Fleck corneal dystrophy, also known as Francois-Neetens speckled corneal dystrophy, is a rare form of corneal dystrophy. It is caused by mutations in PIKFYVE gene. Small opacities, some of which resemble "flecks", are scattered in the stroma of the patients. Other opacities look more like snowflakes or clouds. The disease is non-progressive and in most cases asymptomatic, with mild photophobia reported by some patients. In a single case report, a corneal transplantation was performed for concurrent keratoconus, and at 10 years follow-up there was still no evidence of the inclusions in the stroma. References


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While serious effects are rare and have most often resulted from misuse, adverse reactions have occurred when used properly. The FDA, therefore, requires a so-called black box warning on lindane products, which explains the risks of lindane products and their proper use.The black box warning emphasizes that lindane should not be used on premature infants and individuals with known uncontrolled seizure disorders, and should be used with caution in infants, children, the elderly, and individuals with other skin conditions (e.g., dermatitis, psoriasis) and people who weigh less than 110 lb (50 kg), as they may be at risk of serious neurotoxicity. Environmental contamination
Lindane is a persistent organic pollutant: it is relatively long-lived in the environment, it is transported long distances by natural processes like global distillation, and it can bioaccumulate in food chains, though it is rapidly eliminated when exposure is discontinued.The production and agricultural use of lindane are the primary causes of environmental contamination, and levels of lindane in the environment have been decreasing in the U.S., consistent with decreasing agricultural usage patterns. The production of lindane generates large amounts of waste hexachlorocyclohexane isomers, and "every ton of lindane manufactured produces about nine tons of toxic waste." Modern manufacturing standards for lindane involve the treatment and conversion of waste isomers to less toxic molecules, a process known as "cracking".When lindane is used in agriculture, an estimated 12–30% of it volatilizes into the atmosphere, where it is subject to long-range transport and can be deposited by rainfall.