FP528 : RE-INTERVENTION POST TRABECULECTOMY – OUR EXPERIENCE

Dr.Reetika, Dr.Lalit Kumar Tejwani

RE-INTERVENTION POST TRABECULECTOMY – OUR EXPERIENCE

Trabeculectomy remains the surgery of choice in glaucoma. Surgical complications remain a night-mare for glaucoma surgeons. We retrospectively studied one hundred and seventy one eyes who underwent trabeculectomy. Fifteen cases needed anterior chamber reformation, 17 needed needling with 5-Fluorouracil in a follow-up ranging from six months to 58 months. Two cases needed conjunctival autograft with amniotic membrane. One eye underwent PPV for malignant glaucoma, SF6 was put intracamerally in two cases for persistant CD. One case of Blebitis was seen, which was managed medically. One cornea went into decompensation following combined surgery. Four cases failed, of which two lost to follow up. Almost all cases were on topical antiglaucoma post surgery. Preoperative vision though was recovered in almost all cases, took up-to four to six weeks in some. Re-intervention post trabeculectomy is needed in few cases. Vision recovery post trabeculectomy takes time. Combined surgery may need higher re-intervention. 

Introduction 

Glaucoma is a chronic, progressive optic neuropathy with a characteristic optic nerve head change and corresponding visual field (VF) defects. It is the leading cause of irreversible blindness worldwide. Most of cases are associated with raised intra-ocular pressure (IOP) and treatment options for us are limited to methods lowering IOP and neuroprotection. One of most common surgeries performed is Trabeculectomy or Glaucoma filtering Surgery. Two important aspects of glaucoma surgery are wound modulation and associated lens surgery. Advanced glaucoma & coexisting cataract is a common association in elderly population. At times, it is the thicker crystalline lens, which may necessitate simultaneous Cataract surgery in such advanced glaucoma cases.

Long term results are limited by filtration failure caused by scarring at various levels, i.e. conjunctiva-Tenon’s-episcleral interface, sclera flap, episclera, or ostium (1).Scarring is the result of the natural wound healing process in the form of proliferation of sub-conjunctival fibroblasts and the biosynthesis of extracellular materials(2,3). So wound healing modulation is crucial to prolong the surgical life of Trabeculectomy (1,4).

One of major impact of glaucoma surgery is due to its complications and re- interventions needed in early phase and the delay in vision recovery. Tube Versus Trabeculectomy Study (TVTS) (5) has discussed post surgery complications and intervention needed for same. In this retrospective study, we have compiled the data from two tertiary eye care centers, and have observed the re- intervention need and for the specified reason. Our aim is to understand the sequence post surgery and also intervention needed for same, and also see their impact on follow up.

Methodology :

This is a retrospective chart review of all the trabeculectomies done in two tertiary eye care centers with or without phacoemulsificaton. On wound modulation basis, we have classified cases as single wound modulation (mitomycin C, MMC 0.04% x 4.5 minutes contact time), double modulation (use of Ologen – collagen matrix implant along with MMC) and triple Modulation ( MMC + Collagen matrix implant used which is soaked in anti-VEGF solution). In the double modulation, studies have shown use of collagen implant with varied concentration and contact time of MMC, we have gone for 0.04% with 4 minutes contact time.(6)

Role of anti-VEGF has been studied in glaucoma surgery in the past. (3) In our cases of Triple modulation, we have gone for collagen matrix soaked in anti-VEGF solution, Bevacizumab, with double placement of implant  sub-subscleral and sub-conjunctival space. The concentration of MMC used was 0.04%in all cases. The contact time for same was 4 minutes in initial cases which was reduced to 3.5 minutes in later cases.

All the cases who had been taken back to operation theatre (OR) after primary surgery (including needling) were studied, the reason for re- intervention studied and this was noted. Data for re-intervention was compared across various groups.

Observation and Results:

A total of 171 cases were studied, 106 of these were males, and remaining 65 females. The age range was eight years to 84 years. In systemic history, 34 patients had hypertension, 21 were diabetics and 11 had history of cardiac event in the past.

Sixty seven cases were of primary open angle glaucoma (POAG), 61 primary angle closure glaucoma (PACG), 24 juvenile open angle glaucoma (JOAG) and 19 were secondary glaucoma cases. Almost all of cases were advanced cases with vertical Cup: Disc ratio of 0.9 or more and 36 cases had Glaucomatous Optic Atrophy.  Thirty one cases had history of previous failed trabeculectomy and were Re-Trabeculectomy cases. Two cases had vision of perception of light with inaccurate projection of rays and in them vision was not improved post- surgery.  Four cases had vision of finger counting close to face and they had some improvement of vision post- surgery. One case went in post- surgery corneal decompensation and his vision did not improve. Rest all cases had regained the vision pre- operative status within 4 – 6 weeks and many had improved vision.

In all cases, due to high C:D ratio and advanced status, we had started topical Anti-Glaucoma Medications from three months onwards and we aimed to get the lowest possible IOP with strict control.  Baseline IOP were high in almost all cases (over 22) in spite of 40 cases being on systemic medications. Four of these failed. Follow up was from six months to 58 months.

Of 171, Only Trabeculectomy was done in 91 cases, and combined Phaco-trabceulectomy was done in 80 cases.  Wound modulation wise, single modulation was used in 45 cases, Double modulation in 64 cases and 62 cases were of Triple modulation.

Major re-interventions done were anterior chamber (AC) reformation with air in 15 cases and Needling with 5-Fluorouracil (5-FU) in 17 cases (we studied needling done within 6 months) (table 1).

In two cases Conjunctival autograft was done for melting and leakage. Two cases had persistent Choroidals and intra-cameral SF6 injection was done in both and the choroidal detachment settled. One case had Blebitis with Ologen implant exposure, in which trimming of implant and amniotic membrane graft (AMG) was done under antibiotic care. Pars Plana Vitrectomy (PPV) was done in one case for Malignant Glaucoma.

When we studied these vis a vis wound modulation (table 1) – seven cases of Triple modulation needed AC reformation, six in Double modulation and two in single modulation. The first 20 cases of Triple had MMC contact time of four minutes, and later 42 cases had 3.5 minutes.  When we studied this AC reformation of seven cases, three had contact time of 4mins, and four had 3.5 mins. So this re-intervention was decreased when we reduced contact time by 0.5 mins in Triple modulation group.

Six cases of single modulation needed Needling + 5FU, eight in double modulation and three of Triple modulation. The overall Needling need was % wise maximum in Single Modulation.

SF6 was needed in two cases and both were of Triple Modulation, Re-suturing with conjunctival autograft was needed in one case of Triple and one of Double modulation. Blebitis case was of Double Modulation. PPV and decompensated cornea were both Triple modulation cases.

Of the four which failed, two were single modulation, and two double modulation cases.

When we studied this as procedure wise- Trabeculectomy vs Combined (table 2), then 11 cases in Combined needed AC reformation and four in Trabeculectomy. Needling with 5 FU was needed in six cases in combined but in 11 cases in Trabeculectomy cases. In Combined category, one case needed SF6 intra-cameral, one needed PPV, one went into decompensation and one needed auto-grafting due to melting.

Complications were clearly more in Triple modulation and Combined group, but they were not major complications and had no major outcome on long term prognosis. Needling was needed more in single modulation cases.

Discussion

Tube Versus Trabeculectomy Study (TVTS) is one of the most important studies related to complications following glaucoma surgery. They studied complications and re-interventions following glaucoma surgery. They considered additional procedures which required return to OR as re-interventions. They did needling and AC reformation on slit lamp and hence these procedures were not included in re-intervention. They included 105 eyes in their study out of which 43 % cases underwent combined  surgery, which is almost similar to our rate i.e. 46.8%. Their re-intervention rate was 18 % which is less than ours, i.e. 22.2%, which may explained by the difference in selection criteria or definition for re-intervention.

Of 105 eyes, needling was needed in six eyes in TVTS and this was needling done in OR only, not counting those done on slit lamp. Twenty-one cases in TVTS had Shallow/ Flat AC and ten had choroidal detachment, four with aqueous misdirection and three with suprachoroidal haemorrhage. They had reported 70 % post-operative intervention rate in trabeculectomy group, of which most common was Laser suture lysis (55 cases out of 74 were laser lysis).  The remaining 19 cases can be counted as major re-interventions, which makes it as 18 % rate, which is less in our study. One factor we can consider is better wound modulation with double and triple modulation techniques, which may give better long term results.

The rate of AC reformation was more in double and Triple modulation- this was more so between day 10 – day 16 which may be due to fact that collagen matrix itself delays healing of conjunctiva and so when by day – 10 vicryl suture became loose, it started giving some micro-leaks which caused delayed swallowing and when such cases were performed AC reformation with air and were given pressure bandage for a day, it recovered slowly. This was more in Triple modulation and also more when MMC was used for 4 mins contact time in triple modulation series, but became less when it was 3.5 mins. One more step to reduce this delayed shallowing was to bring conjunctiva slightly anterior to cornea, so that when vicryl losses and it slips, adhesions are formed posterior to it already.

Follow up may affect the rate of interventions, but have taken the re- interventions needed within first 6 weeks, and needling upto 6 – 12 months. Our follow up was 6 to 58 months. The final outcome in terms of IOP fall less than 20 % to baseline, we had achieved this in almost all cases, except4, and due to advanced glaucoma profile we added topical AGM in our all cases.

None of cases had IOP less than five at follow up after three months.

We feel Triple modulation when done with MMC contact time of 3.5 mins gives a good balance between re-intervention and long term success rate. However, combined surgery does have high rate of re-intervention and should be considered in cases when glaucoma is very advanced, lens is cataractous or lens thickness is more or case is of PACG, such cases will need simultaneous phacoemulsification for better long term outcome.

Longer follow up with better protocols are needed to study more in this aspect. However we believe a glaucoma surgeon should not shy away from re-intervention in his cases and should always counsel patients for the common ones which may be needed in over 20% cases, like AC reformation and Needling with 5 FU.

References

1. Azuara-Blanco A, Katz LJ. Dysfunctional filtering blebs. SurvOphthalmol. 1998 Sep-Oct;43(2):93-126.
2. Skuta GL, Beeson CC, Higginbotham EJ, et al. Intraoperative mitomy­cin versus postoperative 5- fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology. 1992;99(3):438–444.
3. Daneshvar R. Anti-VEGF Agents and Glaucoma Filtering Surgery. J Ophthalmic Vis Res. 2013;8(2):182–186.
4. Seibold LK, Sherwood MB, Kahook MY. Wound modulation after filtration surgery. Surv Ophthalmol. 2012;57: 530–550.
5. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC; Tube Versus Trabeculectomy Study Group. Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol. 2012 May;153(5):804-814.e1.
6. Dada T, Midha N, Shah P, Sidhu T, Angmo D, Sihota R. Innovations in glaucoma surgery from Dr. Rajendra Prasad Centre for Ophthalmic Sciences. Indian J Ophthalmol. 2017 Feb;65(2):103-108.

Table 1: Re-intervention in various type of wound modulation (single = MMC 0.04 % x 4.5mins, double = MMC 0.04 % x 4 mins + Ologen implant, Triple = MMC 0.04 % x 4mins/ 3.5 mins + Ologen implant soaked in Bevacizumab)

Re-intervention	Single modulation ( n= 45)	Double modulation ( n=64)	Triple modulation (n=62)	Total (n=171)
AC reformation	2  (4.4%)	6 (9.4%)	7 (11.3%)	15 (8.8%)
Needling +5 FU	6 (13.4%)	8 (12.5%)	3 ( 4.8%)	17 (9.9%)
SF6 intra-cameral	0	0	2	2
Re-suturing	0	1	1	2
Blebitis Mx	0	1	0	1
PPV	0	0	1	1
	8 (17.8%)	16 (25%)	14 (22.5%)	38(22.2%)

Table 2: Re-intervention based on type of surgery  (Trabeculectomy with mound modulation, and combined Phaco –Trabeculectomy)

Re-intervention	Trabeculectomy (n= 91)	Phaco-Trabeculectomy ( n= 80)	Total ( n = 171)
AC Reformation	4 (4.4%)	11 (13.8%)	15 (8.8%)
Needling + 5 FU	11 (12.1%)	6 ( 7.5%)	17 (9.9%)
SF6 intra-cameral	1	1	2
Re-suturing	1	1	2
Blebitis Mx	0	1	1
PPV	0	1	1
	17 (18.7%)	21 (26.3%)	38 (22.2%)