Rarely, acute attacks persist despite a patent iridotomy, nearly always necessitating surgery for cataract extraction and/or filtration.70

Argon and Nd:YAG iridotomies have virtually replaced surgi-

cal iridectomy as the preferred technique for performing iridec- tomy.245–251 The term iridotomy is used to indicate laser-induced

openings in the iris, whereas iridectomy indicates surgical removal of iris tissue. Although surgical iridectomy is a relatively safe and simple procedure, it is invasive and presents a small but still present risk of intraocular complications such as cataract, bleeding, and endophthalmitis. Surgical iridectomy is now reserved for such infrequent situations such as: the laser fails to produce a patent iridotomy; laser iridotomies repeatedly close; a laser is neither available nor functioning properly; opacities of the cornea interfere with laser treat-

ment; or the patient is uncooperative or unable to sit at the slit lamp.194,252–256 Often if the eye comes to filtration, an additional

surgical iridectomy may be advisable.

Argon laser iridotomies, in contrast to those performed with a Nd:YAG laser, may close at a later date, subjecting the eye to redevelopment of angle closure.257 Closure of laser iridotomies is usually by regrowth of iris pigment epithelium.258 Fleck257 has calculated that a 15- m opening is theoretically large enough to prevent pupillary block; however, localized iris edema, pigment epithelial proliferation, and changes in iridotomy size after pupil dilation may obstruct a small opening.Therefore it is recommended that an iridotomy between 150 and 200  m should be created.

If an acute attack can be terminated by medical means, the physician can proceed directly to laser iridotomy, or wait 1–2 days for the cornea to clear and intraocular inflammation to subside. The physician must observe the IOP and the patient carefully to ensure that a repeat attack does not occur.

Laser iridoplasty (gonioplasty) and pupilloplasty  As mentioned above and addressed in Chapter 31, other argon laser interventions have their role in the management of acute PACG. The peripheral iridoplasty (also referred to as gonioplasty) is a viable treatment in three settings: (1) acute PACG from pupillary block, unresponsive to medical treatment, and where a perforating laser iridotomy is precluded by excessive shallowing of the anterior chamber, inflammation or corneal edema; (2) plateau iris syndrome; and (3) acute phacomorphic angle closure. Though easiest to perform in areas

free of PAS, iridoplasty is remarkably effective in the management of acute angle closure, with either 180° or 360° of treatment.259,260

This technique has proven to be as effective as intensive medical therapy with pilocarpine, timolol, and acetazolamide.241

The role of iridoplasty in managing angle-closure disease caused by plateau iris is discussed more fully below. In brief, by itself it

is effective in opening the angle, sometimes for the long term; when combined with, or after,261–264 a laser iridotomy, it may well

serve as an effective treatment for this condition.265 As mentioned, pupilloplasty refers to laser techniques which can interrupt pupillary block by distorting the pupil into a tear-shaped configuration, focally interrupting decreased flow through the iris–lenticular junction, thus facilitating aqueous egress into the anterior chamber. Both techniques are important components of the laser armamentarium in managing acute angle-closure disease.

Surgical management of PACG

There are slightly different considerations for surgical intervention for the acute and the long-term manifestations of PACG. If IOP elevation persists despite a patent laser iridotomy in acute disease and subsequent medical therapy, there are several compelling surgical options that have been proffered, but not yet universally

embraced: filtering surgery alone; lens extraction alone, with or without goniosynechialysis; combined lens extraction with trabeculectomy; or goniosynechialysis alone.266–268 Often pressure reduction is the primary focus in this context, with surgery often made challenging by persistently elevated IOPs, diminished corneal clarity, shallow anterior chamber, and inflammation accompanying the acute crisis. Surgical goals for chronic PACG are comparable to the considerations for operating in eyes with uncontrolled POAG: long-term IOP reduction towards a target range, stabilization of progressive disc and/or visual field deterioration, and addressing the juxtaposition of cataractous visual loss in conjunction with the need for glaucoma surgery. However, most of these procedures have not been evaluated for PACG in a randomized controlled fashion with different populations, and the literature must be approached with caution.

Trabeculectomy with and without antimetabolite seem to be equally valid approaches.269–271 One major center in the study of

PACG reported a significantly higher rate of trabeculectomy failure (over one-third of cases) and complications in medically uncontrolled PACG eyes than in eyes which were medically controlled, suggesting that filtration surgery may not be the ‘procedure of choice’ in such circumstances.272 Neverthless, acute PACG eyes in

both Asia and the US require filtering surgery between one-third and one-half of the time.273

Because of the causative role of a large, anteriorly located lens in pupillary block,174 lens removal and intraocular lens (IOL) implantation is an attractive primary surgical approach: it offers the patient the likelihood of improved vision, and it is a technique that is familiar to many more surgeons throughout the world than is trabeculectomy.Although it has been recommended as a primary intervention274 and appears capable of restoring angle anatomy to a more normal configuration,275 it nevertheless can be a daunting operative procedure in the semi-acute setting, confronting the surgeon with such challenges as a shallow anterior chamber, a convex lens prone to anterior capsular tears, and a flacid iris from ischemic damage.268 A particularly exciting and well-controlled study found phacoemulsification/IOL surgery to be comparable to, and in fact more advantageous than, laser iridotomy in the management of acute PACG.223 The applicability of this approach among different populations and its long-term safety and efficacy in the hands of surgeons with various techniques and skill levels remain to be clarified.

The combination procedures of cataract with filtration surgery,276 or cataract with glaucoma shunt have also been described in the contect of PACG management.277 But in the absence of data as to the advantages or disadvantages of a one-stage combined versus twostage procedure for coexistent uncontrolled acute PACG with cataract, the decision as to which approach to follow remains subjective.

Goniosynechialyis refers to the deliberate intra-operative shearing

or peeling of synechial adhesions in the angle, either mechanically or with a viscoelastic dissection, for at least 180°.266,267 Originally

proposed by Campbell and Vela as an intervention appropriate for

eyes with PAS documented to be less than a year old, it has since been used in conjunction with cataract surgery.278,279 The proce-

dure’s duration of effectiveness is, however, unclear, with UBM studies documenting only a short-term effect of opening the angle.280

Management of the fellow eye

Fellow eyes of an eye presenting with acute PACG require a laser iridotomy. Implicit in the three-stage classification of PAC disease is the clinical reality that many eyes steadily progress through the natural history of the condition, unless that course is interrupted. Although it appears there is considerable ethnic variation among

the rates of disease progression – with Caucasian eyes showing slow

conversion to complete angle closure, sometimes after more than 25 or 30 years,192,281–288 in contrast to Mongolian and Chinese eyes

suffering rapid development of disease289 – it is important to consider a presenting eye in terms of its stage-specific manifestations.

Eyes identified in the early stages of either demonstrating iridotrabecular touch without elevated IOPs (PAC suspects), are less likely than eyes with elevated IOPs and/or PAS yet normal discs and fields (PAC), to benefit from early laser iridotomies.227 But, as discussed above, we still await long-term controlled studies of specific populations to determine how tight the criteria for angle embarrassment needs to be to obtain maximum benefit from early iridotomies with an acceptably low rate of complications. Elevated IOP is of course seen more commonly in eyes the greater the PAS. However, increased IOP is also found in eyes without synechiae, suggesting that transient apposition between the iris and trabecular meshwork can chronically damage the outflow channels, as histologically demonstrated by Sihota and colleagues.45 Again the clinical conclusion is the necessity of vigorous surveillance, with periodic gonioscopic, disc, and field assessments.

In contrast, at the other end of the disease spectrum are PACG eyes with demonstrable glaucomatous damage to the disc and field, which by and large require laser iridotomy to eliminate the component of pupillary block; yet such an intervention is not always sufficient to completely manage the glaucomatous process, especially in Asian populations.149 Whether early phacoemulsification/IOL surgery is a viable alternative to laser iridotomy for managing the eye with glaucomatous damage has not been completely determined.

As emphasized previously, miotics alone are not considered an appropriate prophylactic measure to forestall PAC progression, since they don’t reliably prevent, and may in fact precipitate, acute attacks. Their chronic administration may exacerbate the development of PAS, cataracts, and conjunctival changes detrimental to successful filtration surgery. Similarly, there is no evidence to support the reliability of provocative tests in predicting which eyes are at risk of progression or need intervention.

Sequelae of acute PACG

In the early post-iridotomy period, elevated IOP may occur as a result of release of pigment and other debris, incomplete or sealed iridotomy, unrecognized plateau iris syndrome, inflammation, extensive PAS, or corticosteroid administration.290,291 Elevated IOP can also occur months to years later and has been reported

in 24–72% of eyes following surgical iridectomy for angle-closure glaucoma.194,247,249,252–255 Though these older studies lack the con-

sistent criteria now in use for staging PAC disease, their findings reflect the need for vigorous surveillance. Patients must be explicitly warned of the need for lifelong care even when iridotomy has apparently ‘cured’ their acute glaucoma.

In Chinese patients, over 50% of eyes with acute PACG after iridotomy develop elevated IOPs, most within 6 months.48 Furthermore, as many as 17% of such patients become blind in an eye with an acute attack within 6 or so years; therefore, close monitoring is mandatory, even with successful breaking of the attack and after iridotomy.149 It is commonplace to recognize that once optic nerve damage can be demonstrated after an acute attack – i.e., PACG is manifest – iridotomy won’t sufficiently control pressure, and supplemental medical therapy or surgery is required.47

The treatment of the PACG after iridotomy is similar to that for open-angle glaucoma, with a stepwise escalation of medical therapy and filtering surgery as needed, but with more frequent gonioscopy.

Some researchers have reported that synechial closure may be alleviated by argon laser iridoplasty (gonioplasty), enhancing visuali-

zation of the trabecular meshwork and giving access to perform trabeculoplasty if needed.262–264 However, its long-term effective-

ness for pressure control has not yet been established, with synechiae often reappearing over time.

While typical glaucomatous visual field loss following an acute attack of PACG occurs in the minority of eyes (about 40%), nerve

fiber layer loss can be demonstrated in most patients whose attack’s duration was longer than 48 hours.292–294 The severity of visual

field loss is directly correlated with the level of IOP during the attack.295 The characteristics of field loss after an acute attack vary in different accounts: some report a predilection for broad arcuate damage;296 others note generalized perimetric defects;297 and yet others remark on the vulnerability of the nasal field.298

The development of visually significant cataract is a relatively common occurrence following acute-angle attacks (nearly all of whom were treated with iridotomies), reported in nearly a third of such eyes.149 Cataract rates after surgical iridectomies were even higher.53 The distinction between cause and effect, however, is unclear. Large, cataractous lenses are often a contributor to pupillary block, so many patients already have some lens opacity when the attack occurs. Most investigators believe that surgical iridectomy accelerates the development of lens changes. Although argon laser can produce localized lens changes, no data exist yet to prove laser iridotomy as a cause of generalized lens opacity. A review of patients treated with argon laser peripheral iridotomy showed no statistically significant differences from ageand sex-matched controls in the development or severity of cataract development.51

Corneal damage can occur both from the acute attack itself and, to a limited extent, from the laser iridotomy treatment. A decrease

in central corneal endothelial cell density has been reported following acute attacks of angle-closure glaucoma.54–56 The decrease in

cell density correlates with the duration of the attack; in fact, longer attacks may cause as much as 77% endothelial cell loss.56,86 The loss of

endothelial cells also correlates with other indicators of ocular damage, including visual field loss and optic disc cupping.57 Occasionally corneal decompensation requiring penetrating keratoplasty occurs after an acute attack. Patients with Fuchs’ endothelial dystrophy have shallower anterior chamber depths, shorter axial lengths, and a greater propensity for increased IOP after penetrating keratoplasty.58

At the corneal surface, the argon laser can cause superficial burns, especially if a contact lens is not used during iridotomy; such burns, however, usually disappear within a few days. Deeper but mild endothelial loss after laser iridotomy has been noted.67 The Nd:YAG laser can cause a localized area of denuded cor-

neal endothelial cells, especially if a contact lens is not used59 or if the treated iris is very close to the corneal endothelium.60,61

However, there is usually no generalized decrease in endothelial cell density with clinical sequelae following iridotomy.62–66 However, patients with pre-existing endothelial dystrophy who suffer an acute angle-closure attack may be more susceptible to

the effects of laser iridotomy, developing corneal decompensation after treatment.61,63

Correlating older and newer terminologies for angle closure

The following section is an attempt to accommodate the rich clinical literature of angle-closure disease within the newer structural classification used today. Since the gonioscopic estimation of the