In this issue of Retina Today, Mehran Taban, MD; Christine Sonnie, RN; Brandy C. Hayden, BS; and Jonathan E. Sears, MD, provide surgical pearls for using ultrasound biomicroscopy for the diagnosis and surgical management of cyclodialysis clefts in a series of patients with hypotony treated with external cycloplexy with radial sutures.

We extend an invitation to readers to submit pearls for publication in Retina Today. Please send submissions for consideration to Dean Eliott, MD (dean_eliott@meei.harvard.edu); or Ingrid U. Scott, MD, MPH (iscott@psu.edu). We look forward to hearing from you.

—Ingrid U. Scott, MD, MPH; and Dean Eliott, MD

Ocular hypotony is associated with significant visual dysfunction depending on its severity and duration. One etiology of hypotony is cyclodialysis cleft (CDC), a disinsertion of the longitudinal ciliary muscle fibers from the scleral spur. Originally described as a planned surgical treatment for intractable glaucoma, CDC may be observed following trauma or as an inadvertent surgical event from a variety of procedures involving iris or angle manipulation such as goniotomy, trabeculectomy, phacoemulsification, intraor extra-capsular cataract extraction, iridectomy, and sclerotomy. It can also be present in cases of anterior proliferative vitreoretinopathy (PVR) with traction on the ciliary body causing an occult CDC.1

DIAGNOSIS

The diagnosis of CDC requires clinical suspicion, as its signs are often limited; these can include a combination of a shallow anterior chamber, a peaking of the pupil, partial mydriasis, or just hypotony. Gonioscopy can identify a CDC, but it is often limited, especially for smaller clefts, in cases with factors precluding an adequate view, such as hyphema, corneal edema, and shallow anterior chamber. Immersion B-scan has been used with limited success.2 Magnetic resonance imaging (MRI) has also been attempted; however, its high cost, limited accessibility, and relative poor resolution make it an unacceptable choice.3 Even scleral transillumination has been described.4

Ultrasound biomicroscopy (UBM) can provide high-resolution (37 μm) images of angle structures, compared with a resolution of approximately 190 μm for standard Bscan ultrasound. UBM has been used to diagnose CDCs,5-8 although there are limited reports of its use in diagnosing and guiding the management of CDC in a large series. We are unaware of the use of external direct cyclopexy in previously reported series. The purpose of this study, therefore, is to evaluate UBM in guiding the diagnosis and surgical management of CDCs in a small series of patients with hypotony. The surgical technique employed to close the CDCs was external cycloplexy with radial sutures.

METHODS

After receiving approval from the Cleveland Clinic institutional review board, we performed a retrospective analysis of patients with hypotony (intraocular pressure [IOP] <6 mm Hg) of unclear etiology at the Cole Eye Institute between 2002 and 2008. Patients with known causes of hypotony such as a glaucoma shunt, filtering procedure, or chronic retinal detachment were excluded. Patients had imaging with UBM to evaluate for the presence of CDC. Patients who were determined to have a CDC as the potential cause of hypotony underwent surgical repair to close the clefts. Following surgery, UBM was repeated to evaluate the state of the CDC.

UBM AND SURGICAL PROCEDURE

Patients underwent imaging with UBM 1840 (Humphrey Instruments Inc., San Leandro, CA), 50 MHz with a resolution of 37 μm, penetration depth of 5 mm, and scan width of 5 mm. The UBM was used to scan for CDC across 360° of the ciliary body region. All scans were performed by an experienced certified ultrasonographer trained in UBM.

External cyclopexy by radial sutures was employed to close the CDCs (Figure 1). Written informed consent was obtained from each patient before surgery. All patients underwent surgery under retrobulbar anesthesia using bupivacaine 0.75%. Following localized conjunctival dissection and cauterization to obtain hemostasis, the extent of the CDC was marked. Next, using a 9-0 Prolene (Ethicon, Inc., Somerville, NJ) suture, full-thickness bites were taken that spanned from 4.0 to 1.5 mm (radially) from the limbus through the ciliary body. Enough interrupted bites were placed, separated by approximately 0.5 mm to cover the cleft extension. Suture knots were then buried through the sclera, and the conjunctiva was closed with a 6-0 plain gut suture.

RESULTS

Twenty patients (20 eyes) were found to have hypotony of unclear etiology; UBM identified a potential (possible or definite) CDC in 10 cases (50%; Table 1). Four patients had a history of infectious uveitis, , two patients a history of vitrectomy surgery for epiretinal membrane, two patients had a history of blunt trauma, one patient a history of retinal detachment and aphakia, and one patient had a history of anterior chamber IOL explant and sutured posterior chamber IOL in preparation for corneal transplant.

Ten eyes underwent external cyclopexy with radial sutures and had a median follow-up of 13.5 months (range, 5-36 months) following surgery. Median duration of hypotony among patients with CDC undergoing surgery was 3 months (range, 1-24 months), with median IOP of 1 mm Hg (range, 0-4 mm Hg). Following external cyclopexy, the median IOP was 8 mm Hg (range, 0-28 mm Hg), representing a median increase of 5 mm Hg (range, 0-28 mm Hg). However, among those with definite CDC (n=5 eyes: cases 1-4, 10), the median IOP following external cyclopexy was 21 mm Hg (range, 14-28 mm Hg), representing a median increase of 18 mm Hg (range, 10-28 mm Hg). On the other hand, among those with possible CDC (5 eyes: cases 5-9), the median IOP following external cyclopexy was 4 mm Hg (range, 0-8 mm Hg), representing a median increase of 4 mm Hg (range, 0-5 mm Hg).

Characteristics of successful outcomes included definite identification of cleft and hypotony duration of 3 months or less. Patients with a history of infectious uveitis had an unfavorable outcome with to no partial elevation of their IOP.

Examples of UBM for definite CDC are illustrated in Figure 2. Sample pre- and postoperative UBMs are shown.

DISCUSSION

Hypotony can be a devastating ocular condition, and, if untreated, can lead to visual loss and phthisis. The etiologies of hypotony include retinal detachment, PVR, trauma, wound leakage, uveitis, retrolenticular membranes with ciliary body detachment, intraocular foreign body, and CDC.9 CDC can often be difficult to diagnose and treat. UBM can guide the surgical management of CDC by accurately directing the placement of radial sutures around the cleft region using external cyclopexy. However, in our study, only cases with a definite CDC as identified by UBM met surgical success (elevation of IOP) in the current series. Cases of questionable or possible CDC did not benefit significantly from undergoing surgery. Furthermore, patients with a history of infectious uveitis and/or hypotony for longer than 3 months had an unfavorable outcome, with partial to no elevation of IOP.

Hypotony can be associated with only 2 clock hours of ciliary body detachment.5 A possible mechanism of hypotony associated with ciliary body detachment is the reversal of flow that occurs with a hypertonic ciliary body stroma. A decrease in aqueous humor production secondary to the ciliary body detachment9-11 and increased aqueous humor outflow via the suprachoroidal space12-13 have been proposed as potential mechanisms of hypotony in cases of CDC.

Management of CDC ranges from medical therapy (cycloplegia) and laser photocoagulation to a variety of surgical procedures such as direct cyclopexy, indirect cyclopexy, iris-based inclusion cyclopexy, anterior scleral buckling, and silicone tube fixation.7,11,14-18 The prognosis of CDC-induced hypotony depends on both the degree and duration of the hypotony. A visual acuity of 20/25 is more likely if the hypotony is reversed within 2 months of its occurrence, and the prognosis is worse with an IOP less than 4 mm Hg. Our study also demonstrates that the prognosis is poorer in surgical patients with hypotony for more than than 3 months' duration.

It is important to note that anterior PVR can cause traction on the ciliary body, leading to an occult CDC. Lewis et al1 reported that, in a series of anterior PVR, four of 17 eyes had an occult CDC. These cases require release of the anterior traction to help the closure of clefts.19 In the absence of a cyclodialysis, hypotony can be caused by atrophy of the ciliary tips from epiciliary proliferation, thermal treatment of the long posterior ciliary arteries, or infectious uveitis.

There are potential limitations to our study, which are primarily related to its retrospective nature and the associated potential biases. The study is also based on a small series of cases; however, a randomized investigation of a relatively rare entity (ie, CDC) is clearly challenging. Two patients underwent vitrectomy with silicone oil placement (cases 7 and 9); however, these cases did not have significant elevation of IOP, and therefore surgical success cannot be attributed based on silicone oil placement.

CONCLUSION

This study demonstrates that UBM is a key diagnostic and management tool for ocular hypotony of unclear etiology, especially in cases of poor view of the anterior segment and iridocorneal angle. In our series, about 50% of patients who have undergone previous nonglaucoma ocular surgery had a suspicion of CDC. Of these patients, approximately half benefited from surgery. Patient selection may be improved by operating on patients with definite clefts with hypotony for less than 3 months and not associated with infections.

Mehran Taban, MD, is a Vitreoretinal Fellow in the Retina Department at the Cole Eye Institute, Cleveland Clinic, OH. Dr. Taban states that he has no financial interest in the material presented in this article.

Christine Sonnie, RN, is a surgical and clinical nurse in the Retina Department at the Cole Eye Institute, Cleveland Clinic, OH. Ms. Sonnie states that she has no financial interest in the material presented in this article. She can be reached at sonniec@ccf.org.

Brandy C. Hayden, BS, is Manager of Ultrasound Technology for the Ophthalmic Ultrasound Service at the Cole Eye Institute, Cleveland Clinic, OH. Ms. Hayden states that she has no financial interest in the material presented in this article. She can be reached at haydenb@ccf.org.

Jonathan E. Sears, MD, is an Associate Professor in the Retina Department at the Cole Eye Institute, Cleveland Clinic, OH. Dr. Sears states that he has financial interest in the material presented in this article. He can be reached at +1 216 444 8157; fax: +1 216 445 2226; e-mail: searsj@ccf.org.

Dean Eliott, MD, is Associate Director of the Retina Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School, and is a Retina Today Editorial Board member. He may be reached by phone: +1 617 573-3736; fax: +1 617 573- 3698; or via e-mail at dean_eliott@meei.harvard.edu.

Ingrid U. Scott, MD, MPH, is a Professor of Ophthalmology and Public Health Sciences, Penn State College of Medicine, Department of Ophthalmology, and is a Retina Today Editorial Board member. She may be reached by phone: +1 717 531 8783; fax: +1 717 531 8783; or via e-mail at iscott@psu.edu.

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