Although very, very rare, pupillary block is a specific type of angle closure glaucoma that can be caused by DMEK surgery
How can DMEK surgery cause pupillary block? The eye continually produces a fluid called aqueous humor in the posterior chamber of the eye (the large round chamber behind the lens of the eye in which is located the retina and optic nerve). This fluid, the aqueous humor, then flows around the outer edge of the lens of the eye and under the iris before flowing through the pupil into the anterior chamber of the eye (the narrow space between the back of the cornea and front of the lens where the iris rests). Normally the aqueous humor then drains from the anterior chamber and the eye itself through a trabecular meshwork of tiny channels located in the narrow angle where the front of the iris joins the back of the cornea.
When a large air or gas bubble is placed in the anterior chamber during DMEK surgery it can cause the iris to be pushed back against the lens of the eye (either the natural lens or an intraocular lens), sealing the iris against the lens and preventing aqueous humor being produced in the posterior chamber from being able to flow into the anterior chamber as described above. In the absence of a functioning iridotomy (one that is open, not blocked, and is sufficiently large) intraocular pressure can spike in the posterior chamber and push the peripheral edge of the iris into the angle where the iris meets the back of the cornea thereby blocking this angle where the trabecular meshwork of tiny channels is located.
When this angle is blocked because the central part of the iris has been pushed back and sealed against the lens of the eye it is called pupillary block angle closure glaucoma. Unless the cause of the pupillary block is treated quickly and aqueous humor flow is restored, the aqueous humor will just keep building up in the posterior chamber until the intraocular pressure is so elevated that there is risk of permanent damage to the eye. Examples of damage that can occur are a permanently dilated pupil or optic nerve damage.
Please be aware that some DMEK surgeons do not routinely do an iridotomy; they prefer to perform one only if there is a spike in intraocular pressure that causes pupillary block AND reducing the air/gas bubble does not eliminate the pupillary block.
SYMPTOMS OF PUPILLARY BLOCK: eye feels full or swollen or hard, turns red, vision deteriorates and patient experiences nausea and vomiting. URGENT TREATMENT IS REQUIRED to prevent permanent damage to the iris/pupil, the optic nerve and other features of the eye.
Two sources especially helpful in the preparation of this explanation are:
DMEK Triple May 2014 right eye
DMEK Triple August 2014 left eye
Dr. Francis Price, Indianapolis, Indiana
Follow up by Dr. Alan Kozarsky, Atlanta, Georgia
Mentor, Fuchs' Friends