Small-incision phacotrabeculectomy versus phacoemulsification in refractory acute primary angle closure with cataract


The timely management of acute PAC is important for reducing the risk of irreversible
damage to the optic nerve head and preventing recurrent attacks and chronic angle
closure glaucoma (CACG) progression 13]. The retinal fiber layer thickness may decrease significantly within 16 weeks after
the attack 14]. Delay in presentation and the time needed to terminate the attack have been found
to have a detrimental effect on the final outcome 13]. Conventional options involve the use of medical treatment, paracentesis and laser
peripheral iridotomy. In hospital clinics a few patients may be refractory to these
treatments and the attack may remain unbroken. Operative options should be considered
to lower IOP as soon as possible, but the timing of operations in an acute setting
is controversial.

Recently, cyclodiode laser has been described as a safe and effective alternative
in the management of medically uncontrolled acute PAC, and the authors demonstrate
a good result in five patients only 15]. Most ophthalmologists would consider that lensectomy or trabeculectomy is suboptimal
in such situation because of greater risk of operative complications due to the small
dimensions of the chamber and the tendency for choroidaleffusion. The complications
of lensectomy are: corneal edema, posterior capsular rupture, bleeding, fibrinous
inflammatory reaction, and posterior capsular opacification 16]. The complications of trabeculectomy are: shallow anterior chamber, transient IOP
elevation, hyphaema, and aqueous misdirection 17]. In medically unresponsive cases of acute PAC, higher risk of surgical failure and
complications make trabeculectomy not a preferred choice 17]. In recent times, technological advances in phacoemulsification and small-incision
trabeculectomy (SIT) make this option much more viable.

In cases of acute PAC or acute angle-closure glaucoma, phacoemulsification alone has
been shown to achieve good IOP control 18]–20]. But IOP-spikes may appear in the early postoperative period and pose a potential
threat 21]. Phacotrabeculectomy plus intraocular lens implantation has been shown superior than
trabeculectomy which is also superior than phacoemulsification in decreasing IOP for
primary angle closure-glaucoma (PACG) 22]. Phacotrabeculectomy is more effective than phacoemulsification alone in controlling
IOP in medically uncontrolled CACG eyes with coexisting cataract 23]. In eyes with synechial angle closure and cataract, the preferred option is to perform
phacotrabeculectomy 24]. With the progress of surgical technique, able to skillfully handle intraoperative
and postoperative complications, more and more doctors tend to solve the two problems
in combination.

The new procedures and devices aim to lower IOP with a higher safety profile than
filtering surgery (trabeculectomy/drainage tubes) are collectively termed “minimally
invasive glaucoma surgery (MIGS)” 25]. But these technologies are mainly for open angle glaucoma, surgery for “closed angle”
is still dominated by trabeculectomy for Asian eyes 26]. The aim of SIT is to pursue least tissue injury, less complications and better filtering
effect. SIT has been introduced in the form of small incision with 3 mm fornix-based
conjunctival flap, 1–2 mm short scleral tunnel instead of scleral flap, suture or
no suture for incision, reducing operation area and tissue injury 27], 28]. The surgical technique is generally efficacious and relatively safe comparing to
the standard trabeculectomy. One study including 41 eyes with medically uncontrolled
glaucoma adopted the surgical technique. The glaucoma type included chronic simple
glaucoma, chronic narrow-angle glaucoma, pseudoexfoliation glaucoma and pigmentary
glaucoma. Most of these patients had IOP at or below the target IOP after mean follow-up
of 25 months 29]. Another revised procedure of SIT avoids cutting Tenon’s capsule 30]. The use of a small 2.5 mm limbal incision obviates subconjunctival fibrosis, and
it is safer with higher success rate than conventional trabeculectomy 31].

One important difference between the above SIT studies is the glaucoma type, open
angle vs. closed angle over 180° in ours. The patients enrolled in our study suffered
with both refractory acute PAC and coexisting cataract. We compared small-incision
phacotrabeculectomy with phacoemulsification in treating the two problems. Based on
the patients’ preoperative status and eye characteristics, we also revised the procedure
in order to achieve the best outcome, including the width of the peritomy, flap size,
suture method and etc. The BCVA of most patients was improved in phacotrab group (75
%) and phaco group (80 %). The surgical success rate was 83.33 % in phacotrab group
and 72 % in phaco group respectively. The difference in mean IOP at 12 months between
the two groups appeared marginal. A longer follow-up would be useful to confirm whether
small-incision phacotrab is more effective in IOP control.

Merits of small-incision phacotrabeculectomy for refractive acute PAC with cataract
include: less postoperative inflammatory reaction as phaco, better IOP control in
the long term, less possibility of IOP lowing medication and progression to glaucoma.
In addition, combined phacotrabeculectomy may help elderly patients with less psychological
and financial burden. Any operative option should base on the specific condition of
ocular diseases and the premise of no violation of evidence-based medicine, taking
the most advantageous way for patients. In patients with medically uncontrolled glaucoma
and cataract, the options are to perform trabeculectomy first then phacoemulsification,
phacoemulsification first and then trabeculectomy, or phacotrabeculectomy 32]. The surgical indications of combined phacotrabeculectomy should be reserved for
any one of the following conditions: refractory to drug or laser treatment with high
IOP, attack history or moderate to severe optic nerve damage, tendency to malignant
glaucoma, requirement of vision improvement, no chance to have 2 separate surgeries
due to ocular or systemic conditions, and poor adherence or inconvenience of follow-up,
etc. Small-incision phacotrabeculectomy may offer clinical and technical advantages
over the standard combined operations where conventional treatment fails.

This study may not have sufficient follow-up duration and sample size to look at other
parameters, such as additional IOP lowing medication and glaucomatous progression.
Multicenter randomized controlled clinical trials are required to confirm these observations.