The vitreous membrane (or hyaloid membrane or vitreous cortex) is a layer of collagen separating the vitreous humour from the rest of the eye. At least two parts have been identified anatomically. The posterior hyaloid membrane separates the rear of the vitreous from the retina. It is a false anatomical membrane. The anterior hyaloid membrane separates the front of the vitreous from the lens. Bernal et al. describe it "as a delicate structure in the form of a thin layer that runs from the pars plana to the posterior lens, where it shares its attachment with the posterior zonule via Weigerts ligament, also known as Eggers line". References
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If there are attacks more than approximately 3 times per year or severe attacks, surgical excision of the affected gland should be considered. Epidemiology
Sialadenitis of the parotid gland accounts for a much larger percentage of hospital admissions than sialadenitis of the submandibular gland. Submandibular sialadenitis has been said to only account for 10% of all cases diagnosed as sialadenitis. Chronic sialadenitis has been classified as a relatively common presentation, whereas bacterial sialadenitis and sclerosing polycystic sialadenitis are defined as rare. Chronic sclerosing sialadenitis has been shown to affect predominantly males who are over the age of 50, with 40% of cases having an allergic disease, such as chronic sinusitis or bronchial asthma.One study found that 112 patients from England and Wales ranging from 12 to 81 years of age complained of symptoms from their diagnosed sialadenitis, with the group having a mean age of 39 and a standard deviation of 16 years. The study also found that more patients underwent surgery to treat their sialadenitis between the ages of 20 and 69 years but that there were many more patients who complained of symptoms between the ages of 20 and 49, and then went on to be diagnosed with sialadenitis. In each group studied, most patients suffered from sialadenitis in their twenties but there was also found to be a significant number of females whose symptoms started in their thirties and forties.