Occult globe perforation during posterior sub-tenon injection diagnosed by ultrasound biomicroscopy.

Inadvertent globe perforation during posterior sub-tenon (PST) injection is rare, and the use of ultrasound biomicroscopy (UBM) in the diagnosis of occult globe perforation is not reported yet in the literature. We hereby intend to discuss the case of a 42-year-old male who presented with left eye loss of vision following PST triamcinolone acetate (TA) injection. On examination, right eye vision was 20/20 and it was 20/120 for the left eye. Fundus examination of the left eye showed a whitish fluffy mass like preretinal lesion over the macula with vitreous haze. The patient was thoroughly investigated for intermediate and posterior uveitis. However, all reports turned out to be within the normal limits. The 360° UBM scan of the left eye showed well-defined hypoechoic scleral tract suggestive of globe perforation at 2 o'clock position. The, whitish preretinal mass in the left eye was suspected to be intravitreal TA deposit following an inadvertent globe perforation during the posterior sub-tenon TA injection. UBM can be considered important diagnostic aid in ruling out possibility of occult globe perforation in certain circumstances. Copyright:

Introduction

Posterior sub-tenon (PST) injection of triamcinolone is widely used in a variety of inflammatory conditions such as uveitis and macular edema. Although considered a safe procedure, it is not risk free. The complications of PST include subconjunctival hemorrhage, conjunctival swelling, rise in intraocular pressure (IOP), cataract formation/progression, ptosis, and rarely globe perforation. The reports of occult globe perforation following PST injections are rare.[1] We hereby report a case of occult globe perforation during PST injection which was diagnosed by ultrasound biomicroscopy (UBM).

Case Report

A 42-year-old male presented with the complaints of painless loss of vision along with floaters in the left eye for the past 15 days. The patient was a known case of hypertension and hypercholesterolemia, and there was not any history of trauma. The patient had a history of redness and decreased vision in the left eye for which he was given some peri-ocular injection elsewhere 1 month ago. The patient was, however, unable to locate the site of injection. Old documents regarding the treatment were not available, he was however thoroughly investigated for intermediate and posterior uveitis. The investigations included were complete blood count with ESR, routine urine examination with culture and sensitivity, hepatitis B surface antigen, anti -hepatitis C virus antibody, Mantoux test, immunoglobulin (Ig) M and IgG for toxoplasma, serum angiotensin-converting enzyme level, and chest X-ray PA view. All the reports turned out to be within the normal limits, and the patient was sent to our institution for further opinion.

On examination, the best-corrected visual acuity in the right eye was 20/20, whereas it was 20/120 in the left. Anterior segment examination and IOP were normal in both the eyes. Fundus examination of the left eye showed significant vitreous haze along with whitish mass like preretinal lesion over macula [Figure 1a]. Fundus of the other eye was within normal limits. The whitish mass seen in the left eye was suspected to be intravitreal triamcinolone acetate (TA) deposit following an inadvertent globe perforation during the posterior subtenon injection. Organized vitreous hemorrhage and fungal granuloma were the other differentials considered and the patient was advised an UBM examination for tracing the tract of perforation.

Figure 1

(a) Color fundus photo of the left eye showing significant vitreous haze with whitish mass over macula (black arrow), (b) ultrasound biomicroscopy radial scan of left eye at 2 o’clock position showing well-defined hypoechoic scleral tract with conjunctival bleb (blue arrow)

A 360° UBM scan of the left eye showed well-defined hypoechoic tract in the sclera along with overlying conjunctival bleb at 2 o’clock position [Figure 1b]. The patient was advised a vitrectomy along with vitreous biopsy. The patient is yet to decide regarding his surgery.

Discussion

Globe perforation during PST injection is rare but has been reported in the literature.[1] Since the globe perforation following such injections is quite small, they remain occult and undiagnosed as in the present case. The diagnosis was even more challenging since the patient did not have any documents regarding the procedure. However, a history of some sort of peri-ocular injection and the scleral tract identified by UBM at 2’o clock position, which is the preferred site for PST,[2] clinched the diagnosis.

In a retrospective review, the reported incidence of globe perforation following PST injection was noted to be 1.56%.[1] The globe perforation was identified immediately by the patient or the surgeon. To the best of our knowledge, there is no case report describing the role of UBM in diagnosing occult globe perforation following PST injection till date.

Singh et al. have reported a case of accidental globe perforation during PST injection of TA for diabetic macular edema.[3] The patient complained of painful loss of vision following injection and had obvious uveal show suggestive of globe perforation.

Gomez-Ulla et al. also reported a case of inadvertent globe perforation following PST injection of TA for posterior uveitis.[4] The patient complained of intense pain and loss of vision during the injection, and the needle was withdrawn immediately. Dilated fundus examination showed white fluid in the vitreous cavity.

Giny et al. reported a similar case of globe perforation during sub-tenon injection of TA during cataract surgery resulting in supero-temporal retinal detachment which was diagnosed on table by the presence of disappearance of red glow, shallowing of anterior chamber with iris prolapse and rocky hard eye on digital palpation.[5]

In contradiction to the above-mentioned signs of globe perforation, our patient did not report any symptoms of inadvertent globe perforation except for floaters which could very well be attributed to coexisting vitreous inflammation.

Role of UBM in the detection of occult scleral perforation has not been reported yet. However, its role in identifying the healing of sclerotomy wound during vitrectomy has been reported.[67] In a study done by Gutfleisch et al., scleral tunnel could be detected in 100% of patients with 20 G vitrectomy, whereas it was 10% in 25 G, 30% in 23/1 G (one-step system) and 10% in 23/2 G (two-step system) vitrectomy eyes at 30 days postoperatively.[6] In an another major UBM based study done by Rizzo et al., it was found that 25 G sclerotomy tract could be seen in all patients with straight insertion group even after 1 month of surgery.[7]

PST injection is a blind procedure and it is not risk free. UBM can be used as an important diagnostic tool in ruling out the possibility of occult globe perforation in certain circumstances.

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Conflicts of interest

There are no conflicts of interest.