Page 90 - The Indian Digital Edition September-October 2020

tomography will show thinning of the retinal nerve fiber layer (Figure 3).
Affected children typically do not manifest nystagmus, due to the relative OCULAR
preservation of vision until later in life (1). Diagnosis may be delayed due to CHARACTERISTICS
slow progression of vision loss . Patients may also present with an acquired
(4)
dyschromatopsia, commonly tritanopia (blue/yellow) . OF DOA INCLUDE
(3)
REDUCED VISUAL
DIFFERENTIAL DIAGNOSIS ACUITY, VISUAL FIELD
DOA must be differentiated from other entities that cause bilateral optic disc SCOTOMAS, COLOUR
pallor such as glaucoma, Leber hereditary optic neuropathy, Leigh syndrome, VISION DEFECTS AND
Wolfram syndrome, Costeff syndrome and toxic or nutritional neuropathies. RARELY PROGRESSIVE

DOA may be difficult to differentiate from glaucoma, especially normal- EXTERNAL
tension glaucoma. The appearance of the optic nerve in DOA may be helpful OPHTHALMOPLEGIAS
in distinguishing it from glaucoma as the pallor will usually be temporal and
symmetric and although disc excavation may be present, it is more commonly
absent . Visual field scotomas are
(6)
located more centrally with DOA
FIGURE2B. LEFT EYE 30-2 VISUAL FIELD SHOWING MILD PARACENTRAL SCOTOMAS
and the clinician will be able to use
patterns of progression to discern
etiology over time. Additionally, field
loss secondary to DOA will likely occur
earlier in life than loss secondary to
glaucoma . Genetic testing could
(5)
be considered to further support the
diagnosis of DOA. Interestingly, OPA1
gene polymorphisms have been tied
to cases of normal tension glaucoma .
(1)
Leber hereditary optic neuropathy
(LHON) is another differential in cases
of bilateral optic atrophy. Patients with
LHON generally experience moderate
to severe central vision loss within
a six-month period during young
adulthood, whereas DOA may have a
lesser degree of loss that occurs over
time. LHON is inherited maternally
and affects males more often than
females. Genetic testing may be used
to differentiate LHON from DOA .
(7)
Leigh, Wolfram and Costeff
syndromes may be ruled out by
absence of characteristic systemic
manifestations along with appropriate
laboratory and imaging testing.
Laboratory testing along with detailed
medical history can help exclude toxic
or nutritional etiologies .
(7)
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