BASICS

DESCRIPTION

• Clinical condition characterized by an abnormal funduscopic appearance of the macula and decrease or absence of the foveal reflex and varying degrees of macular hypoplasia

• Macular vessels often traverse near or across the normally avascular zone of the fovea.

• Optic nerves and peripheral retina may appear normal.

• Visual acuity typically in the 20/100–20/200 range but variable depending on degree of hypoplasia

EPIDEMIOLOGY

Unknown.

RISK FACTORS

• Commonly associated with albinism and aniridia

• Family history

Genetics

• When seen in combination with aniridia or albinism the genetics of those syndromes apply. Also reported with Axenfeld–Reiger spectrum.

• Isolated autosomal dominant macular hypoplasia may be due to mutations in PAX6 (11p13).

• Autosomal recessive inheritance also reported including foveal hypoplasia with anterior segment dysgenesis (FHASD, 16q23.2–24.2).

GENERAL PREVENTION

Genetic counseling and/or prenatal testing (if mutated gene known or syndrome recognized in family).

PATHOPHYSIOLOGY

• Results from incomplete development of the fovea.

• In albinism, the absence of melanin in the retinal pigmented epithelium leads to a failure of induction of proper macular development

• In aniridia or isolated macular hypoplasia due to PAX6 mutation it is presumed that there is a failure of induction of a gene(s) downstream from PAX6, responsible for macular differentiation.

ETIOLOGY

Thought to result from incomplete embryologic development of the fovea, which typically develops in stages:

• Stage 1: Indistinct pigmented area

• Stages 2 and 3: Development of the annular reflex

• Stage 4: Appearance of the foveal pit

• Stage 5: Development of the foveal reflex

COMMONLY ASSOCIATED CONDITIONS

• Achromatopsia

• Albinism

• Aniridia

• Less common: Axenfeld–Reiger

• Nystagmus

• Reduced vision

DIAGNOSIS

HISTORY

Poor vision, possible nystagmus.

PHYSICAL EXAM

• Full ocular examination including careful evaluation of the macula

• Careful examination with indirect ophthalmoscope by noting presence or absence of annular ring and foveal light reflex and anomalous patterns of macular vessels

• Assess vision, nystagmus

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

None needed.

Follow-up & special considerations

Consider molecular genetic testing where appropriate.

Imaging

Initial approach

• OCT can be used for grading.

– Widespread thickening of the retina throughout the entire fovea with no difference in thickness from the surrounding macula

– High reflectivity of the inner retina

Diagnostic Procedures/Other

Visual field, especially Goldmann, may be helpful.

Pathological Findings

• Absence of foveal differentiation and red-free zone

• Continuation of ganglion cell layer throughout macula

• Associated with reduction in the thickness of the optic nerve and in the volume of gray matter in the visual cortex

• Abnormalities in the length and mean surface area of the calcarine fissure present in visual cortex

DIFFERENTIAL DIAGNOSIS

• Epiretinal membrane

• Macular drag (e.g., retinopathy of prematurity, familial exudative retinopathy)

• High myopia

• Blonde fundus

• Congenitally anomalous retinal vascular (e.g., macrovessel, tortuosity)

• Optic atrophy with secondary macular nerve fiber loss

• Optic nerve hypoplasia

• Retinal/macular dystrophy

TREATMENT

MEDICATION

None.

ADDITIONAL TREATMENT

General Measures

• Amblyopia therapy as indicated

• Genetic counseling

• If photophobia consider Corning lenses

Issues for Referral

• Genetic counseling/ocular genetics

• Low vision

Additional Therapies

Maximization of vision potential with spectacles, contact lenses, and/or low-vision aids.

COMPLEMENTARY & ALTERNATIVE THERAPIES

None proven or indicated.

SURGERY/OTHER PROCEDURES

• None for foveal hypoplasia

• Strabismus and nystagmus surgery as indicated (nystagmus surgery unlikely to yield great visual acuity improvement)

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• As needed for amblyopia and strabismus monitoring and treatment

– Low-vision evaluation

Patient Monitoring

• Monitor patients for associated conditions of aniridia and albinism and congenital nystagmus

• Visual development and function

• If asymmetric, amblyopia can occur.

• Strabismus.

PROGNOSIS

• Visual prognosis based on associated conditions and degree of macular hypoplasia

• Presence of anomalous blood vessels in macula (e.g., crossing midline raphe, extending close or through putative fovea) associated with worse visual prognosis

COMPLICATIONS

Low vision, nystagmus, amblyopia, strabismus.

ADDITIONAL READING

• Brodsky MC, Baker RS, Hamed LM. “Pediatric Neuro-Ophthalmology”, 2nd ed. Springer: New York, New York, 1996:304–307,314.

• Schroeder HW, et al. Hereditary foveal hypoplasia. Klin Monbl Augenheikd 2003;220(8):559–562.

• Holmstrom G, et al. Optical coherence tomography is helpful in the diagnosis of foveal hypoplasia. Acta Ophthalmol 2010;88(4):439–442.

• Mietz H, et al. Foveal hypoplasia in complete oculocutaneous albinism. A histopathologic study. Retina 1992;12(3):254–260.

• Huynh SC, et al. Macular and nerve fiber layer thickness in amblyopia: the Sydney Childhood Eye Study. Ophthalmology 2009;116(9):1604–1609.

CODES

ICD9

362.89 Other retinal disorders

CLINICAL PEARLS

• Look for this condition in patients with significant subnormal vision and without nystagmus.

• Look closely for this condition in patients who do not respond as expected to amblyopia therapy.

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