Veterinary Ophthalmology (2015) 18, 2, 116–122
DOI:10.1111/vop.12193
Outcome of conjunctival flap repair for corneal defects with and without an acellular submucosa implant in 73 canine eyes Daniel M. Dorbandt,1 Phillip A. Moore2 and Kathern E. Myrna Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA
Address communications to: K. E. Myrna Tel.: 706 542-3221 Fax: 706 542-6460 e-mail: [email protected] 1 Present address: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, 1008 W. Hazelwood Drive, Urbana, IL 61802, USA 2 Present address: Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
Abstract Objective To report and compare the success rate of a conjunctival pedicle flap (CPF) alone vs. a CPF with an underlying acellular submucosa implant for the repair of deep or perforating corneal wounds in dogs. Procedures Records of 69 dogs (73 eyes) receiving a CPF with or without an acellular submucosa implant between 2004 and 2012 were reviewed. Successful outcome was defined as a comfortable eye with vision at the last post-operative evaluation. Age, breed, underlying corneal disease, surgical time, lesion characteristics, topical therapies, and postoperative complications were investigated. Results Groups consisted of dogs that had a CPF alone (n = 37) and dogs that had a CPF plus an acellular submucosa implant (n = 36). Age, lesion size, surgical time, and time to discontinuation of topical anti-proteolytic medications was not significant between groups. Topical antibiotic use was terminated 13 days sooner (P ≤ 0.01) in dogs with an acellular submucosa implant. The combined success rate of all corneal wounds was 93% with success rate of corneal perforations, descemetoceles, and deep stromal wounds being 89%, 95%, and 100%, respectively. There was no difference in overall success rate between groups. Increasing age was associated with a negative outcome (P ≤ 0.01). Lesion size, presence of a corneal perforation, and concurrent keratoconjunctivitis sicca was not associated with a negative outcome. Conclusions A comparable success rate is achieved for deep or perforating corneal wounds stabilized with a CPF alone vs. a CPF plus acellular submucosa. Glaucoma, persistent uveitis, and cataract formation were not reported as post-operative complications in this study population. Key Words: acellular submucosa, conjunctival flap, corneal bioscaffold, corneal implant, corneal perforation, descemetocele
INTRODUCTION
The use of conjunctival tissue as a technique to stabilize deep and perforating corneal wounds was first described in the veterinary literature during the early 1950s.1,2 The conjunctival pedicle flap,3–7 conjunctival island graft,6–9 conjunctival hood flap,6,7 and the 360-degree conjunctival flap6,7,10 are all reported to have a high success rate.3–10 The goal of transposing conjunctival tissue is to provide a fibrovascular supply, structural support, or both.1–10 Hakanson et al.3,4 reported the conjunctival pedicle flap (CPF) maintained functional vision in 71–92% of eyes with dehiscence of the flap occurring in 4–7% of eyes.
Unfortunately, the use of conjunctival tissue reduces corneal clarity due to fibrosis.1–10 Alternative techniques have been investigated to reduce fibrosis and improve corneal clarity. Such procedures include corneal transplantation11–15 or implantation of collagen-containing tissue such as equine renal capsule,16 amniotic membrane,17–19 bovine pericardium,20 and acellular submucosa.21–31 Fresh and frozen corneal transplants have a high success rate, but graft rejection is a common complication as evidenced by vascularization and fibrosis of the transplanted cornea.11–15 However, despite rejection, the corneal button maintains a translucent nature.11–15 Veterinary corneal banks are © 2014 American College of Veterinary Ophthalmologists
conjunctival flap repair in dogs 117
limited, thereby limiting the availability of fresh or frozen cornea. The use of acellular submucosa in veterinary ophthalmology was first reported in 1999 by Lewin21 with other reports22–31 occurring over the past 15 years. Sources of this biomaterial include submucosa of porcine small intestine and porcine urinary bladder. A collagen bioscaffold is formed by decellularization of the submucosa through physical, chemical, and enzymatic processes.32–35 Acellular submucosa has a decreased susceptibility to bacterial colonization,36 the potential to inhibit matrix metalloproteinases,37 and a low antigenic potential.32 In addition, the extracellular matrix of the submucosa plays a role in angiogenesis, cell proliferation, and cell migration.32,34 In turn, these cells remodel the extracellular matrix.32,34 Commercial availability and extended shelf life make acellular submucosa a viable alternative for corneal reconstruction. Acellular submucosa, when used in conjunction with a CPF, is reported to have a positive visual outcome in 93% of cases with a corneal perforation.27 The purpose of this study was to compare the outcome of a CPF alone vs. a CPF with underlying acellular submucosa when repairing deep or perforating corneal wounds in dogs. A secondary objective of this study was to establish a current success rate for CPF repair, taking into account lesion size and concurrent ocular diseases. Such a report has not been described in over 25 years.3,4 With this clinical data, we hope to provide more accurate prognostic information for clients. MATERIALS AND METHODS
The medical records of all dogs that had a CPF to stabilize deep or perforating corneal wounds were reviewed at the University of Georgia Veterinary Teaching Hospital between 2004 and 2012. Patients received a CPF with or without an acellular submucosa implant (Acell; Acell Inc., Columbia, MD, USA, or Vet BioSISt; Cook Inc., Hertfordshire, UK), depending on surgeon preference. Exclusion criteria included dogs that had a fresh or frozen corneal transplant, lens involvement, or those with
DOI:10.1111/vop.12193
Outcome of conjunctival flap repair for corneal defects with and without an acellular submucosa implant in 73 canine eyes Daniel M. Dorbandt,1 Phillip A. Moore2 and Kathern E. Myrna Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, GA 30602, USA
Address communications to: K. E. Myrna Tel.: 706 542-3221 Fax: 706 542-6460 e-mail: [email protected] 1 Present address: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, 1008 W. Hazelwood Drive, Urbana, IL 61802, USA 2 Present address: Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
Abstract Objective To report and compare the success rate of a conjunctival pedicle flap (CPF) alone vs. a CPF with an underlying acellular submucosa implant for the repair of deep or perforating corneal wounds in dogs. Procedures Records of 69 dogs (73 eyes) receiving a CPF with or without an acellular submucosa implant between 2004 and 2012 were reviewed. Successful outcome was defined as a comfortable eye with vision at the last post-operative evaluation. Age, breed, underlying corneal disease, surgical time, lesion characteristics, topical therapies, and postoperative complications were investigated. Results Groups consisted of dogs that had a CPF alone (n = 37) and dogs that had a CPF plus an acellular submucosa implant (n = 36). Age, lesion size, surgical time, and time to discontinuation of topical anti-proteolytic medications was not significant between groups. Topical antibiotic use was terminated 13 days sooner (P ≤ 0.01) in dogs with an acellular submucosa implant. The combined success rate of all corneal wounds was 93% with success rate of corneal perforations, descemetoceles, and deep stromal wounds being 89%, 95%, and 100%, respectively. There was no difference in overall success rate between groups. Increasing age was associated with a negative outcome (P ≤ 0.01). Lesion size, presence of a corneal perforation, and concurrent keratoconjunctivitis sicca was not associated with a negative outcome. Conclusions A comparable success rate is achieved for deep or perforating corneal wounds stabilized with a CPF alone vs. a CPF plus acellular submucosa. Glaucoma, persistent uveitis, and cataract formation were not reported as post-operative complications in this study population. Key Words: acellular submucosa, conjunctival flap, corneal bioscaffold, corneal implant, corneal perforation, descemetocele
INTRODUCTION
The use of conjunctival tissue as a technique to stabilize deep and perforating corneal wounds was first described in the veterinary literature during the early 1950s.1,2 The conjunctival pedicle flap,3–7 conjunctival island graft,6–9 conjunctival hood flap,6,7 and the 360-degree conjunctival flap6,7,10 are all reported to have a high success rate.3–10 The goal of transposing conjunctival tissue is to provide a fibrovascular supply, structural support, or both.1–10 Hakanson et al.3,4 reported the conjunctival pedicle flap (CPF) maintained functional vision in 71–92% of eyes with dehiscence of the flap occurring in 4–7% of eyes.
Unfortunately, the use of conjunctival tissue reduces corneal clarity due to fibrosis.1–10 Alternative techniques have been investigated to reduce fibrosis and improve corneal clarity. Such procedures include corneal transplantation11–15 or implantation of collagen-containing tissue such as equine renal capsule,16 amniotic membrane,17–19 bovine pericardium,20 and acellular submucosa.21–31 Fresh and frozen corneal transplants have a high success rate, but graft rejection is a common complication as evidenced by vascularization and fibrosis of the transplanted cornea.11–15 However, despite rejection, the corneal button maintains a translucent nature.11–15 Veterinary corneal banks are © 2014 American College of Veterinary Ophthalmologists
conjunctival flap repair in dogs 117
limited, thereby limiting the availability of fresh or frozen cornea. The use of acellular submucosa in veterinary ophthalmology was first reported in 1999 by Lewin21 with other reports22–31 occurring over the past 15 years. Sources of this biomaterial include submucosa of porcine small intestine and porcine urinary bladder. A collagen bioscaffold is formed by decellularization of the submucosa through physical, chemical, and enzymatic processes.32–35 Acellular submucosa has a decreased susceptibility to bacterial colonization,36 the potential to inhibit matrix metalloproteinases,37 and a low antigenic potential.32 In addition, the extracellular matrix of the submucosa plays a role in angiogenesis, cell proliferation, and cell migration.32,34 In turn, these cells remodel the extracellular matrix.32,34 Commercial availability and extended shelf life make acellular submucosa a viable alternative for corneal reconstruction. Acellular submucosa, when used in conjunction with a CPF, is reported to have a positive visual outcome in 93% of cases with a corneal perforation.27 The purpose of this study was to compare the outcome of a CPF alone vs. a CPF with underlying acellular submucosa when repairing deep or perforating corneal wounds in dogs. A secondary objective of this study was to establish a current success rate for CPF repair, taking into account lesion size and concurrent ocular diseases. Such a report has not been described in over 25 years.3,4 With this clinical data, we hope to provide more accurate prognostic information for clients. MATERIALS AND METHODS
The medical records of all dogs that had a CPF to stabilize deep or perforating corneal wounds were reviewed at the University of Georgia Veterinary Teaching Hospital between 2004 and 2012. Patients received a CPF with or without an acellular submucosa implant (Acell; Acell Inc., Columbia, MD, USA, or Vet BioSISt; Cook Inc., Hertfordshire, UK), depending on surgeon preference. Exclusion criteria included dogs that had a fresh or frozen corneal transplant, lens involvement, or those with
