What is optic nerve hypoplasia

Figure 1. Various features of optic nerve hypoplasia

Sometimes, the patients with optic nerve hypoplasia were referred to me as optic neuritis.

Optic nerve hypoplasia (ONH) is defined as small disc size. Then, How small is the ONH?
The optic disc size can be measured by distance from optic nerve head to macula.

Figure 2. Definition of ONH.

Normal optic disc (DD) was placed 2 and half or 3 discs between macula and optic nerve head (DM).
If the 4 or more discs can be placed between macula and optic nerve head, we can say it is ONH. In other words, ONH was diagnosed when DM/DD is over than 4.

Treatment of Optic neuritis

Traditionally , treatment of optic neuritis that improve final visual acuity is not proven.

Optic neuritis treatment trials (ONTT) have reported that systemic corticosteroid did not improve final visual acuity. As a result, ophthalmologists should explain hazards and benefits of  systemic corticosteroid, and the decision is up to the patients.

I think that this situation is kind of awkward because the patients don't have any idea about optic neuritis and doctors may seem to be incompetent.

During my short term training in Kinki University, Japan, the professor of Kinki University has recommended systemic corticosteroid to the patients.

That's because the possibility of neuromyelitis optica (NMO).

The patients of NMO should be treated using systemic corticosteroid as soon as possible. If the patients do not respond, plasma exchange should be considered.