RecruitingNCT05554835
Mitochondrial
Chronic Progressive External Ophthalmoplegia
Also known as CPEO, progressive external ophthalmoplegia, PEO
Chronic progressive external ophthalmoplegia is a mitochondrial myopathy characterised by slowly progressive bilateral ptosis and ophthalmoplegia with preserved pupillary reflexes, caused by dysfunction of the extraocular muscles. It may oc
ORPHA:663 ↗Gene MT-TS1Gene MT-TL2Gene MT-TNGene MT-TL1Prevalence Approximately 1 in 100,000Onset Variable; typically adolescence to adulthood
3
studies recruiting now
as of 7 Sept 2026
14
studies registered in total
as of 7 Sept 2026
5
countries with a recruiting site
as of 7 Sept 2026
26 Sept 2022
most recent study posted
among recruiting studies
Recruiting trials
RecruitingNCT02435940
Inherited Retinal Degenerative Disease Registry
RecruitingNCT01694940
North American Mitochondrial Disease Consortium Patient Registry and Biorepository (NAMDC)
Showing the 3 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
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Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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About Chronic Progressive External Ophthalmoplegia
Chronic progressive external ophthalmoplegia is a mitochondrial myopathy characterised by slowly progressive bilateral ptosis and ophthalmoplegia with preserved pupillary reflexes, caused by dysfunction of the extraocular muscles. It may occur as an isolated condition or as part of broader mitochondrial syndromes such as Kearns-Sayre syndrome. The genetic basis is heterogeneous, involving both primary mtDNA deletions and nuclear gene mutations (most commonly POLG) that cause secondary mtDNA instability.
Common clinical features
Bilateral ptosis (often the presenting feature)Progressive limitation of extraocular eye movementsDiplopia (less common due to symmetrical progression)Proximal limb myopathyExercise intoleranceDysphagia (in severe or syndromic forms)Ragged red fibres on muscle biopsy
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Before you apply
Things trial teams commonly ask about for Chronic Progressive External Ophthalmoplegia. Not eligibility rules; those are set by each study.
- Genetic characterisation is essential: CPEO caused by POLG mutations may have different disease courses and trial eligibility compared to mtDNA deletion forms; pursue comprehensive testing.
- Ophthalmological measurements including Hertel exophthalmometry, ocular motility charts, and ptosis grading should be documented at a specialist neuro-ophthalmology centre.
- Overlapping features with Kearns-Sayre syndrome should be systematically excluded (cardiac conduction, CSF protein, pigmentary retinopathy) as this affects both diagnosis and applicable trials.
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).