When this angle is narrowed or closed, pressure increases over time, causing damage to the optic nerve and leading to blindness. Primary open-angle glaucoma (also called primary or chronic glaucoma) involves the slow clogging of drainage canals resulting in increased eye pressure, which causes progressive optic nerve damage. This manifests as a gradual loss of the visual field, starting with a loss of peripheral vision, but eventually all vision will be lost if the condition is not treated. This is the most common type of glaucoma, accounting for 90% of cases in the United States, but is less prevalent in Asian countries. Onset is slow and painless, and loss of vision is gradual and irreversible. With narrow-angle glaucoma (also called closed-angle glaucoma), the iris bows forward, narrowing the angle that drains the eye, increasing pressure within the eye. If untreated, it can lead to the medical emergency of angle-closure glaucoma. With angle-closure glaucoma (also called closed-angle, primary angle-closure or acute glaucoma), the iris bows forward and causes physical contact between the iris and trabecular meshwork, which blocks the outflow of aqueous humor from within the eye. This contact may gradually damage the draining function of the meshwork until it fails to keep pace with aqueous production, and the intraocular pressure rises. The onset of symptoms is sudden and causes pain and other noticeable symptoms, and the condition is treated as a medical emergency. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the closing of the angle between the iris and cornea.
This makes the sperm completely unable to penetrate the zona pellucida. The sperm in Type 2 globozoospermia has some acrosomal covering surrounded by large droplets of cytoplasmic material, suggesting secondary degenerative changes. There is also a conical nucleus. It is thought that infertility in this type of globozoospermia is due to incorrect chromatin packaging which prevents proper fertilization. Symptoms
Aside from the effect on fertility globozoospermia is symptomless. People with globozoospermia have normal physical and mental development, normal clinical features and normal hormonal profile. Genetics
Table 1: Gene mutations that have been identified in globozoospermia and the impact these mutations have on sperm function and successful fertilization. Diagnosis
The presence of round headed sperm in a semen analysis sample confirms the diagnosis of globozoospermia. The lack of acrosome can be ascertained by either morphology staining or immunofluorescence. Treatment
Until 1995, the only options for people with globozoospermia who wished to conceive were adoption or sperm donation. With the advancement of assisted reproductive techniques (ART) it is now possible for those with globozoospermia to conceive using their own sperm. The main technique used is intracytoplasmic sperm injection (ICSI) where fertilisation is achieved by a single sperm being injected into the egg. Some studies have shown it is possible for a viable embryo to be created with this technique alone, however others have found it necessary to also use calcium ionophore treatment for fertilisation to be successful. Calcium ionophore treatment is used to artificially activate the oocyte.