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Goktas and Goktas1 describe an intriguing case of a young woman with assumed bilateral tonic pupils in the absence of pupillary cholinergic supersensitivity. In the article, the lack of cholinergic supersensitivity is explained by reinnervation of the iris sphincter.
A tonic pupil occurs because of postganglionic parasympathetic denervation of the iris sphincter. The denervated segments show cholinergic super-sensitivity to pilocarpine. Aberrant regeneration of accommodative fibres into the iris sphincter, called the reinnervation process, follows segmental denerva-tion. Once the sphincter segments become reinner-vated more completely by the accommodative fibres, the response to the cholinergic supersensitivity may diminish or resolve completely. Therefore, the degree of parasympathetic degeneration and regeneration of the efferent pupillomotor fibres influences the degrees of cholinergic supersensitivity and light-near dissociation.2
In this denervation-reinnervation process, there are two time periods where cholinergic supersensitivity is expected to be absent. Since cholinergic supersensitiv-ity usually takes a few weeks to develop following postganglionic parasympathetic denervation, testing with 0.125% pilocarpine may fail to demonstrate cho-linergic supersensitivity in this interval. The second time period is in the later stages of the denervation-reinnervation process, in which postganglionic nerves have grown back into the denervated sphincter seg-ments. Once aberrant regeneration has taken place, the receptor’s sensitivity goes down and loses cho-linergic supersensitivity.
This case presented by Goktas and Goktas1 describes denervation followed by a reinnervation processes. The case demonstrates minimal reaction to light, no response to dilute pilocarpine, and a
tonic response to accommodation, which probably indicates that denervated sphincter segments were reinnervated by accommodative fibres. However, further studies, which will demonstrate denervation and innervation of the iris sphincter, may yield a bet-ter understanding of this unusual clinical finding.
Furthermore, in contrast to idiopathic tonic pupils, bilateral tonic pupils with anisocoria of less than 1 mm usually indicate a generalised peripheral or autonomic neuropathy, paraneoplastic syndrome, or connective tissue disease.3 Therefore, anti-gangli-oside antibodies and antineuronal antibodies, such as anti-Hu, anti-Yo, and anti-Ri, should be tested to identify the aetiology.
In conclusion, a lack of cholinergic supersensitiv-ity is a rare but outstanding finding in cases of tonic pupil. Cholinergic supersensitivity provides useful information to clinicians regarding disorders of inner-vation of the iris sphincter.
Declaration of interest: The authors report no con-flicts of interest. The authors alone are responsible for the content and writing of the paper.
RefeRences
1. Goktas A, Goktas S. Bilateral tonic pupils in the absence of pupillary cholinergic supersensitivity. Neuro-Ophthalmology 2011:35;12–14.
2. Kardon RH, Corbett JJ, Thompson HS. Segmental dener-vation and reinnervation of the iris sphincter as shown by infrared videographic transillumination. Ophthalmology 1998;105:313–321.
3. Bremner FD, Smith SE. Bilateral tonic pupils: Holmes-Adie syndrome or generalised neuropathy? Br J Ophthalmol 2007;91:1620–1623.
Neuro-ophthalmology, 36(2), 76, 2012Copyright © 2012 Informa Healthcare USA, Inc.ISSN: 0165-8107 print/1744-506X onlineDOI: 10.3109/01658107.2011.654043
Received 10 November 2011; revised 28 November 2011; accepted 28 November 2011
Correspondence: Berker Bakbak, Department of Ophthalmology, Selcuk University Selcuklu Faculty of Medicine, Konya, Turkey. E-mail: [email protected]
10 November 2011
28 November 2011
28 November 2011
© 2012 Informa Healthcare USA, Inc.
2012
Neuro-ophthalmology
0165-81071744-506X
10.3109/01658107.2011.654043
36
7676
2
654043
NOPH
LETTER TO THE EDITOR
Bilateral Tonic Pupils in the Absence of Pupillary cholinergic supersensitivity
Berker Bakbak, Sansal Gedik, and Bengu Ekinci Koktekir
Department of Ophthalmology, Selcuk University Selcuklu Faculty of Medicine, Konya, Turkey
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