Malignant glaucoma, also known as ciliary cycloobstructive glaucoma, was first described by VonGraefe [2] and is a rare but very serious glaucoma. The most common occurrence is after anti-glaucoma filtration surgery [3]. It can also be observed after cataract phacoemulsification combined with intraocular lens implantation, eye trauma, and the use of miotic [4-6]. To sum up, there were total of about 12000 cataract phacoemulsification combined with intraocular lens implantation from 2015 to 2018, 20 cases of malignant glaucoma occurred, the incidence rate was 0.016%, and the occurrence time was 4 days to 3 months postoperation. The results of the study were basically consistent with the relevant reports [7].
After malignant glaucoma occurs, it is generally manifested as a shallowness of the anterior chamber, elevated or normal ocular pressure [8]. The application of miotic can not reduce IOP, but leads to further increase of ocular pressure. The pathogenesis of malignant glaucoma is complex, and the etiology is still unclear [8-10]. Related studies [11] have shown that this type of patient has anatomic abnormalities such as short axis, shallow anterior chamber, narrow frontal angle, hypertrophy of the ciliary body, and relatively large lens. Usually, the eyes are symmetrical. In this study, preoperative examination of these patients found that the anterior chamber was generally shallow; Confirm that abnormal anatomy is the main cause of malignant glaucoma [12].It is suggested that we should be highly alert to the possibility of malignant glaucoma postoperation in patients with such anatomic abnormalities. Since cataract phacoemulsification combined with intraocular lens implantation broke the balance of aqueous humor circulation after surgery, resulting in malignant glaucoma, the mechanism includes the following aspects :( 1)The inflammatory reaction after surgery causes the adhesion of the ciliary body to the vitreous body and the reverse flow of the aqueous humor, resulting in the forward migration of the intraocular lens and the iris septum.(2) Surgical trauma causes the bottom of the vitreous base to be separated from the flat part of the ciliary body, causing the aqueous humor to flow back into the vitreous body. (3) The lens capsule and intraocular lens adhere too tightly to form a lens-capsule complex, leaving the vitreous cavity and the posterior chamber without effective liquid flow pathways. The routine surgical treatment of malignant glaucoma including vitreous puncture with 18-20 syringe needle, suction of liquid in the vitreous cavity, injection of liquid or gas into the anterior chamber, YAG laser posterior capsule membrane incision, but the results were often very poor, the success rate is less than 50%.According to the characteristics of the above mechanism, to fundamentally treat malignant glaucoma, the following are needed to do:(1)Remove the adhesion of the ciliary process to the vitreous body, thereby reducing the posterior chamber pressure;(2)Relieve the posterior capsule membrane and vitreous anterior boundary membrane to obtain a reconstruction of the aqueous humor, flow channel to prevent aqueous humor reflux;(3)Remove the peripheral vitreous body and remove the causes of the anterior iris migration caused by the front of the posterior vitreous body. In this study, 25G vitrectomy was adopted to treat malignant glaucoma, and good results were obtained. Summarizing our experience: (1) Keep a close eye on the condition before surgery. When the treatment with drugs and lasers does not work, early vitrectomy should be performed to prevent anterior angle adhesion and corneal turbidity and loss of surgical opportunities. (2) During the operation, the anterior segment vitreous and the vitreous body around iris incision should be removed to ensure that the flow of aqueous humor is unobstructed and to establish a channel for the flow of water from the vitreous cavity to the anterior chamber. (3) Expand the posterior capsule incision as much as possible to ensure that the anterior chamber can be significantly deepened when the posterior capsule is removed during surgery. Our experience is generally 4-6 mm, avoiding IOL from attaching to the posterior capsule postoperative, and no cases of IOL displacement occur.
In the past, 20G vitrectomy had the disadvantages of relatively complicated surgical procedures, more complications, long surgery time, severe inflammation after surgery, and severe discomfort postoperative, resulting in patients and doctors generally avoiding the surgery [13-14].However, with the development of technology, the continuous improvement of the 25G vitreous cutting system, now vitrectomy incision is smaller(25G about 0.55 mm, 20G about 0.89 mm), The surgical procedure is greatly simplified, with fewer complications, rapid healing, no need for sutures, and short surgical time. The total surgical time is 19-45 minutes, averaging 32 minutes. After the operation, the incision adopts a suture free method. Because of seamless wire stimulation, conjunctiva congestion is not obvious. The patients' comfort is good, and the visual function is restored quickly after surgery [15]. The results showed that the BCVA was 0.8±0.1, the anterior chamber depth was 2.4±0.5mm, IOP was 16.1±2.5mmHg,and the difference between the above three indicators was statistically significant pre- and postoperation.
To sum up, 25G minimally invasive vitrectomy can effectively treat malignant glaucoma. It is convenient to operate in surgery. IOP can be significantly reduced. 25G minimally invasive vitrectomy can effectively improve visual acuity with fewer complications. However, due to the small number of cases in this study, the follow-up time is short, and it is still necessary to further increase the sample size and follow-up time. If necessary, multi-center samples can be collected to evaluate the long-term surgical efficacy.