This study included 40 eyes from 40 patients that had primary open-angle glaucoma (POAG) with age-related cataract. The patients were recruited from the outpatient clinics of Alpha Vision Center, Zagazig, Egypt between August 2013 and January 2016. The study was approved by the Ethical Committee of Alpha Vision Center. The study adhered to the tenets of the Declaration of Helsinki.
Cases were included if they were ≥ 40 years old at the time of surgery, with POAG and age-related cataract. The diagnosis of open-angle glaucoma was based on history, clinical examination and typical glaucomatous visual field loss by Humphrey field analyzer (HFA; Carl Zeiss Meditec Inc., Oberkochen, Germany).
The indications for surgery were the presence of significant cataract interfering with vision (visual acuity ≤0.5) in the presence POAG. Patients were included if cataract was associated with uncontrolled glaucoma, (IOP > 21 mmHg despite maximally tolerated medical therapy) or if the IOP was ≤21 mmHg with use of at least two antiglaucoma drugs with medication intolerance, poor patient compliance, patients could not attend medical supervision or had visual field deterioration.
Patients were excluded if they had closed-angle glaucoma, other types of open angle glaucoma (OAG), e.g. pigmentary glaucoma, inflammatory glaucoma or neovascular glaucoma, previous ocular trauma or surgery, lens subluxation or other eye diseases affecting the vision, e.g. anterior uveitis. Patients were also excluded if there was a large perforation of the Descemet’s membrane with iris prolapse during surgery (cases with microperforation, which is defined as small perforation with no associated iris prolapse, occurring during surgery were not excluded) or if they had other intraoperative complications that might affect the IOP, e.g. vitreous loss.
A written informed consent was obtained from every patient after explanation of the procedure and the possible consequences of the surgery.
Eligible patients were randomized (using a computer-assisted program) to receive either phaco-viscocanalostomy (Phacovisco group), or phaco-viscocanalostomy with Ologen® implant (OloPhacovisco group).
Patient examinations
Patient histories were taken including age, gender, previous ocular surgery, trauma or any previous ocular inflammation, e.g. keratitis, iridocyclitis, etc. Slit-lamp examination was done for examination of anterior chamber angle, determination of the type of glaucoma and the degree of cataract, measuring IOP (using Goldmann applanation tonometer), assessment of optic nerve head and retinal examination, if possible. Visual acuity (VA) was expressed in decimal fraction.
Surgical technique
All operations were carried out by (AAMG) using peribulbar anesthesia.
After phacoemulsification, a traction suture in the cornea was made using 8–0 polyglactin 910 (Vicryl®, Ethicon Inc., Bridgewater, NJ, USA).
A fornix based conjunctival flap was fashioned and no cautery was applied. Hemostasis was only achieved by using a microsponge soaked with 1/100,000 adrenaline. A superficial scleral flap of 5 × 5 mm was made and dissection was done 2 mm into the clear cornea. A smaller deeper flap of 4 × 4 mm was made until deroofing of Schlemm’s canal was achieved. Decompression of the eye was done through one of the paracentesis incisions, then blunt dissection with a microsponge was done to create a descematic window that extended over Descemet’s membrane until 1 to 2 mm inside the clear cornea. Subsequently, the sides of the deep flap were freed from the adjacent sclera by Vannas scissors and the deep flap was cut by the same scissors (Fig. 1).
The juxtacanalicular trabeculum was removed and then the two openings of Schlemm’s canal were cannulated on both sides using a viscocanalostomy cannula (Eagle labs, Rancho Cucamonga, CA, USA) and high-viscosity sodium hyaluronate (Healon GV; Abbott Medical Optic Inc., Santa Ana, CA, USA) was injected into the canal on both sides.
In the Phacovisco group, the superficial flap was closely sutured using four interrupted 10–0 nylon sutures, and then Healon GV was injected into the subscleral lake.
In the OloPhacovisco group, a 4 × 4 mm piece of Ologen® (Model: 862051 “12mm(D) x 1mm (H)”) (Aeon Astron Europe B.V., Leiden, The Netherlands) was fashioned to be nearly of the same size as the cut deep scleral flap to fit inside the subscleral reservoir (Fig. 2). Then the superficial flap was sutured tightly over it using four interrupted 10–0 nylon sutures (Ethilon®, Ethicon Inc., Bridgewater, NJ, USA). Some air was injected from the paracentesis inside the eye. Then conjunctiva was closed using 8–0 polyglactin 910 sutures (Vicryl®, Ethicon Inc., Bridgewater, NJ, USA).
Postoperative management included topical administration of 0.5% moxifloxacin drops with a tapered schedule of 1% prednisolone acetate. Antiglaucoma medication was ceased after surgery in all cases.
Postoperatively, follow-up examination was done on days 1, 7, 14 and 30, then every 2 months for 2 years. The follow-up examination included assessment of IOP, VA and slit-lamp examination. Postoperative complications were recorded. Signs of inflammation, such as cell infiltration and flare, were recorded and graded from 0 to 4.
Nd:YAG laser goniopuncture was considered in all cases with elevated postoperative IOP above 21 mmHg after discontinuation of corticosteroid eye drops for at least 14 days. The Nd:YAG goniopuncture was performed using an Ellex Super Q YAG laser machine (Ellex Medical Lasers Ltd., Mawson Lakes, SA, Australia) and the gonioscopy mirror of Goldman three mirror universal laser lens (Ocular, Bellevue, Washington, USA) with a laser power setting of about 3 to 6 mJ and using about 2 to 15 shots aiming at the opening of the trabeculo-Descement window, the number of laser shots needed to open the Descemet’s membrane was counted and recorded in each group. Antiglaucoma drugs were prescribed if the IOP was elevated above 21 mmHg after considering Nd:YAG laser goniopuncture.
The main outcome measures were the IOP at the 2-year follow-up and the overall success, which included complete success when IOP was ≤21 mmHg without any antiglaucoma drugs, and qualified success if IOP was ≤21 mmHg with the use of a single antiglaucoma medication. Failure was considered if IOP ≤ 21 mmHg could not be reached even with the use of a single antiglaucoma medication and after performing Nd:YAG laser goniopuncture, at any follow-up visit. The secondary outcome measures were surgical complications, the use and results of Nd:YAG laser goniopuncture and visual acuity results. The last data for failed cases were used for further statistical analysis.
Statistical analysis
The data were analyzed was using the software Statistical Package for Social Science (SPSS) version 16.0 (SPSS Inc., Chicago, Illinois, USA). Continuous variables were expressed as mean ± SD and compared using student t tests; two tailed test was used to detect significance between the two groups and one tailed t test was used to detect the significance before and after intervention in the same group. Mann-Whitney U test was used for nonparametric analysis. Categorical variables were expressed as percentages and were analyzed using the chi square (χ2) test. A value < 0.05 was considered statistically significant.
