Viscocanalostomy in rhesus monkeys

Ernst R. Tamm, Roberto G. Carassa, Daniel Albert, B. T. Gabelt, Sarit Patel, Carol A. Rasmussen, Paul L. Kaufman

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Objective: To examine structural changes and aqueous humor outflow after viscocanalostomy in live normal monkey eyes. Methods: Viscocanalostomy surgery was performed in 1 eye of each of 4 rhesus monkeys. Outflow facility was determined before and after surgery. All eyes were fixed and examined by light and/or electron microscopy 36 or 63 days postoperatively. Results: Schlemm canal was replaced by scar tissue at the surgical site. The juxtacanalicular zone contained homogeneous material, probably high-molecular-weight 1.4% sodium hyaluronate. The sclera external to Schlemm canal was overhydrated, and remains of a scleral lake were present in 1 animal. Multiple defects were present in the endothelial lining of Schlemm canal inner and outer wall. Fine fibrillar material and sheath-derived plaque material partly bridged the defects. Along the inner wall, aggregations of thrombocytes covered some defects in the endothelial lining of the canal. At 90° to 180° from the surgical site, small and fewer breaks in the inner wall were seen. Postsurgery outflow facility (n = 2) was approximately 30% higher in the treated eye than in the contralateral control, corrected bilaterally for presurgery baseline. Conclusions: The most likely explanations for the increase in outflow facility in monkeys after viscocanalostomy are focal disruptions of the inner wall endothelium of Schlemm canal and disorganization of the juxtacanalicular zone, resulting in direct communication of juxtacanalicular zone extracellular spaces with the lumen of Schlemm canal. The continuous presence of sodium hyaluronate might prevent repair of these defects by interfering with thrombocyte function. Clinical Relevance: In nonhuman primates, viscocanalostomy appears to decrease outflow resistance through persisting focal disruption of the inner wall endothelium and opening of the juxtacanalicular or cribriform region of the trabecular meshwork, the tissue most affected by pathologic changes in primary open-angle glaucoma in humans.

Original languageEnglish (US)
Pages (from-to)1826-1838
Number of pages13
JournalArchives of ophthalmology
Volume122
Issue number12
DOIs
StatePublished - Dec 1 2004
Externally publishedYes

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Macaca mulatta
Hyaluronic Acid
Endothelium
Haplorhini
Blood Platelets
Trabecular Meshwork
Sclera
Aqueous Humor
Extracellular Space
Lakes
Primates
Cicatrix
Electron Microscopy
Molecular Weight
Communication
Light

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Tamm, E. R., Carassa, R. G., Albert, D., Gabelt, B. T., Patel, S., Rasmussen, C. A., & Kaufman, P. L. (2004). Viscocanalostomy in rhesus monkeys. Archives of ophthalmology, 122(12), 1826-1838. https://doi.org/10.1001/archopht.122.12.1826

Viscocanalostomy in rhesus monkeys. / Tamm, Ernst R.; Carassa, Roberto G.; Albert, Daniel; Gabelt, B. T.; Patel, Sarit; Rasmussen, Carol A.; Kaufman, Paul L.

In: Archives of ophthalmology, Vol. 122, No. 12, 01.12.2004, p. 1826-1838.

Research output: Contribution to journalArticle

Tamm, ER, Carassa, RG, Albert, D, Gabelt, BT, Patel, S, Rasmussen, CA & Kaufman, PL 2004, 'Viscocanalostomy in rhesus monkeys', Archives of ophthalmology, vol. 122, no. 12, pp. 1826-1838. https://doi.org/10.1001/archopht.122.12.1826
Tamm ER, Carassa RG, Albert D, Gabelt BT, Patel S, Rasmussen CA et al. Viscocanalostomy in rhesus monkeys. Archives of ophthalmology. 2004 Dec 1;122(12):1826-1838. https://doi.org/10.1001/archopht.122.12.1826
Tamm, Ernst R. ; Carassa, Roberto G. ; Albert, Daniel ; Gabelt, B. T. ; Patel, Sarit ; Rasmussen, Carol A. ; Kaufman, Paul L. / Viscocanalostomy in rhesus monkeys. In: Archives of ophthalmology. 2004 ; Vol. 122, No. 12. pp. 1826-1838.
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abstract = "Objective: To examine structural changes and aqueous humor outflow after viscocanalostomy in live normal monkey eyes. Methods: Viscocanalostomy surgery was performed in 1 eye of each of 4 rhesus monkeys. Outflow facility was determined before and after surgery. All eyes were fixed and examined by light and/or electron microscopy 36 or 63 days postoperatively. Results: Schlemm canal was replaced by scar tissue at the surgical site. The juxtacanalicular zone contained homogeneous material, probably high-molecular-weight 1.4{\%} sodium hyaluronate. The sclera external to Schlemm canal was overhydrated, and remains of a scleral lake were present in 1 animal. Multiple defects were present in the endothelial lining of Schlemm canal inner and outer wall. Fine fibrillar material and sheath-derived plaque material partly bridged the defects. Along the inner wall, aggregations of thrombocytes covered some defects in the endothelial lining of the canal. At 90° to 180° from the surgical site, small and fewer breaks in the inner wall were seen. Postsurgery outflow facility (n = 2) was approximately 30{\%} higher in the treated eye than in the contralateral control, corrected bilaterally for presurgery baseline. Conclusions: The most likely explanations for the increase in outflow facility in monkeys after viscocanalostomy are focal disruptions of the inner wall endothelium of Schlemm canal and disorganization of the juxtacanalicular zone, resulting in direct communication of juxtacanalicular zone extracellular spaces with the lumen of Schlemm canal. The continuous presence of sodium hyaluronate might prevent repair of these defects by interfering with thrombocyte function. Clinical Relevance: In nonhuman primates, viscocanalostomy appears to decrease outflow resistance through persisting focal disruption of the inner wall endothelium and opening of the juxtacanalicular or cribriform region of the trabecular meshwork, the tissue most affected by pathologic changes in primary open-angle glaucoma in humans.",
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AU - Tamm, Ernst R.

AU - Carassa, Roberto G.

AU - Albert, Daniel

AU - Gabelt, B. T.

AU - Patel, Sarit

AU - Rasmussen, Carol A.

AU - Kaufman, Paul L.

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N2 - Objective: To examine structural changes and aqueous humor outflow after viscocanalostomy in live normal monkey eyes. Methods: Viscocanalostomy surgery was performed in 1 eye of each of 4 rhesus monkeys. Outflow facility was determined before and after surgery. All eyes were fixed and examined by light and/or electron microscopy 36 or 63 days postoperatively. Results: Schlemm canal was replaced by scar tissue at the surgical site. The juxtacanalicular zone contained homogeneous material, probably high-molecular-weight 1.4% sodium hyaluronate. The sclera external to Schlemm canal was overhydrated, and remains of a scleral lake were present in 1 animal. Multiple defects were present in the endothelial lining of Schlemm canal inner and outer wall. Fine fibrillar material and sheath-derived plaque material partly bridged the defects. Along the inner wall, aggregations of thrombocytes covered some defects in the endothelial lining of the canal. At 90° to 180° from the surgical site, small and fewer breaks in the inner wall were seen. Postsurgery outflow facility (n = 2) was approximately 30% higher in the treated eye than in the contralateral control, corrected bilaterally for presurgery baseline. Conclusions: The most likely explanations for the increase in outflow facility in monkeys after viscocanalostomy are focal disruptions of the inner wall endothelium of Schlemm canal and disorganization of the juxtacanalicular zone, resulting in direct communication of juxtacanalicular zone extracellular spaces with the lumen of Schlemm canal. The continuous presence of sodium hyaluronate might prevent repair of these defects by interfering with thrombocyte function. Clinical Relevance: In nonhuman primates, viscocanalostomy appears to decrease outflow resistance through persisting focal disruption of the inner wall endothelium and opening of the juxtacanalicular or cribriform region of the trabecular meshwork, the tissue most affected by pathologic changes in primary open-angle glaucoma in humans.

AB - Objective: To examine structural changes and aqueous humor outflow after viscocanalostomy in live normal monkey eyes. Methods: Viscocanalostomy surgery was performed in 1 eye of each of 4 rhesus monkeys. Outflow facility was determined before and after surgery. All eyes were fixed and examined by light and/or electron microscopy 36 or 63 days postoperatively. Results: Schlemm canal was replaced by scar tissue at the surgical site. The juxtacanalicular zone contained homogeneous material, probably high-molecular-weight 1.4% sodium hyaluronate. The sclera external to Schlemm canal was overhydrated, and remains of a scleral lake were present in 1 animal. Multiple defects were present in the endothelial lining of Schlemm canal inner and outer wall. Fine fibrillar material and sheath-derived plaque material partly bridged the defects. Along the inner wall, aggregations of thrombocytes covered some defects in the endothelial lining of the canal. At 90° to 180° from the surgical site, small and fewer breaks in the inner wall were seen. Postsurgery outflow facility (n = 2) was approximately 30% higher in the treated eye than in the contralateral control, corrected bilaterally for presurgery baseline. Conclusions: The most likely explanations for the increase in outflow facility in monkeys after viscocanalostomy are focal disruptions of the inner wall endothelium of Schlemm canal and disorganization of the juxtacanalicular zone, resulting in direct communication of juxtacanalicular zone extracellular spaces with the lumen of Schlemm canal. The continuous presence of sodium hyaluronate might prevent repair of these defects by interfering with thrombocyte function. Clinical Relevance: In nonhuman primates, viscocanalostomy appears to decrease outflow resistance through persisting focal disruption of the inner wall endothelium and opening of the juxtacanalicular or cribriform region of the trabecular meshwork, the tissue most affected by pathologic changes in primary open-angle glaucoma in humans.

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