Angle recession, first described by Collins in 18928, from study of post-concussion enucleated eyeballs is just one, from among the myriad pathogenic mechanisms, contributing to raised IOP in the post-traumatic secondary glaucoma complex13. Histologically, angle recession is seen as presence of a tear between the longitudinal and circular fibers 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 trauma3,5,9,14,15. 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 outflow. On clinical examination with gonioscopy, the findings include widened ciliary body band, prominent scleral spur, and a grayish membrane encroaching the angle13,16–18. In most of the cases the secondary glaucoma is refractory to medical management and require surgical intervention17. 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 glaucoma18–21. 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 insult22. Although rise in IOP in the early period 1-3 months is usually attributable to post traumatic inflammation, 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 22–24. Various surgical modalities have been tried with mixed results; while conventional glaucoma surgeries like filtering surgeries, cyclphotodestruction are fraught with risk of potentially sight and organ threatening complication like late bleb infection25, ocular decompression retinopathy26 and serous retinal detachment27. 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 inflammation and compromised visual outcome28. Modified 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 inflammation. Failure rates of trabeculectomy are higher in angle recession compared to POAG, with 43% versus 74% success reported in one study25. Another study by Manners et al observed that compared with POAG the success rate of trabeculectomy is significantly lesser (74% versus 43%) with early surgical failures29. 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 trabeculectomy31. 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 profile than other modalities10,33,34 although data on their efficacy and safety profile as a primary intervention for proactive control of refractory rise in IOP and consequent glaucoma progression is scarce. In this study, we assessed efficacy 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 glaucoma22. 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 glaucoma35. 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 field analysis could not be carried out initially although in the 81% patients with visual acuity >0.5 LogMAR didn’t show any visual field abnormalities. Visual field analysis of the remaining patients on improvement of visual acuity depicted generalized visual field constriction in 2 patients especially those associated with surgical failure at 1 year. Osman et al (two cases) and Turalba et al (five cases) reported 100 % success rates in the management of traumatic glaucoma at the end of one year followup36. 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 significance 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 significant (p <0.05). (Fig 7 )
There were intraoperative challenges faced by the surgeon while implantation of AGV in angle recession glaucoma. Certain novel modifications 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 modifications to avoid egression of fluid, 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 significant improvement in mean visual acuity 0.41±1.5 at last follow up post AGV which was statistically significant (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 efficacy 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.