|Year : 2021 | Volume
| Issue : 2 | Page : 297-298
Management of hypotony induced by transscleral diode cyclophotocoagulation in failed Ahmed glaucoma valve surgery
Vanita Pathak-Ray1, Anusha Badduri2, Isha Gulati2
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 Submission||15-Jul-2020|
|Date of Acceptance||18-Sep-2020|
|Date of Web Publication||01-Apr-2021|
Dr. Vanita Pathak-Ray
Glaucoma Fellowship, University of Toronto, Canada. Centre for Sight, Road No 2 Banjara Hills, Hyderabad - 500 034, Telangana
Source of Support: None, Conflict of Interest: None
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 Jul 29];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. We present the management of a series of cases, who developed hypotony subsequentially to titrated transscleral diode cyclophotocoagulation (TSCPC) for failed AGV.
| Case Reports|| |
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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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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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), 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|| |
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. 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 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; yet others do not believe so.
Several management options exist following failure of the AGV–some authors prefer a sequential GDD to bleb excision; others have used TSCPC with moderate results.,
Ness et al. and Semchyshyn et al. 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|| |
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.
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[Figure 1], [Figure 2]