Journal of Neuro-Ophthalmology, September 2014, Volume 34, Issue 3

Reversal of Pupillary Atonia After Removal of an Encircling Band

We describe a patient who developed an atonic pupil after placement of an encircling band during retinal detachment surgery. When the band was removed 18 months later, the pupil signs showed partial recovery demonstrating a degree of reversibility of the parasympathetic paresis. We speculate that in this case mechanical deformation of the sclera by the encircling band had produced a conduction block of the short posterior ciliary nerve fibers as they pass forward in the underlying suprachoroidal space.

Reversal of Pupillary Atonia After Removal of an Encircling Band Fion D. Bremner, MD, PhD, FRCOphth, Hadi Zambarakji, DM, FRCOphth, Cavelle Griffiths, BSc, MCOptom Abstract: We describe a patient who developed an atonic pupil after placement of an encircling band during retinal detachment surgery. When the band was removed 18 months later, the pupil signs showed partial recovery demonstrating a degree of reversibility of the parasympa-thetic paresis. We speculate that in this case mechanical deformation of the sclera by the encircling band had produced a conduction block of the short posterior ciliary nerve fibers as they pass forward in the underlying supra-choroidal space. Journal of Neuro-Ophthalmology 2014;34:268-270 doi: 10.1097/WNO.0000000000000105 © 2014 by North American Neuro-Ophthalmology Society Afixed dilated pupil is a recognized though rare post-operative complication of anterior segment surgery. It is classically described after penetrating keratoplasty (1) but also may occur after other anterior segment proce-dures including trabeculectomy (2) and cataract extrac-tion (3). In these cases, the parasympathetic blockade is usually postreceptoral (because the pupil will not con-strict with topically administered full-strength pilocar-pine drops) and permanent. We describe an unusual case of a patient with a fixed dilated pupil after retinal detachment surgery in which parasympathetic function partially recovered after removal of the scleral encircling band. CASE REPORT A 23-year-old woman underwent surgery for a macula-off rhegmatogenous retinal detachment in her left eye. She had a moderate degree of myopia (23D) but no other history of ocular disease. She enjoyed good general health and was taking no regular medications. The surgery, per-formed under general anesthetic, involved placement of a circumferential silicone explant (buckle) between the 11 o'clock and 4 o'clock meridians, a 360° encircling band (2.5 mm diameter) and transscleral cryopexy. The follow-ing day she noticed on removing the eye patch that her left pupil was dilated; ophthalmic examination confirmed suc-cessful reattachment of the retina. Postoperative recovery was unremarkable but the pupil remained dilated and nonreactive to light. She returned 18 months, later having noticed problems focusing. Visual acuity was 20/20 in the right eye and 20/ 200 in the left eye. Anterior segment examination was unremarkable with normal intraocular pressures and no signs of ocular ischemia; funduscopy showed that the retina remained fully attached. Eye movements were full on the right but slightly restricted on the left both horizontally and vertically. The patient's eyelids were symmetric and normal. The left pupil was larger than the right (Fig. 1), and there was almost no observable light response (LR) or near response (NR) of the left pupil. On slit-lamp biomicroscopy, the pupil appeared round with no visible sector palsy. Pupillometry con-firmed significant attenuation of the pupillary constrictor responses (LR and NR; Fig. 2, Table 1) in the left eye, although the mydriatic response to sudden noise (the "startle reflex") was preserved. The right pupil and deep tendon reflexes were normal. In view of her persistent symptoms, the patient underwent surgery to remove both segmental and encircling buckles, which were found lying 2 mm posterior to the insertions of the rectus muscles. During National Hospital for Neurology and Neurosurgery (FDB), London, United Kingdom; and Barts Health NHS Trust (HZ, CG), Whipps Cross University Hospital, London, United Kingdom. The authors report no conflicts of interest. Address correspondence to Fion D. Bremner, MD, PhD, FRCOphth, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, United Kingdom; E-mail: fion.bremner@uclh. nhs.uk 268 Bremner et al: J Neuro-Ophthalmol 2014; 34: 268-270 Clinical Observation Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. the surgical procedure and within minutes of cutting the encircling buckle, the left pupil became smaller. The following day the patient noticed that her left pupil was smaller than the right and when examined at her postoperative visit 2 weeks later the left pupil now reacted to light. Ten weeks after surgery, pupillometry showed that the left pupil was smaller, and the pupillary constrictions to a light stimulus and an accommodative effort were larger (Table 1; Figs. 1, 2). Pupillometry was repeated once more 4 months later and showed similar results. Topical 0.5% apraclonidine was used to test the integrity of the sympathetic innervation of the iris dilator muscle; this weak a1-agonist had no effect on the resting size of either pupil. DISCUSSION Although our patient did not have any previous pupil assessment, it is her recollection, supported by old photo-graphs, that her pupils were normal and similar in size before retinal detachment surgery. Following this pro-cedure, the left pupil became fixed and dilated. The lack of response to light can be partly attributed to a reduced afferent drive from the reattached retina. We did not record the pupil responses to uniocular light stimulation or look for a relative afferent pupil defect. However, this does not explain the increase in resting diameter of the left pupil or the absence of any pupil constriction with an accommoda-tive effort. These changes suggest that surgery caused a marked efferent blockade of parasympathetic impulses to the iris sphincter muscle. The findings in our patient's left pupil are not similar to Adie's tonic pupil, which include sector palsy, light-near dissociation, and slowed constriction associated with aber-rant regeneration of postganglionic parasympathetic fibers after injury to the ciliary ganglion. The changes we noted are better described as atonic. It appears that this was a purely parasympathetic blockade. The normal lid position, preserved startle response, and absence of mydriatic effect from apraclonidine indicate that the sympathetic supply to the iris dilator muscle was unaffected. Also, there was no clinically apparent disturbance of corneal sensation. Changes to the pupil and accommodation have been reported after various transscleral treatments for diabetic retinopathy or peripheral retinal degeneration-including cryotherapy (4), argon laser photocoagulation (5), and diode laser photocoagulation (6). Pupil changes have rarely been reported after retinal detachment surgery. Adler and Scheie (7) provided the first description of 2 cases of atonic pupils after "extensive (transscleral) electro-coagulation"; in patient 1, after several weeks the pupil became smaller and recovered a small degree of "tonic" responsiveness to light. Kronfeld (8) reported postopera-tive sector palsy in 5 eyes in which the affected meridian corresponded to the site of scleral buckling. There are a small number of additional cases published in which the pupil has become either tonic (9) or atonic (10,11) after placement of an encircling band or endolaser. In all cases, the pupil showed supersensitivity to dilute musca-rinic agonists (methacholine or pilocarpine) confirming prereceptoral parasympathetic blockade and, in most cases, the pupil remained abnormal with no spontaneous recovery. Our case is unique in documenting the effects of removing an encircling band in a patient who had developed an atonic pupil at the time of its placement. We would interpret the partial reversal of the parasympa-thetic paresis within minutes of removing the encircling band as evidence that the pupil changes were because of conduction block rather than loss of the short posterior FIG. 1. Top: Before removal of the buckle, the left pupil is larger than the right. Bottom: After removal of the buckle, the anisocoria is reversed. Photographs taken with full room lights on. FIG. 2. Pupillary responses to light (LR) and to an accom-modative effort (NR). The responses are very small before removal of the encircling band (solid line) but improve after removal of the band (dashed line). LR, light response; NR, near response. Bremner et al: J Neuro-Ophthalmol 2014; 34: 268-270 269 Clinical Observation Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. ciliary nerves (SPCN). The lack of any pupil signs that might indicate aberrant regeneration (tonic constriction to light and near, sector palsy, and light-near dissociation) further supports our view that the SPCN were preserved but nonfunctioning between her first and second operations. It is not clear whether the mechanism of this conduction block was primarily ischemic or mechanical. There were no clinical signs suggestive of ocular ischemia. The SPCN travel in the suprachoroidal space as they pass forward towards the iris and are presumably susceptible to mechan-ical deformation from scleral indentation. It is interesting that in our patient there was no evidence of dysfunction of the sympathetic and trigeminal nerves, which also pass in the suprachoroidal space. In the case reported by Vallde-peras et al (11), a 11-year-old boy developed permanent corneal anesthesia after placement of an encircling band; however, additional trigeminal or sympathetic paresis was not described in any of the other published cases of pupil changes after retinal detachment surgery and was not detect-able in our case. We speculate that the SPCN may be more susceptible to mechanical deformation than the other nerves traveling in the same anatomical compartment. After removal of the encircling band, the left pupil became smaller than the right and remained so 4 months later. This raises the question of whether the larger right pupil was functioning normally. The amplitude of the LR in this eye was below the lower limit of the normal range for our laboratory (12), and it is possible that the extensive prophylactic cryotherapy to this eye had damaged some of the SPCN giving rise to a larger than normal resting pupil-lary diameter in this eye. However, the light reflex response of the pupil in the left eye remained smaller than in the right eye even after removal the encircling band suggesting that the SPCN function was still better in the eye with the larger pupil. Different degrees of denervation supersensitivity might have accounted for some of this reversed anisocoria; in the context of SPCN dysfunction in Holmes-Adie syn-drome, it is a common finding that affected pupils become progressively miotic over time despite persisting signs of parasympathetic paresis. Unfortunately, we were not able to test this hypothesis by pharmacological means using a dilute muscarinic agonist (e.g., 0.1% pilocarpine) because the corneal surfaces of both eyes in this myopic patient were compromised by years of contact lens wear rendering such testing invalid. REFERENCES 1. Urrets-Zavalia A. A fixed, dilated pupil iris atrophy and secondary glaucoma. A distinct clinical entity following penetrating keratoplasty in keratoconus. Am J Ophthalmol. 1963;56:257-265. 2. Jain R, Assi A, Murdoch IE. Urrets-Zavalia syndrome following trabeculectomy. Br J Ophthalmol. 2000;84:338-339. 3. Golnik KC, Hund PW, Apple DJ. Atonic pupil after cataract surgery. J Cataract Refract Surg. 1995;21:170-175. 4. Uno T, Ikuyama M, Tanabe T, Kawamura R, Ideta H. Accomodative loss after retinal cryotherapy. Am J Ophthalmol. 2009;147:116-120. 5. Rogell GD. Intrenal opthalmoloplegia after argon laser panretinal photocoagulation. Arch Ophthalmol. 1979;97:904-905. 6. Patel JI, Jenkins L, Benjamin L, Webbie S. Dilated pupils and loss of accommodation following diode panretinal photocoagulation with sub-tenon local anaesthetic in four cases. Eye (Lond). 2002;16:628-632. 7. Adler FH, Scheie HG. The site of the disturbance in tonic pupils. Trans Am Ophthalmol Soc. 1940;38:183-189. 8. Kronfeld PC. Segmental impairment of pupillary motility after operations for retinal detachment. Trans Am Ophthalmol Soc. 1961;59:239-251. 9. Newsome DA, Einaugler RB. Arch Ophthalmol. 1971;86:233- 234. 10. Ebrahim B, Frohman L, Zarbin M, Bhagat N. Tonic pupil following pars plana vitrectomy and endolaser. Case Rep Med. 2009;2009:970502. doi: 10.1155/2009/970502. 11. Valldeperas X, Arango A, Blazquez A, Romano M. Tonic pupil and corneal anesthesia after vitrectomy and encircling band for reteinal detachment in an ex-premature child. Case Rep Ophthalmol. 2010;1:66-70. 12. Bremner FD. Pupil evaluation as a test for autonomic disorders. Clin Auton Res. 2009;19:88-101. TABLE 1. Pupil measurements before and after removal of the encircling band in the left eye and compared with the right eye Right Eye Left Eye Before Removal of Buckle Left Eye 10 Weeks After Removal of Buckle Pupil size in darkness (mm) 7.12 7.52 6.27 Pupil size in bright lit room 7.04 7.52 5.06 LR amplitude (%) 13.6 2.3 14.9 NR amplitude (%) 19.6 2.3 22.1 LR (light reaction): relative constriction (%) of the pupil to a standard 1 second light stimulus presented under "open-loop" Maxwellian optics; NR (near reaction): relative constriction (%) of the pupil to an accommodative effort. 270 Bremner et al: J Neuro-Ophthalmol 2014; 34: 268-270 Clinical Observation Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.