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Ocular Size Abnormalities 705

Ocular Size Abnormalities Client Education
Sheet
VetBooks.ir Diseases and Disorders
PHYSICAL EXAM FINDINGS
BASIC INFORMATION
Buphthalmos: larger globe and signs of indicating active glaucoma) or normal
(chronic glaucoma) with buphthalmos;
Definition glaucoma: typically low (<10 mm Hg) with phthisis
• Buphthalmos: a larger than normal globe; • Red eye (congested conjunctival and episcleral bulbi
an acquired condition resulting from blood vessels) ○ Fluorescein dye application with buphthal-
glaucoma • Diffuse corneal edema with possible stria mos to rule out corneal ulcer secondary
• Microphthalmia: a smaller than normal (white streaks in the cornea from breaks in to exposure keratitis
globe; a congenital and potentially inherited Descemet’s membrane) ○ Neuro-ophthalmic exam (p. 1136) to
condition sometimes associated with other • Corneal vascularization secondary to chronic assess vision (e.g., menace response)
ocular anomalies exposure (e.g., lagophthalmos) • Additional tests vary, depending on underly-
• Phthisis bulbi: a shrunken globe; an acquired • Fixed and dilated pupil if secondary to ing cause (e.g., uveitis).
condition due to severe ocular trauma or primary glaucoma or miotic pupil if glau-
chronic intraocular inflammation (e.g., coma is secondary to uveitis Advanced or Confirmatory Testing
uveitis) • Lens subluxation/luxation • Buphthalmos: ocular ultrasound if corneal or
• Blindness ocular media opacities preclude evaluation of
Synonyms Microphthalmia: smaller globe and the intraocular structures (e.g., assess for cataract
Buphthalmia (buphthalmos), microphthalmos following: or intraocular mass)
(microphthalmia) • Appearance of enophthalmos (caudal • Ocular histopathologic exam if eye is
displacement of the eye) enucleated due to blindness and ocular pain
Epidemiology • Prolapsed third eyelid (p. 970) (common with buphthalmos)
SPECIES, AGE, SEX • Other intraocular abnormalities (cataracts,
• Buphthalmos may occur and microphthalmia retinal folds/dysplasia) TREATMENT
does occur congenitally. • ± Small palpebral fissure (e.g., small eyelid
• Phthisis bulbi: no age predisposition opening) or entropion and/or conjunctivitis Treatment Overview
if eyelids are normal length despite small eye The management of ocular pain is paramount,
GENETICS, BREED PREDISPOSITION • Vision may be normal, reduced, or absent. independent of the appearance of the globe.
• Glaucoma resulting in buphthalmos is Phthisis bulbi: shrunken globe and the Pain control may require enucleation. No
inherited in several breeds (p. 387). following: treatment may be required if the ocular
• Microphthalmia is inherited in several breeds • Appearance of enophthalmos size abnormality is not accompanied by
and is commonly associated with multiple • Prolapsed third eyelid evidence of discomfort, inflammation, or
ocular defects (recommend consultation with • ± Corneal edema; deep corneal vascularization elevated IOP.
a veterinary ophthalmologist). • ± Entropion, conjunctivitis, posterior synechiae,
cataract, iris atrophy Acute and Chronic Treatment
ASSOCIATED DISORDERS • Vision typically reduced or absent • For buphthalmos: if the animal’s globe is
Buphthalmos associations: blind and if glaucoma remains medically
• Lagophthalmos (incomplete closure of the Etiology and Pathophysiology uncontrolled, options include
eyelids) with or without secondary corneal • Buphthalmos: result of untreated, poorly ○ Enucleation, evisceration with intraocular
ulceration and chronic keratitis managed, or progressive glaucoma prosthesis, or chemical ablation of blind
• Lens subluxation/luxation • Microphthalmia: congenital deficiency of eyes with chronic primary glaucoma;
• Intraocular neoplasia (p. 559) optic vesicle or failure of normal growth chemical ablation is not recommended
Microphthalmia associations: and expansion of optic cup; inherited in cats
• Other congenital ocular anomalies, including condition ○ Enucleation of eyes with intraocular
cataracts, anterior segment dysgenesis, and • Phthisis bulbi: acquired condition that neoplasia
retinal dysplasia/folds usually follows chronic intraocular inflam- ○ Enucleation of eyes with congenital
• Collie eye anomaly, including choroidal mation or severe trauma glaucoma
hypoplasia with or without optic nerve • For microphthalmos: enucleation is war-
coloboma, staphyloma, retinal detachment, DIAGNOSIS ranted if eye is blind and entropion or
and intraocular hemorrhage chronic conjunctivitis occurs.
Phthisis bulbi associations: Diagnostic Overview • For phthisis bulbi: treatment of underlying
• Untreated or poorly responsive intraocular The definitive diagnosis depends on the general uveitis; recommend enucleation if eye is
inflammation (e.g., uveitis [p. 1023] or severe appearance of the ocular globe and signalment blind and entropion or chronic conjunc-
ocular trauma [p. 213]) of the patient. tivitis occurs; if phthisis bulbi occurs in
a cat, enucleation is warranted to prevent
Clinical Presentation Differential Diagnosis trauma-induced ocular sarcoma (p. 559)
HISTORY, CHIEF COMPLAINT • Buphthalmos: exophthalmos (forward
Condition is most likely unilateral but can be displacement of the globe) PROGNOSIS & OUTCOME
bilateral. • Microphthalmos, phthisis bulbi: ruptured
• Buphthalmos: enlargement of globe due globe, enophthalmos • Prognosis for vision is grave in cases of
to congenital, primary, or secondary glau- buphthalmos and phthisis bulbi.
coma Initial Database • Prognosis for vision varies for microphthal-
• Microphthalmia: small eye from birth • Complete ophthalmic exam (p. 1137): mia because it depends on the degree of
• Phthisis bulbi: progressive shrinkage of globe ○ Measurement of intraocular pressure severity and the presence of other ocular
associated with severe uveitis or trauma (IOP): may be elevated (>25 mm Hg, anomalies.

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