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Glaucoma Physician

Article

Management of Glaucoma Following Cataract Surgery in Children

A multifaceted approach leads to best outcomes.

By: Hamed Esfandiari, MD
Glaucoma Physician December 1, 2021 Vol Ophthalmology Management 25, Issue December 2021 Page(s): E1-E5

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Cataract is considered among the leading causes of reversible blindness in children, requiring early surgery for normal visual development. Glaucoma is a known complication of lensectomy for congenital cataract with or without concurrent intraocular lens (IOL) implantation.1 The estimated prevalence of glaucoma after pediatric cataract surgery is reported to be as high as 40%, depending on the length of follow-up.

Several risk factors have been identified for glaucoma following cataract surgery (GFCS), including microcornea (corneal diameter less than 10 mm), nuclear cataract, and surgery in the first year of life, and they probably decrease with primary IOL implantation, although the role of IOL implantation is controversial.2

Modern instrumentation and techniques have decreased the rates of previously common unfavorable surgical outcomes, such as retained lens fragments and cortex opacification, as well as the need for secondary surgery for posterior capsule opacification. However, glaucoma remains a common long-term complication of lensectomy.

Although in some cases, congenital cataract is part of a wider spectrum of ocular abnormalities that predispose the eye to the development of glaucoma, the pathophysiological mechanism of increased intraocular pressure (IOP) in postlensectomy glaucoma remains unclear in most cases.

Chemical and mechanical mechanisms have been proposed. Diffusion of chemical mediators or inflammatory cytokines from the vitreous to the anterior chamber may compromise trabecular meshwork function. Alternatively, lensectomy may cause Schlemm’s canal or the trabecular meshwork to collapse and pose an unfavorable static and dynamic configuration.3 To date, no genetic predisposition for the development of post-lensectomy IOP elevation has been identified.

Management of Glaucoma Following Cataract Surgery

The first-line treatment for GFCS is usually topical ocular hypotensive therapy; however, medications are effective only in about half of affected patients.4 Commonly used eyedrops include beta blockers, carbonic anhydrase inhibitors, and in cases of inadequate response, pilocarpine. Routine retinal exam is recommended with pilocarpine due to the higher risk of retinal detachment in this condition.

Alpha-adrenergic agonists should be avoided as they are associated with extreme fatigue and somnolence in children. Prostaglandin analogs generally are not effective in children.

A substantial proportion of patients require surgical intervention to adequately control IOP. Surgical options include angle surgery, trabeculectomy with or without antifibrotics, glaucoma drainage devices, and cyclodestructive procedures.

The standard surgical interventions for GFCS traditionally have been either trabeculectomy or glaucoma drainage devices. They reduce IOP by bypassing the poorly functioning physiologic outflow system. A literature review indicates that glaucoma drainage devices have a favorable safety profile and good efficacy in the management of postlensectomy glaucoma.5-7 However, some surgeons would start with angle surgery to enhance the outflow through physiologic pathways, mainly because of its excellent safety profile.8

Enhancing Physiologic Outflow: Trabeculotomy

Ab-externo trabeculotomy involves a fornix-based localized peritomy in the superior or temporal quadrant, while hemostasis is achieved using wet-field cautery. A rectangular or triangular, 3-mm, limbus-based, partial-thickness scleral flap is fashioned, followed by a radial incision to expose Schlemm’s canal under high magnification. A scleral cut down is performed from the surgical blue zone to the white zone until egress of aqueous humor is noted. The Harms trabeculotome is then passed into each end of Schlemm’s canal up to the joint and gently rotated into the anterior chamber through the trabecular meshwork (Figure 1). The scleral flap is sutured, and the knots are buried in the sclera. The conjunctiva is closed using 10-0 Vicryl sutures. Postoperative medications include topical antibiotic and steroid drops tapered over 4 weeks. The reported success rate of angle surgery with rigid probe has ranged from 16% to 57%.8,9 Considering the notable success of illuminated microcatheter-assisted 360º trabeculotomy in primary congenital glaucoma, this procedure has been adopted in GFCS with promising outcomes.10

 

Figure 1. In ab-externo trabeculotomy, the probe is advanced into each end of Schlemm’s canal up to the joint (about 60º) and gently rotated into the anterior chamber through the trabecular meshwork. Any resistance indicates false passage, and the probe should be withdrawn and repositioned.
Figure 1. In ab-externo trabeculotomy, the probe is advanced into each end of Schlemm’s canal up to the joint (about 60º) and gently rotated into the anterior chamber through the trabecular meshwork. Any resistance indicates false passage, and the probe should be withdrawn and repositioned.

 Instead of a rigid probe, after exposing Schlemm’s canal, a microcatheter is introduced into 1 end of the canal and gradually advanced into the canal to be retrieved from the other end (Figure 2). Two ends of the microcatheter are grasped and pulled into the anterior chamber to create a 360º trabeculotomy. The success with this procedure is reported to be as high as 70% over 3 years of follow-up,10 and it is becoming a first-line surgical intervention for GFCS.

Figure 2. In ab-externo trabeculotomy, once Schlemm’s canal is identified, the catheter is introduced into 1 cut end of Schlemm’s canal and then gradually advanced circumferentially, using the illuminated tip as confirmation of the position within the canal.
Figure 2. In ab-externo trabeculotomy, once Schlemm’s canal is identified, the catheter is introduced into 1 cut end of Schlemm’s canal and then gradually advanced circumferentially, using the illuminated tip as confirmation of the position within the canal.

Bypassing the Physiologic Pathway: Trabeculectomy vs Glaucoma Shunt Procedure

Although trabeculectomy with and without adjunctive antifibrotic therapy has a high rate of failure,11 glaucoma drainage devices have proved safe and effective in postlensectomy glaucoma.5-7 The factors that limit the success of trabeculectomy in children include thick Tenon’s capsules and vigorous wound-healing responses that lead to subconjunctival fibrosis and bleb failure.2,10,12

Two of the most frequently implanted glaucoma drainage devices are the Ahmed Glaucoma Valve (AGV; New World Medical) and the Baerveldt Glaucoma Implant (BGI; Johnson & Johnson Vision). The BGI does not have a system to control IOP and requires intraoperative flow restriction to provide enough time for fibrosis to develop around the plate and regulate aqueous outflow. This modification limits immediate flow postoperatively and leads to uncontrolled IOP. Because some of these children have severe postlensectomy glaucoma, this postoperative ocular hypertension may have a detrimental effect on remaining visual function.

After approximately 1 month, when healing takes place around the plate, BGI results in excellent IOP control.6 When implanting the BGI, a fornix-based conjunctival flap is created, and Tenon’s dissection is advanced toward the equator until enough space is created for the implant. The lateral wings of the 350-mm BGI are advanced under the superior and lateral rectus muscles. The plate is sutured to the sclera 8 mm to 10 mm posterior to the limbus. The tube is cut short with the bevel up to have approximately 2 mm to 3 mm of intracameral length. The tube is completely ligated near the plate junction with a 7-0 polyglactin suture and tested with balanced salt solution to confirm water tightness. The tube is then inserted into the anterior chamber through a tunnel created with a 23-gauge needle and secured to the sclera with a 7-0 polyglactin loop stitch. Scleral patch graft is preferred over graft-free techniques to cover the tube in the pediatric population. The conjunctiva and Tenon’s are pulled back over the shunt and sutured to the limbus.

Implantation of an AGV involves a fornix-based conjunctival peritomy in the supratemporal quadrant and blunt dissection using Westcott or Stevens scissors to create a plane for plate insertion. The device is primed with 2 mL to 3 mL of balanced salt solution and is gently inserted into the sub-Tenon space. The plate is secured to the sclera 8 mm to 10 mm posterior to the limbus. The tube is trimmed bevel up with an estimated intracameral length of 2 mm. A 23-gauge needle is inserted into the anterior chamber bevel up, parallel to the iris, and 1 mm to 3 mm posterior to the limbus. In contrast to primary congenital glaucoma, anterior displacement of the tube rarely happens in GFCS if the tube is not inserted close to the cornea at the time of surgery. A scleral patch graft is placed over the tube. Tenon’s fascia and the conjunctiva are closed using a Vicryl suture.

Graft-free techniques are being used more frequently for adult glaucoma to avoid tube exposure, with good short-term and intermediate-term results.13 However, there is no evidence for their long-term outcomes; full-thickness sclera seems to be the most durable patch graft after shunt procedure in childhood glaucoma. Moreover, some techniques, such as passing the tube into a long intrascleral tunnel, can result in anterior tube insertion into the anterior chamber and endothelial cell loss (Figure 3).

Figure 3. In an eye with glaucoma following cataract surgery, Ahmed Glaucoma Valve (New World Medical) implantation was performed with the intrascleral tunnel technique, and tube exposure developed 5 years later. The tube was inserted very close to the cornea and led to localized corneal edema.
Figure 3. In an eye with glaucoma following cataract surgery, Ahmed Glaucoma Valve (New World Medical) implantation was performed with the intrascleral tunnel technique, and tube exposure developed 5 years later. The tube was inserted very close to the cornea and led to localized corneal edema.

An AGV is easy to handle and provides immediate IOP control, which are important considerations when attempting to clear the cornea and enhance visual function. However, with an AGV, there is a risk of a hypertensive phase in the early postoperative period, as well as higher IOPs compared to BGI.6,7 Several studies have indicated similar outcomes with both devices in postlensectomy glaucoma in patients who received glaucoma drainage devices. 5-7 However, all of these studies had small sizes.

The incidence of a hypertensive phase with the AGV for GFCS was reported to be 30%, consistent with other studies of adult glaucomas.14 A hypertensive phase in GFCS was shown to be an unfavorable prognostic factor. 15

In summary, while the treatment of GFCS should be individualized for each patient, currently, topical hypotensive medication, illuminated microcatheter assisted 360º trabeculotomy, and glaucoma drainage devices are the most effective choices for long-term IOP control.

Hamed Esfandiari, MD, is dual fellowship trained in glaucoma and pediatric ophthalmology and is on the faculty of the department of ophthalmology at Olmsted Medical Center in Rochester, Minnesota. He reports no related disclosures. Reach him at hmdesfandiary@gmail.com.

References

  1. Lawrence MG, Kramarevsky NY, Christiansen SP, Wright MM, Young TL, Summers CG. Glaucoma following cataract surgery in children: surgically modifiable risk factors. Trans Am Ophthalmol Soc. 2005;103:46-55.
  2. Kirwan C, O'Keefe M. Paediatric aphakic glaucoma. Acta Ophthalmol Scand. 2006;84(6):734-739. doi:10.1111/j.1600-0420.2006.00733.x
  3. Daniel MC, Dubis AM, Theodorou M, et al. Childhood lensectomy is associated with static and dynamic reduction in schlemm canal size: a biomechanical hypothesis of glaucoma after lensectomy. Ophthalmology. 2019;126(2):233-241. doi: 10.1016/j.ophtha.2018.08.031
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  6. Esfandiari H, Kurup SP, Torkian P, Mets MB, Rahmani B, Tanna AP. Long-term clinical outcomes of Ahmed and Baerveldt drainage device surgery for pediatric glaucoma following cataract surgery. J Glaucoma. 2019;28(10):865-870. doi:10.1097/IJG.0000000000001335
  7. Pakravan M, Esfandiari H, Yazdani S, et al. Clinical outcomes of Ahmed glaucoma valve implantation in pediatric glaucoma. Eur J Ophthalmol. 2019;29(1):44-51. doi: 10.1177/1120672118761332
  8. Bothun ED, Guo Y, Christiansen SP, et al. Outcome of angle surgery in children with aphakic glaucoma. J AAPOS. 2010;14(3):235-239. doi:10.1016/j.jaapos.2010.01.005
  9. Chen TC, Walton DS, Bhatia LS. Aphakic glaucoma after congenital cataract surgery. Arch Ophthalmol. 2004;122(12):1819-1825. doi: 10.1001/archopht.122.12.1819
  10. Lim ME, Dao JB, Freedman SF. 360-degree trabeculotomy for medically refractory glaucoma following cataract surgery and juvenile open-angle glaucoma. Am J Ophthalmol. 2017;175:1-7. doi:10.1016/j.ajo.2016.11.011
  11. Beauchamp GR, Parks MM. Filtering surgery in children: barriers to success. Ophthalmology. 1979;86(1):170-180. doi: 10.1016/s0161-6420(79)35547-6s
  12. Mandal AK, Bagga H, Nutheti R, Gothwal VK, Nanda AK. Trabeculectomy with or without mitomycin-C for paediatric glaucoma in aphakia and pseudophakia following congenital cataract surgery. Eye (Lond). 2003;17(1):53-62. doi:10.1038/sj.eye.6700180
  13. Pakravan M, Hekmat VR, Pakravan P, Hassanpour K, Esfandiari H. Graft-free glaucoma drainage device implantation: short tunnel small flap technique. Eur J Ophthalmol. 2019;29(1):57-60. doi:10.1177/1120672118761458
  14. Budenz DL, Barton K, Gedde SJ, et al. Five-year treatment outcomes in the Ahmed Baerveldt comparison study. Ophthalmology. 2015;122(2):308-316. doi: 10.1016/j.ophtha.2014.08.043
  15. Esfandiari H, Shazly T, Shah P, et al. Impact of same-session trabectome surgery on Ahmed glaucoma valve outcomes. Graefes Arch Clin Exp Ophthalmol. 2018;256(8):1509-1515. doi:10.1007/s00417-018-3967-z

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