Irritant diaper dermatitis (IDD, also called a diaper/nappy rash) is a generic term applied to skin rash in the diaper nappy area that are caused by various skin disorders and/or irritants. Generic irritant diaper/nappy  dermatitis is characterized by joined patches of erythema and scaling mainly seen on the convex surfaces, with the skin folds spared. Diaper/nappy dermatitis with secondary bacterial or fungal involvement tends to spread to concave surfaces (i.e. skin folds), as well as convex surfaces, and often exhibits a central red, beefy erythema with satellite pustules around the border. It is usually considered a form of irritant contact dermatitis. The word "diaper" is in the name not because the diaper/nappy itself causes the rash but rather because the rash is associated with diaper use, being caused by the materials trapped by the diaper (usually feces). Allergic contact dermatitis has also been suggested, but there is little evidence for this cause. In adults with incontinence (fecal, urinary, or both), the rash is sometimes called incontinence-associated dermatitis (IAD).The term diaper candidiasis is used when a fungal origin is identified. The distinction is critical because the treatment (antifungals) is completely different. Causes
Irritant diaper dermatitis develops when skin is exposed to prolonged wetness, increased skin pH caused by the combination, and subsequent reactions, of urine and feces, and resulting breakdown of the stratum corneum, or outermost layer of the skin. This may be due to diarrhea, frequent stools, tight diapers, overexposure to ammonia, or allergic reactions.
Retinal migraine is a retinal disease often accompanied by migraine headache and typically affects only one eye. It is caused by ischaemia or vascular spasm in or behind the affected eye. The terms "retinal migraine" and "ocular migraine" are often confused with "visual migraine", which is a far-more-common symptom of vision loss, resulting from the aura phase of migraine with aura. The aura phase of migraine can occur with or without a headache. Ocular or retinal migraines happen in the eye, so only affect the vision in that eye, while visual migraines occur in the brain, so affect the vision in both eyes together. Visual migraines result from cortical spreading depression and are also commonly termed scintillating scotoma. Symptoms
Retinal migraine is associated with transient monocular visual loss (scotoma) in one eye lasting less than one hour. During some episodes, the visual loss may occur with no headache and at other times throbbing headache on the same side of the head as the visual loss may occur, accompanied by severe light sensitivity and/or nausea. Visual loss tends to affect the entire monocular visual field of one eye, not both eyes. After each episode, normal vision returns. It may be difficult to read and dangerous to drive a vehicle while retinal migraine symptoms are present. Retinal migraine is a different disease than scintillating scotoma, which is a visual anomaly caused by spreading depression in the occipital cortex at the back of the brain, not in the eyes nor any component thereof.