Juvenile onset open angle glaucoma (JOAG) due to its rarity is not well characterized. We aimed to assess the extent of interocular asymmetry of baseline intraocular pressure (IOP), disc morphometry and visual field defects at presentation in patients with primary JOAG. Retrospective, single-centre, hospital-based study.Fifty-two consecutive JOAG patients who presented with glaucomatous optic neuropathy in at least one eye, without any secondary causes of glaucoma.Participants were evaluated for baseline clinical features. The optic disc parameters were measured using scanning laser ophthalmoscopy (Heidelberg Retina Tomograph). Reliable and reproducible visual field tests using standard 30-2 Humphrey automated perimetry were analysed.Interocular asymmetry of baseline IOP, vertical cup:disc ratio and mean deviation.Fourteen patients (27%) had glaucomatous optic neuropathy in only one eye at initial presentation; the fellow eyes of which had IOP 21 mmHg. In 20 out of 52 patients (39%) one eye remained perimetrically unaffected. Patients presenting with bilateral optic neuropathy were found to be significantly younger (24.4 ± 10.6 years) in age compared to those with unilateral optic neuropathy (32 ± 8.2 years) (P = 0.02).One-fourth of primary JOAG patients present as a unilateral optic neuropathy with 60% of these having normal IOP in the fellow eyes. Primary JOAG may present with considerable asymmetry with a small proportion presenting as a unilateral disease.