Screening for vision problems in children may improve future vision and educational achievement. Screening adults without symptoms is of uncertain benefit. Diagnosis is by an eye exam.The World Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment. This includes cataracts, the infections river blindness and trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness. Many people with significant visual impairment benefit from vision rehabilitation, changes in their environment, and assistive devices.As of 2015 there were 940 million people with some degree of vision loss. 246 million had low vision and 39 million were blind. The majority of people with poor vision are in the developing world and are over the age of 50 years. Rates of visual impairment have decreased since the 1990s. Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work. Classification
In 2010, the WHO definition for visual impairment was changed and now follows the ICD-11. The previous definition which used "best corrected visual acuity" was changed to "presenting visual acuity".
The esophagus is a closed and collapsed tube, and continuous flow of gas or putrid substances from the stomach indicates a health problem—such as reflux serious enough to be bringing up stomach contents or a fistula between the stomach and the esophagus—which will demonstrate more serious manifestations than just foul odour.In the case of allyl methyl sulfide (the byproduct of garlics digestion), odour does not come from the stomach, since it does not get metabolized there. Systemic diseases
There are a few systemic (non-oral) medical conditions that may cause foul breath odour, but these are infrequent in the general population. Such conditions are:
Fetor hepaticus: an example of a rare type of bad breath caused by chronic liver failure. Lower respiratory tract infections (bronchial and lung infections). Kidney infections and kidney failure. Carcinoma. Trimethylaminuria ("fish odour syndrome"). Diabetes mellitus. Metabolic conditions, e.g. resulting in elevated blood dimethyl sulfide.Individuals affected by the above conditions often show additional, more diagnostically conclusive symptoms than bad breath alone. Delusional halitosis
One quarter of the people seeking professional advice on bad breath have an exaggerated concern of having bad breath, known as halitophobia, delusional halitosis, or as a manifestation of olfactory reference syndrome. They are sure that they have bad breath, although many have not asked anyone for an objective opinion. Bad breath may severely affect the lives of some 0.5–1.0% of the adult population.