This article is more than 5 years old. Information may no longer be current.
Treating Glaucoma with Professor Por-Tying Hung
Click Here to Manage Email Alerts
What is your medical regimen for dealing with an acute angle closure attack? Do you ever perform paracentesis?
Dr. Hung: I learned to perform anterior chamber paracentesis in the 1970s by beveling a wheeler knife through the cornea to let fluid drain slowly. With the medications currently available, performing paracentesis is rarely necessary now.
The principle behind my response to an acute angle closure attack is to set a target time for all medications to reach the most effective hypotensive time zone simultaneously, and to perform laser iridectomy at that point. I use oral carbonic anhydrase inhibitors, intravenous osmotic agents, and a few drops of weak pilocarpine for thinning of the iris and miosis only. Beta-blockers are also an option, but one should avoid prostaglandins. A sedative is very important to calm the patient, and sleep is useful sometimes.
In the case of non-pupillary block mechanism, I find it helpful to add 5 to 10 shots of argon laser iridoplasty soon after the iridectomy.
Do drugs such as prostaglandins have a role in chronic angle closure?
Dr. Hung: My colleagues and I first reported in early 2002 that prostaglandins work well for managing chronic angle closure glaucoma after an iridectomy.1 Their use is probably off-label as their indication is for open-angle glaucoma. The exact mechanism of action in chronic angle closure is still unclear if the angle is opened up and functioning by iridectomy already.
What do you believe is the role for lens extraction in chronic angle closure?
Dr. Hung: In 1982 in his textbook for secondary glaucoma, Robert Ritch proposed that primary angle-closure glaucoma may be considered secondary glaucoma from the lens.2 With the expansion of our glaucoma knowledge, “primary” seems arbitrary and artificial today. In angle-closure glaucoma, even the pupillary block mechanism is under challenge.3
Understanding that glaucoma is a multifactorial disease, I would recommend lens extraction on a case-by-case basis depending on the condition of the patient’s eyes and his overall health. I would also consider the facility where the procedure would be performed and the experience of the surgeon. However, I do not perform clear lens extraction in an eye with well-controlled glaucoma and good vision; I would perform extraction for established angle-closure glaucoma with poor vision from cataract.
In a case where the lens is clearly the cause of the narrow angle, with a large phacomorphic component and no cataract, I would assume this is the lens “swelling stage” of early cataract. With no other specific lesion, such as spheric lens, or high IOP, then I would wait and explain the necessity of watchful waiting to patient. However, a simple laser iridectomy or even lens extraction may be considered if necessary.
Is malignant glaucoma a risk for laser iridotomy?
Dr. Hung: After teaching residents and performing more than 500 laser iridectomies yearly for the past few decades, I consider malignant glaucoma from a laser procedure a rarity in cases of good, careful laser iridectomy, even though such events have been reported.
How do you perform gonioscopy in the office?
Dr. Hung: My tips are to also examine the disc stereoscopically through the goniolens, which is easiest when using a Goldmann lens. A Zeiss goniolens is easier and more comfortable for the patient; however, with a quick hand, I can use a Goldmann goniolens with normal saline solution instead of sticky methylcellulose solution.
What tips do you have for performing laser iridectomy?
Dr. Hung: First, with laser iridectomy, fewer laser shots are better, to reduce the total energy use for the procedure. For this purpose, a precise focus of each shot with adequate slit lamp magnification is important. Second, a third of Asian patients who undergo argon laser iridectomy will develop an IOP of more than 8 mm Hg. Careful monitoring or use of hypotensive drugs prior to or soon after the procedure is important for advanced glaucoma with disc change. And third, a skillful examination of cornea endothelial change by slit lamp should be a routine prelaser procedure to avoid possible cornea damage from the laser.
References
- Hung PT, Hsieh JW, Chen YF, Wei T. Efficacy of latanoprost as an adjunct to medical therapy for residual angle-closure glaucoma after iridectomy. J Ocul Pharmacol Ther. 2000;16:43-47.
- Ritch R, Shields MB. The Secondary Glaucomas. CV Mosby: London. 1982.
- Hung PT, Chou LH. Provocation and mechanism of angle-closure glaucoma after iridectomy. Arch Ophthalmol. 1979;97:1862-1864.