FP675 : To Compare Outcomes of Anterior Chamber & Parsplana Insertion of Aurolab Aqueous Drainage Implant-AADI

Dr. Devendra Maheshwari, M12691, Dr. Neelam Pawar, Dr. Rama Krishnan R, Dr. Sindhushree Rajagopal

 

INTRODUCTION:

Glaucoma drainage implants (GDIs) are frequently used for managing refractory glaucoma^{1, 2} and are found to be beneficial in eyes that have had prior unsuccessful laser or filtration surgeries, or when traditional filtration surgery is contraindicated due to ocular anatomy and pathology.

In general the implant tube is inserted into the anterior chamber. However, in selective cases, the insertion of the drainage tube into the anterior chamber is contraindicated because of a shallow anterior chamber,vitreous prolapse, presence of peripheral anterior synechiae or in cases of preexisting corneal disease or decompensation. In such cases, the drainage tube can be inserted through the pars plana with a simultaneous pars plana vitrectomy (PPV).^{3, 4, 5, 6}

AADI (Aravind Aqueous Drainage Implant) developed in India by Aurolab Pvt.Ltd (Madurai) is a non valved implant based on Baerveldt principle and is made of permanent implantable grade silicone proven for patient safety.It has got a large surface area (350mm²)which may be more effective in controlling long-term intraocular pressure (IOP) than those implants with smaller plates and may need fewer post operative anti glaucoma medications.

Despite the common use of PP devices very little literature exists for their efficacy in relation to the more commonly performed AC tube insertion. The main purpose of our study was to determine the success rates, postoperative complication rates andclinical outcomes of anterior chamber placement versus vitreous cavity placement of the tube of glaucoma drainage device (AADI) in patients with refractory glaucoma.

STUDY DESIGN: Non-randomized retrospective study

METHODS: After getting approval from Institutional ethics committee, a retrospective review was performed of all medical records of patients who underwent AADI implant surgery between April 2014 to April 2016in a tertiary eye care centre.The medical records were reviewed to determine demographic, preoperative, and postoperative data at predetermined time points. Data collected included age , sex, diagnosis ,implantation quadrant, tube location, slit lamp and fundus examination , lens status, visual acuity,IOP, previous surgeries,number of glaucoma medications used,complications, length of follow up.The preoperative IOP was determined as a mean of 3 measurements before the operation.The site of placement of the tube was decided based on the clinical status of the patient’s eye.The tube was placed in the vitreous cavity only in those cases where anterior chamber placement was contraindicated due to reasons as mentioned above or if the patient required simultaneous vitreoretinal procedure.

INCLUSION CRITERIA: Uncontrolled primary or secondary glaucomas on maximally tolerated medical therapy unsuitable for trabeculectomy.

EXCLUSION CRITERIA: Previous glaucoma valve surgery in the operated eye,inflammatory or ocular surface disease with severe conjunctival scarring and patients who were lost to follow up.

The main outcome measures included intraocular pressure, number of glaucoma medications, best corrected visual acuity, and complications at 1 month,3 months,6 months and 12 months of follow up

STATISTICAL ANALYSIS:

Statistical analysis was done by using two sample t test and Chi square test for demographic data. Mann Whitney U test was done for comparing the anterior chamber versus pars plana group and Wilcoxon signed rank test was used to determine final outcome with regards to intraocular pressure control between the two groups at the end of follow up .Chi square test was done to compare the success rates between the two groups. P value of < 0.05 was considered to be significant.  All the statistical analysis were performed by STATA 11.1(Texas)

RESULTS: 67 eyes of patients with refractory glaucoma, notamenable to medical therapy, who underwent either anterior chamber or pars plana insertion of AADI implant, were included in the study. Among the 67 eyes, 34 eyes had drainage tube implanted in the anterior chamber and remaining 33 eyes had the tube implanted in the vitreous cavity.3 patients were lost to follow up (2 in AC group and 1 in VC group) and hence only 64 eyes were finally included in the statistical analysis.

The mean age of patients was 48.67± 18.35 years and the range was 8-77 yrs. The mean age of the patients in AC group was 51.69 ±19.15 years and the VC group was 45.66 ± 17.29 years. Out of 64 patients, 47 were male (73.4%) and 17 (26.6%) were female. (TABLE 1)

TABLE 1: DEMOGRAPHIC DATA

	AC group	VC group	Total	P Value
Age(Y, mean±SD)	51.69 ±19.15	45.66 ± 17.29	48.67± 18.35	0.1911
Sex n (%) (Female/Male)	12(37.5)/20(62.5)	5(15.6)/27(84.4)	17(26.6)/47(73.4)	0.0482

1 Two sample t test

2 Chi squared test

Mean preoperative IOP was 37.41 ± 8.58 mm Hg in AC group  ,which reduced to 17.47± 11.39  mm Hg,14.94±6.92 mm Hg ,14.13±5.03mm Hg and 14.03±4.78mm Hg  at  post operative 1 month , 3 months,  6 months and 1 year respectively, the reduction being statistically significant (p value <0.005). Mean preoperative IOP was 43.78 ± 10.38 mm Hg in pars plana group  which reduced to 19.90 ± 12.58mm Hg, 15.77±9.74mm Hg , 15.73±8.72 mmHg and 14.69±6.69mm Hg  at  post operative 1 month , 3 months,  6 months and 1 year respectively, the reduction being statistically significant (p value <0.005). (TABLE 2)

TABLE 2: MEAN PREOPERATIVE AND POSTOPERATIVE INTRAOCULAR PRESSURE

IOP	AC		VC		P-value M
	n	Mean(SD) Min – Max	n	Mean(SD) Min – Max
Pre-op	32	37.41(8.58) 25 – 55	32	43.78(10.38) 26 – 60	0.016
Day1	32	22.00(9.78) 3 – 40	31	19.90(11.18) 5 – 43	0.292
Month1	32	17.47(11.39) 2 – 48	31	19.90(12.58) 6 – 55	0.478
Month3	32	14.94(6.92) 4 – 34	31	15.77(9.74) 2 – 60	0.740
Month6	30	14.13(5.03) 6 – 30	30	15.73(8.72) 5 – 56	0.731
Month12	30	14.03(4.78) 7 – 28	29	14.69(6.69) 2 – 35	0.891
P-value W	<0.001		<0.001		–

^MMann-Whitney U test, (comparing AV VS VC in all visits)

^WWilcoxon sign rank test (comparing final visit iop with baseline iop)

Mean number of antiglaucoma medications required preoperatively was 2.56 ± 0.91,which was reduced to 0.97 ± 0.93 in case of AC group and in pars plana group the number of antiglaucoma medications preoperatively was 3.47 ± 0.51,which was reduced to 1.47 ± 0.78. (Table 3)

TABLE 3 MEAN NUMBER OF ANTIGLAUCOMA EDICATIONS

No. of AGM	AC		VC
	n	Mean(SD)	n	Mean(SD)
Pre-op	32	2.56(0.91)	32	3.47(0.51)
Day1	32	1.72(0.85)	32	2.28(1.25)
Month1	32	1.12(0.98)	32	2.28(1.25)
Month3	32	0.19(0.90)	32	1.59(0.84)
Month6	30	1.17(0.91)	31	1.39(0.84)
Month12	30	0.97(0.93)	30	1.47(0.78)

Visual acuity outcomes between the two groups were similar at baseline as well as at all follow up visits except on day 1 follow up in pars plana group where there was significant decrease in visual acuity probably owing to associated vitreoretinal procedure and extensive corneal edema postoperatively due to uncontrolled high IOP, however no significant change in visual acuity was noted at the end of follow up.

TABLE 4: BEST CORRECTED VISUAL ACUITY IN LOGMAR

VA	AC			VC			P-value M
	n	Median (Snellen’s equivalent)	Min – Max	n	Median (Snellen’s equivalent)	Min – Max
Pre-op	32	0.78(6/36)	0.0 – 2.90	32	1.63(~6/36)	0.0 – 2.90	0.020
Day1	31	1.00(6/60)	0.18 – 2.90	32	2.60(HM)	0.30 – 2.90	0.0006
Month1	32	1.00(6/60)	0.0 – 2.90	31	1.04(6/60)	0.0 – 2.90	0.184
Month3	32	0.89(~6/60)	0.0 – 2.90	31	0.78(6/36)	0.0 – 2.90	0.446
Month6	29	1.00(6/60)	0.0 – 2.90	30	0.78(6/36)	0.0 – 2.90	0.426
Month12	28	0.89(~6/60)	0.0 – 2.90	29	0.89(~6/60)	0.0 – 3.20	0.462
P-value W	0.644			0.132			–

 ^M Mann Whitney U test (comparing AV VS VC in all visits)

^W Wilcoxon signed rank test (comparing final visit VA with baseline VA)

At the end of 1 year , in the pars plana group , 3 patients had choroidal detachments, 1 patient developed fractional retinal detachment , one had vitreous hemorrhage for which vitreous lavage was done and one patient required explantation of AADI implant due to development of postoperative endophthalmitis. However, in the AC group only major complication noted was choroidal detachment which was seen in3patients, one patient had developed corneal decompensation and one had tube erosion but all of them were treated and recovered with conservative management.None of the patients in the AC group required explantation of the tube or any form of resurgery.

DISCUSSION

Glaucoma drainage devices in the recent years have proven to be quite beneficial in refractory glaucomas. Though several studies have been done to evaluate the efficacy and safety of these devices very few studies in literature has been done to compare the clinical outcomes of drainage tube placement in anterior chamber versus vitreous cavity.

In this study the mean preoperative intraocular pressure was 37.41 ± 8.58 mmHg and 43.78 ± 10.38 mmHg  which reduced to 14.03 ± 4.78 mmHg and 14.69 ± 6.69 mmHg in the AC group versus the VC group respectively at the end of 1 year,  the difference being statistically insignificant as evidenced by the Mann Whitney U test although the pressure reductions from baseline were statistically significant.This study hence shows that the mean intraocular pressure reduction was almost similar in both the groups which correlate well with previous similar study done with baerveldt implant⁷.

Though complication rates were almost similar in both the groups, frequent surgical intervention and tube explantation was required only in the pars plana group whereas the complications encountered with tube placement in the anterior chamber were all managed conservatively. This is in contrast with previous studies where pars plana insertion did not reveal any additional risk for the patient^{6, 7}

Limitations of the current study included its retrospective design, lack of controls, and smaller sample size and also lack of long term follow up.

CONCLUSION

To conclude, significant IOP reductions were noted to be similar in both the groups. AADI implantation is safe and effective in refractory glaucoma in both AC &PP groups though long term prospective studies are needed to ascertain this further.

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