Microphthalmos
Bernadette L. Koch, MD
DIFFERENTIAL DIAGNOSIS
Common
Trauma, Orbit
Retinopathy of Prematurity (ROP)
Retinal Detachment (RD)
Coloboma
Less Common
Persistent Hyperplastic Primary Vitreous (PHPV)
Congenital Microphthalmos
Rare but Important
Infection, Other Pathogen, Orbit
Toxocariasis, Orbit
ESSENTIAL INFORMATION
Helpful Clues for Common Diagnoses
Trauma, Orbit
Key facts
Any trauma may lead to globe rupture
Imaging
Small globe ± ocular hemorrhage or detachment ± gas within globe
If foreign body: BB common; wood may be air or intermediate attenuation
Posterior scleral rupture may lead to deep anterior chamber
Retinopathy of Prematurity (ROP)
Retrolental fibroplasia
Key facts
Vasculoproliferative disorder in low birth weight premature infants
Secondary to exposure to supplemental O2
Imaging
Noncalcified, retrolental mass = retinal detachment
Bilateral microphthalmia, hyperdense globe ± calcification as late findings
Retinal Detachment (RD)
Key facts
3 potential spaces/ocular detachments
Posterior hyaloid (between posterior hyaloid membrane and inner sensory retina)
Subretinal (between inner sensory retina and outer retinal pigmented epithelium)
Posterior choroidal (between choroid and sclera)
Ocular detachments occur in trauma, persistent hyperplastic primary vitreous (PHPV), ROP, ocular masses, Coats disease, or infection
Imaging
Retinal detachment = V-shaped density
Total retinal detachment may simulate persistent hyperplastic primary vitreous
Coloboma
Key facts
Normal or small globe size
Gap or defect of ocular tissue; may involve any structures of embryonic cleft
Optic disc coloboma (ODC): Defect confined to optic disc
Choroidoretinal coloboma (CRC): Separate from or extends beyond disc, arises from globe wall
Morning glory disc anomaly (MGDA): Central tuft of glial tissue within defect
Peripapillary staphyloma (PPS): Congenital scleral defect at optic nerve head; nearly all unilateral
Imaging
Focal outpouching of vitreous
Bilateral or unilateral
Usually with microphthalmos, rarely with macrophthalmos
± optic tract and chiasm atrophy
Retrobulbar colobomatous cyst may communicate with globe
Sclera enhances, glial tuft in MGDA may enhance
Rarely dystrophic calcification at margins
± other abnormalities if associated with syndromes (Meckel, Walker-Warburg, Aicardi, CHARGE), basal cephaloceles, midline facial clefting
Helpful Clues for Less Common Diagnoses
Persistent Hyperplastic Primary Vitreous (PHPV)
Key facts
Remnants of primary vitreous and primitive hyaloid artery (failure of involution) occur along course of Cloquet canal: Anterior, posterior, or both (most common)
2nd most common cause of leukocoria after retinoblastoma
Sporadic, unilateral; bilateral more common in association with syndromes (Walker-Warburg, Norrie)
Imaging
Noncalcified, tubular, cylindrical, or triangular-shaped enhancing tissue within vitreous compartment
Microphthalmos, retinal detachment ± ↑ attenuation of entire vitreous body common
Small dysplastic lens and shallow anterior chamber with anterior involvement
Congenital Microphthalmos
Key facts
Microphthalmia = eye < 2/3 normal size, or < 16 mm axial dimension
Anophthalmia: Complete absence of globe or only vestigial remnant
Imaging
Small globe; unilateral or bilateral
± intracranial structural abnormalities (more common in bilateral)
± coloboma or cyst
Helpful Clues for Rare Diagnoses
Infection, Other Pathogen, Orbit
Key facts
Viral (herpes simplex, herpes zoster, CMV, rubella, rubeola, mumps, EBV)
Bacterial (syphilis, Lyme, brucellosis, cat scratch, E. coli)
Fungal (candidiasis) or parasitic (Toxocara canis)
Most patients are not imaged
Most treated without sequelae of microphthalmia
Imaging
Thickened, enhancing sclera (scleritis)
Thickened, enhancing uvea (uveitis)
↑ attenuation/signal of vitreous secondary to ↑ protein ± uveitis ± ocular detachment in endophthalmitis
Endophthalmitis: Intraocular infectious or inflammatory process involving vitreous cavity or anterior chamber
Toxocariasis, Orbit
Key facts
Inflammatory response to nematode Toxocara canis causes chorioretinitis
Granulomatous inflammation surrounds dead larvae
May appear as focal posterior or peripheral retinal granuloma
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