Comparison of Clinical Outcomes Following Gel Stent Implantation via Ab-Externo and Ab-Interno Approaches in Patients with Refractory Glaucoma

Figures & data

Table 1 Demographic and Baseline Characteristics of the Patients in Ab Interno and Ab Externo Groups

	Ab Interno	Ab Externo	p value
N (Patients)	94	91
Mean age (years) (Mean ± SD)	75.0 ± 9.56	72.9 ± 13.4	0.231
Gender (%)
Male	47.9%	36.3%	0.110
Female	52.1%	63.7%
N (Eyes)	105	98
Mean Preop IOP (Mean ± SD)	23.3 ± 6.5	24.3 ± 7.2	0.274
Mean IOP lowering medications (Mean ± SD)	3.3 ± 0.8	3.3 ± 0.9	0.749
Mean cup-disc ratio	0.9 ± 0.1	0.9 ± 0.1	0.821
Prior Conjunctival surgery n (%)
N (Eyes)	105	98
Yes	37 (35.2%)	37 (37.8%)	0.710
No	68 (64.8%)	61 (62.2%)
Prior Cataract Surgery n (%)
N (Eyes)*	101	93
Yes	91 (90.1%)	84 (90.3%)	0.958
No	10 (9.9%)	9 (9.7%)

Note: *N <203 because history of prior cataract surgery was not available in some case records.

Figure 1 Mean IOP and percent change in IOP (from baseline) at different time points in eyes implanted with the Xen gel stent via an ab interno or ab externo approach. Error bars indicate standard deviation.

Figure 2 Mean number of medications at each visit in eyes implanted with a Xen gel stent via an ab interno or ab externo approach. Error bars indicate standard deviation.

Figure 3 Non-cumulative frequency distribution (percentage) of various IOP ranges in Xen gel stent eyes. (A) Ab interno group. (B) Ab externo group.

Table 2 Comparison of Eyes Achieving ≥20% Reduction in Intraocular Pressure Between Ab Interno and Ab Externo Group

Time Point	Ab Interno	Ab Externo	p-value
3 M	89%	94%	0.309
6 M	86%	96%	0.050
9 M	95%	85%	0.089
12 M	94%	96%	0.721

Table 3 Complete Success, Qualified Success, and Failure Rates in the Ab Interno and Ab Externo Groups at Different Postoperative Time Points

Different Criteria Used To Evaluate Success And Failure Rates	Ab Interno				Ab Externo
	Time Point (Months)
	3	6	9	12	3	6	9	12
Complete success (without medications)
≥ 20% reduction in IOP from baseline	55%	47%	40%	41%	69%	63%	52%	46%
≥ 20% reduction in IOP from baseline and post-op IOP ≤18 mmHg	55%	47%	40%	41%	68%	63%	52%	46%
≥ 20% reduction in IOP from baseline and post-op IOP ≤15 mmHg	52%	46%	40%	40%	64%	60%	52%	43%
≥ 20% reduction in IOP from baseline and post-op IOP ≤12 mmHg	38%	30%	31%	20%	45%	46%	33%	27%
Qualified success (with same or fewer medications than baseline)
≥ 20% reduction in IOP from baseline	33%	37%	51%	50%	23%	29%	28%	46%
≥ 20% reduction in IOP from baseline and post-op IOP ≤18 mmHg	31%	35%	51%	50%	21%	29%	28%	46%
≥ 20% reduction in IOP from baseline and post-op IOP ≤15 mmHg	25%	30%	32%	41%	18%	26%	26%	41%
≥ 20% reduction in IOP from baseline and post-op IOP ≤12 mmHg	13%	15%	17%	24%	10%	12%	13%	26%
Failure
IOP >18 mmHg or <6 mmHg at any two consecutive visits	8%				4%

Figure 4 Mean IOP and percentage change in IOP (from baseline) in Xen gel stent eyes with and without prior conjunctival surgery. (A) Ab interno group. (B) Ab externo group. Error bars indicate standard deviation.

Figure 5 Mean IOP and percentage change in IOP (from baseline) in Xen gel stent eyes with and without prior cataract surgery. (A) Ab interno group. (B) Ab externo group. Error bars indicate standard deviation.

Table 4 Postoperative Procedures and Adverse Events (at Any Postoperative Visit) Observed in Ab Interno and Ab Externo Groups

	Ab Interno	Ab Externo	p value
Postoperative procedures
5-FU required at any time point	48%	49%	0.846
Bleb needling rate at any time point	40%	39%	0.858
Adverse events
IOP >10 mm Hg from baseline	5%	2%	0.447
Numerical hypotony (≤ 6mmHg)	32%	29%	0.556
Clinical hypotony	1.9%	1.0%	0.602
Choroidal effusions	3%	3%	1
Migrated XEN	1%	3%	0.355
Exposed XEN	1%	3%	0.355
Broken XEN	1%	1%	1
Endophthalmitis	0%	1%	0.483

Abbreviations: FU, Fluorouracil; IOP, Intraocular pressure.