OPTIC
NERVE HYPOPLASIA: Hypoplasia of one or both optic nerves
may occur as an isolated developmental defect or in association
with other ocular, cranial, or facial malformations. The
disc is usually small with normal-sized vessels and
is surrounded by a yellowish peripapillary
halo with a pigmented rim. The entire structure approximates
the size of a normal disc and is associated with
thinning of the retinal nerve fiber layer with reduction
in the number of the ganglion cells.
Optic nerve hypoplasia is associated with all levels of visual
acuity and with a variety of visual field defects. Often, patients
are asymptomatic but are diagnosed when a screening field reveals
an unexpected altitudinal visual field defect.
CAUSES:
Reported causes and associated abnormalities of optic nerve hypoplasia
include DeMorsier syndrome (with septum pellucidum agenesis
and growth hormone deficiency), intrauterine CMV infection, congenital
cysts or tumors of the anterior visual pathway, maternal
drug use including quinine, LSD, alcohol, anticonvulsants, porencephaly,
toxemia, polydramnios, other genetic causes, and maternal
diabetes mellitus (1).
MATERNAL
DIABETES MELLITUS: Peterson and Walton (2) first
reported a syndrome characterized by segmental
optic nerve hypoplasia, altitudinal or sector visual field defect,
and normal visual acuity in 17 children of diabetic
mothers. In 1986, Nelson (2) described altitudinal visual field
defects in children of maternal diabetic mothers
who had congenital hypoplasia of the optic nerve. Kim and coworkers
(3) have described a subtype of this abnormality,
called superior segmental optic nerve hypoplasia, in children
of juvenile diabetic mothers with particular disc
characteristics. Most children were born to insulin-dependent
diabetic mothers and were premature by term but not
by weight. They had no other birth defects or endocrinopathies.
Visual acuity was 20/25
or better and color vision was normal, but all affected eyes had
inferior altitudinal defects and small
optic discs. Few of the cases reported had other congenital anomalies.
Children of diabetic mothers are at increased
risk for other central nervous system malformations, neural tube
defects, microcephaly, and deafness. Hypoglycemia,
hyperglycemia, insulin therapy, artificial sweeteners, vascular
disease, hypoxia, abnormalities of ketones
and amino acids, glycosylation of proteins, maternal life style
and hormonal changes, have all been considered
as possible teratogenic factors. The frequency of occurrence of
optic nerve hypoplasia in children of diabetic
mothers is not known but seems to be low.
ASSOCIATED FINDINGS:
Presence of other associated abnormalities or findings in patients
with optic nerve hypoplasia—such as seizures, developmental
delay, cerebral palsy, focal neurologic defects, hydrocephalus,
hydranencephaly, facial hemiatrophy, retina lacunae (as
in Aicardi’s syndrome), Klippel-Trenaunay-Weber syndrome,
Down syndrome, Trisomy D, neonatal hypoglycemia, dwarfism,
hypopituitarism, hypothyroidism, diabetes insipidus, osteogenesis
imperfecta, chondrodysplasia punctata, mandibular dysostosis,
sexual precocity, ventricular septal defect, and Goldenhar-Gorlin
syndrome—mandate further investigations like neuroimaging
and endocrine evaluation (1).
REFERENCES
1. Nelson M, Lessell S, Sadun AA. Optic nerve
hypoplasia and maternal diabetes mellitus. Arch Neurol 1986:43:
20-25.
2. Petersen RA, Walton DS. Optic nerve hypoplasia
with good visual acuity and visual field defect. Arch Ophthalmol
1977; 95:254-258.
3. Kim RY, Hoyt WF, Lessell S, Narahara MH.
Superior segmental optic hypoplasia. A sign of maternal diabetes.
Arch Ophthalmol 1989; 107: 1312-1315.
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