The Hummelsheim procedure involves splitting the vertical recti muscles and reattaching the temporal halves adjacent to the insertion site of the lateral rectus muscle.1 This procedure is indicated for lateral rectus palsy when the preservation of the anterior segment circulation is a concern. Anterior segment ischemia has been reported after the detachment of two recti muscles. The risk of this complication increases when a third rectus muscle is detached because the vertical recti muscles do not have a posterior ciliary artery.
A 53-year-old woman presented to our hospital with complaints of binocular double vision and deviation of the left eye, which she had for the past 3 years. There was no preceding history of trauma or contributory systemic comorbidities. Her uncorrected visual acuity was 6/24 in the right eye and 6/18 in the left eye. Her best corrected visual acuity was 6/6 N6 in both eyes with +1.50 diopters (D) of hypermetropia and 2.00 D of near addition in both eyes. The anterior segment was normal. There was left esotropia of 30 degrees. The alternate prism cover test revealed 50 prism diopters (PD) of esotropia, with the right eye fixing for near and distance. There was grade 4 limitation of abduction in her left eye with an absence of abduction saccades (Figure 1). She had uncrossed diplopia on Worth four-dot test and no stereopsis. The forced duction test for abduction was positive in her left eye. Her dilated fundus and the rest of the neurological examination were normal. Magnetic resonance imaging of her brain and orbit were normal. Her blood investigations (complete hemogram, blood sugars, and lipid profile) were within normal limits. She was diagnosed as having isolated non-resolving lateral rectus palsy in the left eye.
(A–B) Preoperative esotropia in primary position and grade 4 limitation of abduction in the left eye. (C–D) Postoperative improvement in primary gaze alignment and abduction in the left eye.
The patient underwent a left medial rectus recession (limbal approach) of 6 mm with Wright's modification of Hummelsheim's muscle union procedure under local anesthesia. A 360 degree conjunctival peritomy was performed in the left eye. The medial rectus muscle was recessed 6 mm from the insertion site. The lateral rectus and vertical recti muscles were isolated and dissected. The superior and inferior rectus muscles were carefully split to preserve the ciliary vessels in the nasal half. The temporal halves of the vertical recti muscles were secured with a 6-0 polyglactin suture, disinserted, and reattached adjacent to the lateral rectus muscle insertion along the spiral of Tillaux. Muscle union sutures were placed 8 mm from the lateral rectus muscle insertion site, uniting the temporal halves of the vertical recti muscles to the paretic lateral rectus muscle (Figure 2). The conjunctiva was closed with an 8-0 polyglactin suture.
Intraoperative images showing transposition of the temporal half of the superior rectus muscle to the lateral rectus muscle with muscle union suture and ciliary muscle sparing in the nasal half of the inferior rectus muscle.
On the first postoperative day, her best corrected visual acuity in the left eye was 6/9, with residual esotropia of 14 PD for near and 20 PD for distance. Her abduction improved from grade 4 to grade 2. The anterior segment examination of her left eye showed 2+ cells and flare with 4 mm with a sluggishly reacting pupil. Her intraocular pressure was 15 mm Hg in the right eye and 9 mm Hg in the left eye, measured by non-contact tonometry. Her fundus examination was normal. She had grade 3 anterior segment ischemia (Lee and Olver grading). She was prescribed topical prednisolone acetate 1% eye drops hourly, homatropine hydrobromide 2% eye drops twice daily, dexamethasone 4 mg injections intravenously twice daily, and prednisone 30 mg tablets once daily, which was tapered over 3 weeks.
One week postoperatively, she was symptomatically better. Her best corrrected visual acuity was 6/9 in the left eye and uveitis reduced in severity (1+ cells and flare). She was advised to taper the topical and oral steroids and follow up after 15 days. One month later, her best corrected visual acuity was 6/9 in the left eye and the uveitis resolved, but she had a sluggish reacting pupil. Two months postoperatively, there was sectoral iris vasculature discontinuity in her left eye (Figure 3).
Iris angiogram showing sectoral iris vasculature discontinuity in the left eye 2 months after surgery.
Hummelsheim described the first partial tendon transposition procedure for paralytic lateral rectus muscle in which temporal halves of the superior and inferior rectus muscle are transposed to the lateral rectus muscle.2 Foster described augmented transposition by a lateral fixation suture joining the transposed muscle to sclera to achieve enhanced abduction.3 The augmented Hummelsheim procedure involves resecting 4 to 5 mm of vertical recti muscles before transposition. It does not require placement of lateral fixation sutures, which may confer the advantage of simplifying subsequent surgery if needed. Wright's modification of Hummelsheim's muscle union procedure comprises suturing the transposed muscle halves to the paretic muscle.4 This procedure spares the anterior ciliary vessels in the non-transposed halves of the vertical recti.
Anterior segment ischemia occurs when the anterior ciliary arteries are disrupted during strabismus surgery. The risk factors are: full-thickness vertical muscle transposition combined with horizontal rectus recession,5 surgery on three or more recti muscles, prior retinal surgeries, older age, blood flow abnormalities, diabetes mellitus, hypertension, atherosclerosis, and thyroid orbitopathy.6 Lee and Olver classified anterior segment ischemia into four grades: grade 1, decreased iris perfusion; grade 2, pupillary abnormalities; grade 3, uveitis; and grade 4, keratopathy, cataract, and hypotony.7
Al Enezi and Al Wayel reported anterior segment ischema in a young patient with myopia following transposition surgery.8 Our patient was hypermetropic. We performed a medial rectus recession with Wright's modification of the Hummelsheim procedure in our patient, which reduced her esotropia and improved her range of abduction postoperatively. The anterior segment ischemia resulted despite no systemic comorbidities and performing a ciliary vessel–sparing technique in our patient. Mudock and Mills reported anterior segment ischemia following a similar surgery to our case, despite using a microvascular dissection technique.9
We performed a 360 degree limbal peritomy in our patient. Limbus-based conjunctival incisions disrupt the perilimbal conjunctival Tenon's circulation, which can lead to anterior segment ischemia.10,11 A fornix-based conjunctival incision was precluded in our patient, due to the fragile conjunctiva.
Anterior segment ischemia is a rare, recognized complication of strabismus surgery on multiple rectus muscles. Recognizing predisposing factors, performing staged procedures, and meticulous surgical techniques can prevent this complication to a certain extent, although not completely.
- Wright KW. Transposition surgery for rectus muscle palsy. In: Wright KW, ed. Colour Atlas of Strabismus Surgery: Strategies and Techniques, 3rd ed. New York: Springer-Verlag; 2007:161–165.
- Rosenbaum AL, Santiago AP. Selected transposition procedures. In: Rosenbaum AL, Santiago AP, eds. Clinical Strabismus Management: Principles and Surgical Techniques. Philadelphia: W.B. Saunders; 1999:479–480.
- Foster RS. Vertical muscle transposition augmented with lateral fixation. J AAPOS. 1997;1:20–30. doi:10.1016/S1091-8531(97)90019-7 [CrossRef]
- Wright KW, Hong P. Strabismus surgery. In: Wright KW, Strube YNJ, eds. Pediatric Ophthalmology and Strabismus, 3rd ed. Oxford, England: Oxford University Press; 2012:378.
- Nishida Y, Inatomi A, Aoki Y, et al. A muscle transposition procedure for abducens palsy, in which the halves of the vertical rectus muscle bellies are sutured on to the sclera. Jpn J Ophthalmol. 2003;47:281–286. doi:10.1016/S0021-5155(03)00021-2 [CrossRef]
- Simon JW, Price EC, Krohel GB, Poulin RW, Reinecke RD. Anterior segment ischemia following strabismus surgery. J Pediatr Ophthalmol Strabismus. 1984;21:179–185.
- Lee JP, Olver JM. Anterior segment ischemia. Arch Ophthalmol. 1990;109:174. doi:10.1001/archopht.1991.01080020020006 [CrossRef]
- Al Enezi MH, Al Wayel AH. Anterior segment ischemia in a young myopic following transposition surgery. Middle East Afr J Ophthalmol. 2008;15:31–33. doi:10.4103/0974-9233.53372 [CrossRef]
- Murdock TJ, Mills MD. Anterior segment ischemia with microvascular dissection. J AAPOS. 2000;4:56–57. doi:10.1016/S1091-8531(00)90013-2 [CrossRef]
- Coats DK, Olitsky SE. Slipped and lost muscles. In: Coats DK, Olitsky SE, eds. Strabismus Surgery and Its Complications. Berlin. Germany: Springer-Verlag; 2007:242–245.
- Murdock TJ, Kushner BJ. Anterior segment ischemia after surgery on 2 vertical rectus muscles augmented with lateral fixation sutures. J AAPOS. 2001;5:323–324. doi:10.1067/mpa.2001.118668 [CrossRef]