Normal External Anatomy
of the Left Eye
Understanding
Glaucoma
Carunculum
Glaucoma is a group of eye diseases that usually
steals sight without warning and often without
symptoms. It is a condition in which normal fluid
pressure inside the eyes (intraocular pressure, or
IOP) slowly raises when the aqueous humor which
normally flows in and out of the eye cannot drain
properly. Instead, the fluid collects and causes
pressure damage to the optic nerve (a bundle of more
than 1 million nerve fibers that connect the retina
with the brain) with subsequent loss of vision. There
are two major subtypes of glaucoma based on the
eye’s anatomy: Open Angle and Narrow Angle.
Lacrimal
puncta
Pupil
Iris
Sclera
Open Angle Glaucoma
Canal of Schlemm
(drainage canal)
Aqueous flow
Narrow Angle Glaucoma
Aqueous flow
Canal of Schlemm
(drainage canal)
Iris
Trabecular
meshwork
Iris
Trabecular
meshwork
Lens
Lens
Ciliary process
Ciliary process
Open angle glaucoma is the most common form of glaucoma. The most likely
site of disease is a malfunction of the trabecular meshwork which works
more poorly over time. The site of obstruction is the trabecular meshwork that
covers the entrance to the aqueous humor channels (Canal of Schlemm)
which drain the fluid from the eye.
Narrow angle glaucoma, is less common and different from open angle
glaucoma. Eye pressure usually goes up very fast. This happens when the
drainage canal gets blocked or covered. The angle between the iris and the
cornea is not as wide and open as it should be. Outer edges of the iris bunch up
over the drainage canal when the pupil enlarges too much or too quickly.
Optic Disk
Sagittal View of the Eye
Canal of Schlemm
(drainage canal)
Normal
Optic Nerve
Advanced Glaucoma
Optic Nerve
Retina
Cornea
Vitreous
humor
Iris
Pupil
Lens
Optic disk
Anterior
chamber
(aqueous fluid)
Ciliary process
Vitreous body
Inferior rectus muscle
Optic nerve
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