India
| | - Murali Ariga
- HOD- Ophthalmology, Sundaram Medical Foundation, Chennai, India
| | - Maneesh Singh
- Executive Director, Netralayam, the Superspeciality Eye Care Centre, Kolkata, India
| | - Ronnie George
- Glaucoma Services, Sankara Nethralaya, Medical and Vision Research Foundations, Chennai, India,
Correspondence to: Dr. Ronnie George, Glaucoma Services, Sankara Nethralaya, Medical and Vision Research Foundations, 18, College Road, Chennai, Tamil Nadu, India. E-mail:
| | - Prafulla Sarma
- Consultant, Glaucoma Clinic, Prime Eye Care Center, Guwahati, Assam, India
| | | | - Reena M Choudhry
- HOD, Glaucoma Services, ICARE Eye Hospital and Post Graduate Institute, Noida, India
| | - Rajul Parikh
- Consultant, Shreeji Eye Clinic and Palak’s Glaucoma Care Center, Mumbai, India
| | - Manish Panday
- Director, Glaucoma, Ratan Jyoti Netralaya Ophthalmic Institute and Research Centre, Gwalior, India
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Xu J, Li R, Xu H, Yang Y, Zhang S, Ren T. Recent progress of continuous intraocular pressure monitoring. NANO SELECT 2021. [DOI: 10.1002/nano.202100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jiandong Xu
- Institute of Microelectronics Tsinghua University Beijing 100084 China
- Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China
| | - Ruisong Li
- Department of Electrical Engineering and Computer Science and Department of Bioengineering College of Engineering University of California Berkeley California 94720 USA
| | - Haokai Xu
- Institute of Microelectronics Tsinghua University Beijing 100084 China
- Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China
| | - Yi Yang
- Institute of Microelectronics Tsinghua University Beijing 100084 China
- Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China
| | - Sheng Zhang
- Shenzhen International Graduate School Tsinghua University Shenzhen 518055 China
| | - Tian‐Ling Ren
- Institute of Microelectronics Tsinghua University Beijing 100084 China
- Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China
- Center for Flexible Electronics Technology Tsinghua University Beijing 100084 China
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The Utility of iCare HOME Tonometry for Detection of Therapy-Related Intraocular Pressure Changes in Glaucoma and Ocular Hypertension. Ophthalmol Glaucoma 2021; 5:85-93. [PMID: 34082179 DOI: 10.1016/j.ogla.2021.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/30/2021] [Accepted: 05/21/2021] [Indexed: 11/21/2022]
Abstract
PURPOSE To assess whether iCare HOME rebound tonometry can detect therapy-related changes during self-monitoring of intraocular pressure (IOP). DESIGN Prospective clinical trial. PARTICIPANTS A total of 43 eyes (n = 27 subjects) with open-angle glaucoma or ocular hypertension were enrolled during standard-of-care clinic visits. Participants were grouped into control eyes managed on stable therapy (n = 18 eyes) or therapy change eyes undergoing selective laser trabeculoplasty (SLT, n = 8 eyes), initiating topical therapy (n = 8 eyes), or adding a second medication to existing monotherapy (n = 9 eyes). METHODS Subjects recorded IOP 4 times daily for 1 week using iCare HOME tonometry. Upon tonometer return, subjects underwent SLT or new medication start; an additional week of iCare HOME measurements was collected after 4 to 6 weeks. Control subjects recorded an additional week of measurements after 6 weeks. Measurements were grouped into 4 time periods (5-10 am, 10 am to 3 pm, 3-8 pm, 8 pm to 1 am). Goldmann applanation tonometry (GAT) was performed at each study visit for comparison. MAIN OUTCOME MEASURES Detection of therapy response defined as an IOP reduction of ≥20%. RESULTS For eyes that demonstrated a therapy response by GAT (n = 11), iCare HOME detected a therapy response in 90.9% of eyes in ≥1 time period and 45.5% of eyes in all 4 time periods. In eyes without a GAT-measured therapy response (n = 14), iCare HOME detected a response for 71.4% (n = 10) of eyes in ≥1 time period and for 7.1% of eyes (n = 1) at all 4 time periods. In treatment eyes, intraday and interday average minimum and maximum IOP, as well as interday IOP range, were significantly reduced after therapy without a significant change in intraday IOP range. Control group eyes did not demonstrate a significant change in average IOP minimum, maximum, or range between study weeks. CONCLUSIONS Home tonometry with iCare HOME reliably detects therapy-related IOP changes in patients with glaucoma and ocular hypertension. Treatment responses correlated well with in-office GAT and may detect treatment responses missed by GAT. Intraocular pressure measurements via home tonometry provide additional clinical information regarding intraday and interday IOP fluctuation beyond standard of care in office GAT measurements. The iCare HOME is a valuable tool to monitor therapeutic efficacy in patients with glaucoma.
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Chikasirimobi TG, Ndinyo M, Ondieki MN, Miti I, Ejiochi-Iyoke NJ, Osuagwu UL, Zeried FM, Agho K, Ogbuehi KC, Mashige KP. A comparison of postural and diurnal variations in intraocular pressure using the iCare rebound tonometer and Perkins applanation tonometer in admitted adults in Kenya. AFRICAN VISION AND EYE HEALTH 2021. [DOI: 10.4102/aveh.v80i1.617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Background: Elevated intraocular pressure (IOP) remained the most important known risk factor for glaucoma.Aim: To compare the postural and diurnal IOP variations using the iCare rebound tonometer (RT) and Perkins applanation tonometer (PAT).Setting: Kakamega County Hospital, Kenya.Methods: Elevated intraocular pressure measurements were taken by two (masked) examiners with two devices in the morning (06:00–09:00), midday (12:00–15:00) and evening (18:00–21:00), in the sitting followed by supine positions in one randomly selected eye of 24 oculo-visual healthy hospital-admitted patients. Effects of the time of the day and position of the body within and between devices were analysed with the Statistical Package for Social Sciences.Results: The mean IOP measured by the RT ranged from 6 mmHg to 24 millimetres of mercury (mmHg) in the sitting position and from 10 mmHg to 26 mmHg in the supine position. The mean IOP measured using PAT ranged from 6 mmHg to 21 mmHg in the sitting position and from 8 mmHg to 24 mmHg in the supine position. The IOP measured by both devices significantly varied with position (p 0.05). Perkins applanation tonometer on average gave a significantly higher IOP (1.7 mmHg [p = 0.003] and 1.3 mmHg [p = 0.034]) at 06:00 compared to that at 12:00 and 18:00, respectively. The IOP readings with the RT were on average 2.2 mmHg and 3.0 mmHg higher at 06:00 compared to that at 12:00 and 18:00, respectively (p 0.0005).Conclusion: Significant reductions were observed in postural and diurnal IOPs in the sitting positions and in the afternoon, respectively. Diurnal IOP variations were slightly higher when measured by RT compared to when measured by PAT.
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8
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Firat PG, Dikci S, Firat İT, Demirel S, Firat M, Öztürk E, Gök ZE. Correlation between intraocular pressure obtained with water drinking test versus modified diurnal tension curve measurement in pseudoexfoliation glaucoma. Int Ophthalmol 2021; 41:2879-2886. [PMID: 33877501 DOI: 10.1007/s10792-021-01847-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 04/08/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of this paper was to study the correlation and agreement between the intraocular pressure (IOP) peak value and fluctuations detected with the modified diurnal tension curve (mDTC) and the water drinking test (WDT) in pseudoexfoliation glaucoma (XFG) patients. METHODS This prospective observational study enrolled 42 eyes of 42 XFG patients. The IOPs were measured at 2-h intervals from 8 am to 4 pm with a Goldmann applanation tonometer by a single observer to establish the mDTC. The WDT was then performed between 4 and 5 pm on the same day and the IOP was measured 4 times at 15-min intervals after water ingestion. The IOPpeak, IOPmean, IO min, and IOPfluctuation were measured with both the mDTC and WDT. The paired sample t test, Spearman's correlation coefficient and Bland-Altman plots were used for statistical analysis. RESULTS The mean age of the 42 patients consisting of 24 females and 18 males was 66.9 ± 6.8 years, and the mean central corneal thickness was 517.7 ± 29.1 µm. The mean values with the mDTC and WDT measurements were 15.05 ± 2.75 mmHg and 17.17 ± 3.25 mmHg (p ≤ 0.0001, r = 0.884) for IOPmean, 16.76 ± 3.45 mmHg and 18.92 ± 3.94 mmHg (p ≤ 0.0001, r=0.787) for IOPpeak, and 13.61 ± 2.56 mmHg and 15.11 ± 2.84 mmHg (p ≤ 0.0001, r=0.824) for IOPmin, respectively, and a positive correlation was present between these values. CONCLUSION There was a positive correlation between the peak, minimum, and mean IOP values determined using the mDTC and WDT in treated XFG patients. WDT can be used as an alternative in the assessment of the IOP in these patients as a more practical method.
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Affiliation(s)
- Penpe Gül Firat
- Department of Ophthalmology, Inonu University School of Medicine, TR-44280, Malatya, Turkey.
| | - Seyhan Dikci
- Department of Ophthalmology, Inonu University School of Medicine, TR-44280, Malatya, Turkey
| | | | | | - Murat Firat
- Department of Ophthalmology, Elbistan State Hospital, Kahramanmaraş, Turkey
| | - Emrah Öztürk
- Department of Ophthalmology, Malatya State Hospital, Malatya, Turkey
| | - Zarife Ekici Gök
- Department of Ophthalmology, Malatya State Hospital, Malatya, Turkey
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McGlumphy EJ, Mihailovic A, Ramulu PY, Johnson TV. Home Self-tonometry Trials Compared with Clinic Tonometry in Patients with Glaucoma. Ophthalmol Glaucoma 2021; 4:569-580. [PMID: 33845191 DOI: 10.1016/j.ogla.2021.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/27/2021] [Accepted: 03/29/2021] [Indexed: 11/19/2022]
Abstract
PURPOSE This study examined characteristics of intraocular pressure (IOP) as measured during home tonometry in comparison with in-clinic tonometry in patients with glaucoma. DESIGN Retrospective cross-sectional study of glaucoma patients who completed 1 week of self-tonometry at a single academic center. PARTICIPANTS Patients with glaucoma who completed home tonometry trials with the iCare HOME tonometer (iCare USA) for any reason. METHODS Home IOP measurements were compared with in-clinic tonometry performed during the 5 visits preceding home tonometry. Maximum daily IOP was correlated to time of day. Generalized estimating equations were used to evaluate patient characteristics and clinic-derived variables that predicted differences between home and clinic IOP. MAIN OUTCOME MEASURES IOP mean, maximum, minimum, range, standard deviation and coefficient of variation were compared between clinic and home tonometry. IOP mean daily maximum (MDM) and mean daily range were calulated to describe recurrent IOP spiking. RESULTS A total of 107 eyes from 61 patients were analyzed. Mean age was 63.2 years (standard deviation [SD], 14.0 years) and 59.0% were women. Mean clinic and home IOPs were 14.5 mmHg (SD, 4.7 mmHg) and 13.6 mmHg (SD, 5.1 mmHg). Home tonometry identified significantly higher maximum IOP, lower minimum IOP, and greater IOP range than clinic tonometry (P < 0.001). Maximum daily IOP occurred outside of clinic hours (8 am-5 pm) on 50% of days assessed and occurred between 4:30 am and 8 am on 24% of days. Mean daily maximum IOP exceeded maximum clinic IOP in 44% of patients and exceeded target IOP by 3 mmHg, 5 mmHg, or 10 mmHg in 31%, 15%, and 6% of patients, respectively. Patient characteristics that predicted significant deviations between MDM and mean clinic IOP or target IOP in multivariate models included younger age, male gender, and absence of prior filtering surgery. CONCLUSIONS Self-tonometry provides IOP data that supplements in-clinic tonometry and would not be detectable over daytime in-clinic diurnal curves. A subset of patients in whom home tonometry was ordered by their glaucoma clinician because of suspicion of occult IOP elevation demonstrated reproducible IOP elevation outside of the clinic setting. Such patients tended to be younger and male and not to have undergone previous filtering surgery.
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Affiliation(s)
- Elyse J McGlumphy
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Aleksandra Mihailovic
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pradeep Y Ramulu
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Thomas V Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
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Effect of variations of corneal physiology on novel non-invasive intraocular pressure monitoring soft contact lens. Biomed Microdevices 2021; 23:16. [PMID: 33725182 DOI: 10.1007/s10544-021-00555-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2021] [Indexed: 10/21/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness around the world. With its slow asymptomatic progression, there is an emphasis on early detection and frequent monitoring. A novel microfluidic contact lens has been established as a potential way to track the fluctuations of the intraocular pressure (IOP) which is a key indicator for diagnosing and monitoring glaucoma progression. The purpose of this article is to determine the effect of physiological variations of the eye on the performance of the microfluidic contact lens. Ultrasound biomicroscopy (UBM) was used to measure the central corneal thickness (CCT) and radius of corneal curvature (RCC) for a series of 16 fresh enucleated porcine eyes. The effect of these corneal anatomic features on device performance was then assessed by systematically adjusting intraocular pressure from 10 to 34 mmHg and monitoring the device indicator response. The performance of the microfluidic contact lens was determined by finding the amount the indicator fluid shifted in position as a result of 1 mmHg IOP increase. The relationship between IOP and indicator fluid was found to be linear for all eyes. The slope of the indicator fluid movement as a result of the IOP was evaluated against the CCT and RCC of each porcine eye. This yielded low correlation coefficients, 0.057 for CCT and 0.024 for RCC, meaning that these physiological differences showed no systematic impact on the measurements made with the contact lens.
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11
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Dick HB, Gerste RD. Future Intraocular Lens Technologies. Ophthalmology 2020; 128:e206-e213. [PMID: 33373617 DOI: 10.1016/j.ophtha.2020.12.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 12/16/2020] [Accepted: 12/22/2020] [Indexed: 11/18/2022] Open
Abstract
The future of intraocular lens (IOL) technology has already begun with a number of recent innovations. The postoperative change of refractive power will lead to a customized fine-tuning that provides patients with the individual vision they expect and with as much spectacle independence as possible. The latest-generation (2.0) Light-Adjustable Lens (RxSight) was recently introduced into clinical practice, with the first results being very encouraging. Other methods of altering the power of an already implanted IOL are under development. The same can be said about the correction of presbyopia, the so-called last frontier in refractive surgery. Extended depth-of-focus IOLs have been introduced, as has the technology of the pinhole IOL. The latter has therapeutic potential beyond the refractive aspect and has already proven helpful in cases of iris defects and irregular corneas. Several technologies are currently being tested to achieve-finally-an accommodative IOL. One such concept uses the (remaining) strength of the ciliary muscle, whereas another is triggered by the pupil reaction when shifting focus from far to near. Not an IOL itself, but rather a high-tech innovation that so far has mostly been implanted during cataract surgery, is a microelectronic sensor that measures habitual intraocular pressure (IOP) at any given time and promises to revolutionize the management of glaucoma patients. The last generation of this device (Eyemate; Implandata Opthalmics Products GmbH) is implanted during small-incision cataract surgery; the latest development is an even smaller sensor that will be inserted suprachoroidally before, in the near future, such a device will be part of a capsular ring. These IOP sensors are a prime example that IOL technology will continue to be a driving force in ophthalmology, with a positive impact far beyond cataract surgery.
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Koh V, Tham YC, Tan NYQ, Yu M, Thakur S, Teo ZL, Mani B, Wong TY, Aung T, Cheng CY. Six-Year Incidence and Risk Factors of Primary Glaucoma in the Singapore Indian Eye Study. Ophthalmol Glaucoma 2020; 4:201-208. [PMID: 32947057 DOI: 10.1016/j.ogla.2020.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/03/2020] [Accepted: 09/09/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine the 6-year incidence of primary glaucoma and its risk factors in an Indian population in Singapore. DESIGN Cohort population-based study. PARTICIPANTS Indian adults between 40 and 80 years of age living in Singapore. A total of 3400 participants underwent the baseline examination between 2007 and 2009. Of them, 2200 (response rate, 75.5% of those eligible) participated in the 6-year follow-up visit between 2013 and 2015. METHODS Standardized examination and investigations were performed, including indentation gonioscopy, intraocular pressure (IOP) measurement, optic disc examination, and static automated perimetry. Glaucoma was defined according to the International Society Geographical and Epidemiological Ophthalmology criteria. MAIN OUTCOME MEASURES Incidences of primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). RESULTS The age-standardized incidences of primary glaucoma, POAG, and PACG were 1.68% (95% confidence interval [CI], 1.21%-2.32%), 1.37% (95% CI, 0.94%-1.96%), and 0.32% (95% CI, 0.15%-0.66%), respectively. For eyes with ocular hypertension (n = 45) at baseline, the incidence of POAG was 4.83% (95% CI, 1.24%-17.21%) and for eyes with primary angle closure (n = 14) or suspected primary angle closure (n = 101), the incidence of PACG developing was 1.82% (95% CI, 0.37%-9.68%). Baseline factors associated significantly with risk of primary glaucoma developing included older age (per decade; odds ratio [OR], 1.84; 95% CI, 1.44-2.36; P < 0.001), larger vertical cup-to-disc ratio (per 0.1 unit; OR, 2.78; 95% CI, 2.12-3.64; P < 0.001), and higher IOP (per millimeter of mercury; OR, 1.25; 95% CI, 1.13-1.38; P < 0.001). However, 71 of 85 eyes (84.5%) diagnosed with incident glaucoma had IOP of less than 21 mmHg at the time of examination. CONCLUSIONS Our study showed that the overall age-standardized incidence of primary glaucoma was 1.68% in an Indian population in Singapore. In our population, the incidence of POAG was only half and the incidence of PACG was similar to the incidence reported by the Chennai Eye Disease Study.
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Affiliation(s)
- Victor Koh
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Department of Ophthalmology, National University Hospital, National University Health System, Singapore, Republic of Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore
| | - Yih-Chung Tham
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore
| | - Nicholas Y Q Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Department of Ophthalmology, National University Hospital, National University Health System, Singapore, Republic of Singapore
| | - Marco Yu
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore
| | - Sahil Thakur
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore
| | - Zhen Ling Teo
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore
| | - Baskaran Mani
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Duke-NUS, National University of Singapore, Singapore, Republic of Singapore
| | - Tien-Yin Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore; Duke-NUS, National University of Singapore, Singapore, Republic of Singapore
| | - Tin Aung
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore; Duke-NUS, National University of Singapore, Singapore, Republic of Singapore
| | - Ching-Yu Cheng
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore; Duke-NUS, National University of Singapore, Singapore, Republic of Singapore.
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13
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Osmers J, Hoppe O, Strzalkowska A, Strzalkowski P, Patzkó Á, Arnold S, Sorg M, Fischer A. Results of First In Vivo Trial of an Acoustic Self-Tonometer. Transl Vis Sci Technol 2020; 9:18. [PMID: 32879774 PMCID: PMC7442865 DOI: 10.1167/tvst.9.9.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/14/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose Glaucoma is the world's most common cause of irreversible blindness, which makes early diagnosis, with the goal of preserving vision, essential. The current medical intervention is to reduce intraocular pressure (IOP) to slow down progression of the disease. The main goal of this study was to test a novel handheld acoustic self-tonometer on humans. Methods A sound pressure pulse generated by a loudspeaker causes the eye to vibrate. A pressure chamber is placed on the human orbit to form a coupled system comprised of the patient's eye, the enclosed air, and the loudspeaker. A displacement sensor in front of the loudspeaker membrane allows the dynamic behavior of the entire system to be detected. Results For this clinical trial series, a prototype of the acoustic self-tonometer principle was applied. The resulting membrane oscillation data showed sensitivity of patient IOP, but direct allocation of the measured damping and frequency to the IOP was not significant. For this reason, an artificial neural network was used to find relationships among the subjects’ biometric eye parameters in combination with the self-tonometer data for the IOP reference. An expanded measurement uncertainty (kp = 2) equal to 6.53 mm Hg was determined for the self-tonometer in a Bland–Altman analysis using Goldmann applanation tonometer reference measurements. Conclusions The usability and success rate of producing valid measurement values with the device during self-measurements by test subjects was nearly 92%. The cross-sensitivities observed require compensation in a possible redesign phase to reduce the measurement uncertainty by at least 25% to the maximum of 5 mm Hg required to seek medical device approval. Translational Relevance Building on successful laboratory experiments with pig eyes, this article reports the results of testing the acoustic tonometer on humans.
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Affiliation(s)
- Jan Osmers
- University of Bremen, Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), Bremen, Germany
| | - Oskar Hoppe
- University of Bremen, Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), Bremen, Germany
| | - Alicja Strzalkowska
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | - Piotr Strzalkowski
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | - Ágnes Patzkó
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | | | - Michael Sorg
- University of Bremen, Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), Bremen, Germany
| | - Andreas Fischer
- University of Bremen, Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), Bremen, Germany
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14
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Campigotto A, Lai Y. A novel non‐invasive wearable sensor for intraocular pressure measurement. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/mds3.10086] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Angelica Campigotto
- Department of Mechanical Engineering Queen’s University Kingston Ontario Canada
| | - Yongjun Lai
- Department of Mechanical Engineering Queen’s University Kingston Ontario Canada
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McGarva E, Farr J, Dabasia P, Lawrenson JG, Murdoch IE. Initial experience in self-monitoring of intraocular pressure. Eur J Ophthalmol 2020; 31:1326-1332. [PMID: 32340488 PMCID: PMC8358569 DOI: 10.1177/1120672120920217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background/aims Diurnal variation in intraocular pressure (IOP) is a routine assessment in glaucoma management. Providing patients the opportunity to perform self-tonometry might empower them and free hospital resource. We previously demonstrated that 74% of patients can use the Icare® HOME tonometer. This study further explores Icare® HOME patient self-monitoring. Methods Patients were trained by standard protocol to use the Icare® HOME rebound tonometer. Patient self-tonometry was compared to Goldmann applanation tonometry (GAT) over one clinical day. Following this, each patient was instructed to undertake further data collection that evening and over the subsequent two days. Results Eighteen patients (35 eyes) participated. Good agreement was demonstrated between GAT and Icare® HOME for IOPs up to 15 mm Hg. Above this IOP the Icare® tended to over-read, largely explained by 2 patients with corneal thickness >600 um. The mean peak IOP during ‘clinic hours’ phasing was 16.7 mm Hg and 18.5 mm Hg (p = 0.24) over three days. An average range of 5.0, 7.0 and 9.8 mm Hg was shown during single day clinic, single day home and three day home phasing respectively (p =<0.001). The range of IOP was lower in eyes with prior trabeculectomy (6.1 mm Hg vs 12.2 mm Hg). All patients undertook one reading in the early morning at home with an average of 4.8 readings during, and 3.1 readings after office hours. Conclusions This small study shows that self-tonometry is feasible. The findings from home phasing demonstrated higher peak and trough IOPs, providing additional clinical information. Home phasing is a viable alternative. The cost-effectiveness of this approach has yet to be addressed.
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Affiliation(s)
- Emily McGarva
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Jane Farr
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Priya Dabasia
- Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - John G Lawrenson
- Division of Optometry and Visual Sciences, City, University of London, London, UK.,UCL Institute of Ophthalmology, London, UK
| | - Ian E Murdoch
- Moorfields Eye Hospital NHS Foundation Trust, London, UK.,UCL Institute of Ophthalmology, London, UK
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16
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Choritz L, Mansouri K, van den Bosch J, Weigel M, Dick HB, Wagner M, Thieme H, Thieme H, Rüfer F, Szurmann P, Wehner W, Spitzer M, Hesse L, Jünemann A, Plange N, Schmickler S, Dick B, Hakan K. Telemetric Measurement of Intraocular Pressure via an Implantable Pressure Sensor-12-Month Results from the ARGOS-02 Trial. Am J Ophthalmol 2020; 209:187-196. [PMID: 31545953 DOI: 10.1016/j.ajo.2019.09.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 11/27/2022]
Abstract
PURPOSE The aim of this study was to investigate the safety and performance of the second generation of an implantable intraocular pressure (IOP) sensor in patients with primary open angle glaucoma (POAG). DESIGN prospective, noncomparative, open-label, multicenter clinical investigation. METHODS In this study, patients with POAG, regularly scheduled for cataract surgery, were implanted with a ring-shaped, sulcus-placed, foldable IOP sensor in a single procedure after intraocular lens implantation. Surgical complications as well as adverse events (AEs) during 12 months of follow-up were recorded. At each follow-up visit, a complete ophthalmic examination, including visual acuity, IOP, slit lamp examination, and dilated funduscopy as well as comparative measurements between Goldmann applanation tonometry and the EYEMATE-IO implant were performed. RESULTS The EYEMATE-IO implant was successfully implanted in 22 patients with few surgical complications and no unexpected device-related AEs. All ocular AEs resolved quickly under appropriate treatment. Comparative measurements showed good agreement between EYEMATE-IO and Goldmann applanation tonometry (GAT) with an intraclass correlation coefficient (ICC(3,k)) of 0.783 (95% confidence interval [CI]: 0.743, 0.817). EYEMATE-IO measurements were higher than GAT, with a mean difference of 3.2 mm Hg (95% CI: 2.8, 3.5 mm Hg). CONCLUSIONS The EYEMATE-IO sensor was safely implanted in 22 patients and performed reliably until the end of follow-up. This device allows for continual and long-term measurements of IOP.
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17
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Osmers J, Sorg M, Fischer A. Optical measurement of the corneal oscillation for the determination of the intraocular pressure. ACTA ACUST UNITED AC 2019; 64:471-480. [DOI: 10.1515/bmt-2018-0093] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 08/21/2018] [Indexed: 11/15/2022]
Abstract
Abstract
Motivation
Glaucoma is currently the most common irreversible cause of blindness worldwide. A significant risk factor is an individually increased intraocular pressure (IOP). A precise measurement method is needed to determine the IOP in order to support the diagnosis of the disease and to monitor the outcome of the IOP reduction as a medical intervention. A handheld device is under development with which the patient can perform self-measurements outside the clinical environment.
Method
For the measurement principle of the self-tonometer the eye is acoustically excited to oscillate, which is analyzed and attributed to the present IOP. In order to detect the corneal oscillation, an optical sensor is required which meets the demands of a compact, battery driven self-tonometer. A combination of an infrared diode and a phototransistor provides a high-resolution measurement of the corneal oscillation in the range of 10 μm–150 μm, which is compared to a reference sensor in the context of this study. By means of an angular arrangement of the emitter and the detector, the degree of reflected radiation of the cornea can be increased, allowing a measurement with a high signal-to-noise ratio.
Results
By adjusting the angle of incidence between the detector and the emitter, the signal-to-noise ratio was improved by 40 dB which now allows reasonable measurements of the corneal oscillation. For low amplitudes (10 μm) the signal-to-noise ratio is 10% higher than that of the commercial reference sensor. On the basis of amplitude variations at different IOP levels, the estimated standard uncertainty amounts to <0.5 mm Hg in the physiological pressure range with the proposed measuring approach.
Conclusion
With a compact and cost-effective approach, that suits the requirements for a handheld self-tonometer, the corneal oscillation can be detected with high temporal resolution. The cross-sensitivity of the sensor concept concerning a distance variation can be reduced by adding a distance sensor. Existing systematic influences of corneal biomechanics will be integrated in the sensor concept as a consecutive step.
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18
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Diurnal Variation of IOP in Angle Closure Disease: Are We Doing Enough? Rom J Ophthalmol 2019; 63:208-216. [PMID: 31687621 PMCID: PMC6820496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intraocular pressure (IOP) is known to have a definite circadian rhythm and its fluctuation correlates well with glaucoma progression. Twenty-four hour monitoring of IOP is an important indicator intraocular pressure fluctuation, as well as its peaks and spikes. However, Diurnal variation in IOP is well recognized but many decisions in glaucoma management are taken after one or two IOP measurements. Patient directed self-tonometry can be preformed through the twenty-four cycle, and has been the subject of an ongoing debate. In this review, we studied the history of self-tonometry devices and the present technologies for future. The results of various techniques studied revealed that a standardized method of conducting diurnal variation is yet to be ascertained, and for this, a proper research method is required.
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Alqawlaq S, Flanagan JG, Sivak JM. All roads lead to glaucoma: Induced retinal injury cascades contribute to a common neurodegenerative outcome. Exp Eye Res 2018; 183:88-97. [PMID: 30447198 DOI: 10.1016/j.exer.2018.11.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 11/25/2022]
Abstract
Glaucoma describes a distinct optic neuropathy with complex etiology and a variety of associated risk factors, but with similar pathological endpoints. Risk factors such as age, increased intraocular pressure (IOP), low mean arterial pressure, and autoimmune disease, can all be associated with death of retinal ganglion cells (RGCs) and optic nerve head remodeling. Today, IOP management remains the standard of care, even though IOP elevation is not pathognomonic of glaucoma, and patients can continue to lose vision despite effective IOP control. A contemporary view of glaucoma as a complex, neurodegenerative disease has developed, along with the recognition of a need for new disease modifying retinal treatment strategies and improved outcomes. However, the distinction between risk factors triggering the disease process and retinal injury responses is not always clear. In this review, we attempt to distinguish between the various triggers, and their association with subsequent key RGC injury mechanisms. We propose that distinct glaucomatous risk factors result in similar retinal and optic nerve injury cascades, including oxidative and metabolic stress, glial reactivity, and altered inflammatory responses, which induce common molecular signals to induce RGC apoptosis. This organization forms a coherent disease framework and presents conserved targets for therapeutic intervention that are not limited to specific risk factors.
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Affiliation(s)
- Samih Alqawlaq
- Department of Vision Science, Krembil Research Institute, University Health Network, Toronto, ON, Canada; Vision Science Research Program, Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada; Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - John G Flanagan
- School of Optometry and Vision Science Program, University of California at Berkeley, Berkeley, CA, USA
| | - Jeremy M Sivak
- Department of Vision Science, Krembil Research Institute, University Health Network, Toronto, ON, Canada; Vision Science Research Program, Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada; Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
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20
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Markert JE, Jasien JV, Turner DC, Huisingh C, Girkin CA, Downs JC. IOP, IOP Transient Impulse, Ocular Perfusion Pressure, and Mean Arterial Pressure Relationships in Nonhuman Primates Instrumented With Telemetry. Invest Ophthalmol Vis Sci 2018; 59:4496-4505. [PMID: 30208417 PMCID: PMC6133237 DOI: 10.1167/iovs.18-23802] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose To characterize relationships between intraocular pressure (IOP), mean arterial pressure (MAP), ocular perfusion pressure (OPP), IOP transient impulse, and IOP baseline impulse using continuous telemetry in nonhuman primates. Methods We used our validated implantable telemetry system to wirelessly record bilateral IOP and arterial BP at 500 Hz in 7 eyes of 4 male rhesus macaques, aged 4 to 5 years. IOP, MAP, OPP, IOP transient impulse, and IOP baseline impulse were averaged into 1-hour periods over 20 days for each NHP. IOP transient impulse was defined as the portion of total IOP due to transient IOP fluctuations <0.5 seconds duration alone and IOP baseline impulse as the remaining area under the IOP versus time curve. OPP was defined as arterial BP-IOP (calculated continuously), and MAP was the hourly average of the continuous BP curve. Relationships between the variables were analyzed for each 24-hour period using either multivariate linear regression or Spearman Correlation Coefficients as appropriate. Results Over twenty 24-hour periods, IOP transient impulse and OPP showed significant positive relationship in all eyes, which was driven largely by the data during waking hours. There was no significant relationship between IOP and MAP, IOP transient impulse and MAP, or IOP baseline impulse and IOP transient impulse. Conclusions There are significant positive relationships between the frequency and/or size of transient IOP fluctuations (IOP transient impulse) and OPP. A possible explanation of this finding is that higher OPP, as well as a greater number of blinks and saccades (the primary sources of IOP transients), are associated with increased activity.
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Affiliation(s)
- John E Markert
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Jessica V Jasien
- Vision Science Graduate Program, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Daniel C Turner
- Vision Science Graduate Program, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Carrie Huisingh
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Christopher A Girkin
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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