1. **Retina**
1.1. Retinal Seperation
1.1.1. Typically occurs between photoreceptors and the RPE.
1.1.1.1. Seperation of the retrina from the choroid and RPE will lead to retinal atrophy.
1.1.2. Can stay attached at the ora serrata or be torn in that location.
1.2. Retinitis
1.2.1. Inflammation of the retina, typically involving the choroid.
1.2.1.1. Retinitis is rarely the sole ocular lesion.
1.3. Retinal Degeneration
1.3.1. Many possible causes, but all begin in the outer layer and progress inwards (except glaucoma).
1.4. Optic Nerve
1.4.1. **Papilledema**
1.4.1.1. Edema of the optic disk.
1.4.2. Optic Neuritis
1.5. Neoplasia
1.5.1. Retinal Gliomas
1.5.2. Retrinal Primitive Neurectodermal Tumors (PNETs)
1.6. Scleral Ectasia
1.6.1. Bulging of the sclera, typically through a defect (e.g., coloboma).
1.7. Staphyloma
1.7.1. Partial or full thickness defect in the cornea or sclera lined by protruding uveal tissue.
2. **Orbit**
2.1. Orbital Cellulitis & Retrobulbar Abscess
2.1.1. Extension from inflammation in the oral cavity or migrating foreign body.
2.2. Orbital Myositis
2.2.1. Auto-antibodies against type 2M muscle fibers.
2.3. Neoplasia
2.3.1. Orbital Meningioma
2.3.1.1. Neoplasm of meninges surrouding the optic nerve.
2.3.2. Orbital Sarcoma
2.3.3. Lacrimal Gland Adenocarcinoma
3. Glaucoma
3.1. The single most consistently recognized feature of ALL glaucomas in veterinary patients is **elevation in intraocular pressure (IOP).**
3.2. Primary vs. Secondary
3.2.1. Primary glaucoma is typically due to **goniodysgenesis**, which is congential malformation of the filtration apparatus.
3.2.1.1. No other ocular lesions and typically bilateral.
3.2.1.2. Onset is seen in mature to middle-aged patients.
3.2.1.3. Most common in dogs; rare in cats.
3.2.2. Secondary glaucoma is due to impediment of aqueous drainage due to ocular diseases (e.g,. uveitis, synechiae, lens luxation, etc).
3.3. Sequelae of Glaucoma
3.3.1. Optic Disc Cupping
3.3.2. Corneal Edema
3.3.3. Buphthalmos
3.3.3.1. Enlargement and distention of the fibrous coats of the eye.
3.3.4. Exposure Keratitis
4. Uvea
4.1. Suppurative Anterior Uveitis
4.2. FIP & Anterior Uveitis
4.2.1. Ocular manifestation of ocular disease.
4.2.2. Keratic precipitates - inflammatory cells adhered to the corneal epithelium.
4.2.3. Corneal neovascularization.
4.3. Canine Adenovirus-1 (Anterior Uveitis with Corneal Edema)
4.3.1. Uveitis due to type-III hypersensitivity.
4.3.2. Corneal edema due to damaged corneal epithelium.
4.4. Lymphoplasmacytic Anterior Uveitis
4.4.1. Etiology often uncertain; may be nonspecific inflammatory reaction pattern.
4.4.2. Frequent cause of glaucoma in cats.
4.5. Equine Recurrent Uveitis
4.5.1. Recurrent bouts of uveitis of unknown etiology, but associated with *Leptospira* infection.
4.5.2. Most common cause of glaucoma and blindness in horses.
4.5.3. Sequelae include cataract, retinal detachment, fibrovascular proliferation, synechiae, and **glaucoma.**
4.6. Septic Implantation Syndrome
4.7. Neoplasia
4.7.1. Melanoma/Melanocytoma
4.7.1.1. Canine
4.7.1.1.1. Iris >> Choroid.
4.7.1.1.2. 90% are benign.
4.7.1.2. Feline
4.7.1.2.1. Diffuse Iris Melanoma >>> Solitary Mass
4.7.1.2.2. Behavior is difficult to predict.
4.7.1.2.3. If metastasizes, can go to abdominal viscera (e.g., liver, kidney).
4.7.1.2.4. Important cause of glaucoma.
4.7.2. Iridociliary Adenoma
4.7.2.1. Dogs >> Cats.
4.7.2.2. Benign >>> Malignant
4.7.2.3. May contain some melanin pigment.
4.7.3. Feline Post Traumatic Ocular Sarcoma
4.7.3.1. Likely rising from lens epithelium following trauma to lens - latency can range from months to years.
4.7.3.2. Several variants are possible.
4.7.3.2.1. Spindle cell (fibrosarcoma) variant is the most common.
4.7.3.2.2. Osteosarcoma/chondrosarcoma.
4.7.3.2.3. Round cell variant can arise following chronic inflammation.
4.7.3.3. Aggressive, locally infiltrative behavior - can extend along the optic nerve to the brain!
4.7.4. Lymphoma
4.7.4.1. Can be part of disseminated multicentric lymphoma or solitary within the eye.
4.7.4.1.1. Solitary lymphoma has better outcomes than multicentric lymphoma.
4.7.5. Metastatic Neoplasms
4.7.6. Medulloepitheliomas
4.8. **Chorioretinitis**
4.8.1. Inflammation of the choroid and retina.
4.9. **Choroiditis**
4.9.1. Inflammation of the choroid.
4.10. **Hypopyon**
4.10.1. Accumulation of neutrophils in the anterior chamber.
4.11. **Iritis**
4.11.1. Inflammation of the iris.
4.12. Iridocyclitis
4.12.1. Inflammation of the iris and ciliary body.
4.13. **Phthisis Bulbi**
4.13.1. Shrinking, wastage, and hypotony of the eyeball secondary to chronic inflammation (e.g., uveitis).
4.14. **Synechia**
4.14.1. Adhesion of parts, particularly the iris, to other structures.
4.15. **Uveitis**
4.15.1. Inflammation of the uveal tract.
5. Developmental Anomolies
5.1. Defective Organogenesis
5.1.1. Anophthalamos
5.1.1.1. Developmental defect characterized by complete absence of the eye(s).
5.1.2. Microphthalmos
5.1.2.1. Congenitally small eyes, which may be associated with other ocular defects.
5.1.3. Synophthalmos
5.1.4. Coloboma
5.1.4.1. Apparent absence of defect of some ocular tissue, usually resulting from a failure of a part of the fetal tissue to close.
5.2. Defective Differentiation
5.2.1. Mesenchymal
5.2.1.1. Defective Migration
5.2.1.1.1. Choroidal Hypoplasia
5.2.1.2. Incomplete Atrophy
5.2.1.2.1. Persistent Pupillary Membrane
5.2.1.2.2. Goniodysgenesis
5.2.1.2.3. Persistent Hyaloid Artery
5.2.2. Surface Ectoderm
5.2.2.1. Eyelids
5.2.2.2. Cornea
5.2.2.2.1. Dermoid
5.2.2.3. Lens
5.2.3. Neuroectoderm
5.2.3.1. Retinal Dysplasia
5.2.3.2. Optic Nerve Hypoplasia
6. **Eyelids, Conjunctiva, and Lacrimal Glands**
6.1. Eyelids
6.1.1. Blepharitis
6.1.1.1. Inflammation of the eyelids.
6.1.1.1.1. Seen with any disease affecting the haired skin of the eyelids.
6.1.2. Chalazion
6.1.2.1. Chronic, lipogranulomatous infalmmation due to the leakage of Meibomian secretion.
6.1.2.1.1. Typically adjacent to adenoma of the Meibomian gland, but can be associated with any injury of the Meibomian gland.
6.1.3. **Ectropion**
6.1.3.1. Eversion of the eyelid, resulting in exposure of the palpebral conjunctiva.
6.1.4. **Entropion**
6.1.4.1. Inversion of the eyelids in toward the eyeball.
6.2. Conjunctiva
6.2.1. Chemosis
6.2.1.1. Edema and swelling of the conjunctiva - typically accompanies inflammation.
6.2.2. Conjunctivitis
6.2.2.1. Infectious Causes
6.2.2.2. Allergy & Irritation
6.3. Lacrimal Glands
6.3.1. Dacryoadenitis
6.3.1.1. Inflammation of the lacrimal glands.
6.3.2. Prolapse of the 3rd Eyelid
6.3.2.1. Attributed to congenital weakness or laxity of the surrounding connective tissue and cartilage. Often presents bilaterally.
6.3.2.2. Breed Predilection
6.3.2.2.1. Bulldogs, Mastiffs, Cocker Spaniels, Beagles, etc.
6.4. Neoplasia
6.4.1. Papillomas
6.4.1.1. Viral
6.4.1.2. Reactive
6.4.1.3. Squamous
6.4.2. Squamous Cell Carcinoma
6.4.3. Meibomian Gland Neoplasms
6.4.4. Melanocytoma
6.4.5. Hemangioma/Hemangiosarcoma
7. **Cornea & Sclera**
7.1. Cornea
7.1.1. Spontaneous Chronic Corneal Epithelial Defects (SCCED)
7.1.2. Keratoconjuntivitis Sicca (KCS)
7.1.2.1. Inflammation of the cornea and conjunctiva associated with or due to drying of these structures.
7.1.3. Descemetocele
7.1.3.1. Herniation of the Descemet's membrane.
7.1.4. Corneal Pigmentation
7.1.4.1. Pigmentation is suggestive of chronic ulceration and healing.
7.1.5. Fungal Keratitis
7.1.5.1. Usually a sequel to corneal ulceration.
7.1.5.2. Results in stromal abscesses.
7.1.5.3. Often *Aspergillus* sp.
7.1.6. **Keratitis**
7.1.6.1. Inflammation of the cornea.
7.1.7. **Conjunctivitis**
7.1.7.1. Inflammation of the conjunctiva.
7.1.8. Keratoconjunctivitis
7.1.8.1. Inflammation of the cornea and conjunctiva.
7.1.9. **Dermoid**
7.1.9.1. Congenital lesion on the corneal or bulbar conjunctival surface resembling skin.
7.1.10. Pannus
7.1.10.1. Superficial vascularization of the cornea with infiltration of granulation tissue.
7.2. Sclera
7.2.1. Granulomatous Scleritis (Dogs)
7.2.1.1. Idiopathic
7.2.1.2. Secondary to orbital cellulitis or intraocular disease.
7.2.2. Nodular Granulomatous Episcleritis (Collies)
7.2.3. Canine Limbal Melanocytoma
7.2.3.1. Can occur in younger animals.
7.2.3.2. German Shepherds are predisposed.
7.2.3.3. Benign, but can grow big!
8. **Lens**
8.1. **Cataract**
8.1.1. Increased opacity of the lens due to generation of lens fibers.
8.1.1.1. Can lead to uveitis and lens luxation.
8.2. **Nuclear Sclerosis**
8.2.1. Age-related compression of the lens fibers, causing central lens opacity or translucency.
8.3. **Phakitis**
8.3.1. Inflammation of the lens - only occurs if the lens capsule ruptures!
8.4. Lens Luxation
8.4.1. Displacement of the lens - can cause intraocular inflammation and glaucoma.
8.4.1.1. Anterior vs. Posterior
8.4.1.2. Primary vs. Secondary
8.4.1.2.1. Primary is seen with **ADAMTS17 gene mutation**, leading to zonular ligament dysplasia.
8.4.1.2.2. Secondary to many intraocular disease (e.g., inflammation, glaucoma) and/or trauma.
8.5. **Lenticonus**
8.5.1. Conical protrusion of the substance of the crystalline lens.
8.6. **Microphakia**
8.6.1. Abnormally small crystalline lens.
8.7. **Aphakia**
8.7.1. Absense of the lens; can be congenital or acquired.