How is LHON diagnosed?

LHON is a clinical diagnosis and can be confirmed only through a genetic test that can identify the mutation.Footnote1 In addition to this, patients can often provide a history of visual loss in family members.Footnote2

Some of the recommended tests for LHON diagnosis include:Footnote1

  • An eye examination
  • An OCT to measure the retinal ganglion cells (RGCs) and retinal nerve fibre layer (RNFL) alterations
  • A pattern electroretinogram (PERG) to measure the electrical responses in the eyeFootnote3
  • A visual field test to measure the area of central vision loss
  • An MRI or CT scan to rule out inflammation in the eye and central nervous system lesionsFootnote1,Footnote4

Importance of early

If you are experiencing problems with your eyesight, such as sudden blurring or clouding in the centre of your vision, do not wait to see if it gets worse.Footnote5 In particular, patients with LHON are often young adults with preserved peripheral vision, who make excellent candidates for low vision rehabilitation.Footnote5

The sooner a diagnosis is confirmed, the sooner treatment can be initiated when the retinal ganglion cell loss is still quite low.Footnote6

It is important to know that patients sometimes experience nadir (low point in vision) even during treatment, but this should not be a reason to stop the treatment. In some cases, after an initial deterioration of visual acuity and reaching nadir, patients have achieved a clinically relevant recovery after treatment maintenance.Footnote7

Since LHON is a rare disease, it’s often misdiagnosed, resulting in diagnosis delays

Eye testing

Who to talk to8

Look for an LHON specialist such as an ophthalmologist as soon as you experience symptoms. If you cannot approach an ophthalmologist directly, talk to your GP about your suspicions around LHON to speed up the diagnosis. They can refer you to an eye care specialist for further management of your condition.If you have a confirmed LHON diagnosis, you can request to be seen by a neuro-ophthalmologist. They are specialists who understand LHON.

Take urgent action by visiting an ophthalmologist on the first signs of LHON

Genetic testing

Genetic counselling in LHON is difficult because nothing can predict if, when or how severely it can affect a carrier. If the mother has one of the LHON mutations, all her children will inherit it. It will be passed on to the children by mothers and not by fathers.If you plan to be a mother and have a family history of LHON, take a prenatal test to determine the genetic risk. Information from your genetic counselling can help you make your family planning decisions.

Find out if you have relatives in your family with vision loss

Symptom tracker 


Keep track of how your symptoms are progressing.

Diagnosis challenges

The journey to an LHON diagnosis can be long and frustrating. LHON is such a rare genetic condition that even the most experienced doctors may have never seen someone in their practice.Footnote7 People with LHON are often treated for other causes of vision loss first before being diagnosed with LHON.Footnote7

Doctors will look at a person’s medical history, symptoms, physical exam, and genetic test results to confirm a diagnosis.Footnote1

Knowing about LHON can speed up your diagnosis

    1. Yu-Wai-Man P and Chinnery PF. Leber Hereditary Optic Neuropathy. 2000.

    2. Sadun A, et al. Curr Treat Options Neurol. 2011;13(1):109–17.

    3. Asanad S and Karanjia R. StatPearls Publishing; 2021. PMID: 32809476.

    4. Man PYW, et al. J Med Genet 2002;39:162–9.

    5. Theodorou-Kanakari A, et al. Adv Ther. 2018;35:1510–18.

    6. Pemp B, et al. Graefes Arch Clin Exp Ophthalmol. 2019:257;2751–57. 

    7. Carelli V, et al. Eur Ophthalmic Rev. 2019;13(Suppl 2).

    8. Carelli V, et al. Hum Mol Genet. 2017:26;139–50.

Disclaimer: The information on this website is intended only to provide knowledge of Leber’s hereditary optic neuropathy (LHON). This information should not be used in place of advice from your GP or other healthcare professional. If in doubt, please contact your doctor for advice. This website has been produced by Chiesi Pharmaceuticals. The website has been developed in accordance with industry and legal standards to provide information for healthcare professionals and the general public about LHON. Chiesi Pharmaceuticals makes every reasonable effort to include accurate and current information. However, the information provided in this website is not exhaustive.

Patient & Caregiver: In case you need to report an adverse drug reaction, please refer to your physician, asking him to fill in and submit the relevant case report to the concerned Health Authority, according to the Pharmacovigilance requirements in force in your Country. Nevertheless, please be kindly reminded that each patient can report any such cases directly to the national reporting system.

Healthcare Professional: In case you want to report an adverse drug reaction you become aware of, please report it to your Health Authority according to the requirements set by the pharmacovigilance legislation.