Chapter 24

HEREDITARY OPTIC NEUROPATHIES

LHON is an hereditary optic neuropathy, maternally inherited, associated with three primary mitochondrial DNA mutations (nucleotide positions 11778, 14484, and 3460).1 The disease is passed from mother to child and the carrier state to daughter.

URGENCY OF EVALUATION

Any young person with acute vision loss should be evaluated by an ophthalmologist within 24 hours. Many patients with LHON report a more subacute pattern, which should be evaluated within several days.

DIAGNOSIS

Symptoms

Demographics

LHON occurs most frequently in males (male-to-female ratio in the United States is 9:1)² and usually presents in the second and third decades of life. In many cases there is no family history of visual loss.

Visual Loss

Subacute, progressive, painless loss of central vision, usually monocular, over weeks is the classic pattern for LHON. Sequential vision loss in the fellow eye follows within weeks to months of the first eye. Visual loss is usually permanent, although occasional patients may demonstrate some recovery of vision years after the initial loss, most commonly in patients with the 14484 mutation.

Pain

There is usually no pain associated with LHON.

Signs

Visual Acuity

Visual acuity declines progressively to 20/200 or worse, usually bilaterally symmetric by the time the process is complete. Marked asymmetry and milder vision loss can occur, but is not the usual pattern.

Visual Field

The classic defect is a dense central/cecocentral scotoma, often with extension superiorly and marked color vision loss (Fig. 24–1).

Pupils

A relative afferent pupillary defect is present with monocular or asymmetric bilateral disease. This usually becomes less apparent as the optic nerves become more symmetrically impaired.

Optic Disc

During the acute phase of visual loss, the fundus has a characteristic appearance (Fig. 24–2):

With time, the acute signs resolve, and optic atrophy ensues (Fig. 24–3).

Associated Abnormalities

Some patients may have a multiple sclerosis like syndrome.

Red Flags

The following features should raise the question of an alternate diagnosis:

Evidence of intraocular inflammation, suggesting inflammatory or infectious optic neuritis or uveitis with associated optic neuropathy

Other neurologic signs and symptoms (headache, ataxia, cranial nerve palsy), suggesting an intracranial process

Bilateral simultaneous vision loss or loss in fellow eye within 24 to 72 hours, suggesting optic neuritis

Bitemporal or junctional visual field pattern (cecocentral defect in one eye and temporal defect in fellow eye), suggesting a chiasmal process, most likely compressive or inflammatory (see Chapter 7)

Periorbital pain suggests orbital inflammation or optic neuritis

Lack of confirmation on genetic testing (see later)

Differential Diagnosis

Occasionally patients with LHON present without classic demographic and funduscopic features. In these cases, the broad differential diagnosis of optic neuropathy in general must be considered.

Optic Neuritis (Idiopathic) (see Chapter 20)

Acute presentation may resemble LHON, but patients with optic neuritis usually have pain with eye movement and begin to recover vision within several weeks.

Stay updated, free articles. Join our Telegram channel

Join