Feline Congenital Glaucoma and ASD

Feline Congenital Glaucoma

• Reports of domestic cats with spontaneously occurring Anterior Segment Dysgenesis (ASD) and congenital glaucoma are rare.
• Bilateral ASD, including Peter's anomaly, was associated with congenital glaucoma in one eye but not the other in a 7-month-old cat.

Corneal and Iridocorneal Abnormalities

• A young Siamese cat with bilateral congenital glaucoma had an open iridocorneal angle and ciliary cleft in both eyes.
• The cause of the glaucoma was due to the compressed corneoscleral trabecular meshwork.

Feline Neovascular Retinopathy

• Anterior segment dysgenesis associated glaucoma can present concurrently with an avascular peripheral retina, gliosis, and epiretinal neovascularization of the central retina.
• The cause of glaucoma in these cases could also be secondary to peripheral anterior synechiae and intraocular inflammation.

LTBP2 Gene Mutation

• A breeding colony of Siamese cats with an autosomal recessive and fully penetrant mode of inheritance has been associated with a point mutation in the LTBP2 gene.
• This subtype of feline congenital glaucoma is characterized by elevated intraocular pressure, buphthalmos, and elongated ciliary processes by 8 weeks of age.

Clinical Features

• Gonioscopy typically reveals an open or slightly narrowed iridocorneal angle with subtle dysplasia of the pectinate ligament.
• Ultrasound biomicroscopy of the anterior segment reveals severe narrowing of the ciliary cleft.
• Other clinical features include prominent, elongated ciliary processes, spherophakia, iris hypoplasia, and iridodonesis.

Histopathological Features

• Light microscopy reveals the presence of few intrascleral blood vessels, hypoplasia of the iris stroma and ciliary body, elongated ciliary processes, and trabecular meshwork and angular aqueous plexus hypoplasia.
• Inner retinal degeneration and optic nerve atrophy are observed in chronic cases.

Glaucoma in Dogs and Cats

• Glaucoma is a group of conditions characterized by elevated intraocular pressure due to limited aqueous humor outflow through the trabecular meshwork and uveoscleral pathway.
• Elevated intraocular pressure leads to irreversible vision loss and pain in dogs and cats.

Characteristics of Glaucoma

• Globe enlargement (buphthalmos)
• Filtration angle recession
• Corneal opacification secondary to exposure keratitis
• Optic nerve and retinal and vitreous degeneration

Classification of Glaucoma

• Primary glaucoma
• Secondary glaucoma
• Congenital glaucoma
• Classification by gonioscopic appearance of the filtration angle:
  • Open
  • Closed
  • Narrow iridocorneal angle
  • Ciliary cleft
• Classification by stage of disease:
  • Acute
  • Chronic

Congenital Glaucoma

• Congenital glaucoma in veterinary species is a rare condition
• Typically presents within the first year of life
• Associated with multiple anomalies of the anterior segment (anterior segment dysgenesis [ASD])
• Causes of ASD include:
  • Idiopathic factors
  • Genetic mutations
  • In utero exposure to nutritional deficiencies, toxins, or infectious agents
• Microscopic manifestations of ASD include:
  • Ciliary and filtration angle hypoplasia
  • Elongated ciliary processes
  • Incomplete separation of the lens from the cornea
  • Dysplastic uveal tissue that attaches to the corneal stroma (Peter's anomaly)
• Congenital glaucoma can result in:
  • Unilateral or bilateral disease
  • Blind or sighted affected eye
  • Elevated intraocular pressure (>30 mm Hg), but may be normal or low due to buphthalmos and scleral thinning
• Vitreous degeneration, retinal degeneration, and optic nerve degeneration may be present due to sustained elevations of intraocular pressure in utero or within the perinatal period.

Glaucoma in Dogs and Cats

• Glaucoma is a group of conditions characterized by elevated intraocular pressure due to limited aqueous humor outflow through the trabecular meshwork and uveoscleral pathway.
• Elevated intraocular pressure leads to irreversible vision loss and pain in dogs and cats.

Characteristics of Glaucoma

• Globe enlargement (buphthalmos)
• Filtration angle recession
• Corneal opacification secondary to exposure keratitis
• Optic nerve and retinal and vitreous degeneration

Classification of Glaucoma

• Primary glaucoma
• Secondary glaucoma
• Congenital glaucoma
• Classification by gonioscopic appearance of the filtration angle:
  • Open
  • Closed
  • Narrow iridocorneal angle
  • Ciliary cleft
• Classification by stage of disease:
  • Acute
  • Chronic

Congenital Glaucoma

• Congenital glaucoma in veterinary species is a rare condition
• Typically presents within the first year of life
• Associated with multiple anomalies of the anterior segment (anterior segment dysgenesis [ASD])
• Causes of ASD include:
  • Idiopathic factors
  • Genetic mutations
  • In utero exposure to nutritional deficiencies, toxins, or infectious agents
• Microscopic manifestations of ASD include:
  • Ciliary and filtration angle hypoplasia
  • Elongated ciliary processes
  • Incomplete separation of the lens from the cornea
  • Dysplastic uveal tissue that attaches to the corneal stroma (Peter's anomaly)
• Congenital glaucoma can result in:
  • Unilateral or bilateral disease
  • Blind or sighted affected eye
  • Elevated intraocular pressure (>30 mm Hg), but may be normal or low due to buphthalmos and scleral thinning
• Vitreous degeneration, retinal degeneration, and optic nerve degeneration may be present due to sustained elevations of intraocular pressure in utero or within the perinatal period.