Surgical technique: complex glaucoma case requiring Molteno drainage tube extension

Abstract

A 42-year-old man has been under long-term follow-up since he was a child for congenital glaucoma and buphthalmos in both eyes. His left eye best corrected visual acuity (BCVA) was counting fingers, due to end-stage glaucoma. He was on maximal medical therapy with an intraocular pressure (IOP) maintained at mid to low twenties. His right eye, the only seeing eye, had a BCVA of 6/9. This eye had undergone multiple glaucoma laser and surgical procedures, including an initial first Molteno drainage device inserted superonasally that failed in April 2003 due to fibrotic membrane over the tube opening. As a result, he subsequently had a second Molteno drainage device inserted inferotemporally. To further maximize his vision he had an uncomplicated cataract extraction and intraocular lens implant in December 2004, after which he developed postoperative cystoid macular edema and corneal endothelial failure. He underwent a penetrating keratoplasty in the right eye thereafter in March 2007. After approximately a year, the second Molteno device developed drainage tube retraction, which was managed surgically to maintain optimum IOP in the right eye. His right eye vision to date is maintained at 6/12.

Outcome of combined single-loop fixation of intraocular lens with Ahmed glaucoma valve implantation

“…In our patient, the tube retracted as a consequence of trauma. The reported management options for tube retraction include lengthening the tube,11–19 repositioning the plate20 and replacement with a new GDD 21…”

“…Tube lengthening is the preferred recourse as it involves lesser dissection causing minimal disturbance of the bleb around the plate. The tube can be lengthened using residual sterilised GDD tube segments from previous surgeries,11 22-G intravenous catheter,12–15 silastic sleeves and small-diameter silastic tubes 16 17. A commercially available device, the tube extender, though convenient to use, is expensive and bulky 18 19…”

A Novel Method of Extending Glaucoma Drainage Tube: “Tube-in-Tube” Technique

“…The most widely used methods include the use of a 22-gauge angiocatheter and the commercially available Tube Extender. [3][4][5][6][7] The entire tube-plate complex can also be moved anteriorly but extensive tissue dissection is often required which can promote further fibrosis leading to GDD failure. Alternatively, a second GDD can be implanted but it is not always desired.…”

“…Tube retraction occurs more frequently in the paediatric population due to the exaggerated scarring response and ocular/axial length growth. Many extension techniques for tube retraction have been described including rerouting the tube using a commercially available Tube Extender (New World Medical, CA), 3,4 using 22gauge intravenous angiocatheter [5][6][7][8] or Crawford tubing 9 . Alternatively, a second GDD can be inserted at a different site.…”