Risk factors
In general, elevated IOP is a major risk factor in the development of secondary glaucoma. However, there are several risk factors contributing to the fluctuation in IOP levels. Uveitis
Secondary glaucoma is commonly associated with uveitis. Uveitis is the inflammation of the uvea, a middle layer tissue of the eye consisting of the ciliary body, choroid and iris. Various causes have been identified as potential risk factors contributing to the occurrence of secondary glaucoma. These include viral anterior uveitis due to cytomegalovirus infection, and herpetic anterior uveitis caused by herpes simplex virus. The observed pathophysiology of secondary glaucoma in uveitis is found to be linked to the increase and fluctuation of IOP. Inflammation of eye tissues contributes to the blockage of IOP produced in the ciliary body. This results in the accumulation of aqueous and thus elevated IOP, which is a common risk factor for the progression of secondary glaucoma. Paediatric congenital cataract surgery
Paediatric congenital cataract surgery is also identified as a risk factor for the progression of secondary glaucoma. Cataract is an ocular disease, identified by the progressive clouding of the lens. Surgical procedures are often employed to replace the lens and allow for clear vision. However, there is an increased risk of secondary glaucoma development in children due to the secondary IOL implantation procedure. The increased inflammatory sensitivity in the anterior chamber angle may contribute to the risks of secondary glaucoma. Intraocular tumour
Intraocular tumours (uveal and retinal tumours) are also found to be closely associated with the development of secondary glaucoma.
However, he or she may close one eye to compensate for the problem. In children, the reason for not seeing double is that the brain may ignore the image it receives from the squinting eye. This shutting down is known as Suppression. Generally, exotropia progresses in frequency and duration. As the disorder progresses, the eyes start to turn out when looking at close objects as well as those in the distance. If left untreated, the eye may turn out continually, causing a loss of binocular vision or stereopsis. In young children with any form of strabismus, the brain may learn to ignore the misaligned eyes image and see only the image from the best-seeing eye. This is called amblyopia, or lazy eye, and results in a loss of binocular vision, impairing depth perception. In adults who develop strabismus, double vision sometimes occurs because the brain has already been trained to receive images from both eyes and cannot ignore the image from the turned eye. Additionally in adults who have had exotropia since childhood, the brain may adapt to using a "blind-spot", whereby it receives images from both eyes, but no full image from the deviating eye, thus avoiding double vision, and in fact, increasing peripheral vision on the side of the deviating eye. According to a study published in the American Journal of Ophthalmology, over 90 percent of children with intermittent exotropia become nearsighted by the time they’re 20. Causes
The causes of exotropia are not fully understood.