Epidemiology
The overall prevalence of secondary glaucoma across China between 1990 and 2015 was reported to be 0.15%, lower than the overall estimates for East Asia (0.39%). Varying forms of secondary glaucoma
Pigmentary glaucoma has lower incidence in Black and Asian populations, due to their characteristically thicker irises that result in a lower likelihood of pigment release, as compared to the White populations. Incidence of exfoliation syndrome-caused secondary glaucoma is estimated to be approximately 10% of the glaucoma patient population in the United States and over 20% of the patient population in Iceland and Finland.In populations above the age of 40, neovascular glaucoma has a prevalence of 0.4% worldwide. The incidence of pigmentary glaucoma decreases with age while in exfoliation syndrome the incidence increases with age. However, given the derived nature of secondary glaucoma, there may be no significant association between age, ethnicity or gender and the prevalence of the condition.Secondary glaucoma indicated after congenital cataract surgery is found between 6 and 24% of the cases noted, whereas, secondary glaucoma caused by primary IOL implantation was observed as 9.5%. Additionally, for patients with aphakia and secondary IOL implantation, 15.1% of the cases were determined. The incidence risk in primary IOL implantation in children with cataract in both eyes is lower than secondary IOL implantation and aphakic condition. However, this difference is not observed in the general population and populations with cataract in one eye.Due to lack of concrete and specific epidemiological evidence, further research is required to accurately estimate the prevalence of secondary glaucoma and its subtypes.
Erythropoietic protoporphyria (EPP) has similar symptoms as X-linked dominant erythropoietic protoporphyria but the mutation occurs as a loss-of-function in the FECH (ferrochelatase) enzyme; the very last enzyme in the pathway. All individuals studied presented symptoms without mutations in the FECH enzyme. The patterns of inheritance led the researchers to conclude the mutation must come from an enzyme on the X-chromosome with ALAS2 being the most likely candidate. X-linked dominant erythropoietic protoporphyria is distinct from EPP in that there is no overload of Fe2+ ions. Additionally, unlike the other condition the arises out of a mutation of the ALAS2 gene, there is no anaemia. XDEPP is characterized by a buildup of protoporphyrin IX caused by in increased level of function in the ALAS2 enzyme. Because there is a buildup of protoporphyrin IX with no malfunction of the FECH enzyme, all the available Fe2+ is used in the production of heme, causing the FECH enzyme to use Zn2+ in its place,  causing a buildup of zinc-protoporphyrin IX. Diagnosis
See also
Hepatic porphyria

References


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