Clinical, histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses

Abstract

Heterochromic iridocyclitis with secondary keratitis (HIK) is characterized by uveal inflammation with pigment dispersion and suspected corneal endothelial dysfunction. Horses being treated for HIK require diligent and frequent follow-up examinations in combination with aggressive local immune suppression to control the disease. However, HIK may not respond to therapy and enucleation may ultimately be required to ensure the horse's comfort.

Low‐dose intravitreal injection of 4 mg preservative‐free gentamicin and superficial lamellar keratectomy combined with modified Gundersen grafts to control chronic heterochromic iridocyclitis and secondary keratitis in horses

“…The frequency of enucleation was limited to only one patient in this study, which is significantly lower than the percentage of eyes enucleated in the original study describing this condition 1 . However, the limited follow‐up times do not provide enough information regarding the long‐term outcome of the other globes.…”

Low‐dose intravitreal injection of 4 mg preservative‐free gentamicin and superficial lamellar keratectomy combined with modified Gundersen grafts to control chronic heterochromic iridocyclitis and secondary keratitis in horses

“…The frequency of enucleation was limited to only one patient in this study, which is significantly lower than the percentage of eyes enucleated in the original study describing this condition 1 . However, the limited follow‐up times do not provide enough information regarding the long‐term outcome of the other globes.…”

Evaluation of equine corneal disease using spectral domain optical coherence tomography (SD‐OCT)

“…Fixating the OCT was possible, but aligning the fixed OCT and horse eye proved difficult with the current instrument configuration. Therefore, use of the handheld device in a tranquilized horse with its head stabilized was determined to be the most feasible imaging technique, as observed in our previous studies . Improvements in image scan speeds and development of instrument hardware that allows fixation of the hand piece and at the same time allows better access to the equine cornea would decrease image session time and likely improve image quality.…”

“…The use of SD‐OCT for measurement of equine corneal thickness has also been described; but to date, only a single study exists of the use of this imaging modality in horses with corneal disease . This single study used SD‐OCT imaging to describe the corneal lesions of horses with heterochromic iridocyclitis including the characteristic pigmented keratic precipitates, detached Descemet's membrane, and retrocorneal membrane …”

Clinical features and outcomes of horses presenting with presumed equine immune mediated keratitis to two veterinary hospitals in the United Kingdom and Finland : 94 cases (2009–2021)

“…might now be classified as HIK in the context of current literature. 10 The significantly lower intraocular pressure in some of the affected eyes is a novel finding. Previously, in the case series by Gilger et al ( 2005) normal intraocular pressures were described in all cases, although in that study the lack of uveitis was an inclusion criteria, and it describes that no horses presented with aqueous humour flare or miosis.…”

Low‐dose intravitreal injection of 4 mg preservative‐free gentamicin and superficial lamellar keratectomy combined with modified Gundersen grafts to control chronic heterochromic iridocyclitis and secondary keratitis in horses

“…The frequency of enucleation was limited to only one patient in this study, which is significantly lower than the percentage of eyes enucleated in the original study describing this condition 1 . However, the limited follow‐up times do not provide enough information regarding the long‐term outcome of the other globes.…”

Evaluation of equine corneal disease using spectral domain optical coherence tomography (SD‐OCT)

“…Fixating the OCT was possible, but aligning the fixed OCT and horse eye proved difficult with the current instrument configuration. Therefore, use of the handheld device in a tranquilized horse with its head stabilized was determined to be the most feasible imaging technique, as observed in our previous studies . Improvements in image scan speeds and development of instrument hardware that allows fixation of the hand piece and at the same time allows better access to the equine cornea would decrease image session time and likely improve image quality.…”

“…The use of SD‐OCT for measurement of equine corneal thickness has also been described; but to date, only a single study exists of the use of this imaging modality in horses with corneal disease . This single study used SD‐OCT imaging to describe the corneal lesions of horses with heterochromic iridocyclitis including the characteristic pigmented keratic precipitates, detached Descemet's membrane, and retrocorneal membrane …”

Clinical features and outcomes of horses presenting with presumed equine immune mediated keratitis to two veterinary hospitals in the United Kingdom and Finland : 94 cases (2009–2021)

“…might now be classified as HIK in the context of current literature. 10 The significantly lower intraocular pressure in some of the affected eyes is a novel finding. Previously, in the case series by Gilger et al ( 2005) normal intraocular pressures were described in all cases, although in that study the lack of uveitis was an inclusion criteria, and it describes that no horses presented with aqueous humour flare or miosis.…”

Low‐dose intravitreal injection of 4 mg preservative‐free gentamicin and superficial lamellar keratectomy combined with modified Gundersen grafts to control chronic heterochromic iridocyclitis and secondary keratitis in horses

“…The frequency of enucleation was limited to only one patient in this study, which is significantly lower than the percentage of eyes enucleated in the original study describing this condition 1 . However, the limited follow‐up times do not provide enough information regarding the long‐term outcome of the other globes.…”

Evaluation of equine corneal disease using spectral domain optical coherence tomography (SD‐OCT)

“…Fixating the OCT was possible, but aligning the fixed OCT and horse eye proved difficult with the current instrument configuration. Therefore, use of the handheld device in a tranquilized horse with its head stabilized was determined to be the most feasible imaging technique, as observed in our previous studies . Improvements in image scan speeds and development of instrument hardware that allows fixation of the hand piece and at the same time allows better access to the equine cornea would decrease image session time and likely improve image quality.…”

“…The use of SD‐OCT for measurement of equine corneal thickness has also been described; but to date, only a single study exists of the use of this imaging modality in horses with corneal disease . This single study used SD‐OCT imaging to describe the corneal lesions of horses with heterochromic iridocyclitis including the characteristic pigmented keratic precipitates, detached Descemet's membrane, and retrocorneal membrane …”

Clinical features and outcomes of horses presenting with presumed equine immune mediated keratitis to two veterinary hospitals in the United Kingdom and Finland : 94 cases (2009–2021)

“…might now be classified as HIK in the context of current literature. 10 The significantly lower intraocular pressure in some of the affected eyes is a novel finding. Previously, in the case series by Gilger et al ( 2005) normal intraocular pressures were described in all cases, although in that study the lack of uveitis was an inclusion criteria, and it describes that no horses presented with aqueous humour flare or miosis.…”