Controlled anterior chamber paracentesis effective for acute angle-closure glaucoma
After this procedure, laser peripheral iridotomy can be performed.
by Miguel Thomas S. Sarabia, MD
Acute angle-closure glaucoma is a common eye emergency, especially in Asia. The literature now rates it as the most common form of glaucoma worldwide.
In its acute phase, the patient classically presents with an angry, painful eye; a fixed, mid-dilated pupil; vision of 20/200 or less; an edematous cornea; and eye pressure of about 50 mm Hg to 70 mm Hg by applanation. Classic management would be to administer anti-diuretics by mouth, dehydrating agents by IV and topical anti-glaucoma medication such as timolol and pilocarpine in an effort to lower IOP, constrict the pupil and clear up the cornea for laser peripheral iridotomy.
Unfortunately, these measures do not work all the time. In many cases, the pupil remains mid-dilated after 24 hours and the cornea remains cloudy, with pressures still in the range of 30 mm Hg to 40 mm Hg. This is not an ideal case to do laser peripheral iridotomy. Essentially, the angle remains closed even if you succeed in punching a hole in the exposed iris. The patient ends up in the operating room for a trabeculectomy.
In the last 2 years, our clinic has applied a new protocol for acute angle-closure glaucoma patients. We divided the patients into three subgroups: fresh cases, in which the attack occurred within 24 to 48 hours; cases that are about 1 week old; and cases that are 2 weeks old or longer.
For the first two subgroups, we do controlled anterior chamber paracentesis in the outpatient department as a slit lamp procedure. We have found that several objectives are achieved almost instantaneously with this technique:
- IOP drops to about 5 mm Hg after the procedure is done. Much optic nerve damage is avoided from prolonged high IOP.
- The pupil constricts well enough to break the attack.
- The cornea clears enough that vision returns to 20/30 from 20/400 or worse.
- Laser peripheral iridotomy can be done within 1 hour, without the usual medications.
For the third subgroup, we apply the classic medical treatment. If the iris constricts, we do laser peripheral iridotomy, and if it does not, we do a trabeculectomy.
The patient should be given oral acetazolamide, 250 mg, two tabs by mouth. If there is vomiting, this step can be skipped. The patient should be lying down with his head flat and then receives four drops of tobramycin and four drops of pilocarpine 2% every 5 minutes. Afterward, the patient should sit at the slit lamp, with the beam focused on the anterior chamber and peripheral cornea.
Two drops of sterile Betadine (povidone iodine, Purdue Pharma) should be applied from the prep set, and then three drops of sterile Alcaine (proparacaine, Alcon) should be applied. The surgeon then applies a light wire speculum. In some cases, this is not necessary.
The surgeon carefully stabs into the anterior chamber with a 26-gauge needle with the plunger removed, at the 9 o’clock position for the right eye and the 3 o’clock position for the left eye, passing through the clear cornea. Removing the plunger from the syringe will allow aqueous to flow into the syringe spontaneously. Aspirate out 0.5 cc of aqueous or until the iris moves forward and simultaneously constricts. Be careful to avoid hitting the lens.
The speculum is removed, and one tobramycin drop is applied every 5 minutes for four doses. After 10 minutes, IOP and visual acuity should be rechecked.
We have applied this protocol on 18 female patients ranging in age from 48 to 67 years.
Mean pretreatment IOP was 71 mm Hg, and mean pretreatment visual acuity was 20/200. Mean postop IOP after 10 minutes was 7.5 mm Hg, and mean visual acuity after 5 minutes was 20/30.
We sent the patients home with acetazolamide 250 mg by mouth three times daily and one pilocarpine 2% drop every 6 hours.
Mean IOP after 24 hours was 16.5 mm Hg. Seven patients received laser peripheral iridotomy the next day. Mean IOP 24 hours after laser peripheral iridotomy was 17 mm Hg. We have monitored IOP in seven patients for approximately 15 months, and it is still steady at 17 mm Hg to 18 mm Hg without any medication. Four patients who did not receive laser peripheral iridotomy were kept on pilocarpine 2% twice daily and maintained IOP below 20 mm Hg.
- Miguel Tomas S. Sarabia, MD, can be reached at the Tony Chan Memorial Eye Center, Bacolod City, Philippines; e-mail: email@example.com.