Surgical management may be ineffective or result in complications. Laser trabeculoplasty, for example, is often unsuccessful or only temporarily effective. Moreover, the aphakic eye frequently possesses a great degree of peripheral anterior synechiae that precludes laser trabeculoplasty. As a result, the remaining management options for uncontrolled aphakic glaucoma usually include cyclodestructive procedures or incisional surgery combined with either a trabeculectomy or an aqueous shunt device.
CYCLODESTRUCTIVE PROCEDURES
Surgeons often perform this type of procedure in patients who lack good visual acuity (below 20/200). Transscleral cyclocryopexy is an option, but this procedure has been associated with a greater risk of severe pain and inflammation, loss of vision, phthisis, and enucleation.1 I personally prefer to perform transscleral cyclophotocoagulation with a diode laser because of its relative safety and ease of use. Initial success rates may vary from 37% to 74% and may further improve with a repeat procedure during the first year after surgery.2,3
I employ the “slow-burn” method, because it is associated with less pain and inflammation than the older method using higher-energy settings at shorter durations, which cause a “pop” as an endpoint measure of destruction. I place approximately 24 applications posterior to the limbus over 360º with the G-probe. Each application contains approximately 1,250 mW of energy at nearly 4 seconds for a total of 5 J per application (Figure 1).
Figure 1. The author places the edge of the G-probe's footplate at the limbus.
INCISIONAL SURGERY
Challenges
Many patients with uncontrolled aphakic glaucoma possess macular visual acuity (visual acuity above 20/200). Because cyclodestructive procedures may be associated with a 1-to-2–line loss of visual acuity,4 incisional surgery may be a preferable treatment method in these eyes. It is the aphakic eye's anatomy that causes difficulty. The anterior chamber is often attenuated due to peripheral anterior synechiae, the formation of which occurs unhindered owing to the absence of a crystalline lens or IOL. Major complications can ensue, including a flat anterior chamber, massive choroidal effusion or hemorrhage, and retinal detachment. All can result in surgical failure.
Recommendations
Investigators have shown that glaucoma is more common in aphakia than phakia and pseudophakia.5 Similarly, in my experience, glaucoma surgery is more successful in pseudophakic than aphakic eyes. It is helpful to place an anterior or posterior chamber IOL at the time of trabeculectomy or the aqueous shunt procedure in order to restore the anatomic barrier between the anterior and posterior chambers. This technique results in smaller choroidal effusions and a significant decrease in hemorrhagic or “kissing” choroidals.
First, I perform two conjunctival peritomies 180º apart and, with a crescent blade, create a scleral tunnel starting approximately 1.5 to 2.0 mm posterior to the limbus at each location (Figure 2). I cut the sides of the flaps to the limbus with a super-sharp blade and will later use these sites to secure the sulcus-fixated IOL. Next, I create a conjunctival peritomy at another location (site No. 1) where I perform a complete anterior vitrectomy through a corneal-scleral incision (Figure 3). After ascertaining that the anterior vitrectomy is complete, I enlarge the incision to between approximately 6 and 7 mm for the subsequent placement of the IOL.
Figure 2. The author creates two partial-thickness scleral flaps approximately 1.5 to 2.0 mm posterior to the limbus and about 180º apart before making a corneal-scleral incision.
Figure 3. At site No. 1, the author performs a complete anterior vitrectomy through a corneal-scleral incision.
I then place a PC-9 needle (1/4-inch circular needle with a sling 9–0 polypropolene suture; Alcon Laboratories, Inc., Fort Worth, TX) through the eyelet of each haptic of a CZ70BD biconvex posterior chamber IOL (Alcon Laboratories, Inc.) (Figure 4). To secure each suture to the haptic, I use the girth hitch technique,6 which involves bringing the PC-9 needle back through the loop of the sling suture and cinching the suture tightly around the eyelet (Figure 5).
Figure 4. The author places a PC-9 needle with a sling suture through each eyelet of a CZ70BD posterior-chamber IOL haptic.
Figure 5. The author passes the needle and sling suture through the eyelet of the haptic (A). He then brings the needle back through the remaining loop and tightens the suture (B).
After filling the anterior chamber with a viscoelastic, I place a 22-gauge needle 1 mm posterior to the limbus under each of the previously created scleral flaps and into the sulcus via an ab externo approach. Figure 6 shows the view of the needle through the pupil. I then introduce each PC-9 needle into the corneal-scleral incision (site No. 1) and thread it into the 22-gauge needle. Next, I withdraw the 22-gauge needles and remove slack from the sutures while placing the IOL through the incision (site No. 1) and into the sulcus. After positioning the IOL, I tie the sutures under the scleral flaps and close the conjunctival peritomies. At this point, I perform the glaucoma surgery (site No. 2) 60º to 120º away from site No. 1. If there is mobile conjunctiva, I perform a trabeculectomy with an adjunct antifibrotic. Otherwise, I place an aqueous shunt device.
Figure 6. With an ab externo approach into the sulcus, the author places a 22-gauge needle 1 mm posterior to the limbus under the two previously created scleral flaps.
Reliability
In the last 4 years, I have performed combined trabeculectomy (with antifibrotic adjuncts), anterior vitrectomy, and placement of a sulcus-fixated IOL in 15 patients. None experienced a retinal detachment or choroidal hemorrhage, and 13 of 15 patients attained an IOP of less than 20 mm Hg without medication for at least 1 year.
CONCLUSION
Concurrently placing an IOL during incisional glaucoma surgery can be safely executed, and this method appears to increase the surgical success rate for this challenging form of glaucoma.
Thomas E. Bournias, MD, is Director of the Northwestern Ophthalmic Institute and Assistant Professor of Clinical Ophthalmology at Northwestern University Medical School. Dr. Bournias may be reached at (312) 695-8150; bournias@northwestern.edu.
1. Benson MT, Nelson ME. Cyclocryotherapy: a review of cases over a 10-year period. Br J Ophthalmol. 1990;74:2:103-105.
2. Kirwan JF, Shah P, Khan PT. Diode laser cyclophotocoagulation: role in management of refractory pediatric glaucoma. Ophthalmology. 2002;109:316-323.
3. Schlote T, Derse M, Rassmann K, et al. Efficacy and safety of contact transscleral diode laser cyclophotocoagulation for advanced glaucoma. J Glaucoma. 2001;10:294-301.
4. Hampton C, Shields MB, Miller KN, Blasini M. Evaluation of a protocol for transscleral neodymium:YAG cyclophotocoagulation in one hundred patients. Ophthalmology. 1990;97:910-917.
5. Asrani S, Freedam S, Hasselblad V, et al. Does primary intraocular lens implantation prevent “aphakic” glaucoma in children? J AAPOS. 2000;4:1:33-39.
6. Tomikawa S, Hara A. Simple approach to secondary posterior chamber intraocular lens implantation in patients without a complete posterior lens capsule support. Ophthalmic Surg. 1995;26:160-163.
