Perioral dermatitis, also known as periorificial dermatitis, is a common type of skin rash. Symptoms include multiple small (1–2 mm) bumps and blisters sometimes with background redness and scale, localized to the skin around the mouth and nostrils. Less commonly the eyes and genitalia may be involved. It can be persistent or recurring and resembles particularly rosacea and to some extent acne and allergic dermatitis. The term "dermatitis" is a misnomer because this is not an eczematous process.The cause is unclear. Topical steroids are associated with the condition and moisturizers and cosmetics may contribute. The underlying mechanism may involve blockage of the skin surface followed by subsequent excessive growth of skin flora. Fluoridated toothpaste and some micro-organisms including Candida may also worsen the condition, but their roles in this condition is unclear. It is considered a disease of the hair follicle with biopsy samples showing microscopic changes around the hair follicle. Diagnosis is based on symptoms.Treatment is typically by stopping topical steroids, changing cosmetics, and in more severe cases, taking tetracyclines by mouth. Stopping steroids may initially worsen the rash. The condition is estimated to affect 0.5-1% of people a year in the developed world. Up to 90% of those affected are women between the ages of 16 and 45 years, though it also affects children and the elderly, and has an increasing incidence in men.
For some patients the removal was only performed on one eye, resulting in the anisometropia / aniseikonia. Today, this is rarely a problem because when the lens is removed in cataract surgery, an intraocular lens, or IOL is left in its place.Retinal aniseikonia occur due to forward displacement, stretching or edema of retina. Diagnosis
A way to demonstrate aniseikonia is to hold a near target (e.g., a pen or a finger) approximately 6 inches directly in front of one eye. The person then closes one eye, and then the other. The person should notice that the target appears larger to the eye that it is directly in front of. When this object is viewed with both eyes, it is seen with a small amount of aniseikonia. The principles behind this demonstration are relative distance magnification (closer objects appear larger) and asymmetrical convergence (the target is not an equal distance from each eye). Treatment
Optical aniseikonia due to anisometropia can be corrected by spectacles, contact lenses or refractive corneal surgeries.Spectacle correction is done by changing the optical magnification properties of the auxiliary optics (corrective lenses). The optical magnification properties of spectacle lenses can be adjusted by changing parameters like the base curve, vertex distance, and center thickness. Magnification size matched lenses that are used to correct aniseikonia are known as iseikonic lenses.Contact lenses may also provide less difference in retinal image size. Wider and better field of vision is another benefit of contact lens use.