Frequency and Causes of Segmentation Errors in Spectral Domain Optical Coherence Tomography Imaging in Glaucoma

PURPOSE: To determine the frequency and potential causes of segmentation errors in spectral domain optical coherence tomography (SD-OCT) imaging of retinal nerve fiber layer (RNFL) scans. METHODS: Segmentation errors for the RNFL thickness analysis were recorded during a retrospective chart review of 214 eye scans from 132 consecutive patients with glaucoma or glaucoma suspect who underwent a complete eye exam using Spectralis™ OCT scanning from August 2014 to November 2014. Segmentation errors were classified as inner, outer, inner and outer segmentation errors, and degraded images. The risk factors including age, sex, intraocular pressure, spherical equivalents, severity of glaucoma, and associated ocular disorders were evaluated using logistic regression analysis. RESULTS: A total of 71 eye scans included segmentation errors. Risk factors of inner segmentation error (8.9%) were age, epiretinal membrane, and degenerative myopia. Risk factors of outer segmentation error (29.9%) were age, peripapillary atrophy, posterior vitreous detachment, and severity of glaucoma. Risk factors of inner and outer segmentation errors (6.1%) were age and degenerative myopia. The single risk factor of degraded image (2.3%) was degenerative myopia. CONCLUSIONS: Segmentation errors for SD-OCT RNFL scans in glaucoma patients are common. Clinicians should carefully review the scans for segmentation errors when using SD-OCT images in glaucoma diagnosis or during patient follow-up.

A Case of Isolated Third Nerve Palsy with Preeclampsia

PURPOSE: Isolated oculomotor nerve palsy in preeclampsia patients have not been reported in Korea. Herein, we report 1 case of a patient in her 32nd week of gestation diagnosed with preeclampsia experiencing oculomotor nerve palsy in the left eye which improved after delivery. CASE SUMMARY: 28-year-old pregnant woman in her 32nd week of gestation with no underlying diseases visited our clinic with the chief complaint of diplopia and left eye ptosis. The patient suffered headache symptoms 1 week prior and did not undergo any exams. The visual acuity, anterior segment, and, fundus showed no abnormal signs and the pupil light reflex was normal, but the patient showed left eye ptosis with +2 mm/-2 mm on the marginal reflex distance (MRD) exam, 25 prism exotropia and 6 prism hypotropia, supraduction and adduction limitation -2 and, infraduction limitation -1. To exclude other systemic disorders and brain lesions, laboratory tests and brain magnetic resonance imaging (MRI) was performed, and preeclampsia was diagnosed based on high blood pressure (150/110 mm Hg) and mild proteinuria. Imaging and labatory tests showed other disorders thus the patient was treated conservatively. Two weeks after the ocular symptoms appeared, the left ptosis and ocular movement restriction worsened, but systemic signs and tests shown no aggravation, thus we maintained conservative therapy and after delivery at 37-weeks, the symptoms slowly improved and recovered completely after 2 months. CONCLUSIONS: Full systemic examination including MRI and laboratory tests must be performed in pregnant women who suddenly experience ocular symptoms and are diagnosed as oculomotor motor nerve palsy. If diagnosis and treatment are appropriate, good prognosis can be expected in this disease.

A Case of Persistent Shallow Anterior Chamber in Glaucoma Drainage Device Implantation Recovered by Fibrin Glue

PURPOSE: To report a case of persistent shallow anterior chamber after silicone tube intubation, recovered by fibrin glue in glaucoma drainage device implantation (GDI). CASE SUMMARY: A 42-year-old female, diagnosed with neovascular glaucoma at a local clinic visited our clinic for uncontrolled intraocular pressure (IOP) in her right eye. We performed GDI on her right eye. Scleral flap and paracentesis of the anterior chamber were performed. Then, a silicone tube was inserted into the anterior chamber. Despite repetitive infusion of balanced salt solution (BSS), the anterior chamber became persistently shallow due to peritubular leakage. After dropping the fibrin glue in the peritubular space and beneath the scleral flap, attachment occurred. No additional leakage was observed near the scleral flap and after infusion of BSS, a deep anterior chamber was maintained. One day after surgery, IOP in the right eye was 3 mm Hg, deep anterior chamber was maintained, and no leakage of aqueous humor into the conjunctiva occurred. Two months after surgery, IOP was 16 mm Hg and a deep anterior chamber was maintained. CONCLUSIONS: In cases of persistent shallow anterior chamber after silicone tube intubation in intraoperative GDI, the best methods to maintain the anterior chamber is by suture ligation of the peritubular loosened site or infusion of viscoelastic agent to anterior chamber. In the present case, applying the fibrin glue beneath the scleral flap apparently obstructed the peritubular infiltration.