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Halsmer EL, Heatley JJ, Scott EM. Clinical ophthalmic parameters of the Quaker parrot (Myiopsitta monachus). Vet Ophthalmol 2023; 26:428-439. [PMID: 36519702 DOI: 10.1111/vop.13049] [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: 08/23/2022] [Revised: 11/09/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022]
Abstract
PURPOSE Ophthalmic diagnosis in many avian species remains hindered by a lack of normative values. This study aimed to establish normal ophthalmic parameters for select diagnostic tests in clinically normal Quaker parrots. METHODS Ninety-six captive Quaker parrots aged 8-18 years underwent ophthalmic examination to include assessment of neuro-ophthalmic reflexes, phenol red thread test, rebound tonometry, fluorescein staining, palpebral fissure length measurements, slit lamp biomicroscopy, indirect ophthalmoscopy, and ocular ultrasound biometry. RESULTS Menace response, dazzle reflex, and direct pupillary light reflex were present for all Quaker parrots. Tear production (mean ± SD) was 13.3 ± 4.0 mm/15 s and intraocular pressure (IOP, mean ± SD) was 10.6 ± 1.4 and 6.0 ± 1.3 mmHg in the D and P rebound tonometer calibration settings, respectively. For IOP measurement, D and P calibration settings were not interchangeable, with the lesser variation of the D setting preferred in the absence of a gold standard. Ultrasound measurement of the anterior chamber depth increased with age and males had longer axial globe and vitreous lengths. Incidental adnexal and ocular lesions, identified in 36/96 (37.5%) of Quaker parrots, did not statistically affect the created reference data. CONCLUSIONS This work provides reference values and clinical findings to assist with monitoring the health of wild populations and maintaining the health of captive Quaker parrots.
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Affiliation(s)
- Emily L Halsmer
- College of Veterinary Medicine, Lincoln Memorial University, Harrogate, Tennessee, USA
| | - Jennifer Jill Heatley
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Erin M Scott
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, USA
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Hongjamrassilp W, Zhang R, Natterson-Horowitz B, Blumstein DT. Glaucoma through Animal’s Eyes: Insights from the Evolution of Intraocular Pressure in Mammals and Birds. Animals (Basel) 2022; 12:ani12162027. [PMID: 36009617 PMCID: PMC9404445 DOI: 10.3390/ani12162027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/06/2022] [Accepted: 08/07/2022] [Indexed: 12/04/2022] Open
Abstract
Simple Summary Understanding how a disease evolved across the animal kingdom could help us better understand the disease and might lead to novel methods for treatment. Here, we studied the evolution of glaucoma, an irreversible eye disease, in mammals and birds, by studying the evolution of intraocular pressure (IOP), a central driver of glaucoma, and searching for associations between life history traits and IOP. Our results revealed that IOP is a taxa-specific trait that is higher in some species than in others. Higher IOPs appear to have evolved multiple times in mammals and birds. Higher IOPs were found in mammals with higher body mass and in aquatic birds. We also found that higher IOPs evolved through stabilizing selection, with the optimum IOP in mammals and birds being 17.67 and 14.31 mmHg, respectively. This supports the hypothesis that higher IOPs may be an adaptive trait for certain animals. Focusing on species with higher IOPs but no evidence of glaucoma may help identify glaucoma-resistant adaptations, which could be developed into human therapies. Abstract Glaucoma, an eye disorder caused by elevated intraocular pressure (IOP), is the leading cause of irreversible blindness in humans. Understanding how IOP levels have evolved across animal species could shed light on the nature of human vulnerability to glaucoma. Here, we studied the evolution of IOP in mammals and birds and explored its life history correlates. We conducted a systematic review, to create a dataset of species-specific IOP levels and reconstructed the ancestral states of IOP using three models of evolution (Brownian, Early burst, and Ornstein–Uhlenbeck (OU)) to understand the evolution of glaucoma. Furthermore, we tested the association between life history traits (e.g., body mass, blood pressure, diet, longevity, and habitat) and IOP using phylogenetic generalized least squares (PGLS). IOP in mammals and birds evolved under the OU model, suggesting stabilizing selection toward an optimal value. Larger mammals had higher IOPs and aquatic birds had higher IOPs; no other measured life history traits, the type of tonometer used, or whether the animal was sedated when measuring IOP explained the significant variation in IOP in this dataset. Elevated IOP, which could result from physiological and anatomical processes, evolved multiple times in mammals and birds. However, we do not understand how species with high IOP avoid glaucoma. While we found very few associations between life history traits and IOP, we suggest that more detailed studies may help identify mechanisms by which IOP is decoupled from glaucoma. Importantly, species with higher IOPs (cetaceans, pinnipeds, and rhinoceros) could be good model systems for studying glaucoma-resistant adaptations.
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Affiliation(s)
- Watcharapong Hongjamrassilp
- Department of Marine Science, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok 10330, Thailand
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Young Drive South, Los Angeles, CA 90095, USA
- Correspondence: or (W.H.); (D.T.B.)
| | - Roger Zhang
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Young Drive South, Los Angeles, CA 90095, USA
| | - B. Natterson-Horowitz
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Young Drive South, Los Angeles, CA 90095, USA
- David Geffen School of Medicine at UCLA, Division of Cardiology, 650 Charles E. Young Drive South, A2-237, Los Angeles, CA 90095, USA
| | - Daniel T. Blumstein
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Young Drive South, Los Angeles, CA 90095, USA
- Correspondence: or (W.H.); (D.T.B.)
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Zouache MA. Variability in Retinal Neuron Populations and Associated Variations in Mass Transport Systems of the Retina in Health and Aging. Front Aging Neurosci 2022; 14:778404. [PMID: 35283756 PMCID: PMC8914054 DOI: 10.3389/fnagi.2022.778404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/13/2022] [Indexed: 11/17/2022] Open
Abstract
Aging is associated with a broad range of visual impairments that can have dramatic consequences on the quality of life of those impacted. These changes are driven by a complex series of alterations affecting interactions between multiple cellular and extracellular elements. The resilience of many of these interactions may be key to minimal loss of visual function in aging; yet many of them remain poorly understood. In this review, we focus on the relation between retinal neurons and their respective mass transport systems. These metabolite delivery systems include the retinal vasculature, which lies within the inner portion of the retina, and the choroidal vasculature located externally to the retinal tissue. A framework for investigation is proposed and applied to identify the structures and processes determining retinal mass transport at the cellular and tissue levels. Spatial variability in the structure of the retina and changes observed in aging are then harnessed to explore the relation between variations in neuron populations and those seen among retinal metabolite delivery systems. Existing data demonstrate that the relation between inner retinal neurons and their mass transport systems is different in nature from that observed between the outer retina and choroid. The most prominent structural changes observed across the eye and in aging are seen in Bruch’s membrane, which forms a selective barrier to mass transfers at the interface between the choroidal vasculature and the outer retina.
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Chan D, Won GJ, Read AT, Ethier CR, Thackaberry E, Crowell SR, Booler H, Bantseev V, Sivak JM. Application of an organotypic ocular perfusion model to assess intravitreal drug distribution in human and animal eyes. J R Soc Interface 2022; 19:20210734. [PMID: 35078337 PMCID: PMC8790337 DOI: 10.1098/rsif.2021.0734] [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: 01/16/2023] Open
Abstract
Intravitreal (ITV) drug delivery is a new cornerstone for retinal therapeutics. Yet, predicting the disposition of formulations in the human eye remains a major translational hurdle. A prominent, but poorly understood, issue in pre-clinical ITV toxicity studies is unintended particle movements to the anterior chamber (AC). These particles can accumulate in the AC to dangerously raise intraocular pressure. Yet, anatomical differences, and the inability to obtain equivalent human data, make investigating this issue extremely challenging. We have developed an organotypic perfusion strategy to re-establish intraocular fluid flow, while maintaining homeostatic pressure and pH. Here, we used this approach with suitably sized microbeads to profile anterior and posterior ITV particle movements in live versus perfused porcine eyes, and in human donor eyes. Small-molecule suspensions were then tested with the system after exhibiting differing behaviours in vivo. Aggregate particle size is supported as an important determinant of particle movements in the human eye, and we note these data are consistent with a poroelastic model of bidirectional vitreous transport. Together, this approach uses ocular fluid dynamics to permit, to our knowledge, the first direct comparisons between particle behaviours from human ITV injections and animal models, with potential to speed pre-clinical development of retinal therapeutics.
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Affiliation(s)
- D. Chan
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - G. J. Won
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - A. T. Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia, USA
| | - C. R. Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia, USA
| | - E. Thackaberry
- Safety Assessment, Genentech Inc., San Francisco, CA, USA
| | - S. R. Crowell
- Preclinical and Translational Pharmacokinetics and Pharmacodynamics (PTPK) Genentech Inc., San Francisco, CA, USA
| | - H. Booler
- Safety Assessment, Genentech Inc., San Francisco, CA, USA
| | - V. Bantseev
- Safety Assessment, Genentech Inc., San Francisco, CA, USA
| | - J. M. Sivak
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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COMPARISON OF INTRAOCULAR PRESSURE MEASUREMENT USING REBOUND AND APPLANATION TONOMETRY IN LOGGERHEAD ( CARETTA CARETTA) SEA TURTLES. J Zoo Wildl Med 2021; 52:604-609. [PMID: 34130403 DOI: 10.1638/2020-0070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2020] [Indexed: 11/21/2022] Open
Abstract
This study aimed to evaluate intraocular pressure (IOP) estimates in healthy eyes of Caretta caretta using rebound tonometry in comparison with applanation tonometry. Twenty-three healthy C. caretta (housed at the Marine Turtle Research Center) without preexisting ophthalmic disease were enrolled in the study. IOP measurements were obtained by the same ophthalmologist, with the turtle in ventral recumbency between 2:30 p.m. and 4:30 p.m., using a rebound tonometer (RT; TonoVet) in dog calibration mode, and after topical anesthesia, an applanation tonometer (AT; Tono-Pen) in both eyes. The average of three readings per instrument was used for analysis. The agreement between the two tonometers was assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). Moreover, differences in IOP between the two tonometers were analyzed using the Mann-Whitney test. Moderate agreement was found between the two tonometers (ICC, 0.663; 95% confidence interval, 0.206-0.857). The median, Q1, and Q3 IOP obtained with AT (6.2, 4.7, and 9.1 mm Hg) were significantly lower (P = 0.001) than that obtained with RT (9.7, 8.3, and 11.6 mm Hg). It was not possible to obtain an instrument automatically generated mean of four values with AT because of retraction of the globe by the animals, and IOP measurement was unsuccessful in 7 eyes. In conclusion, IOP readings from the RT were statistically higher than those from the AT. RT proved to be more feasible because of the light, short-lasting contact with the cornea.
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FACTORS AFFECTING TEAR PRODUCTION AND INTRAOCULAR PRESSURE IN ANESTHETIZED CHIMPANZEES ( PAN TROGLODYTES). J Zoo Wildl Med 2021; 51:687-690. [PMID: 33480546 DOI: 10.1638/2020-0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2020] [Indexed: 11/21/2022] Open
Abstract
Measurements of intraocular pressure (IOP) and tear production are key components of ophthalmic examination. Chimpanzees (Pan troglodytes) were anesthetized using either tiletamine-zolazepam (TZ; 2 mg/kg) combined with medetomidine (TZM; 0.02 mg/kg), or, TZ alone (6mg/kg). Tear production was lower (P = 0.03) with TZM (5.63 ± 6.22 mm/min; n = 16) than with TZ (11.13 ± 4.63 mm/min; n = 8). Mean IOP, measured using rebound tonometry in an upright body position (n = 8) was 18.74 ± 3.01 mm Hg, with no differences between right and left eyes. However, positioning chimpanzees in left lateral recumbency (n = 27) resulted in higher IOP in the dependent (left) eye (24.77 ± 4.49 mm Hg) compared to the nondependent (right) eye (22.27 ± 4.65 mm Hg) of the same animal (P < 0.0001). These data indicate medetomidine anesthesia markedly lowers tear production in chimpanzees, and that body position should be taken into consideration when performing rebound tonometry.
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A PRELIMINARY STUDY OF INTRINSIC AND EXTRINSIC FACTORS INFLUENCING INTRAOCULAR PRESSURE IN BROOK TROUT ( SALVELINUS FONTINALIS). J Zoo Wildl Med 2021; 51:1012-1016. [PMID: 33480583 DOI: 10.1638/2020-0088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2020] [Indexed: 11/21/2022] Open
Abstract
Reference intervals of intraocular pressure (IOP) are poorly described in piscine species as the factors that may influence it. Rebound tonometry was used to measure IOP in 28 adult brook trout (Salvelinus fontinalis) anesthetized in a buffered solution of 60 mg/L tricaine methanesulfonate (n = 16) or restrained with electronarcosis (n = 12) at 16 mA. There was no significant effect of the eye side, sex, fish origin, and body weight, but IOP values were significantly higher with electronarcosis (mean ± SD: 16.4 ± 5.0 mm Hg) than with immersion anesthesia (10.8 ± 3.3 mm Hg; P = 0.0017). The same restraint method should be used for comparison with previously published IOP values or when evaluating individual variations over time.
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Baker AEG, Cui H, Ballios BG, Ing S, Yan P, Wolfer J, Wright T, Dang M, Gan NY, Cooke MJ, Ortín-Martínez A, Wallace VA, van der Kooy D, Devenyi R, Shoichet MS. Stable oxime-crosslinked hyaluronan-based hydrogel as a biomimetic vitreous substitute. Biomaterials 2021; 271:120750. [PMID: 33725584 DOI: 10.1016/j.biomaterials.2021.120750] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 11/30/2022]
Abstract
Vitreous substitutes are clinically used to maintain retinal apposition and preserve retinal function; yet the most used substitutes are gases and oils which have disadvantages including strict face-down positioning post-surgery and the need for subsequent surgical removal, respectively. We have engineered a vitreous substitute comprised of a novel hyaluronan-oxime crosslinked hydrogel. Hyaluronan, which is naturally abundant in the vitreous of the eye, is chemically modified to crosslink with poly(ethylene glycol)-tetraoxyamine via oxime chemistry to produce a vitreous substitute that has similar physical properties to the native vitreous including refractive index, density and transparency. The oxime hydrogel is cytocompatible in vitro with photoreceptors from mouse retinal explants and biocompatible in rabbit eyes as determined by histology of the inner nuclear layer and photoreceptors in the outer nuclear layer. The ocular pressure in the rabbit eyes was consistent over 56 d, demonstrating limited to no swelling. Our vitreous substitute was stable in vivo over 28 d after which it began to degrade, with approximately 50% loss by day 56. We confirmed that the implanted hydrogel did not impact retina function using electroretinography over 90 days versus eyes injected with balanced saline solution. This new oxime hydrogel provides a significant improvement over the status quo as a vitreous substitute.
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Affiliation(s)
- Alexander E G Baker
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON, M5S 3E5, Canada; Institute of Biomedical Engineering, University of Toronto, 160 College St, Toronto, ON, M5S 3E1, Canada
| | - Hong Cui
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON, M5S 3E5, Canada
| | - Brian G Ballios
- Department of Ophthalmology and Vision Sciences, University of Toronto, 340 College St, Toronto, ON, L0J 1C0, Canada
| | - Sonja Ing
- Institute of Biomedical Engineering, University of Toronto, 160 College St, Toronto, ON, M5S 3E1, Canada
| | - Peng Yan
- Kensington Eye Institute, 340 College St, Toronto, ON, M5T 3A9, Canada
| | - Joe Wolfer
- Toronto Animal Eye Clinic, 150 Norseman St, Etobicoke, ON, M8Z 2R4, Canada
| | - Thomas Wright
- Kensington Eye Institute, 340 College St, Toronto, ON, M5T 3A9, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, 340 College St, Toronto, ON, L0J 1C0, Canada
| | - Mickael Dang
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON, M5S 3E5, Canada
| | - Nicola Y Gan
- Department of Ophthalmology, Tock Seng Hospital, National Healthcare Group Eye Institute, 11 Jln Tan Tock Seng, 308433, Singapore
| | - Michael J Cooke
- Institute of Biomedical Engineering, University of Toronto, 160 College St, Toronto, ON, M5S 3E1, Canada
| | - Arturo Ortín-Martínez
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, 399 Bathurst St, Toronto, ON, M5T 2S8, Canada
| | - Valerie A Wallace
- Department of Ophthalmology and Vision Sciences, University of Toronto, 340 College St, Toronto, ON, L0J 1C0, Canada; Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, 399 Bathurst St, Toronto, ON, M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, ON, M5S 1A8, Canada
| | - Derek van der Kooy
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, ON, M5S 1A8, Canada; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, ON, M5S 1A8, Canada
| | - Robert Devenyi
- Department of Ophthalmology and Vision Sciences, University of Toronto, 340 College St, Toronto, ON, L0J 1C0, Canada; Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, 399 Bathurst St, Toronto, ON, M5T 2S8, Canada; Toronto Western Hospital, 399 Bathurst St, Room 6 E W 438, Toronto, ON, M5T 2S8, Canada
| | - Molly S Shoichet
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, ON, M5S 3E5, Canada; Institute of Biomedical Engineering, University of Toronto, 160 College St, Toronto, ON, M5S 3E1, Canada; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, ON, M5S 1A8, Canada.
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Lee RMH, Bouremel Y, Eames I, Brocchini S, Khaw PT. Translating Minimally Invasive Glaucoma Surgery Devices. Clin Transl Sci 2019; 13:14-25. [PMID: 31568666 PMCID: PMC6951459 DOI: 10.1111/cts.12660] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/08/2019] [Indexed: 11/30/2022] Open
Abstract
Glaucoma is the leading cause of irreversible blindness with over 70 million people affected worldwide. The surgical management of glaucoma aims to lower intraocular pressure by increasing aqueous outflow facility. The latest manufacturing techniques have allowed for the development of a number of novel implantable devices to improve safety and outcomes of glaucoma surgery. These are collectively referred to as minimally invasive glaucoma surgery (MIGS) devices and are among the smallest devices implanted in the human body. This review discusses the design criterion and constraints as well as the user requirements for MIGS devices. We review how recent devices have attempted to meet these challenges and give our opinion as to the necessary characteristics for the development of future devices.
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Affiliation(s)
- Richard M H Lee
- Chelsea and Westminster Hospital NHS Foundation Trust, London, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Yann Bouremel
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Ian Eames
- UCL Department of Mechanical Engineering, London, UK
| | - Steve Brocchini
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK.,UCL School of Pharmacy, London, UK
| | - Peng Tee Khaw
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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Gurley M, Motta P. An Analysis of Extraocular Muscle Forces in the Piked Dogfish (Squalus acanthias). Anat Rec (Hoboken) 2018; 302:837-844. [PMID: 30312010 DOI: 10.1002/ar.23976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 05/02/2018] [Accepted: 05/16/2018] [Indexed: 11/10/2022]
Abstract
Vertebrates utilize six extraocular muscles that attach to a tough, protective sclera to rotate the eye. The goal of the study was to describe the maximum tetanic forces, as well as the torques produced by the six extraocular muscles of the piked dogfish Squalus acanthias to understand the forces exerted on the eye. The lateral rectus extraocular muscle of Squalus acanthias was determined to be parallel fibered with the muscle fibers bundled into discrete fascicles. The extraocular muscles attach to the sclera by muscular insertions. The total tensile forces generated by the extraocular muscles ranged from 1.18 N to 2.21 N. The torques of the extraocular muscles ranged from 0.39 N to 2.34 N. The torques were greatest in the principal direction of movement for each specific muscle. The lateral rectus produced the greatest total tensile force, as well as the greatest torque force component, while the medial rectus produced the second greatest. This is likely due to the constant rotational movement of the eye anteriorly and posteriorly to stabilize the visual image, as well as increase the effective visual field during swimming. Rotational forces in dimensions other than the primary direction of movement may contribute to motion in directions other than the principal direction during multi-muscle contraction that occurs in the vertebrate eye. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:837-844, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Matthew Gurley
- Department of Integrative Biology, University of South Florida, Tampa, Florida
| | - Philip Motta
- Department of Integrative Biology, University of South Florida, Tampa, Florida
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Cannizzo SA, Lewbart GA, Westermeyer HD. Intraocular pressure in American Bullfrogs (Rana catesbeiana) measured with rebound and applanation tonometry. Vet Ophthalmol 2017; 20:526-532. [DOI: 10.1111/vop.12463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Sarah A. Cannizzo
- Department of Clinical Sciences; College of Veterinary Medicine; North Carolina State University; 1060 William Moore Drive Raleigh NC 27607 USA
| | - Gregory A. Lewbart
- Department of Clinical Sciences; College of Veterinary Medicine; North Carolina State University; 1060 William Moore Drive Raleigh NC 27607 USA
| | - Hans D. Westermeyer
- Department of Clinical Sciences; College of Veterinary Medicine; North Carolina State University; 1060 William Moore Drive Raleigh NC 27607 USA
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