FP830 : Short Term Outcomes of Aurolab Aqueous Drainage Implant (AADI)

Dr.Nabeed NPR, N13195, Dr. Ganesh Venkataraman, Dr. Varsha Ramachandra, Dr. Premanand Chandran

Introduction:

Glaucoma is the leading cause of irreversible blindness across the world. Traditional management of glaucoma consists of medical therapy and filtering surgery. The advent of Glaucoma Drainage implants (GDI) have brought in an unprecedented dimension in the management of glaucoma. It is useful, especially in patients with refractory glaucoma.

In a developing country like India the cost of treatment is a huge factor that stands in the way of effective and equal healthcare for all. The two most commonly used GDIs have been Ahmed Glaucoma Valve (AGV) (New World Medical, Rancho Cucamonga, California, USA) and Baerveldt Glaucoma Implant (BGI) (Advanced Medical Optics, Santa Ana, California, USA) costing US$ 260 and US$ 750 respectively¹. This becomes practically non feasible in a developing country.

To solve this practical difficulty, Aurolab in Madurai (India) introduced the Aurolab Aqueous Drainage Implant (AADI). It is a non-valved implant design based on the prototype Baerveldt, and available at an affordable cost of US$ 50. We report our short term outcomes with AADI in this study.

 Methods:

We retrospectively reviewed the records of all patients who underwent AADI surgery between January 2013 and December 2016. The study was approved by the Institute Ethics Committee. Patients with less than 6 months follow up were excluded from the study.

The data collected were age, gender, best corrected visual acuity (BCVA), intraocular pressure (IOP), optic disc findings and number of anti-glaucoma medications (AGM) in the preoperative period. Intraoperative details noted were quadrant of surgery, area of tube placement and patch graft material used to cover the tube. Postoperative data collected were BCVA, IOP, AGM usage, complications and interventions at all visits.

All patients underwent 350 mm² AADI surgery performed by one of the two glaucoma surgeons. The quadrant for implant placement was decided at the discretion of the surgeon. Corneal traction suture was applied with 8-0 polyglactin suture. A three clock hour conjunctival peritomy was performed and the adjacent rectus was identified and isolated. AADI tube patency was checked and then ligated with 7-0 polyglactin suture close to the plate. Plate of the implant was placed under the muscle and secured to sclera 8-10 mm posterior to limbus with 9-0 nylon suture. Tube was cut to adequate length with bevel up and placed in the anterior chamber after entering with 23 gauge needle, 2 mm from the limbus. Tube was secured to sclera with 10-0 nylon suture. Venting slits were done according to the surgeon’s discretion. Corneal or scleral patch graft was used to cover the tube and secured to sclera with 10-0 nylon suture. Conjunctiva was closed with 8-0 vicryl suture.

Complete success was defined as IOP >5 mmHg and <21 mmHg without AGM, and qualified success as IOP <21 mmHg with or without AGM. Failure was defined as IOP <5 mmHg or >21 mm Hg with maximum tolerated medical therapy, loss of light perception, additional glaucoma surgery for IOP control and explantation of the implant.

Descriptive statistics included mean and standard deviation (SD) and difference between preoperative and postoperative IOP, AGM and BCVA were analysed using Friedman test at each time point. Cumulative probability of success was done with Kaplan-Meier survival analysis. P value <0.05 was considered to be statistically significant.

 Results:

Eighty seven patients underwent AADI surgery during the study period, of which 50 patients had more than 6 months follow up; 40 were male and 10 were female. The mean age ± SD was 42.36 ± 23.15 years. The mean follow up period was 14.94 ± 9.19 months. Glaucoma in pseudophakia constituted 18% of the study population. The diagnosis of study patients is shown in Table 1.

Quadrant of implant placement was superotemporal in thirty four (68%), inferonasal in twelve (24%), inferotemporal in three (6%) and superonasal in one (2%) case(s).

Intraocular Pressure:

IOP reduced from preoperative mean of 32.3 ± 11.44 mm Hg to 13.64 ± 4.61 and 13.41 ± 4.68 mm Hg at 6 months and 1 year postoperatively, respectively (Friedman test P <0.044) (Table 2).

Antiglaucoma medications:

The number of AGMs reduced from mean 3.18 ± 0.98 medications preoperatively to 0.78 ± 1.07 at 6 months and 0.73 ± 0.82 at 12 months (Friedman test P= 0.004) (Table 3).

Success:

Complete success was 47% and qualified success was 90% at 1 year follow up. Three patients failed during the follow up period. One of the three patients underwent filtering surgery for uncontrolled IOP. The other two cases developed endophthalmitis and the implants were removed.

Complications:

Postoperatively, six eyes developed hypotony out of which three needed anterior chamber reformation, and rest were resolved with medical management. In two cases, blockage of the tube occurred, one with iris and one with vitreous. Two eyes had long tubes in the anterior chamber which was corrected by trimming. Two eyes had exposure of the tube, of which one developed endophthalmitis and both were explanted. One eye had retraction of the tube from the anterior chamber which was corrected by tube repositioning. One eye had corneal decompensation and another had endophthalmitis.

 Discussion:

GDIs have brought in a paradigm shift in the management of glaucoma. It has also brought in a viable treatment option in refractory glaucoma and failed filtration surgeries. Studies have shown that GDIs have a higher success rate compared to trabeculectomy with mitomycin C².

Our initial experiences with AADI have been encouraging. The reduction in IOP and number of anti-glaucoma medications has been significant. Our results are comparable with similar studies of Baerveldt implant. We are mentioning some of the comparable studies in Table 4.

Retrospective nature of our study and short follow-up were limitations of our study. Glaucoma being a chronic progressive disease, long term study is needed to assess the efficacy and safety of AADI. Another shortcoming is the mixed cohort of glaucoma patients. This can affect the outcomes of the study.

To conclude, AADI is a safe and effective modality in the management of glaucoma. AADI being an indigenous product reduces the financial burden of the patient and makes it an affordable option for a wide population.

References:

1. Kaushik S, Kataria P, Raj S, et al. Safety and effcacy of a low-cost glaucoma drainage device for refractory childhood glaucoma: Br J Ophthalmol. 2017; 1-5.
2. Gedde S.J, Schiffman J.C, Feuer W.J, et al. Treatment Outcomes in the Tube Versus Trabeculectomy (TVT) Study After Five Years of Follow-up. Am J Ophthalmol. 2012; 153: 789–803.
3. Ceballos E. M, Parrish R. K, Schiffman J.C, et al. Outcome of Baerveldt Glaucoma Drainage Implants for the Treatment of Uveitic Glaucoma. 2002;109:2256–2260.
4. Budenz D.L, Barton K, Feuer W.J. Treatment Outcomes in the Ahmed Baerveldt
   Comparison Study after 1 Year of Follow-up. Ophthalmology. 2011;118:443–452.
5. Tsai J.C, Johnson C C, Dietrich M.S. The Ahmed Shunt versus the Baerveldt
   Shunt for Refractory Glaucoma. 2003 Sep;110(9):1814 -21.

Diagnosis	N(%)
Glaucoma In Pseudophakia	9(18.0)
Iridocorneal Endothelial Syndrome	6(12.0)
Primary Open Angle Glaucoma	6(12.0)
Post Keratoplasty	5(10.0)
Post Vitreoretinal Surgery	5(10.0)
Congenital Glaucoma	4(8.0)
Traumatic Glaucoma	4(8.0)
Primary Angle Closure Glaucoma	3(6.0)
Steroid Induced Glaucoma	3(6.0)
Juvenile Open Angle Glaucoma	2(4.0)
Uveitic Glaucoma	2(4.0)
Pseudoexfoliation Glaucoma	1(2.0)
Total	50(100)

Table 1: Diagnoses of patients

Table 2: Preop and postop IOP comparison

AGM	N	Mean	SD	P-Value
Pre-AGM	50	3.18	0.98	0.004
1st month postop	50	1.62	1.31
3rd month postop	50	0.9	1.05
6th month postop	50	0.78	1.07
12th month postop	27	0.72	0.82	0.004

Table 3: Preop and postop AGM comparison

Parameters	Our study	Kaushik et al, BJO 20171	Ceballos et al, Ophthalmology, 20123	Donald et al, Ophthalmology, 20114	Tsai et al, Ophthalmology, 20035
Study Design	Retrospective	Prospective	Retrospective	RCT	Retrospective
Implant	AADI	AADI	BGI	BGI	BGI
No of patients	50	34	24	133	70
Cohort	Mixed	Congenital Glaucoma	Uveitic Glaucoma	Mixed	Mixed
Success rates at 1 year	90%	91.18%	91.7%	86%	73%

Table 4: Comparison of our results with other studies