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Year : 2021  |  Volume : 1  |  Issue : 2  |  Page : 297-298

Management of hypotony induced by transscleral diode cyclophotocoagulation in failed Ahmed glaucoma valve surgery

1 Department of Glaucoma, Centre for Sight, Banjara Hills, Hyderabad, Telangana, India
2 VST Centre for Glaucoma, LV Prasad Eye Institute, Hyderabad, Telangana, India

Date of Submission15-Jul-2020
Date of Acceptance18-Sep-2020
Date of Web Publication01-Apr-2021

Correspondence Address:
Dr. Vanita Pathak-Ray
Glaucoma Fellowship, University of Toronto, Canada. Centre for Sight, Road No 2 Banjara Hills, Hyderabad - 500 034, Telangana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijo.IJO_2317_20

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Valved Glaucoma Drainage Devices like Ahmed Glaucoma Valve (AGV) are prone to bleb encapsulation around the endplate with subsequent uncontrolled intraocular pressure. Aqueous suppression may or may not lead to resolution and the valve may eventually fail. We report the management in a series of 3 eyes of 3 patients who had failed AGV surgery and after receiving transscleral diode cyclophotocoagulation (TSCPC) treatment, presented with hypotony and decreased vision.

Keywords: Ahmed glaucoma valve, failure, hypotony, hypotony maculopathy, transscleral diode photocoagulation, TSCPC

How to cite this article:
Pathak-Ray V, Badduri A, Gulati I. Management of hypotony induced by transscleral diode cyclophotocoagulation in failed Ahmed glaucoma valve surgery. Indian J Ophthalmol Case Rep 2021;1:297-8

How to cite this URL:
Pathak-Ray V, Badduri A, Gulati I. Management of hypotony induced by transscleral diode cyclophotocoagulation in failed Ahmed glaucoma valve surgery. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Aug 3];1:297-8. Available from: https://www.ijoreports.in/text.asp?2021/1/2/297/312369

Ahmed Glaucoma Valve (AGV) is the preferred glaucoma drainage device by many as its valve guards against hypotony' but, rise in intraocular pressure (IOP) may also occur due to the recognized hypertensive phase (HTP). This may ultimately lead to uncontrolled IOP and failure.[1] We present the management of a series of cases, who developed hypotony subsequentially to titrated transscleral diode cyclophotocoagulation (TSCPC) for failed AGV.

  Case Reports Top

Case 1

A 61-year-old-female aphakic patient underwent supero-temporal (ST) AGV surgery, (FP7 model), with the tube in the anterior chamber (AC), for uncontrolled Neovascular Glaucoma, secondary to vascular occlusion. Panretinal photocoagulation and anti-VeGF injection were done prior to AGV. Her vision was 20/80 and cup-to-disc ratio was 0.9 with advanced visual-field changes. She had intracapsular cataract surgery 30 years ago in the right eye and the fellow left eye had 20/40 vision with cataract. She developed HTP by 6 weeks' post-operatively, with a high encapsulated bleb around the endplate [[Figure 1]-Left]. Anti-glaucoma medication (AGM) was commenced but the IOP remained uncontrolled, when limited TSCPC was done 1-year after AGV-fifteen shots strictly guided by 'pops', over three quadrants, (avoiding ST), a total energy of 51.6 J was delivered (total energy was calculated in Joules as power in Watts [W] × treatment duration in seconds[s] × number of shots). Following TSCPC, she developed low IOP, whilst the bleb around the endplate still looked well formed. Three-months post-TSCPC she sought an emergent consult for sudden decrease of vision (DOV), and Goldman IOP was unrecordable; however, AC was deep and the bleb around the plate continued to appear well-formed. She also had hypotony maculopathy but no choroidal effusion. As hypotony did not resolve on conservative management and the bleb height was suggestive of impairment of the valve mechanism, it was ligated with permanent suture (9/0 Prolene) 8-months after TSCPC. It made a relatively poor indent, so two sutures were used. [[Figure 1-Centre, high bleb around plate even one month after tube ligation] At 2-years post-ligature, she had stable vision and IOP (20/80; 11 mmHg). The bleb around the endplate remained well formed, with some decrease in height. [[Figure 1]-Right]
Figure 1: Case 1. Left – increased height (white arrows) of thick-walled bleb around endplate in hypertensive phase of Ahmed Glaucoma Valve. Centre – height of bleb around endplate high (white arrows) even 1 month after tube ligature (black arrow). Right – height of bleb around endplate (white arrows) 18 months after ligature (black arrow)

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Case 2

A 74-year-old one-eyed diabetic gentleman with advanced Primary Angle Closure Glaucoma, presented with uncontrolled IOP and pseudophakic bullous keratopathy and an extremely disorganized anterior segment of his right eye, 8 months after phaco-filtration surgery elsewhere. He underwent penetrating keratoplasty, IOL explant, removal of adherent iris, anterior vitrectomy and AGV-FP7 in the ST quadrant. He gained 20/200 vision with aphakic correction but developed HTP. At 6 months post-AGV, the IOP was uncontrolled with AGM alone, so 3-quadrant TSCPC (total power <60 J) was done. Thereafter, within a month of TSCPC, hypotony with DOV ensued, but the bleb around the endplate continued to be well-formed. [[Figure 2]-Left] In this soft eye, the direction of the tube became anterior, creating localized ST corneal edema due to presumed tube-endothelium touch [[Figure 2].Right-white arrow], whilst the rest of the graft was relatively clear. Ligature of the tube was undertaken [[Figure 2].Right-encircled area]. The IOP improved to 7–8 mm Hg, but the localized corneal edema did not resolve, till the last follow-up available. However, vision did not recover, and though explantation was planned, poor health prevented this.
Figure 2: Case 2. Left – increased bleb height around endplate, as seen with optical section of slit lamp, after transscleral diode cyclophotocoagulation. Right – intra-operative picture of tube ligation with prolene (white circle); white arrow showing localized corneal edema

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Case 3

A 39-year-old female patient with bilateral advanced Juvenile Open-Angle Glaucoma and failed mitomycin C trabeculectomy, also had a history of bilateral Levator Palpebrae Superioris recession for thyroid-related eyelid retraction. Therefore, not wanting to disturb this 'milieu' superiorly, AGV-FP7 was implanted in the infero-temporal (IT) quadrant, with tube in the AC. She too developed HTP and AGV surgery finally failed in three years. She underwent a 3-quadrant TSCPC (total power ~ 55 J); she went into hypotony and developed maculopathy soon thereafter with a DOV from 20/60 to 20/320. The tube was ligated 3-months post-TSCPC, as conservative management failed. Her bleb, too, did not appear collapsed even when IOP was un-recordable. Within a few weeks of the ligature, the IOP recovered and 2 years post-ligature, she has controlled IOP (10 mmHg) but vision did not recover.

Fellow eye received non-valved Glaucoma Drainage Device (GDD), Aurolab Aqueous Drainage Implant (AADI),[1] also in the IT quadrant; post-op recovery was uneventful with stable vision (20/60) and IOP (13 mmHg) without AGM, at 18-months.

  Discussion Top

It is claimed that the valves of AGV remain closed at low IOP. However, independent examinations of the flow characteristics for these devices suggest a wide divergence between these claims and observed function. Prata et al.[2] believe that these are flow-restrictors rather than true valves that open-and-close in response to pressure changes and possibly never close once they are perfused. In vivo, their results indicated that it is the capsule around the endplate that contributed substantially to the measurable resistance to flow. Some authors[3] believe that 'over priming' of the implant may damage the valve mechanism, essentially rendering the implant valveless and at risk of overdrainage, as the force required to prime the valve is not consistent;[4] yet others do not believe so.[5]

Several management options exist following failure of the AGV–some authors prefer a sequential GDD to bleb excision;[6] others have used TSCPC with moderate results.[7],[8]

Ness et al.[7] and Semchyshyn et al.[8] have both reported hypotony post TSCPC, but their cohort did not consist exclusively of the valved GDD, nor were the individual eyes discussed in detail.

In this case-series, we presume that the valves were over-primed, and that excessive tissue encapsulation led to the increase and uncontrolled IOP initially. We hypothesize that the use of TSCPC, after the failure of AGV, seemed to have unraveled the 'valveless' state, as the bleb appearance was suggestive of drainage even at a very low IOP. Partial resistance, as obtained with permanent ligature of the tube, resulted in normalization of the IOP; however, visual recovery was not the norm. Therefore, early consideration of such a ligature is recommended should hypotony occur post-TSCPC, when used after failed AGV surgery.

  Conclusion Top

Cases of hypotony induced by transscleral diode cyclophotocoagulation in failed Ahmed glaucoma valve surgery may need early attention and management by tube ligature.


Dr Bhupesh Bagga, Cornea Consultant, LV Prasad Eye Institute, Prasad Eye Institute, Banjara Hills, Hyderabad, India 500034.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Pathak Ray V, Rao DP. Surgical outcomes of a new affordable non-valved glaucoma drainage device and Ahmed glaucoma valve: comparison in the first year. British Journal of Ophthalmology 2019;103:659-65.  Back to cited text no. 1
Prata JA Jr, Mérmoud A, LaBree L, Minckler DS. In-vitro and in-vivo flow characteristics of glaucoma drainage implants. Ophthalmology 1995;102:894-904.  Back to cited text no. 2
Jones E, Alaghband P, Cheng J, Beltran-Agullo L, Sheng Lim K. Preimplantation flow testing of ahmed glaucoma valve and the early postoperative clinical outcome. J Curr Glau Prac 2013;1:1-5.  Back to cited text no. 3
Moss EB, Trope GE. Assessment of closing pressure in silicone Ahmed FP7 glaucoma valves. J Glaucoma 2008;17:489-493.  Back to cited text no. 4
Cheng J, Abolhasani M, Beltran-Agullo L, Moss EB, Buys YM, Trope GE. Priming the Ahmed glaucoma valve: Pressure required and effect of overpriming. J Glaucoma 2015;24:e34-5.  Back to cited text no. 5
Shah AA, WuDunn D, Cantor LB. Shunt revision versus additional tube shunt implantation after failed tube shunt surgery in refractory glaucoma. Am J Ophthalmol 2000;129:455-60.  Back to cited text no. 6
Ness PJ, Khaimi MA, Feldman RM, Tabet R, Sarkisian SR Jr, Skuta GL, et al. Intermediate term safety and efficacy of transscleral cyclophotocoagulation after tube shunt failure. J Glaucoma 2012;21:83-8.  Back to cited text no. 7
Semchyshyn TM, Tsai JC, Joos KM. Supplemental transscleral diode laser cyclophotocoagulation after aqueous shunt placement in refractory glaucoma. Ophthalmology 2002;109:1078-84.  Back to cited text no. 8


  [Figure 1], [Figure 2]


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