O in Research
- O Donnell Pappas syndrome
- Obstructive asymmetric septal hypertrophy
- Occipital horn syndrome
- Occult spinal dysraphism
- Ochronosis
- Ochronosis- hereditary
- Ocular Albinism type 1
- Ocular cicatricial pemphigoid
- Ocular coloboma-imperforate anus
- Ocular colobomas- ichthyosis- brain malformations and endocrine abnormalities
- Ocular convergence spasm
- Ocular melanoma
- Ocular motility disorders
- Ocular Muscular Dystrophy
- Ocular toxoplasmosis
- Oculo cerebral dysplasia
- Oculo cerebro acral syndrome
- Oculo cerebro osseous syndrome
- Oculo digital syndrome
- Oculo skeletal renal syndrome