{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T15:21:17Z","timestamp":1783005677898,"version":"3.54.5"},"reference-count":36,"publisher":"American Veterinary Medical Association (AVMA)","issue":"7","license":[{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2026,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"sc_a1\">\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>To investigate the effects of atropine on the iridocorneal angle (ICA) and ciliary cleft (CC) of normal equine eyes using ultrasound biomicroscopy (UBM).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a2\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>12 normal adult horses underwent measurement of intraocular pressure (IOP), vertical and horizontal pupil diameter, and UBM of the superior, temporal, inferior, and nasal ICA\/CC in both eyes. Measurements were repeated 2 hours following ophthalmic atropine 1% solution application. Measurements of the ICA and CC, including pectinate ligament distance (PLD), CC length (CCL), height of opening distance (HOD), CC area (CCA), and pectinate ligament angle (PLA) were performed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a3\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Mean IOP significantly decreased following atropine administration (14.17 \u00b1 2.34 mm Hg vs 12.67 \u00b1 1.14 mm Hg). No significant differences in pre- or post-atropine ICA\/CC measurements occurred nasally or temporally. Superiorly, a significant decrease in mean CCL (2.74 \u00b1 0.52 mm vs 2.62 \u00b1 0.43 mm), CCA (2.67 \u00b1 0.72 mm\n                      <jats:sup>2<\/jats:sup>\n                      vs 2.42 \u00b1 0.66 mm\n                      <jats:sup>2<\/jats:sup>\n                      ), HOD (1.15 \u00b1 0.26 mm vs 1.06 \u00b1 0.20 mm), and PLA (80.33 \u00b1 7.02\u00b0 vs 73.67 \u00b1 8.50\u00b0) occurred. Inferiorly, a significant decrease in PLD (1.46 \u00b1 0.23 mm vs 1.39 \u00b1 0.17 mm), HOD (1.44 \u00b1 0.24 mm vs 1.33 \u00b1 0.15 mm), and PLA (73.18 \u00b1 6.81\u00b0 vs 69.98 \u00b1 8.92\u00b0) occurred.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a4\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Atropine causes narrowing of the superior and inferior ICA and CC in normal horse eyes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a5\">\n                    <jats:title>Clinical Relevance<\/jats:title>\n                    <jats:p>Due to its effect in narrowing the ICA and CC, atropine should be used with caution in horses with elevated intraocular pressure or glaucoma.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.2460\/ajvr.26.02.0063","type":"journal-article","created":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T20:10:15Z","timestamp":1775765415000},"source":"Crossref","is-referenced-by-count":0,"title":["Atropine induces narrowing of the superior and inferior iridocorneal angle and ciliary cleft in normal horse eyes"],"prefix":"10.2460","volume":"87","author":[{"given":"Victoria C.","family":"Priester","sequence":"first","affiliation":[{"name":"Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8671-6661","authenticated-orcid":true,"given":"Kelly E.","family":"Knickelbein","sequence":"additional","affiliation":[{"name":"Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1272","reference":[{"key":"B1","series-title":"Veterinary Ophthalmology","first-page":"435","article-title":"Clinical pharmacology and therapeutics","author":"Herring IP","year":"2021","unstructured":"Herring IP. Clinical pharmacology and therapeutics. In: Gelatt KN, ed. Veterinary Ophthalmology. 6th ed. John Wiley & Sons Inc; 2021:435\u2013450."},{"key":"B2","series-title":"Pharmacology of Ocular Therapeutics","first-page":"159","article-title":"Drugs acting through autonomic system for ocular use","author":"Halder N","year":"2016","unstructured":"Halder N, Saxena R, Phuljhele S, Velpandian T. Drugs acting through autonomic system for ocular use. In: Velpandian T, ed. Pharmacology of Ocular Therapeutics. Springer International Publishing; 2016:159\u2013205."},{"issue":"1","key":"B3","series-title":"Vet Ophthalmol","first-page":"43","article-title":"Comparison of the effects of topical and systemic atropine sulfate on intraocular pressure and pupil diameter in the normal canine eye","author":"Kovalcuka L","year":"2015","unstructured":"Kovalcuka L, Birgele E, Bandere D, Williams DL. Comparison of the effects of topical and systemic atropine sulfate on intraocular pressure and pupil diameter in the normal canine eye. Vet Ophthalmol. 2015;18(1):43\u201349. doi:10.1111\/vop.12138"},{"issue":"4","key":"B4","series-title":"Vet Ophthalmol","first-page":"233","article-title":"Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye","author":"Stadtb\u00e4umer K","year":"2006","unstructured":"Stadtb\u00e4umer K, Frommlet F, Nell B. Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye. Vet Ophthalmol. 2006;9(4):233\u2013237. doi:10.1111\/j.1463-5224.2006.00474.x"},{"issue":"4298","key":"B5","series-title":"Br Med J","first-page":"631","article-title":"Atropine glaucoma","author":"Martin JE","year":"1943","unstructured":"Martin JE. Atropine glaucoma. Br Med J. 1943;1(4298):631\u2013632. doi:10.1136\/bmj.1.4298.631"},{"issue":"10","key":"B6","series-title":"J Vet Med Sci","first-page":"977","article-title":"Comparative morphology of the pectinate ligaments of domestic mammals, as observed under the dissecting microscope and the scanning electron microscope","author":"Simoens P","year":"1996","unstructured":"Simoens P, De Geest JP, Lauwers H. Comparative morphology of the pectinate ligaments of domestic mammals, as observed under the dissecting microscope and the scanning electron microscope. J Vet Med Sci. 1996;58(10):977\u2013982. doi:10.1292\/jvms.58.10_977"},{"issue":"5","key":"B7","series-title":"Am J Vet Res","first-page":"720","article-title":"Morphologic features of the aqueous humor drainage pathways in horses","author":"Samuelson D","year":"1989","unstructured":"Samuelson D, Smith P, Brooks D. Morphologic features of the aqueous humor drainage pathways in horses. Am J Vet Res. 1989;50(5):720\u2013727. doi:10.2460\/ajvr.1989.50.05.720"},{"issue":"10","key":"B8","series-title":"Equine Vet J Suppl","first-page":"30","article-title":"The morphology of the equine iridocorneal angle: a light and scanning electron microscopic study","author":"De Geest JP","year":"1990","unstructured":"De Geest JP, Lauwers H, Simoens P, De Schaepdrijver L. The morphology of the equine iridocorneal angle: a light and scanning electron microscopic study. Equine Vet J Suppl. 1990;(10):30\u201335. doi:10.1111\/j.2042-3306.1990.tb04708.x"},{"issue":"4","key":"B9","series-title":"Vet Ophthalmol","first-page":"213","article-title":"Effect of topical atropine on intraocular pressure and pupil diameter in the normal horse eye","author":"Mughannam AJ","year":"1999","unstructured":"Mughannam AJ, Buyukmihci NC, Kass PH. Effect of topical atropine on intraocular pressure and pupil diameter in the normal horse eye. Vet Ophthalmol. 1999;2(4):213\u2013215. doi:10.1046\/j.1463-5224.1999.00081.x"},{"issue":"2\u20133","key":"B10","series-title":"Vet Ophthalmol","first-page":"139","article-title":"Effect of topical 1% atropine sulfate on intraocular pressure in normal horses","author":"Herring IP","year":"2000","unstructured":"Herring IP, Pickett JP, Champagne ES, Troy GC, Marini M. Effect of topical 1% atropine sulfate on intraocular pressure in normal horses. Vet Ophthalmol. 2000;3(2\u20133):139\u2013143. doi:10.1046\/j.1463-5224.2000.00134.x"},{"issue":"11","key":"B11","series-title":"Am J Vet Res","first-page":"2445","article-title":"Unconventional aqueous humor outflow of microspheres perfused into the equine eye","author":"Smith PJ","year":"1986","unstructured":"Smith PJ, Samuelson DA, Brooks DE, Whitley RD. Unconventional aqueous humor outflow of microspheres perfused into the equine eye. Am J Vet Res. 1986;47(11):2445\u20132453. doi:10.2460\/ajvr.1986.47.11.2445"},{"issue":"6","key":"B12","series-title":"Can Vet J","first-page":"470","article-title":"Equine glaucoma: a retrospective study of 13 cases presented at the Western college of veterinary medicine from 1992 to 1999","author":"Cullen CL","year":"2000","unstructured":"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;41(6):470\u2013480."},{"issue":"3","key":"B13","series-title":"Equine Vet J","first-page":"290","article-title":"Prognosis and impact of equine recurrent uveitis","author":"Gerding JC","year":"2016","unstructured":"Gerding JC, Gilger BC. Prognosis and impact of equine recurrent uveitis. Equine Vet J. 2016;48(3):290\u2013298. doi:10.1111\/evj.12451"},{"issue":"5","key":"B14","series-title":"Vet Ophthalmol","first-page":"334","article-title":"Equine glaucoma: a histopathologic retrospective study (1999-2012)","author":"Curto EM","year":"2014","unstructured":"Curto EM, Gemensky-Metzler AJ, Chandler HL, Wilkie DA. Equine glaucoma: a histopathologic retrospective study (1999-2012). Vet Ophthalmol. 2014;17(5):334\u2013342. doi:10.1111\/vop.12080"},{"issue":"6","key":"B15","series-title":"Vet Ophthalmol","first-page":"498","article-title":"Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs","author":"Park S","year":"2016","unstructured":"Park S, Kang S, Lee E, et al. Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs. Vet Ophthalmol. 2016;19(6):498\u2013503. doi:10.1111\/vop.12339"},{"issue":"suppl 2","key":"B16","series-title":"J Am Vet Med Assoc","first-page":"S15","article-title":"Ultrasound biomicroscopy in dogs suggests postoperative ocular hypertension may be associated with ciliary cleft changes related to cataract surgery","author":"Smith HL","year":"2024","unstructured":"Smith HL, Love KR, Westermeyer HD. Ultrasound biomicroscopy in dogs suggests postoperative ocular hypertension may be associated with ciliary cleft changes related to cataract surgery. J Am Vet Med Assoc. 2024;262(suppl 2):S15\u2013S24. doi:10.2460\/javma.24.05.0309"},{"issue":"6","key":"B17","series-title":"Equine Vet J","first-page":"1153","article-title":"Ultrasound biomicroscopy of the equine iridocorneal angle","author":"Knickelbein KE","year":"2022","unstructured":"Knickelbein KE, Lassaline ME, Kim S, Thomasy SM. Ultrasound biomicroscopy of the equine iridocorneal angle. Equine Vet J. 2022;54(6):1153\u20131158. doi:10.1111\/evj.13585"},{"key":"B18","series-title":"Prog Vet Comp Ophthalmol","first-page":"104","article-title":"Evaluation of mydriatics in horses","author":"Gelatt KN","year":"1995","unstructured":"Gelatt KN, Gum G, MacKay EO. Evaluation of mydriatics in horses. Prog Vet Comp Ophthalmol. 1995;5:104\u2013108."},{"key":"B1","series-title":"Veterinary Ophthalmology","first-page":"435","article-title":"Clinical pharmacology and therapeutics","author":"Herring IP","year":"2021","unstructured":"Herring IP. Clinical pharmacology and therapeutics. In: Gelatt KN, ed. Veterinary Ophthalmology. 6th ed. John Wiley & Sons Inc; 2021:435\u2013450."},{"key":"B2","series-title":"Pharmacology of Ocular Therapeutics","first-page":"159","article-title":"Drugs acting through autonomic system for ocular use","author":"Halder N","year":"2016","unstructured":"Halder N, Saxena R, Phuljhele S, Velpandian T. Drugs acting through autonomic system for ocular use. In: Velpandian T, ed. Pharmacology of Ocular Therapeutics. Springer International Publishing; 2016:159\u2013205."},{"issue":"1","key":"B3","series-title":"Vet Ophthalmol","first-page":"43","article-title":"Comparison of the effects of topical and systemic atropine sulfate on intraocular pressure and pupil diameter in the normal canine eye","author":"Kovalcuka L","year":"2015","unstructured":"Kovalcuka L, Birgele E, Bandere D, Williams DL. Comparison of the effects of topical and systemic atropine sulfate on intraocular pressure and pupil diameter in the normal canine eye. Vet Ophthalmol. 2015;18(1):43\u201349. doi:10.1111\/vop.12138"},{"issue":"4","key":"B4","series-title":"Vet Ophthalmol","first-page":"233","article-title":"Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye","author":"Stadtb\u00e4umer K","year":"2006","unstructured":"Stadtb\u00e4umer K, Frommlet F, Nell B. Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye. Vet Ophthalmol. 2006;9(4):233\u2013237. doi:10.1111\/j.1463-5224.2006.00474.x"},{"issue":"4298","key":"B5","series-title":"Br Med J","first-page":"631","article-title":"Atropine glaucoma","author":"Martin JE","year":"1943","unstructured":"Martin JE. Atropine glaucoma. Br Med J. 1943;1(4298):631\u2013632. doi:10.1136\/bmj.1.4298.631"},{"issue":"10","key":"B6","series-title":"J Vet Med Sci","first-page":"977","article-title":"Comparative morphology of the pectinate ligaments of domestic mammals, as observed under the dissecting microscope and the scanning electron microscope","author":"Simoens P","year":"1996","unstructured":"Simoens P, De Geest JP, Lauwers H. Comparative morphology of the pectinate ligaments of domestic mammals, as observed under the dissecting microscope and the scanning electron microscope. J Vet Med Sci. 1996;58(10):977\u2013982. doi:10.1292\/jvms.58.10_977"},{"issue":"5","key":"B7","series-title":"Am J Vet Res","first-page":"720","article-title":"Morphologic features of the aqueous humor drainage pathways in horses","author":"Samuelson D","year":"1989","unstructured":"Samuelson D, Smith P, Brooks D. Morphologic features of the aqueous humor drainage pathways in horses. Am J Vet Res. 1989;50(5):720\u2013727. doi:10.2460\/ajvr.1989.50.05.720"},{"issue":"10","key":"B8","series-title":"Equine Vet J Suppl","first-page":"30","article-title":"The morphology of the equine iridocorneal angle: a light and scanning electron microscopic study","author":"De Geest JP","year":"1990","unstructured":"De Geest JP, Lauwers H, Simoens P, De Schaepdrijver L. The morphology of the equine iridocorneal angle: a light and scanning electron microscopic study. Equine Vet J Suppl. 1990;(10):30\u201335. doi:10.1111\/j.2042-3306.1990.tb04708.x"},{"issue":"4","key":"B9","series-title":"Vet Ophthalmol","first-page":"213","article-title":"Effect of topical atropine on intraocular pressure and pupil diameter in the normal horse eye","author":"Mughannam AJ","year":"1999","unstructured":"Mughannam AJ, Buyukmihci NC, Kass PH. Effect of topical atropine on intraocular pressure and pupil diameter in the normal horse eye. Vet Ophthalmol. 1999;2(4):213\u2013215. doi:10.1046\/j.1463-5224.1999.00081.x"},{"issue":"2\u20133","key":"B10","series-title":"Vet Ophthalmol","first-page":"139","article-title":"Effect of topical 1% atropine sulfate on intraocular pressure in normal horses","author":"Herring IP","year":"2000","unstructured":"Herring IP, Pickett JP, Champagne ES, Troy GC, Marini M. Effect of topical 1% atropine sulfate on intraocular pressure in normal horses. Vet Ophthalmol. 2000;3(2\u20133):139\u2013143. doi:10.1046\/j.1463-5224.2000.00134.x"},{"issue":"11","key":"B11","series-title":"Am J Vet Res","first-page":"2445","article-title":"Unconventional aqueous humor outflow of microspheres perfused into the equine eye","author":"Smith PJ","year":"1986","unstructured":"Smith PJ, Samuelson DA, Brooks DE, Whitley RD. Unconventional aqueous humor outflow of microspheres perfused into the equine eye. Am J Vet Res. 1986;47(11):2445\u20132453. doi:10.2460\/ajvr.1986.47.11.2445"},{"issue":"6","key":"B12","series-title":"Can Vet J","first-page":"470","article-title":"Equine glaucoma: a retrospective study of 13 cases presented at the Western college of veterinary medicine from 1992 to 1999","author":"Cullen CL","year":"2000","unstructured":"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;41(6):470\u2013480."},{"issue":"3","key":"B13","series-title":"Equine Vet J","first-page":"290","article-title":"Prognosis and impact of equine recurrent uveitis","author":"Gerding JC","year":"2016","unstructured":"Gerding JC, Gilger BC. Prognosis and impact of equine recurrent uveitis. Equine Vet J. 2016;48(3):290\u2013298. doi:10.1111\/evj.12451"},{"issue":"5","key":"B14","series-title":"Vet Ophthalmol","first-page":"334","article-title":"Equine glaucoma: a histopathologic retrospective study (1999-2012)","author":"Curto EM","year":"2014","unstructured":"Curto EM, Gemensky-Metzler AJ, Chandler HL, Wilkie DA. Equine glaucoma: a histopathologic retrospective study (1999-2012). Vet Ophthalmol. 2014;17(5):334\u2013342. doi:10.1111\/vop.12080"},{"issue":"6","key":"B15","series-title":"Vet Ophthalmol","first-page":"498","article-title":"Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs","author":"Park S","year":"2016","unstructured":"Park S, Kang S, Lee E, et al. Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs. Vet Ophthalmol. 2016;19(6):498\u2013503. doi:10.1111\/vop.12339"},{"issue":"suppl 2","key":"B16","series-title":"J Am Vet Med Assoc","first-page":"S15","article-title":"Ultrasound biomicroscopy in dogs suggests postoperative ocular hypertension may be associated with ciliary cleft changes related to cataract surgery","author":"Smith HL","year":"2024","unstructured":"Smith HL, Love KR, Westermeyer HD. Ultrasound biomicroscopy in dogs suggests postoperative ocular hypertension may be associated with ciliary cleft changes related to cataract surgery. J Am Vet Med Assoc. 2024;262(suppl 2):S15\u2013S24. doi:10.2460\/javma.24.05.0309"},{"issue":"6","key":"B17","series-title":"Equine Vet J","first-page":"1153","article-title":"Ultrasound biomicroscopy of the equine iridocorneal angle","author":"Knickelbein KE","year":"2022","unstructured":"Knickelbein KE, Lassaline ME, Kim S, Thomasy SM. Ultrasound biomicroscopy of the equine iridocorneal angle. Equine Vet J. 2022;54(6):1153\u20131158. doi:10.1111\/evj.13585"},{"key":"B18","series-title":"Prog Vet Comp Ophthalmol","first-page":"104","article-title":"Evaluation of mydriatics in horses","author":"Gelatt KN","year":"1995","unstructured":"Gelatt KN, Gum G, MacKay EO. Evaluation of mydriatics in horses. Prog Vet Comp Ophthalmol. 1995;5:104\u2013108."}],"container-title":["American Journal of Veterinary Research"],"original-title":[],"link":[{"URL":"https:\/\/avmajournals.avma.org\/view\/journals\/ajvr\/87\/7\/ajvr.26.02.0063.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/avmajournals.avma.org\/downloadpdf\/journals\/ajvr\/87\/7\/ajvr.26.02.0063.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/avmajournals.avma.org\/downloadpdf\/journals\/ajvr\/87\/7\/ajvr.26.02.0063.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T15:14:50Z","timestamp":1783005290000},"score":1,"resource":{"primary":{"URL":"https:\/\/avmajournals.avma.org\/view\/journals\/ajvr\/87\/7\/ajvr.26.02.0063.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,1]]},"references-count":36,"journal-issue":{"issue":"7"},"URL":"https:\/\/doi.org\/10.2460\/ajvr.26.02.0063","relation":{},"ISSN":["0002-9645","1943-5681"],"issn-type":[{"value":"0002-9645","type":"print"},{"value":"1943-5681","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,1]]}}}