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Figure 1. This photo shows a traumatic cataract and major iris damage at the time of presentation to the patient’s left eye. The patient had experienced a globe penetrating injury years earlier in childhood from a pellet gun.
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Figure 2. This gonioscopic view shows the inferior angle of the patient’s presentation.
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Figure 3. This gonioscopic view shows the superior angle of the patient’s presentation.
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Figure 4. This image shows the patient after undergoing her first peripheral iridotomy using an argon laser.
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Figure 5. This image shows the patient after undergoing her second peripheral iridotomy using an argon laser.
A 24-year-old woman presented to the clinic for a routine eye examination and an unusual complaint. She said she experienced headaches when reading and eye pain with vision blurring in her left eye on occasion during intercourse. This began approximately 3 to 4 months earlier.
Her ocular health history was significant because of trauma to her left eye at age 8, when she experienced a penetrating injury to the left eye from a pellet gun that caused a traumatic cataract and major iris damage (Figure 1). She was otherwise in good health and took no medications. She did not wear glasses, but her refraction was +2.00 -1.00×90 for 20/20 OD and +2.50 -75×90 for 20/40 OS. She was given this prescription for help when reading.
Her right eye’s pupil was round with normal reaction, and her left eye’s inferior iris tissue was missing, with the remaining iris tissue reacting normally. A slit lamp exam, as well as gonioscopy, showed narrow but open angles in the right eye. In the left eye, gonioscopy revealed more than three quarters of the left angle was closed with iris adhesions (Figure 2). Only the superior angle had a small area of trabecular meshwork visible (Figure 3). Her intraocular pressures (IOP) were 14 mm Hg OD and 23 mm Hg OS. Ophthalmoscopy undilated, showed a normal central fundus and optic nerve in both eyes.
The presumed diagnosis was intermittent angle closure glaucoma in her left eye. She was rescheduled for conclusive testing. The patient was also scheduled for a consult with a glaucoma specialist. The patient returned for follow up in a week with...
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The presumed diagnosis was intermittent angle closure glaucoma in her left eye. She was rescheduled for conclusive testing. The patient was also scheduled for a consult with a glaucoma specialist.
The patient returned for follow up in a week with no reports of pain or blurred vision in her left eye in any situation. Her pressures at this visit were 15 mm Hg OD, 25 mm Hg OS. She was then asked to remain face down on a table in an adjacent totally dark room, for 30 minutes. When she returned to the examination room, her IOP was retaken and found to be 23 mm Hg OD and 52 mm Hg OS.
Next, as previously discussed with the glaucoma specialist, the patient slowly drank a prepared hyper-osmotic anti-glaucoma liquid medication (glycerin) over ice for a period of 10 minutes. Then, pilocarpine 2% drops were applied to her left eye.
After 1 hour, the superior area of her left iris was more constricted and her pressures had decreased to 18 mm Hg OD and 39 mm Hg OD. As had been previously discussed and arranged, she was seen the next day by the glaucoma specialist.
This is a case that involves a patient with intermittent angle closure who had most of the angle damaged, and as expected, had a narrow angle in the fellow eye. Pilocarpine, while often used in acute angle closure glaucoma, can also increase pupillary block. Pupillary block was unlikely to be an issue for this patient, as she had lost all of the inferior iris tissue in her left eye from her childhood injury. Our patient was diagnosed with chronic angle closure in her left eye, with intermittent attacks of acute angle closure. She was initially treated by a glaucoma specialist with argon laser peripheral iridotomy in the left eye and continued pilocarpine. On follow-up, the specialist enlarged the iris hole with the argon laser (Figures 4 and 5). At the time of this case, argon laser treatment was common; however, today, a YAG laser would be preferred because it is faster, less inflammatory, and does not require retreatment to enlarge the iris hole (as it often closes when iridotomy is performed with the argon laser).4 The right eye may also be a candidate for prophylactic PI because the IOP went up during provocative testing by 8 mm Hg — a significant amount.
This action of pilocarpine was discussed in a Journal of Glaucoma editorial.1 It explains a paradox associated with pilocarpine use as pupil constriction induced by pilocarpine usually leads to slight opening of a narrow angle. It also increases the axial lens thickness, and causes anterior lens movement which then results in the shallowing of the anterior chamber and provides a narrower path for fluid outflow, thus the paradoxical effect of pilocarpine on the angle.
The provocative effect of both a prone position and a dark room, combines both force from the lens and pupil dilation that closes the area for outflow, and can be as high as 90% effective in screening for angle closure glaucoma.2 Without the dark room included in the prone test, it was only 50% effective.2 The rapid pressure rise from the provocative test, causes pain and possible corneal edema depending on the pressure reached.
In general, a peripheral iridotomy (PI) alone, may not be able to prevent eventual field loss in both traumatic and nontraumatic narrow angle glaucoma.3 In some traumatic cases, a surgical iridectomy or a trabeculectomy (bleb) is needed. Again, this case occurred many years ago, when peripheral iridotomies were performed with argon lasers instead of YAG lasers.
PI is a reasonable first approach, when followed by a trabeculectomy (bleb), if needed. Trabeculectomy is a much older surgery, and has an excellent IOP-lowering potential, but we know it has a significant long-term risk of complications than can go off like a time bomb — even years later.5
Today, with nontraumatic or traumatic angle closure glaucoma, after the PI is successful, pilocarpine is out of favor unless the patient has plateau iris syndrome, as we have other drops that can lower the pressure without causing the pupil block and other issues associated with pilocarpine.1
Current popular topical drug options that reduce the production of aqueous humor include beta blockers, carbonic anhydrase inhibitors, and alpha-adrenergic agents that decrease the production of aqueous humor and increase the drainage of fluid from the anterior chamber.
References
1. Ritch R. The pilocarpine paradox. J Glaucoma. 1996;5(4):225-7.
2. Harris LS, Galin MA. Prone provocative testing for narrow angle glaucoma. Arch Ophthalmol. 1972;87(5):493-496. doi:10.1001/archophth.1972.0100002049500
3. Le JT, Rouse B, Gazzard G. Iridotomy to slow progression of visual field loss in angle-closure glaucoma. Cochrane Database Syst Rev. 2018;6(6):CDO12270. doi:1010.1002/14651858.CDO12270.pub2
4. Robin AL, Pollack IP. A comparison of neodymium: YAG and argon laser iridotomies. Ophthalmol. 1984;91(9):1011-101. doi:10.1016/s0161-6420(84)34199-9
5. Parrish R, Minckler D. “Late endophthalmitis”— filtering surgery time bomb? Ophthalmol. 1996;103(8):1167-1168. doi:10.1016/s0161-6420(96)30527-7
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