Diseases starting with O. Find detailed information on symptoms, risk factors, and effective treatment plans for optimal health.
Open-angle glaucoma, also known as primary open-angle glaucoma (POAG), is a chronic, progressive optic neuropathy characterized by increased intraocular pressure (IOP) and subsequent damage to the optic nerve. It is the most prevalent form of glaucoma, accounting for approximately 90% of all glaucoma cases worldwide. Despite its prevalence, POAG is often termed the “silent thief
Onychomycosis, medically referred to as tinea unguium, is a fungal infection of the nail unit caused predominantly by dermatophytes. These pathogenic fungi invade the nail plate, nail bed, and surrounding tissue, leading to discoloration, thickening, and eventual destruction of the nail. Onychomycosis due to dermatophyte is the most common cause of nail fungal disease globally,
Onchocerciasis, commonly referred to as river blindness, is a neglected tropical disease (NTD) caused by the filarial parasitic worm Onchocerca volvulus. It is transmitted to humans through the bite of infected blackflies (Simulium species), which breed near fast-flowing rivers and streams—hence the term “river blindness.” The disease predominantly affects sub-Saharan Africa, but cases also exist
Omphalitis of the newborn refers to an acute, potentially life-threatening bacterial infection of the umbilical stump. It typically manifests within the first two weeks of life and can rapidly progress to neonatal sepsis, particularly in low-resource settings or where hygiene practices during delivery and postnatal care are inadequate. Prompt diagnosis and timely treatment are essential
Oligodendroglioma is a rare, slow-growing primary brain tumor originating from oligodendrocytes—the glial cells responsible for producing myelin in the central nervous system. These tumors are classified under diffuse gliomas, accounting for approximately 5–15% of all gliomas, and predominantly affect adults between the ages of 30 and 50. The World Health Organization (WHO) recognizes two grades
Oligoarticular juvenile idiopathic arthritis (JIA) is the most common subtype of juvenile idiopathic arthritis, a chronic autoimmune disorder affecting children under the age of 16. Defined by the involvement of four or fewer joints within the first six months of disease onset, oligoarticular JIA is further classified into persistent and extended forms based on disease
Oily skin is characterized by overproduction of sebum, a natural oil secreted by the sebaceous glands. While sebum is essential for skin hydration and barrier function, excessive amounts can lead to a greasy appearance, enlarged pores, and an increased likelihood of acne and blackheads. Individuals with oily skin often struggle to maintain a fresh, matte
Allergic rhinitis, commonly known as hay fever, is a hypersensitivity reaction of the nasal mucosa to allergens such as pollen, dust mites, pet dander, or mold spores. Beyond nasal symptoms, a significant subset of patients experience ocular symptoms associated with allergic rhinitis, which can substantially impair quality of life. These symptoms often involve inflammation of
Ocular Surface Squamous Neoplasia (OSSN) encompasses a spectrum of dysplastic and neoplastic lesions of the conjunctiva and cornea, ranging from mild epithelial dysplasia to invasive squamous cell carcinoma. OSSN is the most common non-pigmented malignancy of the ocular surface and is increasingly diagnosed globally due to improved clinical awareness and diagnostic tools. Epidemiology and Risk
Ocular rosacea is a chronic, inflammatory eye condition associated with facial rosacea. It primarily affects the eyes and eyelids, often presenting as redness, burning, dryness, and irritation. Left untreated, ocular rosacea can lead to serious complications, including corneal damage and vision impairment. Early diagnosis and tailored treatment are crucial in managing symptoms and preventing progression.