|Year : 2017 | Volume
| Issue : 1 | Page : 16-21
Comparative evaluation of trabeculectomy with releasable suture versus subconjunctival mitomycin C in post keratoplasty glaucoma
Anuradha Raj, Renu Dhasmana, Harsh Bahadur
Department of Ophthalmology, Himalayan Institute of Medical Sciences, Swami Rama Himalayan University, Jolly Grant, Dehradun, Uttarakhand, India
|Date of Web Publication||19-Sep-2017|
Department of Ophthalmology, Himalayan Institute of Medical Sciences, Swami Rama Himalayan University, Jolly Grant, Dehradun, Uttarakhand
Aim: The aim of the study was to compare the efficacy of trabeculectomy with releasable suture (RS) and trabeculectomy with mitomycin C (MMC) in post keratoplasty glaucoma (PKG). Methods: This observational study was conducted for the patients who developed refractory PKG. Patients who underwent trabeculectomy with RS and with MMC 0.2mg/ml for 2 minutes under the sclera flap were randomly divided into two groups as group I and II respectively. Postoperative follow up of all patients was complete till 6 months for intraocular pressure (IOP) and complications if any. The criteria for surgical success and failure were defined as complete success if final IOP <21 mm Hg achieved without anti-glaucoma medication (AGM), qualified success as achieving the same IOP criteria with AGM and failure as IOP > 21 mm Hg with more than one medications. Results: A total of 52 eyes of 52 patients were included with 26 eyes in each group. Most frequent indication for PK was corneal opacity 25(48.07%). The preoperative mean IOP was 42.11 ± 5.90mmHg and 46.38 ± 8.51mmHg on three AGM in group I and group II respectively. The mean IOP was lowered after both the procedures significantly at all the postoperative follow ups (P=0.000). In group I, the IOP stabilized to 13.12 ± 5.23mmHg by two weeks and remained same till three months with further mild rise in IOP to 17.13 ± 4.28mmHg at six months. In group II, the IOP decreased to 11.27 ± 4.35mmHg on Ist POD and it stabilized at around 22mmHg at two weeks and remained same till six months of follow up. Conclusion: IOP control in trabeculectomy with RS was very good till three months as compared to trabeculectomy augmented by MMC with comparable results at six months of follow up.
Keywords: Postkeratoplasty glaucoma, releasable suture, trabeculectomy
|How to cite this article:|
Raj A, Dhasmana R, Bahadur H. Comparative evaluation of trabeculectomy with releasable suture versus subconjunctival mitomycin C in post keratoplasty glaucoma. Sudanese J Ophthalmol 2017;9:16-21
|How to cite this URL:|
Raj A, Dhasmana R, Bahadur H. Comparative evaluation of trabeculectomy with releasable suture versus subconjunctival mitomycin C in post keratoplasty glaucoma. Sudanese J Ophthalmol [serial online] 2017 [cited 2018 Feb 25];9:16-21. Available from: http://www.sjopthal.net/text.asp?2017/9/1/16/215108
| Introduction|| |
Glaucoma is the most important cause of irreversible visual loss, which amounts to tune of 18% and represents second most leading cause of graft failure after penetrating keratoplasty (PK). Diagnosis of postkeratoplasty glaucoma (PKG) is a challenge because of difficulty in the measurement of intraocular pressure (IOP), visual fields, and optic nerve assessment. Timely and aggressive intervention can salvage the graft and vision both. Carbonic anhydrase inhibitors such as dorzolamide and brinzolamide can lead to graft decompensation on long-term use. Surgery (trabeculectomy) should be considered if medication does not achieve target IOP. Dense perilimbal scarring and fibrosis increase the risk of failure of conventional trabeculectomy. In the recent past, there have been a number of reports on the management of refractory PKG by glaucoma drainage devices (GDDs) with its own limitations. Modification of trabeculectomy with the use of mitomycin C (MMC) helps in its successful outcome. Releasable suture (RS) can help in titration of IOP in the postoperative period. This study was conducted to compare the efficacy of trabeculectomy with RS and trabeculectomy with MMC in PKG. No study has been done to compare both procedures for the management of PKG yet.
| Methods|| |
The observational study was conducted from January 2013 to October 2016. The study was approved by the Institutional Research Ethical Committee and was in accordance with the tenets set forth in the Declaration of Helsinki. The patients who underwent PK optical or therapeutic but developed glaucoma which could not be controlled on topical antiglaucoma medications (AGMs) were included in the study. Criteria to diagnose PKG were persistence of IOP >21 mmHg with maximum treatment during 1st-month post-PK.
The patients who underwent PK with good postoperative graft clarity but developed raised IOP which could not be controlled or noncompliant with topical drugs or difficulty in follow-up and with reexisting glaucoma which worsened and could not be controlled with topical drugs were included in the study.
The patients with a history of glaucoma surgery, uveitis previously, one-eyed patients, very elderly patients, pregnant women, patients with thrombocytopenia, coagulation disorders or immunocompromised status or herpetic keratitis or any history of hypersensitivity, and patients with follow-up of <6 months were excluded from the study.
Informed consent was taken from all patients before enrolling them in the study. Data regarding age, sex, indications, type of PK, presence of glaucoma before PK, medications used, lens status, graft clarity, preoperative IOP, combined cataract surgery, recipient graft size, IOL explantation, iridoplasty, goniosynechialysis, and anterior vitrectomy were recorded. Detailed ophthalmological examination was carried out for all cases, including best-corrected visual acuity (BCVA), slit lamp examination, IOP by applanation tonometry, central corneal thickness, gonioscopy, anterior segment optical coherence tomography, fundus examination, and B-scan if not possible. The patients were randomly selected under two Groups I and II. The allocation of patients under both groups was done by a colleague who was not related to the research by envelope technique. Patients were randomly divided into two groups.
- Group I: Involved the patients who underwent trabeculectomy with RS
- Group II: Involved the patients who underwent trabeculectomy with MMC 0.2 mg/ml for 2 min under the sclera flap.
A single surgeon performed all the surgeries. Under peribulbar anesthesia and aseptic techniques, a corneal stay suture was placed using 8-0 vicryl. A fornix-based conjunctival flap was raised, and hemostasis was achieved with wet field cautery. A half thickness rectangular sclera flap of 4 mm × 4 mm was then dissected up to the clear cornea. In Group II patients, three sponges soaked in 0.2 mg/ml MMC were applied in a diffuse area subconjunctivally and subsclerally for 2 min and the area was then washed thoroughly with saline solution. A paracentesis was created into anterior chamber (AC) with a 30-gauge needle, and air or viscoelastic was injected to maintain the AC depth during surgery. A radial incision was carried out across the scleral spur or the junction between the white and bluish transitional zone of the sclera and by removing the block which consists of scleral spur and trabeculum was excised. A peripheral iridectomy was performed and the scleral flap was sutured using 10-0 nylon. In Group I, two permanent sutures and one RS were applied by the modified method as described by Cohen and Osher. The RS was passed through intact sclera to sclera flap near its base, and then through base, it was passed intrastromally through the cornea and trimmed out to 3 mm. The initial part of suture was tied to the loop with four throws to form a slip knot. The paracentesis was hydrated. A water-tight closure of the conjunctiva was performed by suturing it to the limbus with 8-0 vicryl sutures. One drop each of antibiotic-corticosteroid preparation and atropine was instilled into the conjunctival sac and a patch and a shield were applied on the eye.
Postoperatively, topical cycloplegic agents, antibiotics, and steroid drops were prescribed. The follow-up of these cases was done on the 1st postoperative day (Ist POD) and after 1 week, 2 weeks, and 1, 3, and 6 months. Postoperative complications, BCVA, graft clarity, optic disc cupping, bleb grade by Indiana Bleb Grading Scale, and IOP control were monitored in both groups. Success of surgery was monitored by control of IOP with or without AGM.
The criteria for surgical success and failure were defined before the data analysis.
- Complete success was defined as achieving a final IOP of <21 mmHg without AGM, resolution of corneal edema, no further increase in IOP and with no documented progression of optic disc cupping
- Qualified success was defined as achieving the same IOP criteria with a single AGM
- Failure was defined as IOP >21 mmHg with more than one medication, requirement of resurgery, or development of irreversible complications. The graft was considered to be decompensated where endothelial function deteriorated to the level where graft thickness increased and could not be regressed to normal levels because of excessive graft edema.
In cases of Group I, the time of RS removal was noted. Indications of suture release were IOP >18 mm. The time interval between PK and trabeculectomy was also noted. Increased IOP despite medical treatment and requirements for a second glaucoma surgery was considered as “end of the follow-up period.”
Data were initially entered into an excel spreadsheet and then transferred to Statistical Package for Social Sciences (SPSS) software (Version 22.0, SPSS Inc., Chicago, IL, USA). The descriptive statistics were used to express data in terms of frequency and percentage. Data were expressed in terms of means ± standard deviations (SDs). Independent t-test was used to find the association of preoperative IOP to the IOP changes on Ist POD and 2 weeks and 1, 3, and 6 months postoperatively. Pearson's Chi-square test was used to find out the association between categorical variables such as BCVA and IOP at 6 months postoperatively. P < 0.05 was considered statistically significant.
| Results|| |
A total of 52 eyes of 52 patients were included in the study. The patient characteristics are given in [Table 1]. The age at which PKs were done ranged from 11 to 82 years (mean 52.15 years ± SD). Of 52, 43 (82.69%) eyes underwent optical PK and 6 (11.53%) were of therapeutic PK. In this study, the number of men 40 (76.92%) was higher than women 12 (23.07%). Most frequent indication for PK was corneal opacity 25 (48.07%), followed by pseudophakic bullous keratopathy 15 (28.84%). Both Groups I and II consisted of 26 eyes each. Of these 52 patients, 26 (50%) were pseudophakic, 8 (15.38%) were aphakic, and 18 (34.61%) were phakic. Postoperative follow-up of all patients was complete till 6 months. The RS was released within a mean period of 10.07 days after trabeculectomy. The mean drop in IOP immediately after RS removal was 7.0 mmHg. Graft clarity was Grade 4 in 11 (42.3%) cases in each group. The baseline patient variables among both groups are explained in [Table 1]. The risk factor distribution among the two groups is detailed in [Table 2].
|Table 2: Distribution of risk factors for postkeratoplasty glaucoma in both groups|
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The preoperative mean IOP was 42.11 ± 5.90 mmHg and 46.38 ± 8.51 mmHg on three AGMs in Group I and Group II, respectively. The mean IOP was lower after both the procedures, and the difference was statistically significant at all the postoperative follow-ups (P = 0.000). The mean IOP lowered from 42.11 ± 5.90 to 17.31 ± 4.38 mmHg (P = 0.000) and from 46.38 ± 8.51 to 17.50 ± 4.98 mmHg (P = 0.000) at last follow-up in Groups I and II, respectively.
In Group I, the IOP was 10.35 ± 5.30 mmHg on Ist POD and it stabilized by 2 weeks at 13.12 ± 5.23 mmHg and onward till 3 months. At 6 months, the IOP was 17.13 ± 4.28 mmHg.
In Group II, the IOP decreased to 11.27 ± 4.35 mmHg on Ist POD and it stabilized at around 22 mmHg between 2 weeks and 6 months of follow-up [Table 3].
|Table 3: Intraocular pressure changes after trabeculectomy at various time intervals of follow-up|
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At 6 months of follow-up, the outcome in terms of IOP and BCVA in Group I was P = 0.66 and P = 0.75, which was statistically nonsignificant. In Group II, outcome in terms of IOP was statistically significant (P = 0.054) but nonsignificant for BCVA (P = 0.38).
The complications seen after surgery in both groups are tabulated in [Table 4].
Postoperative complications were more frequent in Group II 12 (23.07%) as compared to Group I 3 (5.76%). Shallow AC was noted in two cases in MMC group and one case of RS group. Reformation of AC was done in these cases, which was successful, except in one case of Group II where graft decompensated eventually. Choroidal detachment occurred in one case as detected by B-scan in MMC group which recovered with the treatment of cycloplegics and topical and systemic steroids. In Group II, wound leakage was seen in one case where glue was applied and it healed, but it failed eventually. In MMC group, five cases had encapsulated bleb; among them, in two cases, 5 mg of 5-fluorouracil (5FU) in 0.1 cc was given subconjunctivally and three cases required bleb revision by needling in addition to 5FU injections, but only two blebs became functional and in three cases trabeculectomy failed. One case with subconjunctival hematoma underwent trabeculectomy again, and in one case, glaucomatous optic atrophy settled eventually [Table 4].
At 6 months follow-up, complete success that is IOP <21 without medication was observed in 25 (96.15%) in Group I as compared to 11 (42.30%) in Group II and there was statistically significant difference (P = 0.000) [Figure 1]. All failures (7 patients) belonged to Group II, and in one case, glaucomatous optic atrophy settled and vision was lost, and in rest of cases, no surgical intervention was done as they were asymptomatic and refused surgery to control IOP [Table 5] and [Figure 2].
| Discussion|| |
The management of PKG is an ophthalmic challenge. The primary modality of the treatment of intractable glaucoma or patients who are not amenable to medications or able to tolerate or continue medications are candidates for surgery. Trabeculectomy not only requires sufficient reduction of IOP but also requires the procedure to be minimally invasive to the corneal graft. Several modifications and variations have been developed to maximize the benefits of treatment while minimizing adverse events. The frequency of graft failure following GDD in PKG was reported to be 44%. This was attributed to corneal endothelial trauma during GDD implantation, which is more relevant to PKG eyes. Alvarenga et al. in 2004 reported their experience on the long-term follow-up of GDD and commented that the frequency of graft failure may increase following GDD. Panda et al. concluded that implanting AGV is a viable option for controlling IOP for 6 months in PKG. However, this technique is associated with complications. Trabeculectomy supplemented with RS can decrease the IOP and reduce posttrabeculectomy complications during the early postoperative period.
The use of 0.2 mg/ml MMC for 2 min improves the overall success while the RS decreases the risk of postoperative complications, especially associated with the use of antimetabolites.
In the present study, the IOP on Ist POD in both groups was same, but in Group I, the mean IOP was lower as compared to Group II till 3 months; however, at 6 months follow-up, IOP in both groups was nearly similar. The RS was released within a mean time period of 10.07 days after trabeculectomy with a range of 5–19 days. The mean drop in IOP immediately after RS removal was 7.0 mmHg, which is in accordance with the results of Thomas et al., who reported decrease in IOP following release of suture to the tune of mean 7.0 ± 5.7 mmHg within critical period of 21 days. According to Thomas et al., if the suture was released within 14 days postoperatively, the reduction in IOP persisted at 1 month; however, in this study, it persisted up till 3 months. In three cases, the RS was released after 2 weeks, and outcome of all these three cases was complete success. The optimal time to release suture for maximum effect on IOP was nearly 3 weeks in this study as reported by Thomas et al. in contrast to Melamed et al., who preferred 3 days. Zhou et al. compared the efficacy and tolerability of trabeculectomies performed with and without RS in the treatment of patients with uncontrolled glaucoma and concluded that two surgical procedures resulted in equivalent efficacy in IOP control with better tolerance with RS than those without RS. In the present study, overall control of IOP was better in RS group with very few complications, which is in concordance with the study by Zhou et al., which demonstrated very few complications in cases of RS as compared to MMC group. Lesser complications in the group with RS was mainly due to the relatively tight sclera flap RS, which can control the aqueous outflow more easily.
Liang et al. compared the postoperative IOP and incidence of early complications after trabeculectomy with RS to standard trabeculectomy in Chinese patients with primary angle-closure glaucoma and demonstrated nonsignificant advantages of RS over standard trabeculectomy. RS was associated with some decrease in visual acuity and increase in postoperative complaints.
Sukhija and Jainreported that early (<1 month) postoperative IOP was a reasonable indicator of long-term IOP control in eyes with advanced glaucoma, which can hold true for this study also, but the follow-up of this study is only 6 months.
The outcome of trabeculectomy with RS was better than with MMC in this study in contrast to the study by Ishioka et al., who reported that trabeculectomy with MMC showed satisfactory results following PK. This study is not in accordance with Ishioka et al which can be due to the fact that they compared the results of trabeculectomy with MMC and without MMC which is different for the present study. Ayyala et al. reported that success rate in IOP control with trabeculectomy with MMC in patients with PKG is 67%–91% and that of graft failure is 12%–18%, which holds true for this study also as the success rate of MMC group is 73.06% (both complete and qualified success).
In contrast, Sharma et al. reported that 87.5% had complete success, 6.25% had qualifi ed success, and 6.25% had failure; after trabeculectomy with MMC in PKG, small sample size of their study may explain the gap between their results with the current study.
Results of amniotic membrane transplant with trabeculectomy in terms of IOP control are comparable to that achieved with the use of MMC. Rong et al. concluded that IOP at 18 months following primary antifi brotic-augmented trabeculectomy in PACG patients is associated with and predicted by the postoperative IOPs at 1 month. Control of early IOP to 13.5 mmHg or less may provide better outcomes which can hold true for these patients also, but the follow-up of this study is only 6 months. Encapsulated blebs were seen in MMC group which refl ects the alteration of fi broblast activity which underwent 5FU subconjunctival injections and bleb revision. In the present study, it was noticed that immediate interventions after surgery played considerable role in maintaining functioning fi ltering blebs and increased the probability of success. This was in accordance with Marquardt's report which stated that intensive postoperative care can signifi cantly increase the proportion of fi ltering blebs achieving target IOP without medication.
Strength of the study
In literature, no study is available to compare the efficacy of trabeculectomy with RS and MMC in PKG. No doubt, the mechanism of the both procedures is different, but the outcome of the both procedures is comparable in terms of IOP control or reduction.
The glaucomatous changes in disc have not been elucidated by any means as it was not possible in most of the cases due to high astigmatism and refractive error. The follow-up of this study is small, so the long-term outcome in terms of IOP control of these both procedures cannot be validated.
| Conclusion|| |
Trabeculectomy with RS holds good in controlling IOP in the postoperative period of 3 months as compared to trabeculectomy augmented by MMC with less complications. At 6 months of follow-up, the IOP control with both procedures was comparable.
| Acknowledgment|| |
We are thankful to Mr. Shubham Pandey, Assistant Professor, Statistics, for statistical analysis and Mr. Surendra Singh Bhandari, Office Assistant, for technical support and photographic documentation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]