XEN^® Gel Stent: A Comprehensive Review on Its Use as a Treatment Option for Refractory Glaucoma

Figures & data

Table 1 Definitions of Success

	Definition of Complete Success (CS)	Definition of Qualified Success (QS)	Definition of Failure (F)
A	>5 and <18 mm Hg and reduction >20% without medications	>5 and <18 mm Hg and reduction >20% with medications	Loss of light perception acuity or worse, need for additional glaucoma surgery, IOP <5 mm Hg, less than 20% IOP reduction
A1	>5 and <18 mm Hg	>5 and <18 mm Hg with medications
A2	>5 and <18 mm Hg and reduction >20% without medications or needling	>5 and <18 mm Hg and reduction >20% with medications but without needling	Loss of light perception acuity or worse, need for additional glaucoma surgery, IOP <5 mm Hg, less than 20% IOP reduction
A3	Reduction >20% without medications	5–18 mm Hg and reduction >20% with medications	Loss of light perception acuity or worse, need for additional glaucoma surgery, IOP <5 mm Hg, less than 20% IOP reduction
B	>5 and <15 mm Hg and ≥ 30% reduction from baseline without medications	>5 and <15 mm Hg and ≥ 30% reduction from baseline with medications	Need for additional glaucoma surgery, IOP <5mmHg
C	Percentage of patients achieving >^_20% mean diurnal IOP reduction from baseline on the same number or fewer medications	NO	IOP reduction <20% on the same number of medications or fewer, additional glaucoma surgery
D	IOP<18 or 16 mmHg without any glaucoma medications	IOP<18 or 16 mm Hg with glaucoma medications	Loss of light perception acuity or worse, need for additional glaucoma surgery, less than 20% IOP reduction
D1	IOP<18 mm Hg without any glaucoma medications	IOP<18 mm Hg with a maximum of 2 glaucoma medications	Necessity of three or more medications or additional glaucoma surgery

Table 2 Efficacy Results of Xen Studies

Publication	Study Design	N Eyes at Baseline	N Eyes at Follow-up (Months)	Glaucoma Type	Follow-Up Months	Baseline IOP	IOP at Follow-Up (Months)	Delta IOP (Δ) % Reduction	Baseline Meds	Meds at Follow-Up (Months)	Delta Meds % Reduction	Success/Failure Criteria	% Successful at (Months)	Reoperation Rate
Pérez-Torregrosa et al 2016^Citation23	Prospective non-controlled and nonrandomized study	30 Xen45+Phaco	28 (12)	30 PACG	12	21.2±3 mmHg	15.03±2.47 mmHg (12)	Δ=6.17 mmHg 29.34% (p < 0.001)	3.07±0.69	0.17 ± 0.65 (12)	Δ=2.9 94.57% (p < 0.001)	1) IOP red ≤18 mmHg w/o meds	1) 90% (12)	0%
Heidinger et al 2016^Citation27	Retrospective study	61 Xen45 or 138 Xen45 + Phaco	199 (12)	113 POAG 72 PEXG 11 OTHER	12	22.8 ± 6.9 mmHg	17.1 ± 5.9 mmHg (12)	Δ=5.7 mmHg 22.7% (P < 0.0001)	2.9 ± 1.0	1.8 ± 1.4 (12)	Δ=1.1 37.93% (p<0.001)	1) IOP reduction ≥ 20% 2) IOP <18 mm Hg with med at 12 mo, 1) IOP red ≤ 20% from baseline 2) IOP ≥ 18 mm Hg and need of additional glaucoma surgery	Complete success 15.4% (12) Qualified success 25% (12)	22.1%
Hengerer et al 2017^Citation25	Retropspective analysis	242 Xen45 or Xen45+Phaco	148 (12)	117 POAG 21 PACG 14 NVG 10 UVG	12	32.19 ±9.1 mmHg	14.24 ±4.0 mmHg (12)	Δ=17.95 mmHg 54.1% (P = 0.000; Wilcoxon test)	3.13 ± 1.0	0.3 ± 0.7 (12)	Δ=2.83 95.6% (P = 0.000; Wilcoxon test)	1) IOP red ≥20% and IOP <18 mm Hg w/o med and secondary intervention including needling 2) IOP red ≥20% and IOP <18 mm Hg w or w/o med and secondary intervention including needling	1) 55.4% (12) 2) 73.0% (12)	27.7%
Galal et al 2017^Citation29	Prospective interventional study	13 Xen45 alone or Xen45+Phaco	13 (12)	13 POAG	12	16±4 mmHg	12±3 mmHg (12)	Δ=4 mmHg 25% (p=0.01 Wilcoxon signed-rank test)	1.9 ± 1	0.3 ± 0.49 (12)	Δ=1.6 84.21% (p = 0.003)	1) IOP reduction ≥20% w/o meds 2) IOP reduction of ≥20% w meds	1) 42% (12) 2) 67% (12)	15.4%
Ozal et al 2017^Citation26	Retrospective consecutive case series study	15 Xen45 alone or Xen45+Phaco	15 (12)	10 POAG 4 PEXG 1 PG	12	36.07 mmHg	16.73 mmHg (12)	Δ=19.3mmHg 53.62% (p<0.001)	3.60 ± 0.50	0.33±0.90 (12)	Δ=3.27 90.83% (p<0.001)	1) Medicated 1yr	1)13.3% (12)	0%
Grover et al 2017^Citation22	Prospective, single arm, open-label, multicenter study	65 Xen45	65 (12)	57 POAG 6 PEXG 1 PG 1 OTHER	12	25.1±3.7 mmHg	15±5.2 mmHg (12)	Δ=10.1 mmHg >27% (p = 0.05)	3.5 ± 1.0	1.7 ±1.5 (12)	Δ=1.8 51.43% (p=0.05)	1) ≥ −20% IOP reduction 2) mean IOP change from baseline	76.3% (12)	8%
Tan et al 2018^Citation21	Retrospective, consecutive, nonrandomized interventional case series	39 Xn45 alone	39(12)	30 POAG 5 PEXG 1 PG 4 UVG 1 NVG 1 STEROID INDUCED	12	24.9 ± 7.8 mmHg	14.5 ± 3.4 mmHg (12)	Δ=10.4 mmHg 41.8% (p<0.005)	3	0.7 (12)	Δ=2.3 76.67% (p<0.005)	1) IOP ≤ 21 mm Hg and ≥ 20% red (Complete: w/o med; Qualified: w med) 2) IOP ≤ 15 mm Hg and ≥ 30% red (Complete: w/o med; Qualified: w med)	1) 87%; 92% (12) 2) 62%; 64% (12)	51.3% (all bleb interventions)
Widder et al 2018^Citation16	Retrospective singlecenter study	233 Xen45 alone or Xen45+Phaco	233 (8.5)	180 POAG 2 PG 44 PEXG 1 JOAG 6 OTHER	8.5 (1–23)	24.3±6.6 mmHg	16.8±7.7 mmHg (8.5)	Δ=7.5 mmHg 30.86% (p < 0.001)	2.6±1.1	0.2±0.7 (8.5)	Δ=2.4 92.31% (p <0.001)	1) “Appropriate IOP” with no meds, no revision 2) “Appropriate IOP” with no meds, 1 revision 3) “Appropriate IOP” with >1 revision	1) 66% (8.5) 2) 90% (8.5) 3) 10% (8.5)	0.9%
Mansouri et al 2018^Citation30	Prospective interventional study	40 Xen 45 alone	87 (12)	15 POAG 10 PEXG 4 OTHER	12	20.0±7.1 mmHg	13.9±4.3 mmHg (12)	Δ=6.1 mmHg 30.5% (p < 0.01)	1.9±1.3	0.5 ± 0.8 (12)	Δ=1.4 73.68% (p < 0.001)	1) ≥20% decrease in IOP 2)unmed IOP <18 or <16 mm Hg 3) med IOP <18 or <16 mm Hg	1)81% (12) 2) <18: 57.5%/<16: 57.5% (12) 3)<18: 80%/<16: 77.5% (12)	10%
		109 Xen45+Phaco		61 POAG 42 PEXG 10 OTHER									1)56.1% (12) 2) <18: 64.2%/<16:57.8% (12) 3)<18: 77.1%, <16: 68.8% (12)
Hohberger et al 2018^Citation31	Monocentric prospective interventional study	81 Xen45 alone	81(6)	72 POAG 31 PEXG 8 OTHER	6	–	–	–	–	–		1) IOP < 18 mmHg at any time point within 6mo of fup w/o med local or further sx 2) IOP <18 mmHg w 1–2 med 3) ≥3med or further sx	1) 46.9% (6) 2) 2.5% (6) 3) 49.4% (6)	–
		30 Xen45+Phaco	30 (6)										53.3% (6) 3.3% (6) 46.7% (6)
De Gregorio et al 2018^Citation24	Nonrandomized prospective	41 Xen45 + Phaco	40 (12)	35 POAG 6 PEXG	12	22.5 ±3.7 mmHg	13.1 ±2.4 mmHg (12)	Δ=9.4 mmHg 41.82% (p <0.05)	2.5±0.9	0.4±0.8 (12)	Δ=2.1 84% (p <0.05)	1) unmed IOP 6–17 mmHg 2) med IOP 6–17 mmHg	1) 80.4% (12) 2) 97.5% (12)	10%
Karimi et al 2019^Citation28	Retrospective review	187 Xen45 or 72 Xen45+ Phaco	259 (12)	208 POAG 17 NTG 13 PEXG 6 PG 6 TRAUMA 5 NVG 1 IATROGENIC 3 OTHER	12	19.3±0.7 mmHg	14.2 ±0.9 mmHg (12)	Δ=5.1 mmHg 26.42% (p < 0.0001)	2.6 ±0.1	0.8 ±0.2 (12)	Δ=1.8 69.23% (p<0.0001)	1) IOP red 2) med red		40.9% (needling)
Reitsamer et al 2019^Citation32	Prospective multicenter nonrandomized trial	120 Xen45 or 98 Xen45 + Phaco	202 (24)	POAG	24	21.4±3.6 mmHg	15.2±4.2 mmHg (24)	Δ=6.2 mmHg 27.8% (p < 0.001)	2.7±0.9	1.1±1.2 (24)	Δ=1.6 59.26% (p < 0.001)	1) IOP reduction ≥ 20% w/o secondary surgical intervention 2) IOP red ≥30% 3) IOP values≤18, ≤15, ≤12 mmHg	1) 65.8% (24) 2) 48.4% (24) 3) 85.1%, 62.7%, 24.2% (24)	41.1% (needling)
Fea et al 2020^Citation33	Prospective multicenter	115 Xen45 or 56 Xen45+ Phaco	149 (12)	134 POAG 27 PEXG 2 JOAG 7 NTG 3 UVG 1 OHT 2 MIXED	12	23.9±7 mmHg	15.5±3.9 mmHg (12)	Δ=8.4 mmHg 35.15% (p <.001)	3.0±1.1	0.5±1.0 (12)	Δ=2.5 83.7% (p < 0.001)	1) IOP ≤18 mmHg w and w/o med 2) IOP ≤16 mmHg w and w/o med 3) IOP ≤14 mmHg w and w/o med	1) 81% w 61.3 w/o (12) 2) 70.8w 54 w/o (12) 3) 43.1% w 35% w/o (12)	1 vitrectomy (0.8%) 147 needling (46.2%) 8 trab (4.6%) 1 ahmed valve(0.8%)1baerveldt(0.8%)1 bleb revision (0.8%)

Abbreviations: POAG, primary open-angle glaucoma; PEXG, presudoexfoliative glaucoma; JOAG, juvenile open-angle glaucoma; PACG, angle closure glaucoma; PG, pigmentary glaucoma; NTG, normal tension glaucoma; UVG, uveitic glaucoma; NVG, neovascular glaucoma; OHT, ocular hypertenision; IOP, intraocular pressure; red, reduction.

Table 3 Needling Results of Xen Studies

Publication	Study Design	N Eyes at Baseline	N Eyes at Follow-Up (Months)	Glaucoma Type	Previous Intervention	Total Number and % of Needling/Revision	Type of Needling/Revision	Timing	No. of Repeated Needling	Complications
Pérez-Torregrosa et al 2016^Citation23	Prospective non-controlled and nonrandomized study	30 Xen45+Phaco	28 (12)	30 PACG	-	0	-	-	-	-
Heidinger et al 2016^Citation27	Retrospective study	61 Xen45 or 138 Xen45 + Phaco	199 (12)	113 POAG 72 PXG 11 OTHER 2 PACG 1 NTG	89 (44.7%) TOT 61 (30.7%) glaucoma sx 45 (22.9%) cataract sx 13 (6.5%) other ocular sx	44 (22.1%)	44 (67.7%) FU 12 (18.5%) Dexamethasone 2 (3.1%) mechanic 7 (10.8%) YAG-laser	6d–582d (med 59.5) at 1st needling	25(12.6%) 1 needling 14 (7%) 2 needling 4 (2%) 3 needling 3 (1.5%) REVISION	N/A
Hengerer et al 2017^Citation25	Retropspective analysis	242 Xen45 or Xen45+Phaco	148 (12)	117 POAG 21 ACG 14 NVG 10 UVEITIC	170 (70.2%) iStent 53 (21.9%) trab 35 (14.5%) cyclophoto 20 (8.3%) Phaco 10 (4.1%) laser	41 (27.7%)	27G+BSS (noMMC)	1 w–3mo	N/A	N/A
Galal et al 2017^Citation29	Prospective interventional study	13 Xen45 alone or Xen45+Phaco	13 (12)	13 POAG	None (criteria of exclusion)	4 (30.7%)	27G (noMMC) at slit lamp	1mo (3eyes) 3mo (1eye)	None	N/A
Ozal et al 2017^Citation26	Retrospective consecutive case series study	15 Xen45 alone or Xen45+Phaco	15 (12)	10 POAG 4PXG 1PG	3 (20%)	None	-	-	-	-
Grover et al 2017^Citation22	Prospective, single-arm, open-label, multicenter study	65 Xen45	52 (12)	57 POAG 6 PXG 1 PG 1 OTHER	45 (69.2%) cataract sx 55 (84.6%) glaucoma sx	21 (32.3%)	Mechanic removal of adhesions	N/A	21 (32.3%) 1 needling 6 (9.2%) 2 needling 1 (1.5%) 3 needling	N/A
Tan et al 2018^Citation21	Retrospective, consecutive, nonrandomized interventional case series	39 Xn45 alone	39(12)	30 POAG 5 PXG 1 PG 4 UVEITIC 1 NVG 1 STEROID INDUCED	12 (30.8%) phaco 3 (7.7%) trab 2 (5.13%) iStent	20 (51.3%)	FU at slit lamp	1w–5mo	2 (1–4)	None
Widder et al 2018^Citation16	Retrospective single-center study	233 Xen45 alone or Xen45+Phaco	233 (8.5)	180 POAG 2 PG 44 PXG 1 JOAG 6 SEC GL	17 (7.3%) trab 6 (2.6%) deep scl 39 (16.7%) ALT/SLT 31 (13.3%) trabectome 6 (2.6%) vtc	80 (34%) 1 revision	Revisional surgery	N/A	23 (10%)	-
Mansouri et al 2018^Citation30	Prospective interventional study	40 Xen 45 alone	87 (12)	15 POAG 10 PXG 4 OTHER	N/A	18 (45%)	27G+MMC 0.01%	158d	N/A	3 (2%) Xen damage
		109 Xen45+Phaco		61 POAG 42 PXG 10 OTHER		37 (34%)		126d
Hohberger et al 2018^Citation31	Monocentric prospective interventional study	81 Xen45 alone	81(6)	72 POAG 31 PXG 8 OTHER	N/A	49.4%	27G+Bevacizumab 1.00mg	N/A	N/A	N/A
		30 Xen45+Phaco	30 (6)			46.7%
De Gregorio et al 2018^Citation24	Nonrandomized prospective	41 Xen45 + Phaco	40 (12)	35 POAG 6 PXG	1 (2.5%) deep sclerectomy	1 (2.5%))needling	N/A	N/A	N/A	N/A
Karimi et al 2019^Citation28	Retrospective review	187 Xen45 or 72 Xen45+ Phaco	259 (12)	208 POAG 17 NTG 13 PXG 6 PG 6 TRAUMA 5 NVG 1 IATROGENIC 3 OTHER	72 (34.4%) SLT 11 (4.2%) trab 7 (3.3%) valve/stent	(40.9%)	30G needle 12 (4.6%) physical 35 (13.5%) pharmacological: 8.5% MMC, 91.5% 5FU 58 (22.45) both	1–3mo	Mean 1.6 per case	N/A
Midha et al 2019^Citation50	Report	40 Xen45	149 (12)	POAG 15 PEXG 10	Criteria of exclusion	18 (45%) Efficacy 81% at 1 yr	N/A	1.15 OR at d1 1.16 OR at w1	36 (24.2%) 1 needling 14 (9.4%) 2 needling 5 (3.4%) 3 needling	IOP at d1 >20 mm Hg -> 80% prob of needling >10 mm Hg ->35% prob
		109 Xen45 + Phaco		POAG 46 PXG 32		37 (34%) Efficacy 56.1% at 1 yr		1.01 OR at d1 1.03 OR at w1
Reitsamer et al 2019^Citation32	Prospective multicenter nonrandomized trial	120 Xen45 or 98 Xen45 + Phaco	202 (24)	POAG	Exclusion criteria	50 (43.9%)	74 (89.2%) antifibrotic agent (MMF, %FU, other)	Mean time to 1st needling 152d	56 (67.5%) 1 needling IOP ≥20%: 59.2% at 12 mo 44.6% at 24mo	N/A
						33 (37.5%)
Fea et al 2020^Citation33	Prospective multicenter	115 Xen45 or 56 Xen+Phaco	149 (12)	134 POAG 27 PXG 2 JOAG 7 NTG 3 UVG 1 OHT 2 Mixed	4 (2.3%) trab 1 (0.6%) deep sclerectomy 1 (0.6%) vtc 1 (0.6%) buckling 47 (27.5%) SLT 1 (0.6%) ALT	79 (46.2%) needling 1 (0.7%) stent revision for exposure Efficacy: 41 (27.5%)	N/A	N/A	41 (27.5%) 1 needling 21 (14%) 2 needling 10 (6.7%) 3 needling 3 (2%) 4 needling 2 (1.3%) 5 needling 2 (1.3%) 6 needling	1 (0.6%) perforation after needling

Abbreviations: POAG, primary open-angle glaucoma; PEXG, presudoexfoliative glaucoma; JOAG, juvenile open angle glaucoma; PACG, angle closure glaucoma; PG, pigmentary glaucoma; NTG, normal tension glaucoma; UVG, uveitic glaucoma; NVG, neovascular glaucoma; OHT, ocular hypertenision; IOP, intraocular pressure; FU, follow-up; trab, trabeculectomy; vtc, vitrectomy; SLT, selective laser trabeculoplasty; ALT, argon laser trabeculoplasty; prob, probability; ciclophoto, cuclophotocoagulation; sx, surgery; FU, follow-up; MMC, mitomycin; d, day; w, week; mo, month; yr, year.

Table 4 Needling Results of Xen Studies

Publication	Intervention	Hyphema	Hypotony (Transient or Persistent)	Choroidal Detachment	Device Obstruction	Device Malposition	Stent Exposure	IOP Spike	Secondary Surgical Intervention				Other
Pérez-Torregrosa et al 2016^Citation23	30 Xen45+Phaco	-	-	-	-	-	-	-	-				Intraop subconj hemorrhage 36.6% Intraop AC hemorrhage 86.6% Intraop hemorrhage at scleral exit point 20% Intraop relocation 20% Intraop reimplant 3.3% Encapsulation of filtration bleb 3.3%
Heidinger et al 2016^Citation27	61 Xen45 +138 Xen45+Phaco	3.5%	8%	-	-	-	1.5%	-	22.1% needling 14.1% rate of reoperation: 53.6% trabeculectomy 28.6% second xen 14.3% TSCPC 3.6% laser trabeculoplasty				Hyphema 3.5%, Aqueous misdirection 0.5% Late-onset endophthalmitis 0.5%
Hengerer et al 2017^Citation25	242 Xen45 or Xen45+Phaco	1.7%	4.0% (T) 0.8% (P)	-	-	-	-	-	27.75% needling 5.8% other: 5% 2nd Xen 0.8% cyclophoto				Intraop conj bleeding 5.0% Cysts 12.0%
Galal et al 2017^Citation29	13 Xen45 or Xen45+Phaco	-	-	15.4%	-	-	7.7%	-	30.7% needling 15.4% trabeculectomy				-
Ozal et al 2017^Citation26	15 Xen45 or Xen45+Phaco	-	-	-	-	6.6%	-	-	-				Intraop bleeding 6.6%
Grover et al 2017^Citation22	65 Xen45	4.6%	24.6%	3.1%	-	1.5%	1.5%	21.5%	32.3% needling 9.2% secondary glaucoma sx w explant 1.5% tube 1.5% cyclophoto				Hyphema 4.6%, seidel positive 9%, macular edema 1.5%, flat AC 9.2, corneal edema 1.5%, vitreous hemorrhage 3% BCVAloss 6.2%
Tan et al 2018^Citation21	39 Xen45 alone	2.8%	18% (T) 3% (P)	-	7.7%	-	-	-	51.3% bleb intervention (17% needling 28% FU of post-trab eyes)				–
Widder et al 2018^Citation16	233 Xen45 or Xen45+Phaco	5.6%	–	3.4% (spont solved in 2w)	–	0.4%	0.9%	2.6%	27% pseudophakic 47% phakic 45% combined				macular edema 1.7% fibrin reaction anterior chamber 0.9% shallow AC 1.3% avascular filtering bleb 8.9%
Mansouri et al 2018^Citation30	40 Xen45 alone	0.7%	0.7% (P)	1.4%	0.7%	0.7%	–	0.7%	37% needling 4.7% deep sclerectomy 1.4% tube 0.7% 2^nd Xen 0.7% Xen repositioning				BCVA loss≥2lines 2% Stent damage 2% Diplopia 0.7% Hypotony maculopathy 0.7% Macular edema 1.4% Retinal detachment 0.7% Steroid response 1.4%, Leak 1.4%
	109 Xen45 + Phaco
Hohberger et al 2018^Citation31	81 Xen45 alone	–	–	–	–	–	–		49.4% needling				–
	30 Xen45 + Phaco								46.7% needling
De Gregorio et al 2018^Citation24	41 Xen45 + Phaco	–	1 (T)	2.5%	2.5%	2.5%	–	–	2.5% needling 2.5% trab				2.5% explantation
Karimi et al 2019^Citation28	187 Xen45 + 72 Xen45+ Phaco	–	30.1%	–	–	–	–	0.8%	40.9% needling 9.3% secondary filtration surgery				IOP spikes 12.7% dysesthetic blebs 3.9% erosion/exposure 2.3%, endophthalmitis 0.4%
Reitsamer et al 2019^Citation32	120 Xen45 or 98 Xen45 + Phaco	4.6%	2.3%	1.8%	1.4%	0.5%	1.8%	2.8%	43.9% needling Xen alone 37.5% needling Xen+Phaco 6.4% secondary intervention				Intraop: 2.8% AC bleeding 0.5% iris damage 0.5% SC hemorrhage 0.5% zonular disinsertion Postop: 0.9% dysesthesia 0.9% shallow AC 0.9% subconj hemorrhage 0.5% Endophtalmitis 0.5% macular edema
Fea et al 2020^Citation33	115 Xen45 or 56 Xen45+Phaco	33 (22%)	7 (4.7%)	16 (10.7%)	–	5 (3.4%)	1 (0.7%)	–	7% tot 5.3% trab 0.7% Ahmed valve 0.7% Baerveldt valve 0.7% vtc 0.7% bleb revision for exposure				1 (0.7%) Fibrin reaction in AC 1 (0.7%) stent rupture 1 (0.7%) malignant glaucoma

Abbreviations: Intraop, intraoperative; postop, postoperative; AC, anterior chamber; BCVA, best corrected visual acuity; subconj, subconjunctival; conj, conjunctival; tot, total.

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