Glaucoma with extremely shallow anterior chamber and cataract was a complex clinical problem. High IOP and narrow anterior chamber for long time may lead to severe visual impairment, decompensation of the corneal endothelium and increasing the difficulties during the surgery, including iris prolapse, capsular rupture, suprachoroidal hemorrhage, crystal dislocation, endothelial damage, malignant glaucoma.[1, 9, 10] It was showed that cilliary or pupillary blockage resulting in the forward displacement of the lens-iris diaphragm was the main mechanism.[6, 11] When medical or laser treatment failed to induce IOP, surgical intervention is necessary. The main focus of the operation was how to overcome the difficulties of surgery in the presence of high IOP and extremely shallow anterior chamber.
Chandler first described the technique of vitreous aspiration by an 18-ga needle via a pars plana incision.[7] As the technology develops, microincisional vitrectomy surgery (MIVS) has been widely used in clinical practice, with the advantages of shorter operation time, faster wound healing, less trauma and reduced postoperative inflammation. Previous studies had comfirmed that the efficacy of PPV was effective for softening the eye and deepening the anterior chamber through removing the anterior vitreous.[12–14] Sharma et al. [1] described vitrectomy–phacoemulsification–vitrectomy in management of malignant glaucoma. He et al. [15] also confirmed that clinical efficcy of modified partial PPV and phacoemulsification for malignant glaucoma. Zhang et al. verified that 23-gauge transconjunctival PPV and PPL was benefit to glaucoma and cataract patients with narrow anterior chamber.[8]
In our research, all patients with high IOP and shallow anterior chamber responded no to medical therapy or laser iridotomy required surgical intervention. However, the anterior chamber was difficult to deepen during surgery. At the beginning of surgery, 25-gauge anterior vitrectomy was performed under the scleral flap in order to reduce positive posterior pressure. In this way, the eyeball softened and the anterior chamber deepened significantly. According to previous experience, we suggest that the removal of vitreous is about 0.5 ml according to Morgan.[16] Matlach et al. [17] suggested continuing to vitrectomy until the anterior chamber deepens intraoperatively. Then phacoemulsification, IOL implantation and trabeculectomy were operated with more space, decreasing the risk of surgery. Anterior chamber was formed and postoperative IOP was well controlled. The mean IOP was 16.72 ± 6.28 mmHg at first week after surgery and maintained stability. At the last visit, the anterior chamber was remained well with a mean depth of 3.0 ± 0.29 mm. The BCVA was improved in all patients. There were no serious complications occurred, such as endophthalmitis, retinal detachment, suprachoroidal hemorrhage, anterior chamber disappearance, corneal decompensation and malignant glaucoma.
The advantages of this technology were as follows: firstly, it reduced the disturbance of conjunctiva and sclera with faster wound healing and less inflammation. Secondly, the scleral incision required no stitches with less time. Thirdly, it also reduced the incidence of malignant glaucoma. Aqueous fluid from posterior chamber could flow into anterior chamber to reduce IOP. Fourthly, only one 25-gauge vitreous cutter was used during vitrectomy. It required no precorneal contact lenses, fiberoptic illumination probe or infusion, which can be easily operated with anterior segment surgeon. It is hoped that our experience will help to simplify the operation and achieve satisfactory result.
The main limitations of our study were as follows: firstly, not all of preoperative corneal endothelium datas were obtained due to corneal edema. Secondly, our study was a retrospective research, which was lack of controlled studies.