Retinal red-free light photographs in two congenital conditions: a case of optic hypoplasia and a case of congenital hemianopia

Optic nerve axons: life and death before birth

In the 2004 Bowman Lecture, I give a panegyric for Sir William Bowman, an estimate of the importance and the epidemiology of anterior visual pathway developmental disorders, followed by a history of the anterior visual system. I review the normal development of the optic nerve and chiasm and the main developmental disorders: Optic Nerve Aplasia, Optic Nerve Hypoplasia and Achiasmia.

Neuro-imaging and positron emission tomography of congenital homonymous hemianopsia

Congenital homonymous hemianopsia is an uncommon asymptomatic visual field defect discovered typically in young adult life that is caused by a diverse group of insults to the retrochiasmal afferent visual system occurring prenatally, at birth, or during early childhood. We treated eight patients with congenital homonymous hemianopsia; seven with damage involving the optic radiations and one with an abnormality of the optic tract. We performed positron emission tomography using 18F-fluoro-2-deoxyglucose on two patients with dense homonymous hemianopsias, lesions of the contralateral optic radiations, and largely intact occipital cortex. These studies showed minimal abnormalities in resting visual cortex glucose metabolism of the affected visual cortex.

Optic nerve hypoplasia

Optic nerve hypoplasia is an easily overlooked, nonprogressive developmental anomaly which results in a wide range of visual deficits. It is frequently associated with clinically significant central nervous system and endocrine abnormalities. Maternal substance abuse is increasingly recognized in many cases. A supranormal regression of optic nerve axons in utero, rather than a primary failure of differentiation, is proposed as the pathogenesis.

Optic nerve hypoplasia: changing perspectives

Optic nerve hypoplasia, having once been regarded as exceedingly rare, is now regarded as one of the major causes of visual loss in infancy. Recognition of subtle forms and segmental forms of optic nerve hypoplasia are important in explaining the evaluation of subnormal vision, and have an added significance in the recognised associations of central nervous system anomalies including abnormalities of the endocrine system. These changing clinical perspectives are reviewed, together with a discussion of the pathogenesis of optic nerve hypoplasia in the light of cell death and nerve fibre degeneration seen in normal development of the neural visual system.

Clinical spectrum of congenital optic nerve hypoplasia: review of 51 patients

Fifty-one patients with congenital optic nerve hypoplasia (CONH) were reviewed. It was found that the risk of having an affected child is higher in an adolescent mother, and that maternal alcohol or drug abuse may be important factors. Frequently the disorder is associated with other neuropsychiatric handicaps, and with neuro-endocrine abnormalities. The findings suggest that CONH probably is not a homogeneous group of disorders; some may be caused by primary failure of differentiation of the retinal ganglion cells, while others may be the product of an acquired transsynaptic degeneration of optic-nerve fibres.

Bilateral optic nerve hypoplasia with normal visual acuity

A 26-year-old man, a 19-year-old man, and a 55-year-old man had bilateral optic nerve hypoplasia. They all had normal vision, but considerable defects in the inferior segments of the visual fields.

Spectrum of optic nerve hypoplasia

Optic nerve hypoplasia is a non-progressive condition characterised by subnormal vision and a subnormal number of optic nerve axons. It may be unilateral or bilateral, isolated or combined with other defects. Analysis of fundus photographs from a series of 7 patients with a stationary abnormality of different degrees showed that the functional defects could be closely correlated with defects in the retinal nerve fibre layer. Our observations show that the condition has a wide range of both functional and anatomical defects and that a subnormal diameter of the optic disc is not a requisite for the diagnosis. Presumably, there is also a wide variety of causes, not only a primary failure of development of retinal ganglion cells. We suggest that optic nerve hypoplasia can be viewed as a non-specific manifestation of damage to the visual system, sustained any time before its full development.