Pupillary Block Causes
1- Posterior Synechia
In which there will be membrane adhesion between the pupillary margin of the iris and the lens. Formation of these membranes occurs after inflammation in the anterior chamber like in chronic uveitis.
Treatment of this condition is with medications early and surgical release of these synechia lately.
- Steroid to reduce inflammation.
- Cyclopentolate or atropine eye drops to dilute the pupil and release of these adhesions.
Elevation in intraocular pressure in this case can be treated with medications such as Timolo Eye Drops.
Sometimes when these adhesions can not be released, we can do iris iridectomy, which is a hole in the iris that communicates between the anterior and the posterior chamber to bypass the block at the pupillary margin.
2- In Pseudophakic Patient
Pseudophakia means removal of natural lens and replace it with anterior chamber or posterior chamber intraocular lens.
Pupillary block causes in pseudophakic patients are either anterior chamber lens or posterior synechia. The anterior chamber I.O.L will be inserted infront of the iris and so it will cover the pupil which can block the flow of aqueous humor.
That is why all cases with anterior chamber I.O.L should have peripheral iridectomy to prevent pupillary block. Posterior chamber I.O.L can cause pupillary block in case of inflammation that occur either post-cataract surgery with formation of posterior synechia or with chronic intra-ocular inflammation or uveitis.
3- Aphakic Patient
With cataract surgery there will be complete extraction of cataract and without Intraocular lens insertion. Either the posterior capsule still intact with no vitreous out in the anterior chamber or the posterior capsule is ruptured with vitreous in the anterior chamber.
Pupillary block causes in aphakic patient will be vitreous in the anterior chamber or vitreous pushing the posterior capsule forward with pupillary blocking.
In case posterior capsule rupture, the vitreous will be in the anterior chamber and block the pupil with pupillary block and High I.O.P. To treat this condition, the surgeon should undergo anterior vitrectomy with iris iridectomy.
In case of intact posterior capsule, the vitreous will push out the capsule anteriorly through the pupil with blockage of the pupil. Treatment of this condition should be with iris iridectomy or with the insertion of posterior I.O.L
4- After Posterior Vitrectomy
Sometimes after posterior vitrectomy with silicon oil injection in the posterior segment, in which silicon oil will push out the intact posterior capsule, posterior I.O.L or even the natural lens through the pupil with pupillary block formation.
Sometimes in case that the posterior capsule is ruptured, the silicon oil can pass to the anterior chamber with raise in the I.O.P. treatment of these conditions with silicon oil is with iris iridectomy.
Usually the position of iris iridectomy is superiorly but in case the silicon oil in the anterior chamber, this iris iridectomy should be done inferiorly.
5- Natural Lens
Natural lens can cause pupillary block in two ways, first the lens becomes large enough to block the pupil margin and this type of glaucoma is called phacomorphic glaucoma.
The second way is the anterior dislocation of the lens through the pupil with pupillary block. Treatment of this condition is with cataract extraction.