A callosity is another name for callus, a piece of skin that has become thickened as a result of repeated contact and friction. Primates
All Old World monkeys, gibbons, and some chimpanzees have pads on their rears known as ischial callosities. Ischial relates to the ischium: it forms the lower and back part of the hip bone. The pads enable the monkeys to sleep sitting upright on thin branches, beyond reach of predators, without falling. The ischial callosities are one of the most distinctive pelvic features which separates Old World monkeys from New World monkeys. Right whales
In whales, the term callosity refers to the rough, calcified skin patches found on the heads of the three species of right whales. These callosities are a characteristic feature of the whale genus Eubalaena; because they are found on the head of the whale and appear white against the dark background of the whales skin, they make it very easy to identify these species. The callosities themselves are grey; the white appearance is due to large colonies of whale lice, whale barnacles and parasitic worms which reside on them. Young whales and diseased individuals are often infested with a different species of cyamid, which gives an orange hue rather than white on these whales.
The pathophysiology of secondary glaucoma in these cases is affected by the type of tumour, location and other tumour-associated factors. Among the many subtypes of uveal tumours, secondary glaucoma is the most prominent among patients with trabecular meshwork iris melanoma. The blockage of vitreous flow due to inflammation in the structures of the trabecular meshwork is also observed in herpetic anterior uveitis patients. In addition to this, angle invasion is a mechanism that is observed to contribute greatly to the development of secondary glaucoma in patients with iris tapioca melanoma, iris lymphoma, choroidal melanoma, and medulloepithelioma. Treatment and management
Pharmacological interventions
Miotic drugs are a class of cholinergic drugs that are frequently employed in the treatment and management of all types of glaucoma. These drugs stimulate the contraction of the pupil causing the iris to pull away from the trabecular meshwork. Consequently, the normal drainage of the aqueous humour is restored, relieving IOP. In addition to causing a direct effect on IOP, these drugs are applied to reduce pigment release (from the iris pigment epithelium) in the treatment of pigmentary glaucoma. Despite the advantages, the widespread use of miotic drugs is limited by its associated side effects. There is an increased risk of development of posterior synechiae in glaucoma secondary to exfoliation syndrome and ocular trauma.