Triple Procedure for Dense Cataractus Neovascular Glaucoma Patients

Introduction Ocular ischemia due to diabetic retinopathy (DR) and central retinal vein occlusion (CRVO) are the most common causes that contribute to the development of neovascular glaucoma (NVG). Ischemic retina derived factors like vascular endothelial growth factor (VEGF) that can affect the anterior segment and initiates neovascularization in the iris (NVI), neovascularization in the angle (NVA). Aqueous outflow is obstructed when neovascular fibrous tissues block the trabecular meshwork and leads to synechial angle closure, thus NVG develops. Intraocular pressure (IOP) rise due to NVG lowers the ocular perfusion leading to further retinal ischemia, and this in turn induces more neovascularization. The management of NVG is very difficult thus; the conventional treatments such as antiglaucoma drugs, trabeculectomy, cyclophotocoagulation and cyclocryotherapy have poor success rates. It is very important to reduce the ischemic drive promptly for the treatment of NVG. Pan-retinal photocoagulation (PRP) is a mandatory and effective in resolving the ischemic condition and decreasing the vasoproliferative factors production.[ This management is particularly difficult in eyes with dense cataract. However, it is possible to overcome this difficulty by doing phacoemulsification and pars plana vitrectomy (PPV) + PRP. Moreover, phacoemulsification combined with PPV enables us to apply PRP from the posterior pole to the ora serrata peripherally. It has been known that Mitomycin C (MMC) increase the success rate of trabeculectomy in patients with NVG. Therefore, in the current study, we performed Intravitreal bevacizumab (IVB) injection, phacoemulsification, PPV + PRP and trabeculectomy augmented with subconjunctival injection of MMC.

The aim of this study is to evaluate safety and efficacy of this combined surgical procedure to alleviate retinal ischemia, reduce IOP, and improve visual acuity in dense cataractus NVG patients.

Subjects and Methods

Twelve eyes of 12 patients with NVG associated with dense cataract enough to obscure fundus visualization (7 males, 5 females) were included in the study in the period from July 2016 to August 2019 at Ophthalmology Department, Faculty of Medicine, Minia University. The patient's age ranged from 47 to 66 years with a mean age of 57.25 ± 5.9 years. The underlying cause for NVG was diabetes mellitus (DM) in 8 eyes (75%) and CRVO in 4 eyes (33.33%). Vitreous hemorrhage was present in half (50%) of the patients. The study was approved by the Local Ethical Review Committee and adhered to the tents of Declaration of Helsinki as well as all patients singed a written consent after discussion of the potential benefits and risks of this triple surgical procedures.

Preoperative examinations: Routine ophthalmological examinations were done after history taking including, age, sex, laterality, etiology of NVG and number of used anti-glaucoma drugs. The ocular examination includes estimation of visual acuity, IOP measurement with Goldman applanation tonometer, slit lamp examination of anterior segment, gonioscopy examination of angle of anterior chamber, biometry and ultrasonography. The demographic data were registered as in (Table 1).

Surgical procedures . In brief: - All procedures were done under peribulbar anesthesia with mild systemic sedation. IVB injection of 1.25 mg (0.05 ml) was given 2-6 days before surgery using a 27-gauge needle at the inferotemporal quadrant at 3.5-4.0 mm posterior to the limbus. Preoperative IV mannitol was given to all cases to lower IOP before surgery beside the full anti-glaucoma drugs including: topical Dorzolamide-Timolol combination, Brimonidine tartrate and oral Acetazolamide (250 mg) three times a day. Subconjunctival injection of MMC in a dose of 0.04mg/ml was done, and a period of 4 minutes was left before Conjunctival opening.

Fornix based Conjunctival incision was performed and a rectangular scleral flap of 3x4 mm was dissected. Separate temporal clear corneal incision phacoemulsification was done with intrabagal one-piece hydrophobic IOL implantation. Then, incision was closed with 10/0 nylon suture. This was followed by three ports 25-G PPV including core vitrectomy, injection of triamcinolone acetonide, induction of PVD, shaving of vitreous base, and dealing with any epiretinal membranes. PRP using diode endo-laser was done up to the far periphery (2000-3000 shots, duration 200 ms; power 400 mw). Fluid-air exchange was then performed and 20% SF6 was injected leaving 10 cc of gas to adjust pressure at the end of surgery. Then, the upper sclerotomies were sutured by vicryl 7/0 and the infusion cannula was left in place connected to the syringe of 20% SF6. Then, Healon was injected into the anterior chamber to maintain depth of anterior chamber and trabeculectomy by Kelly punch and peripheral iridectomy were done. Scleral flap was sutured by two 10/0 nylon sutures at the corners followed by watertight Conjunctival wound closure. More SF6 was injected to adjust IOP and the infusion cannula was removed, and its site was sutured with vicryl 7/0 suture. At the end of surgery, fluid was injected into the AC to test for filtration of bleb and to make sure that the conjunctiva was closed watertight. At last, triamcinolone acetonide subtenon injection was given to all eyes.

Post-operative management: The patients were prescribed prednisolone 1% (predfort, Alcon Co.) eye drops QID and tapered through 8 weeks, cyclopentolate 0.5 % TID, moxifloxacin 0.3 mg (Vigamox, Alcon Co.) eye drops QID for 2 weeks and ointment of tobramycin and dexamethasone at night for 4 weeks. Scheduled follow up visits were advised next postoperative day, one week, two weeks, monthly for three months, and then each three months for 2 years.

All patients underwent full ophthalmologic examination including BCDVA, IOP, gonioscopy, slit lamp examination, and dilated fundus examination. Antiglaucoma medications were prescribed if IOP was more than 21 mmHg. Baseline results and that of 1, 3 and 6 months, 1 and 2 years were included in the statistical analysis. This study main outcome measures were the mean BCDVA (log MAR), the mean IOP and the incidence of complications. Successful surgery was considered when the target IOP =21 mmHg was achieved without serious complications such as suprachoroidal hemorrhage, choroidal effusion, retinal detachment, endophthalmitis, phthisis bulbi, or persistent hypotony (IOP <5 mmHg). Complete success was considered when IOP of 6 -21 mmHg was achieved without any anti-glaucoma drugs, and qualified success when this target IOP was achieved with and without the use of anti-glaucoma drugs. Failure was defined as IOP >21 mmHg despite the use of maximum tolerated medications, hypotony, or the need for another glaucoma surgery.

Statistical analysis: Statistical analysis was performed with SPSS 19. Data were expressed as mean ± standard deviation (SD). Changes in the mean BCDVA and the mean IOP were compared for each follow up visit with baseline using paired t test and graphs construction done by using Graph Pad Prism 5 program. P value < 0.05 was considered statistically significant.