The Glaucoma Care Continuum: From Selective Laser Trabeculoplasty to Minimally Invasive Glaucoma Surgery to Traditional Surgery

Educational Objectives

The goal of this program is to improve the management of open-angle glaucoma (OAG). After hearing and assimilating this program, the clinician will be better able to:

1. Appraise the appropriateness of observation in the management of ocular hypertension.
2. Evaluate the evidence for selective laser trabeculoplasty as a primary treatment for OAG.
3. Justify the stepladder approach for surgical management of OAG.

Summary

Glaucoma care: glaucoma is a chronic and life-long condition; treatment armamentarium for glaucoma ranges from observation to visual rehabilitation

Observation: may be considered for elderly patients with medical comorbidities, mild ocular hypertension (OHT), and no loss of retinal nerve fiber layer (RNFL) thickness; the Ocular Hypertension Treatment Study (OHTS; Kass et al [2002]) demonstrated statistically significant difference between observation and medication; however, the proportion of patients developing open-angle glaucoma (OAG) with observation at 5 yr is <10%; patients with high intraocular pressure (IOP) are at greater risk for OAG; pachymetry is important, as IOP measurement should be adjusted for central corneal thickness; in the OHTS, at 20 yr, only 25% of patients developed visual field loss in either eye; cataract surgery — Mansberger et al (2012) found that cataract surgery decreases IOP in OHTS patients with ocular hypertension; the reduction in IOP was significant and lasted for ≤3 yr; cataract surgery serves a form of treatment; optic disc hemorrhage (ODH) — observation is not appropriate for patients with ODH and loss of RNFL thickness; OHTS data indicate that ODH is a significant predictive factor for conversion from OHT to OAG

Options for primary treatment: the traditional approach is to initiate treatment with topical medications, failing which (selective laser trabeculoplasty) SLT is performed; surgery is the last resort; the speaker does not prefer the traditional approach; poor adherence — data show that adherence to topical medications is <30% after 3 yr; patients often present with ocular adverse effects; Stone et al (2009) found that <33% of patients can instill a single eye drop into the eye without touching the tip of the bottle to the eye; patients often waste eye drops during instillation, requiring early refills that may not be covered by insurance; SLT may be an alternative option

Selective laser trabeculoplasty: equivalent to a prostaglandin analogue; data support SLT as a primary therapy for glaucoma; LiGHT trial (Gazzard et al [2019]) — conducted in the United Kingdom; compared SLT vs eye drops as a primary treatment; the clinical outcomes included medication-free IOP control, need for glaucoma surgery, and disease progression; at 3 yr, ≤80% patients in the SLT group achieved medication-free IOP control and required only one treatment; some patients required trabeculectomy in the medication group, while trabeculectomy was not required in the SLT group; at 3 yr, progression was rapid in the medication group; at 6 yr, difference in disease progression (visual field loss) was significant between the initial medication group and the SLT group; more patients in the initial medication group required glaucoma surgery; the speaker prefers SLT to eye drops as the first-line therapy for primary OAG with OHT, when treatment is necessary; in a survey, ophthalmologists preferred SLT as the primary therapy; patient education — emphasize the fact that glaucoma is not curable and is a chronic condition, and further interventions may be necessary after some years (eg, repeat SLT ≤1 yr)

Surgery: can be considered as first-line treatment; stepladder approach — the speaker prefers minimally invasive glaucoma surgery (MIGS) as the initial procedure, followed by trabeculectomy if necessary; tube shunts are the last resort

Minimally invasive glaucoma surgery: the HORIZON trial (Ahmed et al [2022]) — compared Schlemm canal (SC) microstent (SCM; eg, Hydrus Microstent) plus cataract surgery vs cataract surgery alone; at 5 yr, a higher proportion of patients in the SCM group remained medication-free; IOP reduction from baseline was higher in the SCM group compared with cataract surgery alone group; trabecular meshwork (TM) bypass by stent — TM microbypass stents (eg, iStent) have evolved through 3 generations; the aforementioned SCM is 8 mm long and has 3 windows; the devices are inserted into the SC; tissue excision — using a single-use ophthalmic blade (eg, Kahook Dual Blade), part of the TM can be stripped to deroof the SC (through ≈120 degrees); canaloplasty followed by trabeculotomy (eg, OMNI system) is performed by inserting the catheter into the SC, and trabeculotomy is performed through ≈360 degrees; a viscoelastic material can be injected to dilate the intact portion of SC and the collector channel

Tips for MIGS: a good view is necessary; tilt the microscope by ≈45 degrees; the patient’s head should also be tilted by 45 degrees or as much as possible to obtain a total tilt of 75 to 90 degrees (en face view); a thorough knowledge of anatomy is essential; in blue-eyed individuals, the TM is translucent and identification of landmarks is difficult; stains (eg, Vision Blue) may be used to aid identification; depressing the eye reduces the pressure and blood refluxes into the SC; ensure fixation of the eye to the scope; after depression of the eye, inflate the eye before insertion of the device; maintain anterior chamber using viscoelastic material; hydrate the wound

Choice of MIGS: depends on the surgeon; use a device that is comfortable before exploring other methods; use of anticoagulant and antiplatelet medications dictates the choice between insertion and tissue excision; consider withholding the medication in consultation with the cardiologist; if anticoagulant medications cannot be withheld, insertion of a small device is preferable to 360-degree tissue excision to avoid postoperative blurred vision and persistent hyphema

Traditional glaucoma surgery: trabeculectomy is needed and remains the preferred procedure in advanced or rapidly progressing disease; in an editorial, Singh (2024) stresses the need for trabeculectomy in fast progressors and aggressive disease (5%-12%); paucity of trabeculectomy-trained ophthalmologists may lead to a public health crisis; fast progressors may lose their vision without trabeculectomy; patients with acquired pit of optic nerve in glaucoma progress fast (eg, paracentral scotoma); normal-tension glaucoma (NTG) — Iverson et al (2016) found that the visual field progression rate was 1.1 dB/yr in patients with NTG; after trabeculectomy, the visual field progression rate decreased significantly; filtering bleb — a bleb with good morphology is desirable to avoid complications; however, diffuse bleb leak may require revision to avoid endophthalmitis; an overhanging bleb may require needling and compression suture to ensure adequate distal drainage; however, an overhanging bleb may block the vision and should be excised

Tube shunt: some surgeons prefer primary tube shunt to trabeculectomy (a difficult procedure); Primary Tube Versus Trabeculectomy Study — Gedde et al (2020) found that success rates of primary tube shunt and trabeculectomy were comparable at 3 yr; however, patients undergoing tube-shunt surgery required more glaucoma medications to achieve IOP control; complications with tube-shunt surgery — include erosion and decompensation of the cornea by the tube (requires removal) or the drainage footplate, suture abscess, and leaks; sometimes, although the tube is patent, encapsulation of the drainage plate (due to fibrosis) may hamper aqueous drainage, necessitating a revision tube-shunt surgery

Readings

Ahmed IIK, De Francesco T, Rhee D, et al. Long-term Outcomes from the HORIZON Randomized Trial for a Schlemm’s Canal Microstent in Combination Cataract and Glaucoma Surgery. Ophthalmology. 2022;129(7):742-751. doi:10.1016/j.ophtha.2022.02.021; Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): A multicentre randomised controlled trial. Lancet. 2019;393(10180):1505-1516. doi:10.1016/S0140-6736(18)32213-X; Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial: Six-year results of primary selective laser trabeculoplasty versus eye drops for the treatment of glaucoma and ocular hypertension. Ophthalmology. 2023;130(2):139-151. doi:10.1016/j.ophtha.2022.09.009; Gedde SJ, Feuer WJ, Lim KS, et al. Treatment outcomes in the Primary Tube Versus Trabeculectomy Study after 3 years of follow-up. Ophthalmology. 2020;127(3):333-345. doi:10.1016/j.ophtha.2019.10.002; Iverson SM, Schultz SK, Shi W, et al. Effectiveness of single-digit IOP targets on decreasing global and localized visual field progression after filtration surgery in eyes with progressive normal-tension glaucoma. J Glaucoma. 2016;25(5):408-414. doi:10.1097/IJG.0000000000000240; Kass MA, Heuer DK, Higginbotham EJ, et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol. 2002;120(6):701-713; discussion 829-830. doi:10.1001/archopht.120.6.701; Kass MA, Heuer DK, Higginbotham EJ, et al. Assessment of cumulative incidence and severity of primary open-angle glaucoma among participants in the Ocular Hypertension Treatment Study after 20 years of follow-up. JAMA Ophthalmol. 2021;139(5):1-9. doi:10.1001/jamaophthalmol.2021.0341; Mansberger SL, Gordon MO, Jampel H, et al. Reduction in intraocular pressure after cataract extraction: the Ocular Hypertension Treatment Study. Ophthalmology. 2012;119(9):1826-1831. doi:10.1016/j.ophtha.2012.02.050; Nordstrom BL, Friedman DS, Mozaffari E, et al. Persistence and adherence with topical glaucoma therapy. Am J Ophthalmol. 2005;140(4):598-606. doi:10.1016/j.ajo.2005.04.051; Singh K. Transactional care and the looming glaucoma public health crisis. Ophthalmology. 2024;131(8):877-879. doi:10.1016/j.ophtha.2024.04.017; Singh K, Sherwood MB, Pasquale LR. Trabeculectomy must survive!. Ophthalmol Glaucoma. 2021;4(1):1-2. doi:10.1016/j.ogla.2020.08.009; Stone JL, Robin AL, Novack GD, et al. An objective evaluation of eyedrop instillation in patients with glaucoma. Arch Ophthalmol. 2009;127(6):732-736. doi:10.1001/archophthalmol.2009.96.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Kuchtey was recorded at the 23rd Annual Downeast Ophthalmology Symposium, held September 27-29, 2024, in Bar Harbor, ME, and presented by The Maine Society of Eye Physicians and Surgeons. For more information about upcoming CME activities from this presenter, please visit https://maineeyemds.com. Audio Digest thanks Dr. Kuchtey and The Maine Society of Eye Physicians and Surgeons for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 1.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 1.00 CE contact hours.

Lecture ID:

OP630402

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.