Dr. Devendra Maheshwari, M12691, Dr.Rahul Raja Achlerkar, Dr. Sindhushree Rajagopal, Dr. Rama Krishnan R
| Chief Author Name |
| M12691 | Devendra Maheshwari | drdev_ophthal@hotmail.com |
| Co Authors |
| A16792 | Rahul Raja Achlerkar | rahulach1@gmail.com | 9881132929 |
| R14910 | Sindhushree Rajagopal | sindhuraj200408@gmail.com | 9629015059 |
| R04231 | Rama Krishnan R | drrk@tvl.aravind.org |
TITLE :A short term analysis of anterior chamber & pars plana insertion of AADI implant
INTRODUCTION :
Glaucoma drainage implants (GDIs) are frequently used for managing refractory glaucoma1,2 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 Pars Plana (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 , post operative complication rates and clinical 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 our Institutional ethics committee, a retrospective review was performed of all medical records of patients who underwent AADI implant surgery between April 2014 to March 2015 at glaucoma services, Aravind eye care system, Tirunelveli. 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 glaucoma on maximally tolerated medical therapy unsuitable for trabeculectomy.
EXCLUSION CRITERIA: Previous seton surgery in the operated eye. Inflammatory or ocular surface disease with severe conjunctival scarring. 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 and 6 months of follow up. Complete success was defined as a final IOP between 5 and 21 mmHg without IOP-lowering medication. Qualified success was defined as a final IOP between 5 and 21 mmHg with medication and failure was defined as a final IOP ≤5 or ≥21 mmHg with or without medication, loss of light perception or the occurrence of a serious complication..
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 .Fisher’s exact 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: 61 eyes of patients with refractory glaucoma, not amenable to medical therapy, who underwent either anterior chamber or pars plana insertion of AADI implant were included in the study. Among the 61 eyes, 30 eyes had drainage tube implanted in the anterior chamber and remaining 31 eyes had the tube implanted in the vitreous cavity.
The mean age of patients was 51.54 ± 16.9 years and the range was 11-77 yrs. The mean age of the patients in AC group was 55.1 ± 15.5 years and the VC group was 48.09 ± 17.7 years. Out of 61 patients, 43 were male (70.5%) and 18 (29.5%) were female.
Out of 61 patients , 9 were diagnosed with POAG ( out of which 1 had previously failed trabeculectomy) 14 were diagnosed cases of neovascular glaucoma , 5 patients had glaucoma in pseudophakia, 3 patients with glaucoma in aphakia ( out of which one patient had previously failed trabeculectomy ), 12 patients with post traumatic angle recession glaucoma, 1 patient with steroid induced glaucoma, 3 patients with pseudoexfoliative glaucoma,7 patients with secondary angle closure glaucoma ( 1- post DSEK, 3 – post PKP , 1 – pupillary block, 2 – malignant glaucoma)and remaining 7 patients were diagnosed with silicon oil induced glaucoma.
TABLE 1: DEMOGRAPHIC DATA
| AC group | VC group | Total | P Value | |
| Age(Y, mean±SD) | 55.1±15.5 | 48.09±17.7 | 51.5±16.9 | 0.0741 |
| Sex n (%)
(Female/Male)
|
12(40.0)/18(60.0) |
6(19.3)/25(80.7) |
18(29.5)/43(70.5) |
0.0772 |
1 Two sample t test
2 Chi squared test
Mean preoperative IOP was 37.13 ± 10.3 mm Hg in AC group ,which reduced to 22.33 ±14.0 mm Hg,21.73±13.3mm Hg and 17.83±10.3mm Hg at post operative 1 month , 3 months, and 6 months respectively, the reduction being statistically significant (p value <0.005). Mean preoperative IOP was 39.45 ± 12.2 mm Hg in pars plana group which reduced to 22.65 ±11.7mm Hg, 23.52±12.6mm Hg and 18.84±13.5mm Hg at post operative 1 month , 3 months, and 6 months respectively, the reduction being statistically significant (p value <0.005). (Table 2)
TABLE 2: MEAN PREOPERATIVE AND POSTOPERATIVE INTRAOCULAR PRESSURE
| IOP | AC | VC | Total | P – value* | |||
| Mean (SD) | Range | Mean (SD) | Range | Mean (SD) | Range | ||
| Baseline | 37.13(10.1) | 18 – 60 | 39.45(12.2) | 15 – 60 | 38.31(11.2) | 15 – 60 | – |
| Month 1 | 22.33(14.0) | 3 – 70 | 22.65(11.7) | 1 – 44 | 22.49(12.8) | 1 – 70 | 0.608 |
| Month 3 | 21.73(13.3) | 4 – 68 | 23.52(12.6) | 2 – 46 | 22.64(12.9) | 2 – 68 | 0.582 |
| Month 6 | 17.83(10.3) | 4 – 52 | 18.84(13.5) | 2 – 60 | 18.34(11.9) | 2 – 60 | 0.811 |
| P – value# | <0.001 | <0.001 | <0.001 | ||||
*Mann Whitney U test (comparing AV VS VC in all visits)
#Wilcoxon signed rank test (comparing final visit iop with baseline iop)
Mean number of antiglaucoma medications required preoperatively was 2.37 ± 1.1,which was reduced to 1.67 ± 1.0 in case of AC group and in pars plana group the number of antiglaucoma medications preoperatively was 2.68 ± 0.7,which was reduced to 2.2 ± 0.8. (Table 3 )
Visual acuity outcomes between the two groups were similar at baseline as well as at all follow up visits and no significant change in visual acuity was noted at the end of follow up . (Table 3 )
TABLE 3 : BEST CORRECTED VISUAL ACUITY IN LOGMAR
| Log mar VA | AC
Mean (SD) |
VC
Mean(SD) |
Total
Mean (SD) |
P – value* |
| Baseline | 1.48(0.99) | 1.73(0.97) | 1.61(0.98) | – |
| Immediate Postop | 1.62(0.97) | 2.02(0.80) | 1.83(0.90) | 0.085 |
| Month 1 | 1.51(0.96) | 1.61(0.92) | 1.56(0.93) | 0.811 |
| Month 3 | 1.43(1.01) | 1.42(0.94) | 1.43(0.97) | 0.856 |
| Month 6 | 1.49(1.03) | 1.43(0.95) | 1.46(0.98) | 0.761 |
| P – value# | 0.817 | 0.073 | 0.131 |
At 6 months of follow up in case of pars plana group, AADI explantation was done in 2 patients of which one had tractional retinal detachment with epiretinal membrane and the other had developed endophthalmitis. One patient had vitreous haemorrhage for which vitreous lavage had to be done.However in the AC group only major complication noted was choroidal detachment which was seen in 3 patients 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.(Table 5)
TABLE 4: COMPLICATIONS AT 6 MONTHS FOLLOW UP
| Complications | AC group | VC group |
| Ant Uveitis | 1 | 0 |
| CD | 3 | 1 |
| Tube Endothelium Touch | 1 | 0 |
| Endophthalmitis | 0 | 1 |
| ERM with TRD | 0 | 1 |
Complete success was noted in 4 patients and Qualified success was noted in 21 patients among the anterior chamber group. No case of complete success was noted among pars plana group though qualified success was achieved in 25 patients. Fisher’s exact test was done which shows that p value was not significant. (p =0.110) (Table 6)
TABLE 5: SUCCESS RATES BETWEEN TWO GROUPS
| Success category | AC group | VC group | Total | P value |
| Complete success | 4 | – | 4 | 0.110¥ |
| Qualified success | 21 | 25 | 46 | |
| Total | 25 | 25 | 50 |
¥ Fisher’s exact test
DISCUSSION :
Glaucoma drainage devices in the recent years have proven to be quite beneficial in refractory glaucoma. 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 37.13mmHg and 39.45mmHg which reduced to 17.83 mmHg and 18.84 mmHg in the AC group versus the VC group respectively at the end of 6 months 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.
In our study, complete success was seen only in the anterior chamber group which comes to around 13.3% whereas no patients had complete success in the pars plana group. Qualified success was seen in 70% of anterior chamber group and 80.6% of pars plana group. The success rates could not be compared with previous studies as follow up of patients in our study were only for 6 months.
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 patient6,7
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. Though postoperative complications were similar in both groups frequent surgical intervention was required in pars plana group .Long term follow up however is needed to ascertain the efficacy and safety profile of pars plana tube insertion of AADI implant.
REFERENCES:
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2 Sherwood MB, Joseph NH, Hitchings RA. Surgery for refractory glaucoma: results and complications with a modified Schocket technique.Archives of Ophthalmology. 1987 Apr 1; 105(4):562-9.
3 Reichstein D, Kammer J, Recchia F. Combined 25-gauge vitrectomy and posterior tube shunt placement for advanced glaucoma. Ophthalmology 2011; 118(1): 77–81.
4.Vajaranant TS, Blair MP, McMahon T, Wilensky JT, De La Cruz J. Special considerations for pars plana tube-shunt placement in Boston type 1 keratoprosthesis. Archives of Ophthalmology. 2010 Nov 1;128(11):1480.
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6.De Guzman MH, Valencia A, Farinelli AC. Pars plana insertion of glaucoma drainage devices for refractory glaucoma. Clinical & experimental ophthalmology. 2006 Mar 1;34(2):102-7.
7.Rososinski A, Wechsler D, Grigg J. Retrospective review of pars plana versus anterior chamber placement of Baerveldt glaucoma drainage device.Journal of Glaucoma. 2015 Feb 1; 24(2):95-9.