Medical Care
Management is dependent largely on the mechanism of the glaucoma. In both aphakic/pseudophakic pupillary block, the initial treatment is mydriasis. This is used to either break the block or enlarge the pupil beyond the edges of the AC IOL. Temporizing measures include aqueous suppressants and hyperosmotics. Miotics can help in the long-term management after the acute phase. Epinephrine is avoided because of the risk of macular edema. Ultimately, iridotomy usually is needed in both cases. In aphakia, the iridotomy must be placed over a pocket of aqueous behind the iris, and this may require multiple attempts. Other options include trabeculoplasty, cyclophotocoagulation, and pars plana vitrectomy.
Preoperatively, the use of external pressure reducers to maintain AC depth and to minimize potential complications (eg, vitreous loss, expulsive hemorrhage) may be considered. However, potential adverse effects of optic nerve atrophy or arterial occlusion must be considered. Careful use of epinephrine in local anesthetic may help to preserve perfusion to the optic nerve.
Judicious use of a viscoelastic substance may help to control a postoperative rise in IOP, whereas carbachol and acetylcholine have both been shown to decrease IOP postoperatively. Notably, carbachol was associated with decreased IOP at 24 hours, 2 days, and 3 days postoperatively. Further, the choice of IOL may influence the postoperative course.
Although dictated by the clinical scenario, one may remember the increased incidence of glaucoma with the early generation AC IOL and iris-fixation lens as compared to the PC IOL. Special attention must be devoted to patients with complicating factors (eg, corneal endothelial cell loss, fibrous endothelial metaplasia, angle cicatrization). A decrease in intraoperative trauma and complications would allow the surgeon increased flexibility in the choice of IOL.
Further, Bomer found a correlation between the surgeon's experience and the rise in postoperative IOP. [10] Increased IOP has been noted within 6-7 hours postoperatively and usually returns to normal in 1 week. A modest increase in the IOP poses minimal threat in the nonglaucomatous eye; but, if clinically warranted, beta-blockers, acetazolamide, and apraclonidine have been shown to be of benefit. Of these, apraclonidine is more effective if given 1 hour preoperatively. Further, pilocarpine gel also was shown to be effective, although attention must be paid to inflammation.
Surgical Care
Both argon and Nd:YAG lasers can be used in pupillary block and help to distinguish it from aqueous misdirection. Argon laser trabeculoplasty benefit both pseudophakic and aphakic populations, and it may delay the need for surgical intervention by 18 months, although 36-month follow-up examinations were not encouraging.
Iridoplasty is used to alter the peripheral iris morphology when iridotomy cannot be performed. For instance, shrinking the peripheral iris deepens the AC in iridocorneal touch. The posterior capsule needs to be broken to establish communication between the retrocapsular space and the AC. This technique is helpful in retrocapsular pupillary block or anterior aqueous misdirection.
Posterior aqueous misdirection involves deposition of aqueous fluid in the vitreous cavity and is relieved with vitreolysis using Nd:YAG laser. Cyclodestructive therapy using laser (argon and Nd:YAG) or ultrasound has been described. Generally reserved for patients who have failed other therapies, cyclodestructive therapy is performed using transpupillary, endophotocoagulation, and transscleral approaches. Noureddin compared Nd:YAG cyclocoagulation to filtering procedures and showed that, although both reduced IOP significantly, fewer medications were needed postoperatively in the filtering procedure group. [11] Rekas et al have reported that pars plana vitrectomy can be used to successfully treat malignant glaucoma by creating a pathway between the vitreous cavity and the anterior chamber. [12] Madgula and Anand showed that, using an anterior approach, peripheral iridotomy combined with hyaloido-zonulectomy and anterior vitrectomy can be used to treat malignant glaucoma that is refractory to medical treatment. [13]
Incisional approaches include filtering procedures and drainage implant devices. Filtering procedures are divided into full-thickness and partial-thickness procedures. Although the full-thickness approach is theoretically superior, study data have ranged from no difference in IOP control to higher complication rates when compared to partial-thickness approaches even when using 5-FU. Shields, on the other hand, notes that trabeculectomy has been associated with increased efficacy and safety. [8, 14, 15] Trabeculectomy, while it can still be successful in pseudophakic eyes, seems to be less effective in pseudophakic eyes than in phakic eyes, according to Takihara et al. [16]
However, aphakic eyes are associated with an increased incidence of complications and lower efficacy than phakic eyes. Dao et al have reported some success in treating aphakic eyes with glaucoma by performing a 360° trabeculectomy facilitated with use of an illuminated microcatheter. [17] Nonpenetrating trabeculectomy (viscocanalostomy) has gained popularity, but no data are available comparing aphakic/phakic/pseudophakic populations.
Artificial drainage implants are divided into valved and nonvalved types. These are especially useful when the likelihood of success from filtering procedures is low. Shields reports a 70% success rate with aphakic and pseudophakic populations with a decline to 50% over 5 years, which is consistent with other reported values. [8] Eslami et al report that ciliary sulcus placement of the Ahmed glaucoma valve into the ciliary sulcus effectively lowers IOP, reduces medication use, and has the potential to lower corneal complications in pseudophakic and aphakic eyes. [18] Rabkin-Mainer et al found that the Ahmed glaucoma valve yielded a higher initial success rate (~93%) than the Ex-PRESS shunt (~66%); the Ahmed valve also had a lower reoperation rate (~5%) than the Ex-PRESS shunt (~30%). [19]
Microinvasive glaucoma surgery (MIGS) has become increasingly popular because of the presumed shorter surgical time, less involved postoperative course, and lower level of complications compared with other surgical methods. Various MIGS procedures include iStent Trabecular Micro-Bypass Device, Hydrus Microstent, Xen Implant, CyPass Micro-Stent, and ab-interno trabeculectomy with the Kahook Dual Blade.
According to the FDA, the CyPass Micro-Stent was removed from the market in August 2018 owing to "concerns regarding significant endothelial cell loss and reductions in endothelial cell density." [20]
The COMPARE study found that the Hydrus yielded a higher success rate than the 2-iStent procedure, and both devices had similar safety profiles. [21]
Prevention
Careful surgical technique is indicated to prevent this type of glaucoma.
Long-Term Monitoring
Patients should continue follow-up care until IOP is controlled.
