Unconventional aqueous humor outflow of microspheres perfused into the equine eye.
Abstract: Normal drainage of aqueous humor from the anterior chamber of the equine eye occurred through conventional and unconventional routes. To determine the degree of uveoscleral outflow in the pony, 1- and 3-microns (diam) microspheres were perfused through the anterior chamber for 60 and 90 minutes. Two eyes were treated with pilocarpine before perfusion of spheres to observe any effect on outflow. Presence of spheres was detected by scanning electron microscopy and verified by light microscopy. By 60 minutes of the perfusion, 1- and 3-microns spheres thoroughly infiltrated the anterior uveal trabecular meshwork. The 3-microns spheres were notably excluded from the corneoscleral trabecular meshwork, whereas the 1-micron spheres packed into the corneoscleral trabecular meshwork and mixed with the angular aqueous plexus and intrascleral plexus vessels. After 90 minutes, 1- and 3-microns spheres penetrated the prominent supraciliary space and mixed with the suprachoroidea of the midchoroid. The 1-micron spheres infiltrated tissues more extensively than did the 3-microns spheres, packing into the anterior meshwork and supraciliary space and also moving as far posterior as the suprachoroidea of the peripapillary retina. Spheres also entered the iris, mostly at the root. Several 3-microns spheres moved into the interstitial spaces around axon bundles and vessels in the iris. The 1-micron spheres packed into these spaces in the iris root and were observed in the lumens of iris vessels. Single 1-micron spheres were observed in the lumens of choroidal vessels posteriorly. The present study supported evidence for uveoscleral and uveovortex flow in the horse and indicated that it may be more extensive than that in other species investigated (ie, the dog).
Publication Date: 1986-11-01 PubMed ID: 3789508
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- Journal Article
Summary
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The research investigates the process of aqueous humor outflow from the anterior chamber of a horse’s eye through unconventional routes. The study utilises microspheres of 1- and 3-microns to track the flow progression and compares their infiltration and movement in different parts of the horse’s eye.
Study Methodology
- The research used microspheres with a diameter of 1 and 3 microns. These were perfused into the anterior chamber of the horse’s eye and observed over a period of 60 to 90 minutes.
- For comparison, two eyes were pre-treated with pilocarpine before the perfusion process to assess any modification in the outflow pattern.
- The microspheres’ presence and movement were detected and tracked via scanning electron microscopy and later cross-checked with light microscopy.
Observations and Results
- At the 60-minute mark, the microspheres had significantly infiltrated the anterior uveal trabecular meshwork.
- The 3-micron spheres did not infiltrate the corneoscleral trabecular meshwork as much as the 1-micron spheres, which also reached the angular aqueous plexus and intrascleral plexus vessels.
- After 90 minutes, both sizes of microspheres infiltrated the supraciliary space significantly, and mixed with the suprachoroidea of midchoroid.
- 1-micron spheres infiltrated more extensively than the larger ones. They also reached as far posterior as the suprachoroidea of the peripapillary retina and even entered the iris, mainly at the root.
- 3-micron spheres moved around the axon bundles and vessels in the iris interstitial spaces. In contrast, the 1-micron spheres densely packed into the iris root spaces and were observed in the iris vessels’ lumens.
- Single 1-micron spheres were also seen in the posterior choroidal vessels’ lumens.
Conclusion
- The study demonstrated evidence of uveoscleral and uveovortex flow in horses, suggesting that this unconventional outflow pathway could be more extensive than previously thought, or as compared to other animals, such as dogs.
Cite This Article
APA
Smith PJ, Samuelson DA, Brooks DE, Whitley RD.
(1986).
Unconventional aqueous humor outflow of microspheres perfused into the equine eye.
Am J Vet Res, 47(11), 2445-2453.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Aqueous Humor / drug effects
- Aqueous Humor / physiology
- Eye / drug effects
- Eye / ultrastructure
- Horses / anatomy & histology
- Horses / physiology
- Microscopy, Electron, Scanning
- Microspheres
- Ocular Physiological Phenomena
- Perfusion
- Pilocarpine / pharmacology
Citations
This article has been cited 4 times.- Knickelbein KE, Lassaline ME, Kim S, Thomasy SM. Ultrasound biomicroscopy of the equine iridocorneal angle. Equine Vet J 2022 Nov;54(6):1153-1158.
- Saccà SC, Izzotti A. Focus on molecular events in the anterior chamber leading to glaucoma. Cell Mol Life Sci 2014 Jun;71(12):2197-218.
- Izzotti A, Longobardi M, Cartiglia C, Rathschuler F, Saccà SC. Trabecular meshwork gene expression after selective laser trabeculoplasty. PLoS One 2011;6(7):e20110.
- Cullen CL, Grahn BH. Equine glaucoma: a retrospective study of 13 cases presented at the Western College of Veterinary Medicine from 1992 to 1999. Can Vet J 2000 Jun;41(6):470-80.
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