What is Optic Neuropathy?
Damage to the optic nerve arising out of any cause is termed as optic neuropathy. This damage can also manifest itself as swelling of the optic neurons termed as optic neuritis.
Optic neuropathy is suspected by the ophthalmologist when the patient reports the following warning signs – 4
Ø Visual field defect – Any type of visual field defect is seen. Initially, loss of vision occurs in a small area in the centre of visual field, slowly progressing to complete blindness. 5
Ø Dyschromatopsia – Colour vision is negatively affected. Additionally, deficits are detected in light contrast, brightness, sensitivity to colours, etc. For instance, red colour may be viewed as a lighter shade, or another colour similar to red in a patient shows signs of optical neuropathy. 6
Ø Abnormal pupillary response – The pupil helps the eye to adjust to varied levels of light brightness as well as contrast. This is a reflex action controlled by the optic nerve as well as the oculomotor nerve. 7
In young patients -
Ø Eye pain during eye movement – This is a mild to severe pain 8 surrounding the eyeball (periocular) which worsens during eye movement. 9
Ø Limb weakness – Spastic paraplegia is seen, in addition to other conditions such as optic atrophy, cognitive decline, etc. 10
Ø Ataxia – Mitochondrial diseases are characterized by association of optical neuropathy alongwith cerebellar ataxia as a result of a missense variation in the mitochondrial DNA (valine replaced by alanine). 11
In older individuals –
Ø Loss of vision – Autoimmune disorders such as Systemic Lupus Erythematosus (SLE) can result in autoimmune attacks to the optic region, leading to loss of vision. 12 This vision loss can occur in one eye, and it worsens with increase in body temperature. Most cases of optic neuritis take twelve months to achieve full visual recovery after completing treatment. 13
Ø Fatigue – Fatigue in vision is observed in patients suffering from optic neuritis, for which tinted lenses may be prescribed. 14
Ø Myalgias – Presence of muscular dysfunction (pain / spasm) alongwith optical atrophy is a sign of Arteritic Ischaemic Optic Neuropathy. 15
About Author / Additional Info:
I am a post-graduate in Biochemistry from the University of Mumbai