Pediatric ophthalmology (Proceedings)

• Basic Pediatric Ophthalmic Examination (minimum database)

      - Menace response- not present until 2-3 months of age

      - Palpebral reflex, Dazzle reflex, Pupillary Light Reflex

      - Direct examination with head loops, direct ophthalmoscope

      - Schirmer tear test (can be lower in puppies, ~10mm/min)

      - Fluorescein stain

      - Tonometry (normal to be slightly higher, ~20-25mmHg)

• Normal Pediatric Exam Findings

      - Corneal epithelial opacities

      - Heterochromia iridis

      - Lens capsule pigment deposition

      - Neonate tapetal reflex (blue until 4 months of age)

      - Subalbanotic fundus in blue-eyed animals

• Pediatric Ophthalmic Abnormalities

      - ADNEXA

          ■ Dermoids (congenital mass of tissue in an abnormal position)

          ■ Eyelid agenesis (feline)- involves upper eyelid coloboma; bilateral; can have other anomalies: persistent papillary membranes, choroidal colobomas

          ■ Entropion- temporary eyelid eversion (<11mo. of age), Hotz Celsus (>11mo.)

          ■ Ectropion- Outward rolling of eyelid

                o Conjunctival tissue is exposed

                o Lagophthalmos (inability to close lids completely) may occur

                o Low grade conjunctivitis is most common

          ■ Macroblepharon - Abnormally large palpebral fissure

                o Lagophthalmos leading to instability of pre-corneal tear film which can lead to keratitis

                o A required feature in St. Bernard, Clumber Sp, and Bloodhound

                o Canthalplasty may help reduce size of palpebral fissure

          ■ Distichiasis

                o Hairs that arise from the meibomian gland duct openings

                o In most cases, they are not clinically relevant because fine hairs float in the pre-corneal tear film

                o Can cause irritation and a reflex lacrimation, blepharospasm, conjunctivitis, keratitis, ulceration

                o Cryotherapy for removal

          ■ Ectopic cilia

                o A variant of distichiasis- cilia emerges through the palpebral conjunctiva

                o Typically occurs in upper eyelid

                o Blepharospasms (can be intense)

                o "Non-healing" ulcer in a young dog typically in dorsal cornea

                o Excessive lacrimation

                o Sharp surgical excision, +/- cryotherapy

          ■ Caruncular trichiasis- usually benign, can cause keratitis and eipiphora

      - CONJUNCTIVAL AND LACRIMAL SYSTEM

          ■ Prolapse gland of the third eyelid

                    » Weakness in connective tissue attachment between nictatating membrane ventrum and periorbital tissues

                    » Typically occurs prior to 2 years of age

                    » Chronic conjunctivitis and discharge

                    » Tear production is initially greater than normal eventually becoming subnormal

                    » Surgical replacement recommended- anchoring or pocket technique

          ■ Bent cartilage

                    » Eversion or inversion (rare) of the shaft of the cartilage of the third eyelid

                    » Inherited in German Shorthair pointer, but seen in other breeds

                    » Thought to result from rapid growth of the posterior portion of the cartilage compared to that of the anterior portion

          ■ Papilloma – canine oral papilloma virus in young animals

                    » Lesions can occur on the eyelid, conjunctiva, or cornea

                    » Most spontaneously regress, but ocular forms may not

                    » Wide excision if needed, +/- cryotherapy

          ■ Imperforate punctum/ micropunctum- unilateral or bilateral epiphora

                    » Most common malformation of the nasal-lacrimal duct

                    » Treatment

                         • None, cosmetic

                         • Excise conjunctiva over opening and cannulate for 3 weeks

          ■ Lacrimal gland aplasia and hypoplasia – zero tears at a young age, unilateral, small breed dogs

     - UVEA

          ■ Congenital glaucoma- rare; rapid onset of globe swelling; goniodysgenesis

          ■ Uveal cysts- Golden Retrievers, Boston Terriers; benign

          ■ Persistent pupillary membranes- incomplete atrophy of mesoderm; hereditary in Basenji

      - LENS

          ■ Cataracts

                    » Congenital- nuclear and nonprogressive

                    » Nutritional neonatal cataracts (associated with milk replacement products low in specific amino acids)

                    » Juvenile

                         • Suspected or proven heritable in 145 breeds

                         • Appear before 6 years of age

                         • Can progress to maturity within a few months, but can take several years

                         • Lens induced uveitis is common

                         • Uveitis can be severe because of rapid development

          ■ Congenital lens malformations

                    » Microphakia- abnormally small lens

                    » Lens Coloboma

                    » Lenticonus

          ■ Spontaneous lens luxation

                    » Predisposed breeds- Terrier breeds

                    » Poorly developed lens zonules

                    » 2-5 years old

      - VITREOUS

          ■ Embryonic anatomy of the hyaloid system

          ■ Persistent hyaloid artery- failure of all or part of the hyaloid artery to regress

          ■ Persistent hyperplastic tunica vasculosa lentis- hyaloid system and vitreous become hyperplastic during early fetal development and persist

      - RETINA and OPTIC NERVE

          ■ Retinal dysplasia- typically hereditary

                    » Folds

                         • Linear folding of the sensory retina

                         • Linear, "V", or "Y" streaks (grey in non-tapetum; grey or green in tapetum)

                    » Geographic

                         • Irregular or horseshoe-shaped area

                         • Most often in central tapetal fundus

                         • Hyper-reflective with variable pigment

                    » Complete with retinal detachment

                    » Typically hereditary

                    » Other causes: Canine herpes virus, vit A deficiency, x-ray, drugs, intrauterine trauma

          ■ Dwarfism and Ocular Defects

                    » Inherited in the Labrador Retriever and Samoyed

                    » Short appendages with normal axial skeleton

                    » Ocular lesions from mild retinal dysplasia to blinding with cataracts and retinal detachment

          ■ Retinal degeneration

                    » Canine retinal degeneration- hereditary rod and cone degeneration

                    » Nutritional retinal degeneration- taurine deficiency in cats; taurine deficiency has been linked with feline cardiomyopathy

          ■ Optic Nerve Aplasia- complete absence of retinal ganglion cells and optic n.

          ■ Optic Nerve Hypoplasia-small optic n.; number of axons is so low that visual and PLR deficits are present and pupil is dilated

          ■ Micropapilla- small optic n.; PLR and pupils are normal and vision is present

          ■ Optic Nerve Coloboma- malformation of optic nerve head; non-visual if severe

          ■ Collie Eye Anomaly

                    » Congenital syndrome involving defects of the posterior vascular and fibrous tunics

                    » Severity varies from choroidal hypoplasia and non-visually impairing to optic n. colobomas and retinal detachment with vision loss

     - INFECTIOUS DISEASES

          ■ Canine distemper virus- conjunctivitis, chorioretinitis, KCS, optic n. disease

          ■ Infectious canine hepatitis- Arthus type reaction, CAV-1 vaccine can cause symptoms, but now CAV-2 vaccine has eliminated that problem

          ■ Demodectic and sarcoptic mange- eyelid involvement with hyperemia, alopecia, and pruritus

          ■ Neonatal conjunctivitis- infection before resolution of physiologic ankyloblepharon

          ■ Follicular conjunctivitis- secondary to chronic antigenic stimulation; usually occurs less than 18 months of age in dogs; Tx- saline washes and topical steroids

          ■ Feline herpes virus-I

                    » Conjunctival hyperemia, chemosis, corneal ulceration (geographic or dendritic)

                    » Most common etiology for conjunctivitis in the cat (NOT allergies, cats rarely get allergic conjunctivitis)

                    » Young kittens will present with URI and runny eyes

                    » Secondary bacterial infections are common and corneal ulcerations can deteriorate and perforate (most common in the kitten)

                    » Kittens severely affected get significant scarring of the conjunctival membranes known as symblepharon

                    » replicates in the conjunctival and corneal epithelium

                    » The virus lays dormant in the Trigeminal Nerve

                    » Treatment- Topical antivirals (idoxuridine, trifluridine, cidofovir), Oral antivirals (famcyclovir), Oral L-lysine

          ■ Feline infectious peritonitis (Coronavirus)

                    » Chronic progressive anorexia, depression, weight loss, fever

                    » Pyogranulomatous uveitis with anterior and posterior involvement

                    » Chorioretinitis, perivascular cuffing, exudative retinal detachment, optic neuritis

     - HYDROCEPHALUS

          ■ Results in malformation of the orbit due to bone remodeling from increased intracranial pressure and enlargement of the clavarium

          ■ The eyes are pushed ventrolaterally giving a "sunset" appearance to the globes

          ■ Bilateral blindness with normal PLRs is most common ocular finding

          ■ Rarely, it can produce papilledema

      - MULTIPLE OCULAR ANOMALIES

          ■ Often associated with merling gene (incomplete dominance); most common is Australian Shepherd

          ■ Anomalies

                         • Microphthalmia, scleral staphylomas, choroidal colobomas, choroidal hypoplasia, retinal dysplasia, retinal detachment, cataract, lenticular colobomas, persistent pupillary membranes, iridial colobomas, dyscorias, corectopia, goniodysgenesis, corneal epithelial dysplasia

          ■ Often uni- or bilateral deafness is present

      - EXTRAOCULAR POLYMYOSITIS

          ■ Common in young, large breed dogs, specifically Golden Retrievers

          ■ Immune-mediated against myofibers of extraocular muscles

          ■ Acute onset

                    » Bilateral exophthalmos (no third eyelid protrusion)

                    » Conjunctival hyperemia

                    » Fever, lethargy, inappetance

          ■ Responds well to immunosupressives

          ■ Recurrence is common and if left uncontrolled will lead to muscle fibrosis and strabismus

References:

Essentials of Veterinary Ophthalmology by KN Gelatt; Fundamentals of Veterinary Ophthalmology by Slatter; Small Animal Ophthalmic surgery by KN Gelatt