Clinical Study To Evaluate The Outcome Of Primary AGV Implantation In Angle Recession Glaucoma Following Blunt Ocular Trauma In Indian Eyes

Purpose—To Highlight The Ecacy Of Primary AGV Implantation In Angle Recession Glaucoma Following Blunt Ocular Trauma In Indian Eyes. Design- A retrospective analytical study Materials & Methods— This study included 52 patients of angle recession glaucoma, who presented between Mar 2006 to Feb 2016, out of which 38 patients had undergone primary AGV implantation while the rest were managed with topical anti-glaucoma medications. Preoperative data included age, sex, type & mode of injury, duration of injury, assessment of BCVA and IOP. Extent of angle recession was observed by gonioscopy. The intraocular pressure, visual acuity and number of anti-glaucoma medications were measured postoperatively. The success of this technique was analyzed by using a Kaplan-Meier cumulative survival curve. Results—Following AGV implantation the mean IOP was signicantly reduced to 8.7±2.2 at 1 st day, 10.1±2.2 at 7 th day, 14.2±3.4 at 3 rd month, 15.6±3.7 at 1 year and 15.6±3.6 at 3 rd year follow-up showing statistically signicant values (p<0.001) at each visit. The IOP was successfully controlled at last follow up without topical treatment. Mean BCVA at 3 year post AGV was 0.41±1.5 (logMAR) which was statistically signicant (p<0.001).The success rate by Kaplan- Meier survival curve analysis was 90% at the mean follow up duration of 29.47±3.39 months. Overall surgical complications were noted in the form of prolonged hypotony, hyphema in 7 patients (13.5%). Conclusions—In medically uncontrolled post-traumatic angle recession glaucoma Primary AGV Implantation is a safe and effective surgical procedure with lesser complication rates providing long term IOP control in younger population .


Introduction
Ocular blunt trauma, is one of the leading causes of ocular morbidity across the globe. It can potentially be, a sight threatening condition, depending upon the enormity and magnitude of the impact leading to monocular blindness 1 . It encompasses all the closed globe injuries resulting in the ocular damage due to the force of the energy delivered as a result of trauma 2 Ocular trauma, can occur in any setting; the most common being the sports and domestic injuries, which account for nearly 65-70% of these injuries 3 .
Traumatic glaucoma, consists of a multitude of ocular abnormalities following trauma, owing to various mechanisms, culminating in a common pathway of abnormally raised intraocular pressure (IOP) with associated risk of optic neuropathy 4 . It is a form of secondary glaucoma, occurring in nearly 5-10% of the injured eyes. 5,6 . It can occur instantly after sustaining the injury or after a few years or decades later.
Angle recession glaucoma, is a type of traumatic secondary open angle glaucoma; de ned pathologically, as a separation between the circular and longitudinal bres of the ciliary body muscles.
Studies have shown, that the presence of post-traumatic hyphema is associated with almost 70-100% incidence of angle recession 7-9. The management of angle recession glaucoma, often poses a multifactorial challenge as medical therapy is often ineffective and such cases frequently require either ltering surgery or glaucoma drainage devices 10 . The introduction of valved glaucoma drainage devices, with improved safety pro le, have enabed them to be employed as the primary modality of treatment for this refractory form of glaucoma. 11,12 The aim of this study, is to evaluate the e cacy of Ahmed Glaucoma Valve (AGV), as a primary surgical intervention, in cases of angle-recession glaucoma secondary to blunt ocular trauma in Indian patients.

Materials And Methods
This retrospective, analytical study included 52 consecutive patients of angle recession glaucoma, who had presented to this tertiary hospital, between Mar 2006 to Feb 2016 with uncontrolled intraocular pressure, following blunt trauma, owing to different etiologies. The study adhered to the tenets of the Declaration of Helsinki and was approved by institutional review board of Army Hospital (Research & Referral). Of the 52 patients with traumatic glaucoma, 38 patients had undergone primary AGV (FP7) implantation by a single surgeon (J.K.S.P.) while the rest were controlled successfully with topical antiglaucoma drugs . Preoperative data included age, sex, type & mode of injury, duration of injury to rst contact by an ophthalmologist, assessment of visual acuity using Snellen's chart and converted to LogMAR units, intraocular pressure recorded by Goldmann applanation tonometer(GAT) and extent of angle recession, assessed by gonioscopy, after a quiescent period. Slit lamp examination was done to assess the severity and impact of ocular trauma. Clinical photographs were taken using anterior segment imaging system, on every visit. The number of anti-glaucoma drugs, used before and after the surgery, was taken into consideration. The duration of medical management to timing of AGV implantation was also studied. Data of post operative follow up done at regular intervals upto 3 years and serial IOP was included in the study.

Inclusion & Exclusion Criteria
The patients included in this study ranged between 18 to 42 years of age. Inclusion criteria was patients, examined between March 2006 to Feb 2016, having traumatic angle recession with uncontrolled IOP despite being on maximum anti-glaucoma medication and no lens abnormalities, cyclodialysis or synechiae. The patients who had a history of previous intraocular surgery, corneal decompensation due to any etiology or having no perception of light, were excluded from this study.

Surgical Technique
All the surgeries were performed by a single surgeon (JKSP) under peribulbar anaesthesia. Conjunctival peritomy and forniceal based ap was raised supero-temporally. A subtenon's pocket was created extending upto the equator and a 4 X 4 mm scleral tunnel was prepared by a 2.5 mm crescent blade. After priming the valve with balanced salt solution using a 30-gauze cannula, the valve plate was anchored to sclera by 7-0 nylon sutures, 8 mm away from the limbus. The edge of the tube, was trimmed obliquely with bevel facing upward to ensure intraocular intrusion of about 2 mm. The entry into the anterior chamber was made with a 23-G needle. Tunnel was sealed by 8-0 vicryl sutures. The technique was modi ed by the surgeon by applying 3 compression sutures over the silicon tube, at different places, with 8-0 vicryl sutures, to minimize the possibility of extensive hypotony and choroidal effusion postoperatively. After conjunctival repositioning, sub-conjunctival antibiotics and corticosteroids were injected away from the surgical site. To prevent postoperative hypotony with shallow anterior chamber, injection sodium hyaluronate 1.4% was injected into the anterior chamber.
All patients were evaluated on the rst postoperative day, 1 week, 1 month, every 3 monthly for 1 year and thereafter 6 monthly, for 3 years. A strict postoperative protocol was followed, comprising of topical Moxi oxacin plus 0.1% Dexamethasone for 06 weeks in tapering dosages. Anti-glaucoma medications, were given during the phase of raised intra ocular pressure and subsequently if required. Eye drop Atropine Sulphate 1% was prescribed to the patients for 2 weeks. At each visit patients underwent best corrected visual acuity (BCVA) evaluation, slit lamp examination to assess the corneal clarity, anterior chamber depth, bleb appearance. Anterior segment photographs were taken at every visit and IOP was measured by GAT to monitor the improvement.  The most common site of angle recession was superior in 32 eyes (61.5%) followed by temporal in 10 eyes(19.2%), inferior in 8 eyes (15.4%) and nasal in 2 eyes (3.8%).) (Fig 2 ). The most common site of angle affected by various mode of injury has been depicted in Traumatic mydriasis, was seen in 38 eyes (83.8%) while iridodialysis was observed in 5 eyes (9.6%).  (Fig 5). The mean duration from initial presentation to surgical intervention was 6.

Discussion
Angle recession, rst described by Collins in 1892 8 , from study of post-concussion enucleated eyeballs is just one, from among the myriad pathogenic mechanisms, contributing to raised IOP in the posttraumatic secondary glaucoma complex 13 . Histologically, angle recession is seen as presence of a tear between the longitudinal and circular bers of the ciliary muscles attributable to precipitous iris root traction caused by lateral and posterior displacement of aqueous humor against the iris and angle as result of blunt trauma 3,5,9,14,15 . This may also lead to loss of tension of ciliary muscle on the scleral spur causing narrowing of the Schlemn canal. Additionally, a hyaline membrane also been proposed to grow across the trabecular meshwork leading to further decrease in aqueous out ow. On clinical examination with gonioscopy, the ndings include widened ciliary body band, prominent scleral spur, and a grayish membrane encroaching the angle 13,[16][17][18] . In most of the cases the secondary glaucoma is refractory to medical management and require surgical intervention 17 . It has been found that upto 60 % cases of ocular trauma will develop some degree of angle recession of which 5-20% cases may ultimately progress to angle recession glaucoma [18][19][20][21] . The mean duration of presentation of raised IOP may range from 1 week to many years after the initial trauma although there seems to be twin peaks in incidence of glaucoma one presenting within one year and the other presenting greater than 10 years after the initial traumatic insult 22 . Although rise in IOP in the early period 1-3 months is usually attributable to post traumatic in ammation, hyphema or lens particle associated glaucoma and usually can be managed with medication alone, later sustained rise in IOP(> 6 months ) has been attributable to trauma mediated compromise of angle structures & is refractory to medical management necessitating surgical intervention [22][23][24] . Various surgical modalities have been tried with mixed results; while conventional glaucoma surgeries like ltering surgeries, cyclphotodestruction are fraught with risk of potentially sight and organ threatening complication like late bleb infection 25 , ocular decompression retinopathy 26 and serous retinal detachment 27 . The cyclodestructive procedures such as cyclocryotherapy has not been attempted as a primary surgical modality as it may initially decrease IOP but accompanied with increased in ammation and compromised visual outcome 28 . Modi ed trabeculectomy has shown limited success in angle recession glaucoma. For large angle recession (beyond 120 degree in extent) long term control of IOP was not achieved with conventional glaucoma procedure. The studies have shown that angle recession is a major risk factor for surgical failure, likely related to the younger age of patients and comorbid trauma-related eye damage. The cause of failure of trabeculectomy in young and in trauma cases has been due to recessed and distorted angle with recurrent in ammation. Failure rates of trabeculectomy are higher in angle recession compared to POAG, with 43% versus 74% success reported in one study 25 . Another study by Manners et al observed that compared with POAG the success rate of trabeculectomy is signi cantly lesser (74% versus 43%) with early surgical failures 29 . Ahmed glaucoma valves are gradually gaining popularity in managing refractory glaucoma due to recalcitrant uveitis with reported cumulative success rates of 92% at 2 year follow-up in post uveitis refractory glaucoma 30 .
Study by Chang Kyu Lee et al observed the cumulative probability of success rate of 89% at 6 months, 81% at 1 year, 66% at 3 years, 44% at 10 years, and 26% at 15 years with AGV implantation as secondary surgical intervention after failed primary trabeculectomy 31 . The success rate for AGV implantation in post penetrating keratoplasty was 76% at 2 year follow up as observed by Parihar et al 32 . Glaucoma drainage devices, have been tried in refractory cases of angle recession glaucoma post failed trabeculectomy and laser trabeculoplasty cases and were found to have a better safety pro le than other modalities 10,33,34 although data on their e cacy and safety pro le as a primary intervention for proactive control of refractory rise in IOP and consequent glaucoma progression is scarce. In this study, we assessed e cacy of Ahmed Glaucoma Valve (AGV) implantation, as an initial surgical modality for treatment of refractorily raised intraocular pressure in Indian patients of angle recession glaucoma. Since Indian eyes are susceptible to early glaucomatous damage on account of smaller eyes and heavier pigmentation of trabecular meshwork, it was considered prudent that an aggressive approach be employed, hence surgical intervention was planned at relatively earlier stage with patients having history of glaucoma refractory to maximal topical medication being offered AGV implantation as early as 3 months after the initial traumatic insult.
It was observed that severity of angle recession glaucoma corresponded with degree of angle recession with persistently raised IOP being more consistently found in angle recession of more than 180 degrees. Sihota et al found out hyphema, angle recession of more than 180 degrees, displacement of lens and trabecular pigmentation to be associated with increased chances of progressing to traumatic glaucoma 22 . Clement et al reported angle recession as a major contributor for prolonged IOP disregulation in their study with up to 100% of individuals having trauma-induced hyphema; approximately 9% developing as angle recession glaucoma 35 . In our study, hyphema was present in 73% (38/52 cases) but with varied grades. In about 80%, it was traces to grade I hyphema while 20% had grade II hyphema. Period of absorption of hyphema varied from mean of 2.25±0.95 days in trace to upto 2 week in others. 18 cases (34.6%) with 120 to 180 degree angle recession with hyphema were initially managed medically but subsequently underwent AGV implantation after 3 months of follow up when IOP became gradually uncontrolled despite on maximum medical treatment. Traumatic mydriasis was found in 73% cases (38/52 eyes) ranging from 3.5 to 6.5 mm of pupillary dilatation. 50% patient responded well and 25% continued to have mild to moderate permanent mydriasis and ectropion of pupillary sphincter.
Since most patients had a LogMAR visual acuity of less than 0.6, reliable visual eld analysis could not be carried out initially although in the 81% patients with visual acuity >0.5 LogMAR didn't show any visual eld abnormalities. Visual eld analysis of the remaining patients on improvement of visual acuity depicted generalized visual eld constriction in 2 patients especially those associated with surgical failure at 1 year. Osman et al (two cases) and Turalba et al ( ve cases) reported 100 % success rates in the management of traumatic glaucoma at the end of one year followup 36 . Our study was associated with 76% absolute success rate and functional success rate of 16 % giving an overall success rate of 92% at 1 year while 3 cases (7.9%) were considered as surgical failure at the end of follow up period. We report 90% success rate following primary AGV implantation by Kaplan-Meier survival curve analysis at the mean follow up duration of 29.47±3.39 months. We used Kaplan Meier Curves to analyse the success rate of surgery over the follow up duration. We found that the outcome of surgery was successful in 90% cases over a follow up period of 3 years. (Fig 6). There was no statistical signi cance between the mode of injury and the success rate of the surgery as p value is 0.085. A K-M curve has been plotted to see the correlation between the outcome of surgery with the complications encountered. Here, we see that the outcome of surgery was successful in cases who had no complications during or following the surgery and this correlation was statistically signi cant (p <0.05). (Fig 7 ) There were intraoperative challenges faced by the surgeon while implantation of AGV in angle recession glaucoma. Certain novel modi cations were adopted by the surgeon in standard technique. Making of tunnel, three compression sutures over the tube and ideally tube placement away from angle recession site were the surgeon's novel modi cations to avoid egression of uid, to avoid intraoperative bleed, to prevent tube exposure or extrusion from anterior chamber. Also, in presence of iridodialysis of less than 45 degree and covered with upper lid margin no repair is being performed, in cases where iridodialysis involved more than one quadrant the concurrent repair was done at the time of AGV implantation. Usually improvement in visual acuity is not a goal of AGV implantation. However, we found signi cant improvement in mean visual acuity 0.41±1.5 at last follow up post AGV which was statistically signi cant (p<0.001). This imay have been due to absorption of hyphema, resolved uveitis and control of IOP leading to clearing of corneal oedema.
Thus , primary AGV implantation seems a viable alternative to other surgical procedures for adequate IOP control. To the best of our knowledge, this study is the largest to report the outcome of primary AGV implantation in angle recession glaucoma following blunt trauma and no similar studies have been found in the literature to compare the results of the current study.
This study was undertaken to analyze the e cacy of Primary AGV Implantation in cases of angle recession glaucoma as a result of blunt trauma owing to various etiologies. Although, the current study has proven the successful outcome with the surgical option adopted, but still a randomized prospective study comparing the various surgical options in angle recession glaucoma would be preferred than a standalone non comparative retrospective study with a smaller sample size.

Conclusion
The surgical management of post-traumatic angle recession glaucoma is a challenging task considering the demographic pro le of the patients, who are mostly young and have a recalcitrant disease course. The results of our study have signi cantly proven the e cacy of Primary AGV implantation in such cases with optimum control of intra ocular pressure without a further requirement of topical ANTI-GLAUCOMA MEDICATIONS. This study has also highlighted the relatively lesser complications post-surgery which are a signi cant cause of surgical failure and ocular morbidity when compared to other existing surgical options.

Declarations
Competing Interests-The authors declare that they have no competing interests.  Figure 1