Chan et al. reviewed strategies for the initial management of acute primary angle closure (APAC) [1]. We feel that the authors have overlooked a quick, low-risk option: corneal indentation (indentation gonioscopy, IG).
We find that IG is a quick, easy, patient-friendly technique that often gives an immediate reduction in intra-ocular pressure (IOP) in APAC. The technique requires a standard small diameter four-mirror gonioscopy contact lens without flange (e.g. Posner or Sussman type). In APAC, gonioscopy will confirm closed angle, but gentle pressure on the gonio-lens may allow the angle to open, at least in part [2]. In this case, all that ophthalmologist needs to do is to sustain this pressure, keeping the angle open to allow outflow of aqueous. The patient should be warned of possible discomfort. We like to re-measure the IOP after 10–20 s of indentation; if the IOP has reduced, indentation may be repeated. Successful IG can give a rapid reduction of IOP. This may translate to immediate improvement of symptoms, fewer medications, avoidance of more risky procedures, and more rapid progression to a more definitive treatment such as laser iridotomy.
Good success rates of this technique have been published [3, 4]. Our own clinical audit confirms that IG is definitely worth attempting. Our trainees achieved a clinically useful reduction in IOP in 3 out of 7 cases. These ‘successful’ cases presented with IOP’s of 55, 52, and 52 mmHg, immediate post-indentation IOP’s were 26, 40, and 43 mmHg, respectively (IOP reductions of 52, 23, and 17%). Better IOP response occurred in patients with more recent onset of their symptoms.
We suggest that IG is done as part of the initial management of all cases of APAC. It takes less than a minute, and if successful can lead to quicker resolution of symptoms, faster, easier, safer management. If a four-mirror gonio-lens is unavailable, indentation can be done with any other smooth, round instrument such as a muscle hook or even the fingertip (through closed eyelid) [5]. If IG does not lower the IOP, then the clinician should proceed with other options [1].
References
Chan PP, et al. Acute primary angle closure-treatment strategies, evidences and economical considerations. Eye. 2019;33:110–9.
Whiteside-Michel J. Indentation gonioscopy. In: Morrison JC, Pollack IP, eds. Glaucoma science and practice. New York: Thieme; 2002. p. 48.
Masselos K, Bank A, Francis IC, Stapleton F. Corneal indentation in the early management of acute angle closure. Ophthalmology. 2009;116:25–9.
Elewa LS, Elzankaloni YA, Elkholefy H. Corneal indentation versus anterior chamber paracentesis as an adjuvant to medical treatment in controlling acute primary angle-closure glaucoma. J Egypt Ophthalmol Soc. 2014;107:142–7.
Eke T. Angle closure glaucoma. Ophthalmology. 2009;116:1415–6.
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Pajaujis, M., Eke, T. Comment on: ‘Acute primary angle closure-treatment strategies, evidences and economical considerations’. Eye 33, 1664–1674 (2019). https://doi.org/10.1038/s41433-019-0449-4
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DOI: https://doi.org/10.1038/s41433-019-0449-4
