Microinvasive Glaucoma Surgery: An Evidence-Based Review

Figures & data

Figure 1. Summary of the different types of MIGS. A. Trabectome. B. iStent inject. C. Kahook Dual Blade. D. XEN Gel Stent. E. Hydrus

TM = trabecular meshwork; AC = anterior chamber; nitinol® = alloy of nickel and titanium.Source of images are from the manufacturer websites of each respective MIGS device and receive credit in the References section. Labels found in the images are the original work of the authors of this review article.

Table 1. Trabectome®

Study	Design	Population	Number of Eyes	Intervention	Baseline IOP (mmHg)	Mean IOP reduction (mmHg)	Absolute IOP reduction (%)	Final IOP (mmHg)	% reaching ≥ 20% IOP reduction	Baseline # of Medications	Mean Medication Reduction	Final # of Medications	Most Common Complications (%)	Additional Surgeries (%)	Follow-up Period (months)
Minckler et al., 2005	P	any stage OAG	37	Trabectome® alone	28.2 ± 4.4	11.8	40.0	16.4 ± 2.0	NR	1.2 ± 0.6	0.8	0.4 ± 0.6	59.0: blood reflux, 13.0: minor Descemet’s injury	2.7	12
Mizoguchi et al., 2015	P	any stage POAG or PXG	82	Trabectome® alone	22.3 ± 6.8	8.3	23.0 ± 25.3	14.0 ± 3.0	23.0	2.8 ± 0.8	no significant difference	no significant difference	5.0: IOP spike, 23.0: hyphema, 77.0: microhyphema	15.0	24
Bussel et al., 2015	P	history of failed trabeculectomy at least 3 months prior	58△	Trabectome® alone	23.7 ± 5.5△	7.5△	28.0△	16.2 ± 3.9△	81.0△	2.8 ± 1.2△	0.8△	2.0 ± 1.3△	5.0: transient hypotony△	19.0△	12
			15▲	phaco/Trabectome®	20.0 ± 5.9▲	no significant difference▲	19.0▲	no significant difference▲	87.0▲	2.5 ± 1.6▲	0▲	no significant difference▲	14.0: transient hypotony▲	13.0▲
Parikh et al., 2016	R + CM	any stage and type of OAG	255△	Trabectome® alone	24.7 ± 8.0△	8.8△	21.0△	15.9 ± 3.5△	NR	2.8 ± 1.4△	0.9△	1.9 ± 1.3△	NR	NR	12
			498▲	phaco/Trabectome®	20.7 ± 6.4▲	5.2▲	18.0▲	15.5 ± 3.6▲		2.3 ± 1.2▲	0.6▲	1.7 ± 1.3▲
Esfandiari et al., 2019	R	any stage and type of glaucoma	93	phaco/Trabectome®	20.0 ± 5.6	4.4	NR	15.6 ± 4.6	67.5	1.8 ± 1.2	0.8	1.0 ± 1.2	48.4: hyphema, 27.0: IOP spike	NR	60
Yousef et al., 2020	R + CM	any stage and type of glaucoma	39▲	phaco/Trabectome®	18.3 ± 5.1▲	4.1▲	22.4▲	14.2 ± 3.5▲	NR	2.7 ± 1.2▲	1.2▲	1.5 ± 1.4▲	NR	2.6▲	24
			39✫	phaco/iStent inject®	18.3 ± 5.1✫	0.5✫	2.7✫	18.8 ± 9.0✫		2.7 ± 1.2✫	0.7✫	2.0 ± 1.5✫		2.6✫

P = prospective; R = retrospective; R+CM = retrospective with case matching; NR = not recorded; OAG = open-angle glaucoma; POAG = primary open-angle glaucoma; PXG = pseudoexfoliative glaucoma; IOP = intraoper ative pressure; phaco = cataract surgery; △ = Trabectome® alone; ▲ = phaco/Trabectome®; ✫ = phaco/iStent inject®

Table 2. iStent inject®

Study	Design	Population	Number of Eyes	Intervention	Baseline IOP (mmHg)	Mean IOP Reduction (mmHg)	Absolute IOP Reduction (%)	Final IOP (mmHg)	% reaching ≥20% IOP reduction	Baseline # of Medications	Mean Medication Reduction	Final # of Medications	Most Common Complications (%)	Additional Surgeries (%)	Follow-up Period (months)
Fea et al., 2014	P, RCT	mild-to-moderate OAG uncontrolled on 1 medication, 97% phakic	94■	iStent inject® alone	25.2 ± 1.4■*	12.2 ± 2.5■	48.4■	13.0 ± 2.3■	94.7■	NA	NA	NA	1.0: IOP spike■	NR	12
			98Δ		24.8 ± 1.7Δ*	11.6 ± 2.2Δ	46.8Δ	13.2 ± 2.0Δ	91.8Δ				2.0: discomfortΔ
Voskanyan et al., 2014	P	phakic or pseudophakic subjects with uncontrolled OAG on at least 2 IOP-lowering medications	99	iStent inject® alone	26.3 ± 3.5*	10.2	39.7	15.7 ± 3.7	72.0	2.2 ± 0.4	NR	NR	10.1: elevated IOP, 3.0: stent obstruction, 1.0: progression of pre-existing cataract treated with phaco, 1.0: allergic reaction to IOP-lowering medication, 1.0: stent malposition, 1.0: intraocular inflammation, 1.0: subconjunctival hemorrhage	6.1	12
Hengerer et al., 2019	P	POAG, NAG, PXG, or secondary glaucoma diagnosis that is uncontrolled despite mediction or surgical intervention	44	iStent inject® alone	25.3 ± 6.0	10.7	42.0	14.6 ± 2.0	87.9	3.0 ± 0.9	2.4	0.6 ± 0.8	4.5: cataract progression, 2.3: uveitis	4.5	36
Guedes et al., 2019	R	early, moderate, or advanced OAG, cataract requiring surgery, need for IOP and/or medication reduction, at least 6 months of follow up data	35★	phaco/iStent inject® vs phaco/iStent®	17.3 ± 3.0★	4.6★	26.6★	12.7 ± 1.8★	NR	2.3 ± 1.0★	1.0★	0.4★	0★	0★	6
			38▲		16.5 ± 3.9▲	2.6▲	15.8▲	13.9 ± 2.3▲		1.8 ± 0.9▲	1.4▲	0.4▲	2.6: anterior synechiae - corrected with Nd:YAG laser iridotomy▲	5.3▲
Salimi et al., 2019	R, P	any stage OAG	118	phaco/iStent inject®	17.0 ± 3.8	2.8	17.8	14.0 ± 2.7	NR	2.3 ± 1.3	1.3	1.0 ± 1.1	11.0: IOP spike, 5.0: microhyphema, 6.0: rebound iritis	0	12
Yousef et al., 2019	R + CM	any stage OAG	39★	phaco/iStent inject® vs phaco/Trabectome®	18.3 ± 5.1★	0.0★	0.0★	no significant difference from baseline★	95.0★	2.7 ± 1.2★	0★	no significant difference from baseline★	0★	3.0★	24
			39☆		18.3 ± 5.1☆	4.1☆	22.4☆	14.2 ± 3.5☆	97.0☆	2.7 ± 1.2☆	1.2☆	1.5 ± 1.4☆	0☆	5.0☆
Samuelson et al., 2019	P	mild-to-moderate POAG, preoperative IOP ≤24 mmHg on 1–3 medications, unmedicated diurnal iOP 21–36 mmHg, cataract requiring surgery	387★	phaco/iStent inject® vs phaco alone	24.8 ± 3.3 (diurnal IOP)★	7.0 ± 4.0★	31.0★	17.1 ± 3.6★	75.8★	1.6 ± 0.8★	1.2★	0.4 ± 0.8★	16.1: ocular surface disease, 6.2: stent obstruction, 5.7: inflammation, 2.8: ocular allergies, 2.6: loss of BCVA, 2.6: posterior vitreous detachment★	5.4★	24
			118□		24.5 ± 3.1 (diurnal IOP)□	5.4 ± 3.7□	27.0□	17.8 ± 3.5□	61.9□	1.5 ± 0.7□	0.7□	0.8 ± 1.0□	16.8: ocular surface disease, 4.2: intraocular inflammation, 3.4: ocular allergies, 4.2: loss of BCVA, 4.2: posterior vitreous detachment□	5.0□
Neuhann & Neuhann, 2020	R	any stage OAG	164	phaco/iStent inject®	20.3 ± 6.1	5.4	26.6	14.9 ± 1.9	54.5	2.1 ± 1.1	1.7	0.4 ± 0.8	0	0.6	24

P = prospective; R = retrospective; R+ CM = retrospective and case matching; RCT = randomized control trial; NR = not recorded; NA = not applicable; POAG = primary open angle glaucoma; NAG = narrow-angle glaucoma; PXG = pseudoefoliative glaucoma; OAG = open-angle glaucoma; IOP = intraocular pressure; BCVA = best corrected visual acuity; phaco = cataract surgery; * = washed-out IOP; ★ = phaco/iStent inject®; ■ = iStent inject® alone; ▲ = phaco/iStent® implant; ☆ = Trabectome®; Δ = latanoprost-timolol; □ = phaco alone

Table 3. Kahook Dual Blade®

Study	Design	Population	Number of Eyes	Intervention	Baseline IOP (mmHg)	Mean Reduction (mmHg)	Absolute IOP Reduction (%)	Final IOP (mmHg)	% reaching ≥20% IOP reduction	Baseline # of Medications	Mean Medication Reduction	Final # of Medications	Most Common Complications (%)	Additional Surgeries (%)	Follow-up Period (months)
Sieck et al., 2018	R	all glaucoma types and severity	197	KDB® ± phaco	17.3 ± 0.4	3.4	19.6	13.9 ± 0.3	72.0	2.1 ± 0.1	0.5	1.6 ± 0.1	17.0: hyphema	0.0	12
Berdahl et al., 2018	R	all glaucoma types and severity	53	KDB® alone	23.5 ± 1.1	8.5	36.2	15.0 ± 6.0	69.8	2.5 ± 0.2	1.0	1.5 ± 0.2	15.0: microhyphema	4.0	6
Salinas et al., 2018	R	severe or refractory OAG and ACG	52	KDB® alone	18.4 ± 6.1	4.5	24.0	13.9 ± 3.5	57.7	2.5 +- 1.0	1.2 ± 1.3	1.4 ± 1.1	36.5: hyphema, 13.5: IOP spike	2.0	6
Dorairaj et al., 2018	R	any stage OAG	237Δ	phaco/KDB®	17.9 ± 4.4Δ	4.2Δ	24.0Δ	13.6 ± 2.7Δ	56.1Δ	1.7 ± 0.9Δ	1.1Δ	0.6 ± 1.0Δ	6.3: IOP spike, 4.0: hyphemaΔ	0.0Δ	6
			198▲	phaco/iStent®	16.7 ± 4.4▲	2.7▲	16.4▲	13.9 ± 2.7▲	43.9▲	1.9 ± 0.9▲	0.9▲	1.0 ± 1.0▲	13.0: IOP spike, <1.0: hyphema▲	0.0▲
Miller et al., 2019	R	uveitic glauoma	16	KDB® ± phaco	28.1 ± 8.5	10.7	38.1	17.4 ± 4.7	NR	3.6 ± 0.9	1.5 ± 1.5	2.1 ± 1.7	6.0: CME, 6.0: hyphema	25.0	9
Dorairaj & Tam, 2019	R	ACG	42	phaco/KDB®	25.5 ± 0.7	12.7 ± 0.8	48.8	12.8 ± 0.4	100.0	2.3 ± 0.1	2.2 ± 0.1	0.1 ± 0.1	19.0: hyphema	0.0	6
Lee et al., 2019	R	mild-to-moderate OAG	44Δ	phaco/KDB®	17.2 ± 7.0Δ	2.5 ± 0.7Δ	14.5Δ	14.8 ± 0.6Δ	NR	1.9 ± 0.2Δ	0.9 ± 0.2Δ	1.0 ± 0.2Δ	18.0: IOP spike, 3.0: CMEΔ	0.0Δ	6
			58▲	phaco/iStent®	16.7 ± 0.4▲	2.5 ± 0.5▲	15.0▲	14.2 ± 0.44▲		1.4 ± 0.4▲	no significant reduction at POM6▲	nosignificant difference▲	1.7: IOP spike, 2.0: CME▲	0.0▲
Hirabayashi et al., 2019	R	early-to-advanced primary or secondary OAG	74Δ	phaco/KDB®	17.3 ± 4.8Δ	2.9 ± 5.4Δ	13.0Δ	15.0 ± 3.5Δ	81.7Δ	2.1 ± 1.3Δ	1.1 ± 1.3Δ	1.1 ± 1.3Δ	4.1: CME, 2.7: hyphema (after POW2)Δ	9.5Δ	6
			27☆	phaco/360° trabeculectomy (TRAB™360/GATT)	18.3 ± 5.1☆	2.9 ± 6.8☆	6.2☆	16.0 ± 3.9☆	84.6☆	2.5 ± 1.3☆	1.2 ± 1.1☆	1.4 ± 1.4☆	11.1: CME, 1.4: hyphema (after POW2), 7.4: steroid-related IOP spike☆	22.2☆
ElMallah et al., 2020	R	all glaucoma types and severity	42	KDB® alone	21.6 ± 0.8	3.9	14.9	16.5 ± 0.8	42.9	2.5 ± 0.2	no significant reduction at POM12	no significant difference	NA	14.0	12

KDB® = Kahook Dual Blade®; R = retrospective; NR = not reported; NA = not applicable; OAG = open-angle glaucoma; ACG = angle-closure glaucoma; IOP = intraocular pressure; POW2 = postoperative week 2; CME = cystoid macular edema; GATT = gonioscopy-assisted transluminal trabeculotomy; phaco = cataract surgery; Δ = phaco/KDB®; ▲ = phaco/iStent®; ☆ = phaco/360° trabeculectomy (TRAB™360/GATT)

Table 4. XEN® Gel Stent

Study	Design	Population	Number of Eyes	Intervention	Baseline IOP (mmHg)	Mean IOP Reduction (mmHg)	Absolute IOP reduction (%)	Final IOP (mmHg)	% reaching ≥20% IOP reduction	Baseline # of Medications	Mean Medication Reduction	Final # of Medications	Most Common Complications (%)	Needling (%)	Additional Surgeries (%)	Follow-up Period (months)
Grover et al., 2017	P	refractory glaucoma, failed a prior glaucoma procedure and/or uncontrolled IOP on maximally tolerated medical therapy	65★	XEN® Gel Stent, ab interno, open conjunctiva	25.1 ± 3.7★	9.1★	35.6★	15.9 ± 5.2★	75.4★	3.5 ± 1.0★	1.8★	1.7 ± 1.5★	24.6: hypotony, 21.5: IOP increase (≥10 mmHg from baseline), 9.2: AC tap, 9.2: wound leak/dehiscence, 7.7: wound repair, 4.6: hyphema, 3.1: choroidal effusion, 1.5: AC fill, 1.5: bleb leak, 1.5: corneal edema★	32.3★	13.8★	12
Mansouri et al., 2018	P	OAG and uncontrolled IOP despite medical treatment	40■	XEN® Gel Stent alone, ab interno, closed conjunctiva vs phaco/XEN® Gel Stent, ab interno, closed conjunctiva	20.0 (17.0, 23.0); median (IQR)■	8.0; median■	40.0 (median)■	12.0■	81.0■	2.5 (1.5, 4); median (IQR)■	NR	0	3.4: bleb revision, 2.0: BCVA loss (≥2 lines), 2.0: device damage during needling, 1.4: choroidal detachment, 1.4: ME, 1.4: wound leak, 1.4: steroid response; 0.7: hyptony (IOP <6 mmHg, persisting beyond POM1), 0.7: IOP ≥10 mmHg over baseline	45.0■	4.7	12
			87●■		18.0 (14.0, 23.0); median (IQR)●■	4.1; median●■	22.9 (median)●■	13.9●■	56.1●■	2.0 (1, 3); median (IQR)●■				34.0●■
Reitsamer et al., 2019	P	moderate POAG, medically uncontrolled, use 1–4 topical IOP-lowering medications	114■	XEN® Gel Stent alone ab interno, closed conjunctiva vs phaco/XEN® Gel Stent, ab interno, closed conjunctiva	21.7 ± 3.8■	6.4 ± 5.2■	28.2■	15.4■	62.8■	2.7 ± 0.9■	1.8 ± 1.3■	1.2 ± 1.2■	4.6: hyphema, 2.8: device fracture, 2.8: IOP increase, 2.3: hypotony, 2.3: YAG capsulotomy, 1.8: choroidal effusion, 1.8: conjunctival erosion, 0.9: iritis, 0.9: drug allergy, 0.9: subconjunctival hemorrhage	43.9■	6.4	24
			88●■		21.0 ± 3.4●■	5.9 ± 4.6●■	27.2●■	14.9●■	69.3●■	2.5 ± 0.9●■	1.6 ± 1.2●■	1.0 ± 1.0●■		37.5●■
Olgun et al., 2020	R	any stage OAG	114Δ■	XEN® Gel Stent, ab interno, closed conjunctiva ± phaco vs GATT ± phaco	24.3 ± 3.8Δ■	10.5Δ■	57.9Δ■	13.8 ± 2.1Δ■	97.4Δ■	3.4 ± 0.5Δ■	1.6Δ■	1.8 ± 1.8Δ■	26.3: transient hyphema, 1.8: implant dislocation, 0.9: hypertrophic bleb, 0.9: endophthalmitis, 0.9: iridodialysisΔ■	31.5Δ■	4.4Δ■	24
			107▲		24.9 ± 5.9 ▲	9.6▲	37.1▲	15.3 ± 3.8 ▲	89.7▲	3.3 ± 0.6 ▲	2.1▲	1.2 ± 0.4 ▲	28.0: transient hyphema, 0.9: iridodialysis, 0.9: toxic anterior segment syndrome, 0.9: suprachoridal hemorrhage▲	NA▲	6.5▲
Ucar & Cetinkaya, 2020	R	pseudophakic and POAG, medically uncontrolled	43□	XEN® Gel Stent, ab externo, closed conjunctiva vs XEN® Gel Stent, ab interno, closed conjunctiva	29.2 ± 6.1□	18.4□	NR	10.8 ± 2.1□	81.5□	2.7 ± 1.0□	2.4□	0.3 ± 0.4□	7.0: hypofiltration, 4.7: extended implant into AC, 4.7: implant shortening, 2.3: implant drop, 2.3: overfiltration (hypotonous)□	27.9□	1.5□	12
			44■		27.4 ± 8.6■	16.1■		11.3 ± 1.7■	82.3■	2.7 ± 1.1■	2.4■	0.3 ± 0.3■	4.5: hypofiltration, 2.3: extended implant into AC, 2.3: implant shortening, 2.3: implant outside conjunctiva, 2.3: overfiltration (hypotonous), 2.3: malignant glaucoma■	45.5■	1.9■

P = prospective; R = retrospective; NR = not recorded; NA = not applicable; OAG = open-angle glaucoma; POAG = primary open-angle glaucoma; IOP = intraocular pressure; BCVA = best corrected visual acuity; AC = anterior chamber; CME = cystoid macular edema; ME = macular edema; POM1 = postoperative month 1; GATT = gonioscopy-assisted transluminal trabeculotomy; phaco = cataract surgery; △ = XEN® Gel Stent with or without cataract surgery; ■ = ab interno, closed conjunctiva; ★ = ab interno, open conjunctiva; □ = ab externo, closed conjunctiva; ▲ = GATT with or without cataract surgery; ● = phaco

Table 5. Hydrus®

Study	Design	Population	Number of Eyes	Intervention	Baseline IOP (mmHg)	Mean IOP Reduction (mmHg)	Absolute IOP Reduction (%)	Final IOP (mmHg)	% reaching ≥ 20% IOP reduction	Baseline # of Medications	Mean Medication Reduction	Final # of Medications	Most Common Complications (%)	Additional Surgeries (%)	Follow-up Period (months)
Samuelson et al., 2019	P-RCT	mild-mod POAG	369Δ	phaco/Hydrus® vs phaco alone	25.5 ± 3.0Δ*	7.6Δ	31.8Δ	17.4 ± 3.7Δ	77.3Δ	1.7 ± 0.9Δ	1.4Δ	0.3 ± 0.8Δ	1.6: hyphema, 5.6: uveitis, 0.5: IOP spike, 14.9: focal synechiaeΔ	1.1Δ	24
			187▲		25.4 ± 2.9▲*	5.3▲	24.4▲	19.2 ± 3.8▲	57.8▲	1.7 ± 0.9▲	1.0▲	0.7 ± 0.9▲	3.7: uveitis, 2.7: IOP spike, 2.1: synechiae▲	2.7▲
Laspas et al., 2019	P-RCT	any stage OAG	50Δ	phaco/Hydrus® vs phaco alone	26.4 ± 4.2Δ*	8.1Δ	30.7Δ	18.3 ± 4.0Δ	64.0Δ	2.0 ± 1.0Δ	1.3Δ	0.7Δ	2.0: CMEΔ	4.0Δ	36
			50▲		26.6 ± 4.2▲*	6.0▲	22.6▲	20.6 ± 5.3▲	46.0▲	2.0 ± 1.1▲	0.7▲	1.3▲	NR	NR
Ahmed et al., 2019	P-RCT	phakic and pseudophakic, mild-to-moderate OAG	75☆	Hydrus® alone vs iStent inject® alone	19.0 ± 3.9☆	1.7 ± 4.0☆	8.9☆	17.3 ± 3.7^☆	30.0☆	2.5 ± 0.7☆	1.6 ± 1.2☆	1 ± 1.1☆	6.8: PAS, 5.4: device obstruction in iris/other tissue, 4.1: IOP spike (> 10 mmHg), 2.7: BCVA loss > 2 lines at 12 months, 2.6: new cataract☆	0☆	12
			77★		19.1 ± 3.6★	1.0 ± 4.0★	5.2★	18.1 ± 3.7★	9.0★	2.7 ± 0.8★	1.0 ± 1.2★	1.7 ± 1.4★	13.2: device obsturiction in iris/other tissue, 5.2: IOP spike (> 10 mmHg), 1.3: BCVA loss > 2 lines at 12 months, 1.3: new cataract★	2.6★
Jones et al., 2019	P-RCT	mild-to-moderate POAG, on 1–4 IOP-lowering medications	219Δ	phaco/Hydrus® vs phaco alone	25.6 ± 3.2Δ*	8.1Δ	31.6Δ	17.5 ± 3.9Δ*	78.5Δ	1.6 ± 0.8Δ	1.7Δ	0.4 ± 0.8Δ	6.8: synechiae, 4.6: uveitis/iritis, 2.7: device malposition, 1.8: corneal abrasion, 1.8: subconjunctival hemorrhage, 1.8: device obstruction, 1.4: hyphema, 0.9: IOP spike (≥ 10 mmHg)Δ	0.5Δ	24
			112▲		25.3 ± 2.9▲*	6.0▲	23.2▲	19.3 ± 4.2▲*	54.4▲	1.6 ± 0.9▲	0.9▲	0.8 ± 0.9▲	0.9: synechiae, 0.9: hyphema, 2.7: IOP spike (≥ 10 mmHg)▲	2.7▲

P-RCT = prospective randomized control trial; NR = not reported; POAG = primary open-angle glaucoma; OAG = open-angle glaucoma; IOP = intraocular pressure; BCVA = best corrected visual acuity; PAS = peripheral anterior synechiae; phaco = cataract surgery; * = washed-out IOP; Δ = phaco/Hydrus® ▲ = phaco alone; ☆ = Hydrus® alone; ★ = iStent inject® alone