Indian Journal of Ophthalmology

: 2019  |  Volume : 67  |  Issue : 9  |  Page : 1477-

Ophthalmological signet ring sign by a glaucoma implant

Sunny Chi Lik Au, Simon Tak Chuen Ko 
 Department of Ophthalmology, Tung Wah Eastern Hospital, Hong Kong, HKSAR, Hong Kong

Correspondence Address:
Dr. Sunny Chi Lik Au
Department of Ophthalmology, 9/F, MO Office, Lo Ka Chow Memorial Ophthalmic Centre, Tung Wah Eastern Hospital, 19 Eastern Hospital Road, Causeway Bay
Hong Kong

How to cite this article:
Au SC, Ko ST. Ophthalmological signet ring sign by a glaucoma implant.Indian J Ophthalmol 2019;67:1477-1477

How to cite this URL:
Au SC, Ko ST. Ophthalmological signet ring sign by a glaucoma implant. Indian J Ophthalmol [serial online] 2019 [cited 2022 Oct 2 ];67:1477-1477
Available from:

Full Text

A 58-year-old man with right eye uveitic glaucoma was successfully implanted an Ahmed valve (New World Medical, Rancho Cucamonga, CA, USA) to control his intraocular pressure. Glaucoma drainage device, with increasing popularity,[1] would show up on radiological imaging,[2] and be mistaken as foreign body,[3] especially with its size, superior location to the eye,[4] and heterogeneous radiodensity throughout. The Ahmed valve appears as a signet ring on computed tomography [Figure 1]. The difference in radiodensity of the polypropylene body from the remaining silicone part outlines its ring-shaped appearance. This is more obvious especially with 3D reconstruction [Figure 2], making it a signature of glaucoma implant.{Figure 1}{Figure 2}

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


1Vinod K, Gedde SJ, Feuer WJ, Panarelli JF, Chang TC, Chen PP, et al. Practice preferences for glaucoma surgery: A survey of the American glaucoma society. J Glaucoma 2017;26:687-93.
2Reiter MJ, Schwope RB, Kini JA, York GE, Suhr AW. Postoperative imaging of the orbital contents. Radiographics 2015;35:221-34.
3Mabray MC, Uzelac A, Talbott JF, Lin SC, Gean AD. Ex-PRESS glaucoma filter: An MRI compatible metallic orbital foreign body imaged at 1.5 and 3T. Clin Radiol 2015;70:e28-34.
4Leen MM, Witkop GS, George DP. Anatomic considerations in the implantation of the Ahmed Glaucoma valve. Arch Ophthalmol 1996;114:223-4.