Re-establishment of the Physiological Pathway of Aqueous Humor Drainage in Primary Angle-Closure Glaucoma: Phacoemulsification, Goniosynechialysis, and Goniotomy : The Asia-Pacific Journal of Ophthalmology

Secondary Logo

Journal Logo

Editorial

Re-establishment of the Physiological Pathway of Aqueous Humor Drainage in Primary Angle-Closure Glaucoma: Phacoemulsification, Goniosynechialysis, and Goniotomy

Chan, Poemen P. FRCSEd (Ophth), FCOphth (HK)*,†,‡,§; Tham, Clement C. FCOphth (HK), FRCOphth*,†,‡,§; Lam, Dennis S.C. MD, FRCOphth (UK)∥,¶

Author Information
Asia-Pacific Journal of Ophthalmology: November/December 2022 - Volume 11 - Issue 6 - p 497-499
doi: 10.1097/APO.0000000000000581
  • Open

Primary angle-closure glaucoma (PACG) carries a 3-fold increased risk of severe bilateral visual impairment, and Asians account for >70% of the PACG population worldwide.1–3 The treatment principle aims to eliminate the angle-closure mechanisms to lower intraocular pressure (IOP). Phacoemulsification (PEI) can effectively resolve pupillary block (the most common angle-closure mechanism) and deepen the anterior chamber (AC). It is the logical choice to treat PACG eyes with coexisting cataracts as established by randomized controlled trials.4–7 Even for patients with good central vision, the results of the EAGLE (effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma) study supported the approach of clear lens extraction as the initial treatment of choice for primary angle-closure with IOP ≥30 mm Hg and mild-to-moderate PACG.8

Despite the level I evidence, only 60.6% of the patients who underwent initial clear lens extraction in the EAGLE study were medication-free at the end of the study period (36 mo).8 For medically uncontrolled PACG or advanced glaucoma, combined phacotrabeculectomy is often required to control the IOP,4 which could be technically demanding and result in more surgical complications than PEI alone,9 not to mention the lifelong bleb-related and potentially blinding complications (eg, hypotony, bleb leakage, blebitis, and endophthalmitis). PEI alone may lower the IOP level comparable to that of phacotrabeculectomy but requires more long-term topical medical therapy.4,5 The problem of medication side effects and the associated inconvenience of regular eye drops application could negatively impact patients’ quality of life.10 Cost of medication is also substantial and could be an opportunity cost to the health care system.11,12 Prompt surgical intervention could reduce long-term medication use.13 To improve quality of life and reduce the cost of treatment, additional IOP-lowering procedures should be considered. Ideally, the procedures should be safe, effective, and capable of limiting long-term complications and medication requirements.

The variable degree of IOP reduction in PACG eyes that underwent PEI could be related to the amount of peripheral anterior synechiae (PAS).14,15 Goniosynechialysis (GSL) re-exposes the trabecular meshwork (TM) for aqueous humor drainage. However, previous studies did not demonstrate additional IOP-lowering efficacy.16,17 Irreversible damage to the TM may occur, especially after prolonged synechial closure.18 Aggressive GSL for these eyes could lead to hyphema, inflammation flare-ups, and IOP spikes. This could lead to wipe-out syndrome, particularly for eyes with advanced visual field loss.19 Complementary goniotomy (GT) may address the problem of dysfunctional TM—enhancement of aqueous humor outflow by removing the diseased TM and reducing the resistance of aqueous outflow to the Schlemm canal. It was reported to be effective and safe in PACG.15–19

This issue of APJO covers a 1-year multicenter prospective case series of 83 advanced PACG patients who received combined PEI+GSL+GT in China by Song et al.20 The results showed that PEI+GSL+GT could effectively reduce IOP (mean IOP decreased from the preoperative 27.4±7.3–14.2±2.6 mm Hg at 1 y) and medication use (the types of ocular hypotensive medication was reduced from a mean of 2.0 at the preoperative period to 0.3 at 1 y) with a relatively low rate of reversible complications (9 hyphema, 9 IOP spike, and 8 corneal edema), though the long-term efficacy required future investigation. Indeed, the same study group is conducting a randomized controlled trial to compare the surgical outcomes of phacotrabeculectomy versus PEI+GSL+GT.

PEI+GSL+GT has the potential for effective reduction of IOP and medication use while avoiding the need for additional trabeculectomy and the associated complications. Both GSL and GT belong to minimally invasive glaucoma surgery and promising results have been shown in previous studies.21,22

A good position of the patient’s head and a decent view of the angle structures are critical in GSL and GT. Several surgical steps could be helpful to achieve this:

  • To perform GSL and GT after standard PEI and intraocular lens implantation. Lens removal would deepen the AC and eliminate the lens vault that may obscure angle visualization and instrument manipulation during the angle surgeries.
  • Pharmacological constriction of pupil before proceeding to angle surgery. This could flatten the iris and open the angle structure further. However, pupil constriction could make the AC shallower and the cases in the captioned series did not constrict the pupil before GSL/GT. Further studies on this matter appear warranted.
  • Injection of viscoelastic directed toward the angle. This may also help dissect the PAS away from the TM.23
  • Concerning the patient’s head and the surgeon’s position, the surgeon could sit temporal to the operating eye to approach the angles at the nasal aspect of the eye via a temporal corneal incision. The patient’s head should be rotated 35 to 40 degrees away from the surgeon while the surgical microscope is tilted 30 degrees toward the operator. Poor visualization of the angle is often due to insufficient rotation of the patient’s head.
  • A surgical goniolens (eg, Swan-Jacob gonioprism, SJG; Ocular instruments Inc.) is placed on the cornea with coupling gel to observe the angle and the TM. For good angle visualization, the surgeon should avoid air bubbles in the AC and the coupling gel on the corneal surface. If the position is difficult, a Mori double-mirror goniolens (designed by Kazuhiko Mori, Kyoto, Japan) can provide a coaxial view of the AC and angle structure without tilting the head and microscope.24 Furthermore, all 360 degrees of the angle could be approached without requiring the surgeon to change position.

GSL is performed under the direct visualization with the goniolens. The PAS is physically separated from the TM using a spatula or microforceps. After exposing the TM, GT could be performed using a microblade (Tanito Microhook, TMH; Inami & Co. Ltd) or a Kahook Dual Blad (KDB; New World Medical). For the TMH, the tip of the instrument is inserted through the TM, into the Schelmm canal, and advanced along to incise the inner wall and TM over a 120-degree range. One could also aim for a 110- to 140-degree of GT with the KDB. To excise a narrow strip of TM, the tip of the KDB is directed to the nasal angle, inserted through the TM, into the Schlemm canal, and advanced for several clock hours. This can be repeated in the opposite direction. The resultant free-floating strips of TM can then be removed from the eye afterward.22

After the procedures, viscoelastic agent and blood should be thoroughly aspirated. Postoperative care could be variable depending on the eye condition and the surgeon’s preference. In general, it should include a course of anti-inflammatory and prophylactic antimicrobial eye drops with variable use of IOP-lowering medication and careful monitoring of the postoperative condition. Song et al20 avoided postoperative IOP spike by restricting topical steroid use within 7 days, followed by topical nonsteroidal anti-inflammatory drug eye drops. While the authors believed this early steroid withdrawal step might be critical in preventing IOP spikes, the underlying mechanisms and postoperative regimen require further elucidation.

In summary, PEI+GSL+GT could be a valuable alternative of combined phacotrabeculectomy for controlling IOP in PACG. With careful patient selection and appropriate surgical technique, the IOP-lowering effect of the additional GSL and GT could be effective and safe. This may avoid high-risk surgery and bleb-related complications while reducing medication requirement, exposure to medication side effects, and cost of treatment. It may also improve patients’ quality of life. Risk of postoperative scarring leading to failure of trabeculectomy is not low. On the contrary, risk of reclosure of the angle after GSL and/or Schlemm canal after GT could be quite low, leading to a better long-term success rate. Further study is worthwhile to explore the potential benefit of the procedure in PACG patients with different disease severity.

REFERENCES

1. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006;90:262–267.
2. Friedman DS, Foster PJ, Aung T, et al. Angle closure and angle-closure glaucoma: what we are doing now and what we will be doing in the future. Clin Exp Ophthalmol. 2012;40:381–387.
3. Tham YC, Li X, Wong TY, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology. 2014;121:2081–2090.
4. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology. 2009;116:725–731.
5. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically controlled chronic angle closure glaucoma with cataract. Ophthalmology. 2008;115:2167–2173.
6. Tham CC, Kwong YY, Baig N, et al. Phacoemulsification versus trabeculectomy in medically uncontrolled chronic angle-closure glaucoma without cataract. Ophthalmology. 2013;120:62–67.
7. Lam DS, Leung DY, Tham CC, et al. Randomized trial of early phacoemulsification versus peripheral iridotomy to prevent intraocular pressure rise after acute primary angle closure. Ophthalmology. 2008;115:1134–1140.
8. Azuara-Blanco A, Burr J, Ramsay C, et al. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet. 2016;388:1389–1397.
9. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification vs phacotrabeculectomy in chronic angle-closure glaucoma with cataract: complications [corrected]. Arch Ophthalmol. 2010;128:303–311.
10. van Gestel A, Webers CA, Beckers HJ, et al. The relationship between visual field loss in glaucoma and health-related quality-of-life. Eye. 2010;24:1759–1769.
11. Chan PP, Li EY, Tsoi KKF, et al. Cost-effectiveness of phacoemulsification versus combined phacotrabeculectomy for treating primary angle closure glaucoma. J Glaucoma. 2017;26:911–922.
12. Chan PP, Li EY, Tham CC. Cost-effectiveness in the treatment of glaucoma. US Ophthalmic Rev. 2014;7:131–136.
13. Chan PP, Tang FY, Leung DY, et al. Ten-year clinical outcomes of acute primary angle closure randomized to receive early phacoemulsification versus laser peripheral iridotomy. J Glaucoma. 2021;30:332–339.
14. Shams PN, Foster PJ. Clinical outcomes after lens extraction for visually significant cataract in eyes with primary angle closure. J Glaucoma. 2012;21:545–550.
15. Lee YH, Yun YM, Kim SH, et al. Factors that influence intraocular pressure after cataract surgery in primary glaucoma. Can J Ophthalmol. 2009;44:705–710.
16. Wang N, Jia SB. Phacoemulsification with or without goniosynechialysis for angle-closure glaucoma: a global meta-analysis based on randomized controlled trials. Int J Ophthalmol. 2019;12:826–833.
17. Husain R, Do T, Lai J, et al. Efficacy of phacoemulsification alone vs phacoemulsification with goniosynechialysis in patients with primary angle-closure disease: a randomized clinical trial. JAMA Ophthalmol. 2019;137:1107–1113.
18. Sihota R, Goyal A, Kaur J, et al. Scanning electron microscopy of the trabecular meshwork: understanding the pathogenesis of primary angle closure glaucoma. Indian J Ophthalmol. 2012;60:183–188.
19. Chan PP, Pang JC, Tham CC. Acute primary angle closure-treatment strategies, evidences and economical considerations. Eye. 2019;33:110–119.
20. Song Y, Zhang Y, Li F, et al. One-year results of a multicenter trial: Intraocular pressure lowering effect of combined phacoemulsification, goniosynechialysis and goniotomy for cases of advanced primary angle-closure glaucoma with cataract. Asia Pac J Ophthalmol (Phila). 2022;11:529–535.
21. Gillmann K, Mansouri K. Minimally invasive glaucoma surgery: where is the evidence? Asia Pac J Ophthalmol (Phila). 2020;9:203–214.
22. Dorairaj S, Tam MD, Balasubramani GK. Two-year clinical outcomes of combined phacoemulsification, goniosynechialysis, and excisional goniotomy for angle-closure glaucoma. Asia Pac J Ophthalmol (Phila). 2021;10:183–187.
23. Qing G, Wang N, Mu D. Efficacy of goniosynechialysis for advanced chronic angle-closure glaucoma. Clin Ophthalmol. 2012;6:1723–1729.
24. Mori K, Ikushima T, Ikeda Y, et al. Double-mirror goniolens with dual viewing system for goniosurgery. Am J Ophthalmol. 2007;143:154–155.
Copyright © 2022 Asia-Pacific Academy of Ophthalmology. Published by Wolters Kluwer Health, Inc. on behalf of the Asia-Pacific Academy of Ophthalmology.