Glaucoma drainage devices (GDDs) are currently main players in the management of glaucoma, either as a primary or secondary surgical intervention [1, 2]. The most used GDDs worldwide are Ahmed glaucoma valve (AGV, New World Medical, Rancho Cucamonga, CA) and Baerveldt glaucoma implant (BGI, Johnson & Johnson Vision, New Brunswick, NJ). Many studies have reported the safety and the efficacy of both devices and/or compared their results to conventional glaucoma surgery [1, 3, 4]. The BGI has shown a lower failure rate and fewer postoperative antiglaucoma medication requirement [5]. According to the surface area of its end plate, BGI had originally three models: 500 mm2, 350 mm2, and 250 mm2. Long-term follow-up has shown better results for the 350-mm2 BGI than the 500-mm2 implant for intraocular pressure (IOP) control, and currently, it is the commonest model in practice [6].

Despite the well-validated role of GDD, especially in refractory glaucoma, the relatively high cost of GDD limits their use in developing countries [7]. Treatment costs, either medical or surgical, have a major contribution to the economic burden of glaucoma, which may eventually affect the outcome of the patients [8]. In the developing countries, owing to the limited resources and the lack of awareness, management plans may vary from those made for the same cases in the developed countries [9, 10].

In 2013, a low-cost none valved GDD was introduced to the market in India: the Aurolab Aqueous Drainage Implant (AADI, Aurolab, Madurai, India). The design of this device is based on the BGI 350 mm2 but with a much lower cost (about 70 dollars per device). Few studies, mainly from India, reported that this device is safe and effective in different types of glaucoma [7, 11,12,13]. In this study, we report the 1-year safety and efficacy of the AADI using mitomycin-C and insertion of a ripcord in the tube as modifications of the originally described technique among Egyptian glaucoma patients.

This is a real-world retrospective non-comparative interventional case series. All patients who underwent AADI placement between April 2018 and June 2020 at the Department of Ophthalmology, Ain Shams University Hospitals, Cairo, Egypt, were included. The study protocol was approved by the Research Ethics Committee of the Faculty of Medicine, Ain Shams University. The study adhered to the research ethics stated by the declaration of Helsinki. All patients or their guardians (if less than 18 years old) signed written informed consent before their shunt device surgery.

The medical records and the surgical details for all patients who underwent AADI placement during the designated period were extracted. All patients who completed at least a 1-year follow-up period were included. Demographic data including the patients’ age, gender, residency, and family history of glaucoma were extracted. The data regarding type and duration of glaucoma, number of antiglaucoma medications (AGMs), and history of any previous eye surgery were collected. The data of the baseline ophthalmological assessment, including best-corrected visual acuity (BCVA), anterior segment assessment with the slit lamp, and the last recorded preoperative IOP using the Goldmann applanation tonometer (Keeler ltd., Windsor, UK) or Perkins tonometer Mk2 (Haag-Striet UK Ltd., UK) in pediatric cases were extracted. The surgical notes were revised, and any intraoperative complication was recorded. The follow-up records for all visits up to 1 year or more were revised. Data regarding BCVA, IOP, the number of antiglaucoma medications (AGMs), the need to remove the prolene suture, and any postoperative complications were extracted and analyzed. Records with missing preoperative data, operative details, or IOP at any visit were excluded from the study while records with missing data regarding BCVA or AGM were included in the study with exclusion from the statistical analysis of these variables.

The surgical technique described by Pathak Ray and Rao was used with very few differences, mainly, the use of mitomycin-C and ripcord [7]. After checking the patency, prolene 3-0 suture (Surgiopro™, Medtronic, USA) was inserted inside the tube for initial control of aqueous flow through the AADI, to be released when needed according to IOP (acting as a ripcord), and its free end was fashioned into a loop that was fixed to the sclera with a 9-0 nylon (GMS, Egypt) mattress stitch, for easy retrieval later. The tube was ligated with a 6-0 Vicryl suture (AssuCryl®, Assut sutures, Switzerland). After conjunctival dissection in the planned quadrant, mitomycin-C (Biochem Pharma, India) with a concentration of 0.3 to 0.4 mg/ml (according to the severity of conjunctival affection from previous surgeries) was applied for 2 min, followed by a thorough wash. Devices were placed in the supero-temporal quadrant in most cases. The infero-nasal implantation was chosen in eyes with severe conjunctival scarring, extensive peripheral anterior synechiae in the supero-temporal angle of the anterior chamber, or silicone-filled eyes. Anterior chamber placement of the tube was done in all cases except for three cases that needed pars plana insertion. In those cases, the tube was further shortened and a slightly slanting forward track was created 4 mm from the limbus. In all the patients, the implant was inserted beneath the recti muscles except in one eye with microspherophakia with an axial length of 20.7 mm and the lateral rectus had a congenital anomaly and was posteriorly inserted (10 mm from the limbus) so the decision was to place the implant over the muscles in this eye.

Postoperative topical steroids topical (Pred Forte eye drops, prednisolone acetate 1%, Allergan, Irvine, CA) and antibiotics (Tymer eye drops, gatifloxacin 0.3%, Jamjoom Pharma, KSA) were prescribed for 3 weeks. IOP was measured on the first day postoperatively, and AGMs were adjusted according to the IOP. Most of the patients were kept on their preoperative antiglaucoma regimen with the addition of oral acetazolamide if needed.

The primary outcome was IOP reduction. Complete success was defined as IOP ≥ 5 mmHg and ≤ 21 mmHg or reduction of IOP by ≥ 20% from baseline without any AGM. Qualified success was defined as reaching the same IOP range with the aid of AGM.  Failure of the surgery was defined as loss of vision (no light perception), the need for a second glaucoma surgery, or tube explantation during the follow-up period [7].

A hypertensive phase (HTP) was defined as a rise of IOP > 21 mm Hg, with a high tense cystic bleb around the plate. This may start after 10 days of surgery and persist up to 6 months requiring AGM for control of IOP. The subsequent reduction in bleb height, with step-down of AGM, or discontinuation, was defined as resolving or resolved HTP [14].

Data from the postoperative visits at 1 week, 2 months, 6 months, and 1 year were extracted and analyzed.

The data was statistically analyzed using the Statistical Package for Social Science (SPSS 20). The descriptive statistics were presented as mean, standard deviation (± SD), median and interquartile range, or as frequency and percentage for non-numerical data. A P value less than 0.05 was considered statistically significant. The Kaplan-Meier graph was plotted to show the survival of the AADI over 1 year in terms of total success (complete and qualified) and complete success.