In China, the incidence of closed-angle glaucoma accounts for about 60% to 80% of all glaucoma. Early diagnosis, standardized treatment, and reasonable evaluation of the efficacy are of great socioeconomic significance in reducing the blindness of glaucoma [1]. The principle of treatment for closed-angle glaucoma is mainly surgical, and the traditional method is to select filtering surgery or peripheral iridotomy, including laser peripheral iridotomy, depending on the degree of atrial angle closure and adhesions. With the development of ultrasonic cataract aspiration combined with intraocular lens (IOL) implantation, surgical equipment and techniques have been perfected, surgical results have been improved, and complications have been gradually reduced, and this surgical procedure has been increasingly involved in the treatment of closed-angle glaucoma, with significant clinical results [2]. However, cataract surgery in patients with closed-angle glaucoma has been one of the controversial issues in the ophthalmology community. Opinions differ as to whether cataract surgery alone, glaucoma surgery alone, or combined cataract and glaucoma surgery should be performed in closed-angle glaucoma; whether cataract surgery or glaucoma surgery should be performed first. In the following, we will introduce the efficacy and mechanism of ultrasonic cataract aspiration combined with intra-capsular folding IOL implantation for the treatment of closed-angle glaucoma, the choice of surgical method and controversial issues, in order to make a preliminary discussion on the treatment standard of ultrasonic cataract aspiration combined with intra-capsular folding IOL implantation for the treatment of closed-angle glaucoma. I. Clinical efficacy of ultrasonic cataract extraction for closed-angle glaucoma As early as the 1980s, it was reported in the literature that IOP could be reduced after extracapsular cataract extraction (ECCE) IOL implantation, and it was thought to be related to the increase of anterior chamber depth after the operation. With the increasing popularity of ultrasonic cataract aspiration surgery, improved surgical equipment and techniques, improved surgical outcomes and reduced complications, ultrasonic cataract extraction has become the trend instead of extracapsular cataract extraction. The use of ultrasound emulsification combined with intracapsular IOL implantation has been gradually applied to the treatment of closed-angle glaucoma because of the decrease in IOP and stability, low astigmatism and tissue damage, and rapid recovery of visual acuity. The IOP control rate was 91.9% in closed-angle glaucoma and 72.9% in open-angle glaucoma after ultrasound emulsification combined with IOL implantation. Altan C et al. counted 53 eyes of 49 non-glaucoma patients with wide anterior chamber angle, and observed 6 months after ultrasound emulsification, all of them had a decrease in IOP, an increase in anterior chamber depth and a widening of the chamber angle, and were statistically significant. In the literature, Ge Jian et al. reported that ultrasonic cataract extraction combined with posterior chamber IOL implantation can effectively treat closed-angle glaucoma combined with cataract, which has considerable value in the treatment of closed-angle glaucoma. Pereira et al. used ultrasound biomicroscopy (UBM) and showed that after ultrasonic cataract aspiration, the iris septum of the operated eye was posteriorly shifted, the anterior chamber deepened by about 8.50 mm, and the atrial angle widened by about 10°. NonakaA et al. used the same method and found that the ciliary process was significantly posteriorly shifted after surgery and the atrial angle width was significantly increased compared with that before surgery. Ultrasonic cataract aspiration has the advantages of less surgical trauma, intraoperative anterior chamber stability, and relatively closed surgical operation, which greatly reduces the degree of postoperative inflammatory reaction and lowers the incidence of hypotensive complications; and its internal incision is located 1.5 mm inside the corneal rim, which avoids direct damage to the atrial angle and reduces the possibility of postoperative peripheral iris anterior adhesions; at the same time, the surgical operation on the anterior chamber angle In addition, the stretching and opening effect of the surgical operation on the anterior chamber angle can significantly reduce the intraocular pressure of the operated eye for several years after the operation, which has gradually become one of the effective clinical treatment methods for closed-angle glaucoma. (1) Simple pupillary block The anatomical structure of the anterior segment of the anterior segment of closed angle glaucoma is abnormal, the anterior segment is narrower, the lens is thicker, the anterior and posterior diameters of the lens are longer, the relative position of the pupillary margin is more forward, the pupillary block is greater than the posterior atrial pressure, the pupil is blocked, the posterior atrial pressure increases, the peripheral iris bulges, and a narrow or even closed atrial angle is formed. A narrow or even closed atrial angle is formed. The repeated pupillary block becomes a potential initiating factor for primary angle-closure glaucoma, and the relative position of the lens is also an important factor in the pathogenesis. Ultrasonic emulsion cataract aspiration intracapsular IOL implantation can release the lens factor and effectively treat closed-angle glaucoma from the pathogenesis. (2) Simple non-pupillary block type Diversity of atrial angle closure mechanisms: In contrast to the simple pupillary block type, these patients have a relatively posterior position of the pupillary margin and a flat peripheral iris, but a narrow or even closed atrial angle is formed by a sharp turn at the entrance of the atrial angle, some patients have a bulging peripheral iris, and some patients have an anteriorly positioned ciliary body, but the narrow atrial angle is not related to pupillary block. The posterior atrial IOL implantation with ultrasound-emulsion cataract extraction significantly posteriorly shifted the crystalline iris septum and deepened the anterior chamber, relieving the atrial angle closure caused by peripheral iris bulging. Moreover, it has been reported in the literature that the shallow anterior chamber is an important risk factor for angle-closure glaucoma in Orientals [16] [17]. (3) Multiple mechanisms coexist Pupillary block and non-pupillary block factors are jointly involved in atrial angle closure in this group of patients. The iris root attachment position is more anterior than the pupillary block type, making the peripheral iris closer to the trabecular meshwork. Mild pupillary block is more likely to cause closure of the atrial angle in the most anterior quadrant of the iris root attachment point, followed by closure of the atrial angle at other sites, and the atrial angle at the most posterior site may be the last to close, forming what is clinically known as creeping adhesions of the atrial angle. Ultrasonic cataract extraction can also effectively improve such atrial angle adhesions. 2. Other possible factors (1) Ultrasonic cataract extraction is a closed surgery, and during the surgery, the pressure of the perfusion fluid in the anterior chamber repeatedly impacts the atrial horn, causing the atrial horn to open again or the adhesions to decrease. (2) Intraoperative injection of viscoelastic in the anterior chamber produces an impact and separation effect on the atrial horn and trabecular meshwork. (3) During cataract ultrasonic emulsion aspiration, some inflammatory mediators will be released in the atrial water, such as interleukins and prostaglandins, which have the effect of promoting the degradation of the trabecular meshwork extracellular matrix and can increase the ease of atrial water outflow. (4) Ultrasound itself can cause a decrease in ciliary secretion function. The mechanism of the decrease is: (1) ultrasound in the process of penetrating the tissue, so that the scleral collagen fibers decomposition. This causes tissue damage and degeneration, sclera thinning, and vesicle-like gap under the conjunctiva. The atrial fluid is absorbed through the thinning sclera and infiltrates into the subconjunctival vesicle-like gap. ②Ultrasound can destroy the ciliary epithelium, the cells become degenerative and necrotic. The residual cells are disorganized, the ciliary body is atrophied, and atrial fluid production is reduced. ③Scleral scar contraction, resulting in separation from the ciliary body and widening of the trabecular meshwork gap. The drainage of atrial fluid to the suprachoroidal space increases, and the resistance to trabecular meshwork drainage decreases. In addition, the mechanical effect of ultrasound (micro-massage) improves local blood circulation, increases blood permeability, promotes absorption, loosens adhesions, and facilitates the discharge of atrial fluid. Third, ultrasound emulsification (or combined with other procedures) for the treatment of closed-angle glaucoma is controversial. The main principle of treatment for closed-angle glaucoma is surgery, and the traditional method is to choose iridopexy (anterior chamber angle adhesion closure <1/2 circumference) or filtration surgery (anterior chamber angle adhesion closure >1/2 circumference, and the maximum tolerated dose fails to control IOP in a safe range) according to the degree of anterior chamber angle adhesions. Conventional anti-glaucoma filtration surgery is modern trabeculectomy, which has more postoperative complications such as follicular fibrosis, shallow anterior chamber, low IOP, and cataract. According to the literature, the incidence of cataract after trabeculectomy is 14%-48%, and some of them can occur even within a few months, often requiring re-implantation of posterior chamber type IOL after ultrasonic cataract extraction. Currently, ultrasonic cataract extraction with intracapsular IOL implantation is becoming an effective treatment option for closed-angle glaucoma. More and more doctors prefer to perform cataract ultrasound-emulsification intra-capsular IOL implantation in patients with closed-angle glaucoma combined with cataract. However, there is still no standardized model for the surgical treatment of cataract combined with glaucoma, which has a significant impact on visual quality. At present, there are many types of cataract ultrasound emulsification combined with other surgical procedures for closed-angle glaucoma at home and abroad. Commonly used combination surgical procedures for cataract combined with glaucoma include ultrasonic cataract aspiration with rigid IOL or folded IOL implantation combined with trabeculectomy (T-P), ultrasonic cataract aspiration with IOL implantation combined with non-penetrating trabeculectomy or viscoelastic Schlemm canal dilation, temporal clear corneal incision ultrasonic cataract aspiration with folded IOL implantation combined with trabeculectomy, ultrasonic cataract aspiration with folded IOL implantation combined with trabeculectomy, and ultrasonic cataract aspiration with folded IOL implantation combined with trabeculectomy. The combined use of mitomycin c or 5-fluorouracil in the above combined procedures. In recent years, opinions differ on the surgical approach for patients with closed-angle glaucoma combined with cataract. Generally speaking, there are three main management pathways: filtering surgery followed by cataract extraction; combined cataract-filtering surgery; and cataract surgery alone. For acute closed-angle glaucoma in the aura, preclinical, remission and early stage of chronic closed-angle glaucoma with <1/2 anterior chamber angle adhesions, either peri-iridotomy or laser peri-iridotomy can be chosen; early laser iridotomy is safe and effective in some cases [34], but postoperative cataract formation is often accelerated. In patients with intermediate and advanced stages, filtration surgery was used in the past, but it is prone to shallow anterior chamber, filter bubble scarring, and poor IOP control, leading to complicating cataracts, and it is common to have to perform cataract surgery again shortly after antiglaucoma surgery, increasing the patient's pain and financial burden. Combined surgery has exact efficacy and can avoid two surgeries, but it increases the riskiness and postoperative complications due to the complexity of surgical operation. Ultrasonic cataract aspiration combined with IOL implantation replaces the 5.5 mm thick human lens with an IOL less than 1.0 mm thick, which can significantly deepen the depth of the central anterior chamber and shift the contact plane between the pupillary margin and the lens backward, thus solving the pupillary block state. However, cataract surgery alone may still result in poor postoperative IOP control and require a second filtering procedure. Therefore, the choice of standardized glaucoma combined with cataract surgery is still an important clinical issue to be demonstrated. Although cataract ultrasound emulsification combined with intracapsular folding IOL implantation for the treatment of closed-angle glaucoma has broken the traditional treatment concept and is a major progress in the treatment of closed-angle glaucoma, the evaluation of the efficacy of cataract ultrasound emulsification combined with intracapsular folding IOL implantation in the treatment of closed-angle glaucoma is worthy of further discussion in terms of the indications for surgery, surgical methods, further observation of the degree of recovery of atrial angle opening and atrial aqueous outflow function, fluctuation of IOP, and recovery of visual function. However, the evaluation of the efficacy of the surgery in terms of indications, surgical approach, postoperative observation of atrial opening and restoration of atrial flow, fluctuation of intraocular pressure, and restoration of visual function deserve further discussion. The current evaluation indexes should include: preoperative IOP, visual acuity, visual field, C/D, atrial angle, pupil size, anterior and posterior adhesions and their iris tension, whether the medication can control IOP in the normal range, depth of the central anterior chamber, peripheral anterior chamber and posterior chamber, and lens thickness. The UBM and Areemis digital ultrasound arcuate scanners provide a powerful weapon for clinicians. The former is a static imaging system for the anterior segment of the eye, and the latter is a dynamic imaging system that is a perfect complement to the former, allowing clinicians to obtain the data they need and then make decisions. V. Outlook It is urgent to establish a system for selecting the indications and evaluating the efficacy of cataract ultrasound emulsification combined with intracapsular IOL implantation for closed-angle glaucoma combined with cataract. For closed-angle glaucoma without cataracts, ultrasound-emulsification of the clear lens with intra-capsular IOL implantation needs further study. In addition, what surgery should be performed for patients without clear progressive optic nerve damage; what surgery should be performed for patients with progressive visual field damage, C/D=0.8-0.9, glaucoma combined with cataract; if nerve block is potentially toxic to the optic nerve of glaucoma patients, whether surface anesthesia is relatively safe for patients; whether the surgery should be performed through a scleral tunnel incision or a clear corneal incision, and whether the surgery should be performed through an upper or a temporal incision. There is still no unified conclusion on whether to use a superior or temporal incision, whether to combine trabeculectomy or anterior chamber angle viscoelastic detachment, whether to apply antimetabolic drugs intraoperatively, and whether to implant a drainage valve. It is worthwhile to further discuss, study and summarize the selection of indications, surgical techniques and efficacy evaluation, and to form a standardized and quantitative system for the selection of indications and efficacy evaluation.