Efficacy and safety of ultrasound cycloplasty versus ahmed glaucoma valve for neovascular glaucoma

Abstract

Purpose

To evaluate the efficacy and safety of Ultrasound Cycloplasty (UCP) versus Ahmed Glaucoma Valve (AGV) implantation in the treatment of neovascular glaucoma.

Methods

A total of 80 patients (80 eyes) were enrolled and assigned to receive either UCP or AGV treatment (40 eyes each). Patients were followed up for 6 months postoperatively. Intraocular pressure (IOP), number of IOP-lowering medications, pain score, visual acuity, and complications were recorded. Complete surgical success was defined as an IOP reduction of ≥ 20% from baseline and maintained between 5 and 21 mmHg, without the need for additional medications or further surgery.

Results

Preoperative baseline characteristics showed no significant differences between the two groups. On postoperative day 1, the AGV group showed a greater reduction in IOP compared to the UCP group (p < 0.01). At 6 months postoperatively, the UCP group demonstrated better outcomes in terms of the IOP reduction rate (61.62% vs. 66.97%, p = 0.04) and pain score (0.13 vs. 0.43, p < 0.01) compared to the AGV group. There were no significant differences between the groups in the number of medications used or the rate of surgical success. The AGV group experienced more complications, commonly including tube blockage and plate exposure.

Conclusion

Both UCP and AGV are effective in reducing IOP. However, UCP resulted in more stable postoperative IOP, fewer complications, and offered better safety and patient comfort.

Introduction

Neovascular glaucoma (NVG) is a severe and refractory form of secondary glaucoma that most commonly arises from ischemic ocular conditions such as diabetic retinopathy (DR), ischemic central retinal vein occlusion (CRVO), and ocular ischemic syndrome (OIS) [1–3]. It is characterized by markedly elevated and often difficult-to-control intraocular pressure (IOP) and is associated with a poor visual prognosis if not treated promptly. The pathogenesis of NVG is closely related to retinal ischemia and hypoxia, which lead to an imbalance between angiogenic and anti-angiogenic factors. This imbalance results in increased expression of pro-angiogenic cytokines, particularly vascular endothelial growth factor (VEGF), which promotes pathological neovascularization of the iris and the anterior chamber angle. The proliferation and contraction of fibrovascular membranes can ultimately lead to peripheral anterior synechiae and secondary angle closure, further elevating IOP [4, 5].

Current management strategies for NVG focus on addressing both the underlying retinal ischemia and the resulting elevation in IOP. Anti-VEGF therapy is frequently used to suppress neovascularization and reduce the activity of angiogenic factors. However, medical therapy alone is often insufficient to control IOP in advanced cases, and surgical intervention is frequently required [1, 6, 7]. Ahmed glaucoma valve (AGV) implantation is one of the most commonly used surgical procedures for the treatment of refractory glaucoma, including NVG. By providing an alternative pathway for aqueous humor drainage, AGV implantation can effectively lower IOP in eyes with compromised conventional outflow pathways [7–9]. However, With the continuous advancement of technology, ultrasound-based techniques have been widely applied in the treatment of glaucoma. Ultrasound Cycloplasty (UCP) is a novel therapeutic approach for glaucoma. It operates in a non-invasive, quantifiable, and precisely focused manner to target the non-pigmented epithelial cells in the ciliary body’s crown region. This technique exhibits dual regulatory effects, it reduces aqueous humor production while simultaneously opening scleral outflow channels to enhance aqueous humor drainage, thereby effectively reducing IOP [10, 11]. Compared to traditional ciliary body surgery, UCP is characterized by shorter operative time, minimally invasive approach, milder postoperative inflammatory responses, and fewer complications. Ultrasound cycloplasty effectively reduces intraocular pressure and may help limit further IOP-related damage to ocular structures such as the optic nerve, offering a minimally invasive treatment option for patients with advanced or refractory glaucoma [12, 13]. In this study, UCP and AGV implantation were used to treat patients with NVG, and the clinical efficacy and safety of the two surgical treatment modalities were compared to provide appropriate treatment options for patients with NVG.

Subjects and methods

Ethical approval

This study was a prospective non-randomized controlled trial conducted at Daqing Eye Hospital. It was approved by the hospital’s Ethics Committee and adhered to the tenets of the Declaration of Helsinki.

Subjects

This study collected medical records of all glaucoma patients who underwent AGV implantation and UCP procedures at Daqing Eye Hospital between December 2023 to October 2024 and met the inclusion and exclusion criteria. A total of 80 cases (80 eyes) were included, comprising 40 cases (40 eyes) in the UCP surgery group and 40 cases (40 eyes) in the AGV implantation group.

Inclusion and exclusion criteria

Inclusion criteria:

1. Patients aged 18–80 years;

2. Receipt of anti-VEGF therapy one week prior to surgery; for all patients requiring retinal photocoagulation, the procedure should be performed one week prior, along with anti-VEGF therapy; PRP was indicated for patients with retinal non-perfusion area ≥ 5 disc areas and obvious ocular neovascularization;

3. IOP > 21 mmHg despite maximum use of IOP-lowering medications(Maximum medical therapy is defined as the sequential or concomitant use of at least three topical ocular hypotensive agents from different mechanistic classes, including a prostaglandin analog, a beta-blocker, an alpha-2 adrenergic agonist, and a carbonic anhydrase inhibitor, to achieve maximal IOP reduction [14]).

4. No prior history of UCP (for patients in the AGV group) or AGV implantation (for patients in the UCP group).

Exclusion criteria:

1. IOP < 21 mmHg;

2. Patients complicated with other vision-affecting ocular disorders, including maculopathy, corneal opacity, retinal detachment, intraocular tumors and lens dislocation [15, 16];

3. Concurrent thyroid disease or pregnancy;

4. Patients with the following systemic comorbidities were excluded: unstable cardiovascular disease, uncontrolled severe hypertension, coagulation dysfunction, severe liver or kidney disease, uncontrolled diabetes mellitus, or active systemic infection [16].

5. Age < 18 years or > 80 years.

6. Inadequate follow-up duration (< 6 months).

Clinical data collection

Demographic data were collected and recorded, including gender, age, eye type, number of IOP-lowering medications used preoperatively, and preoperative pain scores. Record uncorrected distance visual acuity (UDVA) and best corrected visual acuity (BCVA). Perform non-contact tonometry, slit-lamp biomicroscopy, and fundus examination. Use ultrasound biomicroscopy (UBM) to measure anterior chamber depth, white-to-white distance, and axial length.

Surgical technique

Selection of surgical methods: The choice is based on the patient’s specific condition. After a thorough explanation and with full informed consent, the patient selects one suitable approach from the options provided. If only one surgical approach is deemed appropriate for the patient, it is considered the sole treatment option.

AGV

After routine preparation and anesthesia, a conjunctival flap with a dome-shaped base is created in the superotemporal area. The sclera is exposed and hemostasis is achieved with cautery, followed by blunt dissection to the posterior pole. Mitomycin C 0.4% is applied to the area posterior to the equator for 3 min and thoroughly irrigated with copious amounts of saline. The glaucoma drainage device is fixed with pre-placed 6 − 0 sutures 8–10 mm behind the corneal limbus, between the superior rectus and lateral rectus muscles. A 3.0 mm × 4 mm, half-thickness scleral flap is created. A clear corneal side incision is made in the inferotemporal area, and viscoelastic is injected into the anterior chamber. The drainage tube is trimmed to the expected intraocular length of about 1.0 mm, and a 23G needle is used to make a parallel scleral puncture at the corner of the scleral flap at the scleral limbus into the anterior chamber for tube insertion. The scleral flap is sutured with 2 interrupted 10 − 0 sutures to secure the tube, and the conjunctiva is closed with a continuous 8 − 0 suture.

UCP

Following identical disinfection, draping, and anesthesia in the UCP group, the microscope was adjusted for clear visualization and the conjunctival sac was thoroughly irrigated with abundant normal saline. A vacuum suction ring was centered on the operative eye, and an appropriately sized transducer (11, 12, or 13 mm) was selected based on eyeball dimensions. The transducer was submerged in normal saline before device activation. All patients received treatment covering 10 zones sequentially: initial treatment of 6 zones, followed by management of the remaining zones after probe rotation. Upon completion, the vacuum suction ring was removed and the device was turned off, with each single treatment duration lasting 8 s. After UCP procedure, tobramycin-dexamethasone ointment was administered to the operative eye, followed by eye patching and patient returning to the ward.

Postoperative follow-up and outcome measurement

All patients were regularly reviewed on the 1st day, 1 week, 1 month, 3 months, and 6 months postoperatively, and slit lamps were used to examine the anterior segment of the eye, measurement of BCVA using the LogMAR Chart, measuring IOP with the non-contact tonometer. Outcome measures included IOP, the number of hypotensive medications, pain scores, BCVA, and complications. Surgical success was defined based on IOP and number of hypotensive medications used at 6 months postoperatively.

Complete success: ≥20% IOP reduction from baseline; IOP > 5 and ≤ 21 mmHg; no additional interventions.

Qualified success: IOP > 21 mmHg (with ≥ 20% and > 5 mmHg reduction) without medications, or IOP of 5–21 mmHg with fewer medications than preoperatively.

Postoperative complications of both procedures were evaluated as safety, including early hypotony, anterior chamber effusion, conjunctival congestion, corneal edema, drain obstruction, choroidal effusion, suprachoroidal hemorrhage, and uveitis. We also compared the number of patients who were re-treated with anti-VEGF medications within 6 months after surgery in both groups. Early hypotony was defined as IOP < 5 mmHg within one week after surgery.

Patients were instructed to rate pain according to their own feelings, with a score of 0 representing no pain felt, 1–3 being mild pain, 4–6 being moderate pain, and 7–9 being intolerable and severe pain.

Statistical analysis

All data were collected and recorded using an Excel spreadsheet, which were analyzed using GraphPad Prism, and Normality of variables was assessed using the Shapiro-Wilk test. Variables with normal distribution were analyzed by one-way ANOVA, while non-normally distributed variables were analyzed using the Kruskal-Wallis rank-sum test. Within-group differences between preoperative and postoperative measurements were analyzed using the Friedman test, with a threshold of P < 0.05 considered statistically significant.

Results

Baseline characteristics

A total of 80 patients with NVG in 80 eyes were included in this prospective study between December 2023 and October 2024 based on inclusion and exclusion criteria. There were 22 males and 18 females in the UCP group and 25 males and 15 females in the AGV group.

The demographic analysis data of the two groups of patients are detailed in Table 1, and the differences between the two groups in terms of gender, mean age, etiology, PRP performed, preoperative BCVA, Axial length, white-to-white, anterior chamber depth, preoperative IOP, and the number of preoperative medications used were not statistically significant.(P > 0.05).

Table 1.

Comparison of general preoperative information between the two groups

	UCP group	AGVgroup	P
Number of eyes	40	40
Number of patients	40	40
Age (years)	62.93 ± 11.80	59.70 ± 12.00	0.229
Sex, n(%)			0.178
Male	18(45.00%)	25(62.50%)
Female	22(55.00%)	15(37.50%)
Eye involved, n(%)			0.284
Left	20(50.00%)	15(37.50%)
Right	20(50.00%)	25(62.50%)
Etiology, n(%)			0.438
DR	18(45.00%)	16(40.00%)
CRVO	15(37.50%)	20(50.00%)
OIS	7(17.5%)	4(10.00%)
PRP performed, n (%)	26 (65.00%)	24 (60.00%)	0.818
Baseline IOP(SD)	47.38 ± 11.92	44.93 ± 10.65	0.254
Preoperative medications(SD)	3.05 ± 1.63	3.32 ± 1.47	0.661
AL	23.28 ± 0.96	23.44 ± 82	0.448
WTW	11.35 ± 0.51	11.52 ± 0.42	0.102
ACD	2.92 ± 0.63	2.88 ± 0.50	0.986
Visual acuity, n(%)			0.693
Visually intact	12(30.00%)	17(42.50%)
CF	9(22.50%)	5(12.50%)
HM	6(15.00%)	5(12.50%)
LP	6(15.00%)	7(17.5%)
NLP	7(17.5%)	6(15.00%)
BCVA, LogMar	2.04 ± 1.03	2.18 ± 1.32	0.754
Post. 6 m BCVA, LogMar	1.98 ± 1.53	2.01 ± 1.66	0.451

UCP = Ultrasound cycloplasty; AGV = Ahmed glaucoma valve; DR = diabetic retinopathy; CRVO = Central retinal vein occlusion; OIS = Ocular ischemic syndrome; IOP = Intraocular pressure; CF = Count fingers; HM = Hand motion; NLP = no light perception; LP = light perception; SD = Standard deviation; AL = Axial length; WTW = White-to-White; ACD = Anterior Chamber Depth; BCVA = Best Corrected Visual Acuity

IOP

Both groups showed significant IOP reduction from preoperative levels at all follow-ups through 6 months (p < 0.05; Fig. 1). Preoperative IOP was 47.68 ± 9.65 mmHg (UCP) and 44.93 ± 10.61 mmHg (AGV), with no significant intergroup difference. At day 1, AGV achieved greater IOP reduction (68.00% vs. 22.82%), with corresponding IOP values of 14.38 ± 5.73 mmHg versus 36.80 ± 16.48 mmHg (p < 0.05). Significant intergroup differences persisted at 1 week and 6 months (p < 0.05), but not at 1 or 3 months (Table 2).

Fig. 1.

Changes in mean preoperative and postoperative IOP in the two groups

Table 2.

Comparison of IOP and IOP reduction at each time period in the two groups [n; Percentage (%)]

	Preoperative IOP	Post.1d IOP reduction(%)	Post.1w IOP reduction(%)	Post .1 m IOP reduction(%)	Post. 3 m IOP reduction(%)	Post .6 m IOP reduction(%)	P a
UCP group	47.68 ± 9.65	36.80 ± 16.48 22.82	19.10 ± 4.98 59.92	17.18 ± 6.49 63.97	17.38 ± 3.11 63.56	15.75 ± 4.79 66.97	< 0.05a
AGV group	44.93 ± 10.61	14.38 ± 5.73 68.00	15.63 ± 5.49 65.22	17.18 ± 4.54 61.78	16.10 ± 5.25 64.17	17.25 ± 5.53 61.62	< 0.05a
P	0.18	< 0.01	0.02	0.510	0.546	0.04

UCP = Ultrasound cycloplasty; AGV = Ahmed glaucoma valve; IOP = Intraocular pressure

^aP<0.05 compared with the same group before surgery

Pre- and postoperative use of IOP-lowering medications in the two groups

The number of preoperative IOP-lowering medications showed no significant difference between groups (p > 0.05; Table 3). Postoperatively, both groups exhibited a significant reduction in medication use compared to preoperative levels (p < 0.05). At day 1 and week 1, the UCP group required 2.43 ± 2.06 and 1.18 ± 1.20 medications, respectively, compared to 0.60 ± 0.93 and 0.58 ± 0.75 in the AGV group, with a statistically significant intergroup difference (p < 0.01, P= 0.03). No significant differences were observed at 1, 3 and 6 months postoperatively (Table 3).

Table 3.

Pre- and postoperative use of IOP-lowering medications and pain scores in the two groups

	Group	Preoperative	Post.1d	Post.1w	Post. 1 m	Post. 3 m	Post. 6 m	P a
Medications	UCP group	3.05 ± 1.63	2.43 ± 2.06	1.18 ± 1.20	0.75 ± 1.06	0.78 ± 1.12	0.50 ± 0.68	< 0.05a
	AGV group	3.33 ± 1.47	0.60 ± 0.93	0.58 ± 0.75	0.40 ± 0.63	0.50 ± 0.82	0.80 ± 1.34	< 0.05a
	P	0.61	< 0.01	0.03	0.27	0.34	0.97
Pain scores	UCP group	6.80 ± 1.88	1.78 ± 1.12	0.43 ± 0.68	0.23 ± 0.53	0.30 ± 0.46	0.13 ± 0.46	< 0.05a
	AGV group	6.93 ± 2.22	4.68 ± 1.45	1.80 ± 1.45	0.45 ± 0.71	0.45 ± 0.71	0.43 ± 0.59	< 0.05a
	P	0.5	< 0.01	< 0.01	0.14	0.61	< 0.01

UCP = Ultrasoundcycloplasty; AGV = Ahmed glaucoma valve

^aP<0.05 compared with the same group before surgery

Pre- and postoperative pain scores in the two groups

As shown in Table 3, there was no statistically significant difference in preoperative pain scores between the two groups (p > 0.05). Both groups demonstrated a statistically significant reduction in pain scores at all postoperative follow-up time points compared to preoperative levels (p < 0.05). At day1, 1 week, and 6 months, statistically significant differences were observed between the two group (all p-values < 0.05).

Success rates

As shown in Fig. 2; Table 4, the complete success rates of the UCP and AGV groups at 1 day, 1 week, and 1 month postoperatively were 30%, 40%, 60%, and 60%, 57.5%, 65%, respectively. The overall success rates for the UCP group at 3 months and 6 months postoperatively were 77.5% and 72.5%, respectively. In the AGV group, the highest overall success rate was observed at 1 month postoperatively (82.5%), which subsequently decreased to 67.5% at the 6-month follow-up. A statistically significant difference in success rates was found between the two groups at 1 day postoperatively (p < 0.05). However, no statistically significant differences were observed at the 1-week, 1-month, 3-month, and 6-month follow-ups.

Fig. 2.

Comparison of postoperative total success rate(%) in the two groups

Table 4.

Comparison of postoperative success rates(%) between the two groups [n; Percentage (%)]

	Post.1d (%)	Post.1w (%)	Post. 1 m (%)	Post. 3 m (%)	Post. 6 m (%)
UCP complete success	12(30%)	16(40%)	24(60%)	25(62.5%)	23(57.5%)
UCP qualified success	4(10%)	13(32.5%)	6(15%)	7(15%)	6(15%)
UCP Total Success	16(40%)	29(72.5%)	34(75%)	37(77.5%)	31(72.5%)
AGV complete success	24(60%)	23(57.5%)	26(65%)	24(60%)	23(57.5%)
AGV qualified success	9(22.5%)	8(20%)	6(15%)	7(17.5%)	4(10%)
AGV Total Success	33(82.5%)	31(77.5%)	32(80%)	31(77.5%)	27(67.5%)
P	< 0.05	0.797	0.770	0.115	0.453

UCP= Ultrasound cycloplasty; AGV= Ahmed glaucoma valve

Complications and re-injection of anti-VEGF medications

As shown in Table 5, postoperative complications in both groups were summarized and compared. For minor postoperative complications, both groups exhibited symptoms such as slight anterior chamber hemorrhage, conjunctival hyperemia, and corneal edema. In the UCP group, these occurred in 1 case (2.5%), 10 cases (25%), and 6 cases (15%), respectively. In the AGV group, they occurred in 3 cases (7.5%), 12 cases (30%), and 8 cases (20%), respectively. All these symptoms resolved spontaneously within one week. Additionally, the AGV group experienced 6cases (15%) of early postoperative hypotony on day 1, potentially due to excessive aqueous drainage causing transient IOP reduction. No such symptoms were observed in the UCP group. Three patients (7.5%) in the AGV group developed uveitis. Other early complications, such as keratitis or corneal epithelial defects, were not observed.

Table 5.

Comparison of postoperative complications and incidence of re-injection of anti-VEGF medications in the two groups [n; Percentage (%)]

	UCP group (%)	AGV group(%)	P
n, (%)	40	40
Hypotony	0(0%)	6(15%)	0.026
Hyphema	1(2.5%)	3(7.5%)	0.615
Conjunctival hyperemia	10(25%)	12 (30%)	0.803
Corneal edema	6(15%)	8(20%)	0.770
Tube obstruction	0(0%)	4(10%)	0.116
Choroidal effusion	1(2.5%)	5(12.5%)	0.201
Suprachoroidal hemorrhage	0(0%)	2(5%)	0.494
Uveitis	0(0%)	3(7.5%)	0.241
Anti-VEGF medications	3(7.5%)	4(10%)	> 0.05
Valve exposure	0(%)	3(7.5%)	0.241

UCP = Ultrasound cycloplasty; AGV = Ahmed glaucoma valve; VEGF = Vascular endothelial growth factor

Within 6 months, the AGV group exhibited a higher incidence of severe complications, with 4 patients (10%) experiencing drainage tube obstruction and 2 patients (5%) developing suprachoroidal hemorrhage. Comparing postoperative complications between the two groups revealed no statistically significant difference (P > 0.05). 3 patients in the UCP group required repeat anti-VEGF injections, as did 4 patients (10%) in the AGV group. The difference between the two groups was not statistically significant (p > 0.05).

Discussion

NVG is characterized by markedly elevated and frequently refractory intraocular pressure, often associated with a poor visual prognosis [17]. VEGF, as an inflammatory and permeable glycoprotein, can bind to vascular endothelial cell receptors, stimulate the formation of new blood vessels, and participate in the pathogenesis of NVG [4]. Currently, anti-VEGF combined with surgical treatment has been proven effective over a long period. With its built-in flow control system, the AGV can dynamically regulate intraocular pressure (IOP), offering advantages over traditional filtering surgeries such as trabeculotomy [18–21]. In recent years, with the improvement of high-intensity focused ultrasound technology, UCP has become an efficient and non-invasive treatment method for NVG, capable of precisely destroying ciliary epithelial cells, reducing damage to adjacent tissues, and effectively lowering intraocular pressure [22, 23].

This study compared the efficacy of AGV and UCP in the treatment of NVG. The results showed that the IOP reduction in the AGV group was 61.62% at 6 months postoperatively, which was in line with the 3-year reduction of 59.4% reported by Jade et al. [20]. The 66.97% IOP reduction at 6 months in the UCP group was notably higher than the 41.27% reported by Paul et al. [24], largely due to differences in baseline IOP. Our cohort had a higher mean baseline IOP (47.68 ± 9.65 mmHg) compared with 24.93 ± 4.27 mmHg in Paul et al. Higher baseline IOP allows greater IOP reduction after glaucoma surgery, whereas lower baseline IOP limits the achievable decrease. Thus, baseline IOP disparity is an important confounding factor when comparing surgical outcomes across studies. In terms of short-term efficacy, IOP control was significantly better in the AGV group than in the UCP group at 1 day and 1 week postoperatively, which is in agreement with the results of Fan et al. [16].However, the IOP decreased smoothly to the normal range at 1 week in the UCP group, reflecting the advantage of slow and smooth decrease of IOP. Long-term follow up showed that the IOP reduction in the UCP group was higher than that in the AGV group at 6 months postoperatively (66.97% vs. 61.62%), with less fluctuation, suggesting that UCP has more stable long-term efficacy.

Surgical success was assessed at each follow-up visit based on intraocular pressure (IOP) measurements and the number of IOP-lowering medications required. On postoperative day 1, the complete and qualified success rates were 30% and 10%, respectively, in the UCP group, compared to 60% and 22.5% in the AGV group. Both procedures demonstrated satisfactory long-term efficacy. At the 3- and 6-month follow-ups, the complete success rates were 77.5% and 72.5% for UCP, and 77.5% and 67.5% for AGV, respectively. These long-term outcomes indicate that both interventions effectively controlled IOP, with UCP showing more stable success rates over time while AGV demonstrated greater IOP fluctuations.Notable discrepancies were observed when comparing our results with previous literature. Chen et al. reported UCP success rates of 77.05% on postoperative day 1 and 66.53% at 6 months, while Luo et al. documented rates of 65% at 3 months and 61% at 6 months, showing a slight declining trend [10, 25]. The shorter follow-up duration in our study, which did not evaluate outcomes beyond 6 months, may explain these variations. Huang et al. demonstrated that the surgical success rates of AGV implantation were 85.7%, 71.4% and 71.4% at 6, 12 and 18 months postoperatively, indicating that its efficacy declined with extended follow-up. The maximum follow-up duration in this study was 6 months. In the AGV group, the success rate was 77.5% at 3 months and decreased to 67.5% at 6 months, presenting a downward trend in short-term outcomes. Limited by the follow-up period, only the short-term efficacy trend was consistent with the findings of previous studies [26].

Postoperative BCVA remained unchanged in both groups, consistent with the advanced stage of NVG where optic nerve damage is often irreversible. Therefore, surgery primarily aimed to lower IOP, alleviate pain, and preserve existing vision, rather than improve visual acuity.

Postoperative pain scores were significantly higher in the AGV group than in the UCP group at 1 day, 1 week, and 6 months, though no significant differences were observed at 1 and 3 months. Meanwhile, postoperative pain scores were significantly reduced compared with preoperative levels in both groups. Fan et al. also reported that on postoperative day 1, the pain scores in the AGV group were significantly higher than those in the UCP group (1 (1, 1) vs. 0 (0, 3)) [16]. Consistent with our findings, Wang et al. demonstrated that UCP yielded better pain relief across multiple postoperative time points [27]. These findings indicate better postoperative comfort with UCP, likely attributable to its non-invasive nature, which minimizes collateral tissue damage and reduces foreign body sensation, pain, and inflammation [28]. In contrast, AGV involves intraocular implantation, and mechanical irritation from the drainage valve may intensify early inflammatory responses and compromise patient comfort.

The rate of postoperative complications was significantly higher in the AGV group than in the UCP group, which may be closely related to the invasive operation of AGV. The occurrence of drain obstruction (10%) may be due to fibrin leakage, which requires adequate intraoperative flushing of the anterior chamber and optimisation of the orifice position to reduce the risk. The occurrence of hypotony (15%) may be associated with excessive drainage of atrial fluid and valve dysfunction, suggesting the need for close postoperative monitoring of IOP and adjustment of IOP-lowing medication doses. In contrast, the noninvasive nature of UCP resulted in significantly fewer complications, with only a few patients experiencing mild conjunctival congestion (25%) or corneal oedema (15%), which may be related to the transient effect of ultrasound energy on the superficial tissues, but none of which affected long-term outcomes. All complications resolved spontaneously within one week without serious sequelae such as phthisis bulbi. Only a few patients (10% vs. 7.5%) in the AGV and UCP groups required a second intravitreal injection of anti-VEGF medication within 6 months after surgery, suggesting that both were effective in improving retinal ischaemia and reducing neovascularisation.

This study has limitations. It was a non-randomized controlled trial, and patients were allowed to choose their own surgical procedure, which may introduce selection bias. Meanwhile, the sample size was relatively small and the follow-up duration was short, which might underestimate long-term complications and fluctuations in therapeutic efficacy. In addition, the included patients were neovascular glaucoma, and the results need to be cautious for other types of glaucoma. In the future, multi-center, large-sample randomized controlled trials need to be conducted, follow-up time should be extended, and further research is needed on the impact of optimizing UCP energy parameters and improving AGV design on efficacy.

Conclusion

Both UCP and AGV implantation can effectively treat NVG, significantly reduce postoperative IOP, and effectively alleviate the symptoms of ocular pain caused by high IOP. However, there were differences in postoperative long-term efficacy and complications, with high postoperative fluctuation of AGV and a high rate of complications. As a novel technology, UCP demonstrates unique advantages in the long-term treatment of NVG with its precise, safe, and non-invasive characteristics, which enhance postoperative comfort and reduce the occurrence of surgical complications.

Author contributions

Shuang Zhang：reviewed and edited the manuscript. Shulian Ji: participated and completed the survey; and reviewed and edited the manuscript. Xiaolin Li: participated and completed the survey; and reviewed and edited the manuscript. Shanshan Hu: participated and completed the survey; and reviewed and edited the manuscript. Yanjiang Fu: reviewed and edited the manuscript.

Funding

This work was supported by Daqing Municipal Guideline Science and Technology Project [No.zdy-2025-117].

Data availability

Data will be made available on request.

Declarations

Ethical approval

The research protocol has been approved by the Ethics Committee of Daqing Eye Hospital and follows the principles outlined in the Declaration of Helsinki. Informed consent was obtained from all participants.

Consent to participate

Both verbal and written informed consent were obtained from all 80 patients.

Consent for publication

Not Applicable.

Competing interests

The authors declare no competing interests.