Onychoschizia (from Ancient Greek ὄνυξ ónyx "nail" and σχίζω schízō "to split") is a common nail disorder characterized by lamellar splitting — horizontal layering and peeling of the distal (free) edge of the nail plate. It is one of the two main types of brittle nails, the other being onychorrhexis (longitudinal splitting).
Clinical presentation The condition typically presents with thin horizontal layers that peel away at the free edge of the nail, often giving a white, frayed, or ragged appearance. It most commonly affects the fingernails and usually involves multiple nails. It is frequently part of the broader brittle nail syndrome.
Causes The most common cause is repeated exposure of the nails to water and drying agents. Other contributing factors include: Frequent hand washing, soaps, and detergents Nail cosmetics (nail polish, acetone-based removers) Aggressive manicures or nail filing Ageing (natural dehydration of the nail plate) Nutritional deficiencies (iron, zinc, biotin) Certain dermatological conditions such as psoriasis and lichen planus may feature such nails. nail biting, and repeated trauma such as typing, can contribute to nail splitting. Dehydration likely plays a role. Nutritional deficiencies that can result in nail splitting include iron, selenium, and zinc.
Diagnosis Diagnosis is by its appearance, but sometimes blood tests are required to look for iron deficiency, thyroid problems, and kidney problems.
Treatment Treatment focuses on protection and hydration of the nail: Avoidance of irritants (water, chemicals, harsh nail products) Regular application of moisturizing creams containing urea or glycerin Wearing gloves during wet work Biotin supplementation (2.5–5 mg daily) may be beneficial in some cases, particularly if a deficiency is present An acceptable alternative is gel nails.
Other animals It also occurs in hooved animals such as horses.
See also List of cutaneous conditions
References