What are the key findings of a posterior staphyloma?
Bulge on the posterior side of the eyeball + thinning of the sclera
Why is this not a coloboma?
A coloboma is a focal discontinuity of one of the structures of the eye (iris, retina, choroid, or optic disc) with possible vitreous herniation. This defect is normally present from birth. A staphyloma is caused by thinning of the outer layer of the eye.
What causes a staphyloma?
A weakening of the outer layer (sclera) of the eye due to degenerative or inflammatry conditions. It is often related to axial myopia in which the eye shows elongation in the anteroposterior axis. Other conditions in which a staphyloma may be seen include glaucoma, trauma, scleritis, and necrotizing infections.
The left eye has a greater diameter (30 mm) in comparison to the right eye (26 mm). The enlargement is more pronounced in the anteroposterior axis.
In addition, there is uveoscleral thinning on the posterior side of the left eye.
The optic nerve and extraocular muscles are symmetric and have a normal thickness.
There are no intracranial or bony abnormalities.