Ju-Yeun Lee

Correlation between Extraocular Muscle Size Measured by Computed Tomography and the Vertical Angle of Deviation in Thyroid Eye Disease.

The aim of this study was to investigate extraocular muscle (EOM) volume and cross-sectional area using computed tomography (CT), and to determine the relationship between EOM size and the vertical angle of deviation in thyroid eye disease (TED). Twenty-nine TED patients (58 orbits) with vertical strabismus were enrolled in the study. All patients underwent complete ophthalmic examination including prism, alternate cover, and Krimsky tests. Orbital CT scans were also performed on each patient. Digital image analysis was used to quantify superior rectus (SR) and inferior rectus (IR) muscle cross-sectional areas and volumes. Measurements were compared with those of controls. The correlation between muscle size and degree of vertical angle deviation was evaluated. The mean vertical angle of deviation was 26.2 ± 4.1 prism diopters. The TED group had a greater maximum cross-sectional area and EOM volume in the SR and IR than the control group (all p<0.001). Area and volume of the IR were correlated with the angle of deviation, but the SR alone did not show a significant correlation. The maximum cross-sectional area and volume of [Right IR + Left SR − Right SR − Left IR] was strongly correlated with the vertical angle of deviation (P<0.001). Quantitative CT of the orbit with evaluation of the area and volume of EOMs may be helpful in anticipating and monitoring vertical strabismus in TED patients.

Initial Pattern of Optic Nerve Enhancement in Korean Patients with Unilateral Optic Neuritis

Purpose The purpose of this study was to demonstrate whether the pattern of optic nerve enhancement in magnetic resonance imaging (MRI) can help to differentiate between idiopathic optic neuritis (ON), neuromyelitis optica (NMO), and multiple sclerosis (MS) in unilateral ON. Methods An MRI of the brain and orbits was obtained in patients with acute unilateral ON. Patients with ON were divided into three groups: NMO, MS, and idiopathic ON. The length and location of the abnormal optic nerve enhancement were compared for ON eyes with and without NMO or MS. The correlation between the pattern of optic nerve enhancement and the outcome of visual function was analyzed. Results Of the 36 patients with ON who underwent an MRI within 2 weeks of the onset, 19 were diagnosed with idiopathic ON, 9 with NMO, and 8 with MS. Enhancement of the optic nerve occurred in 21 patients (58.3%) and was limited to the orbital segment in 12 patients. Neither the length nor the location of the optic nerve enhancement was significantly correlated with visual functions other than contrast sensitivity or the diagnosis of idiopathic ON, MS, or NMO. Patients with greater extent of optic nerve sheath enhancement and more posterior segment involvement showed higher contrast sensitivity. Conclusions Our data revealed that the pattern of optic nerve enhancement was not associated with diagnosis of idiopathic ON, NMO, or MS in Korean patients with unilateral ON. We believe further studies that include different ethnic groups will lead to a more definitive answer on this subject.

Analysis of Retinal Layer Thicknesses and Their Clinical Correlation in Patients with Traumatic Optic Neuropathy

The aims of this study were 1) To evaluate retinal nerve fiber layer (fRNFL) thickness and ganglion cell layer plus inner plexiform layer (GCIPL) thickness at the fovea in eyes affected with traumatic optic neuropathy (TON) compared with contralateral normal eyes, 2) to further evaluate these thicknesses within 3 weeks following trauma (defined as “early TON”), and 3) to investigate the relationship between these retinal layer thicknesses and visual function in TON eyes. Twenty-nine patients with unilateral TON were included. Horizontal and vertical spectral-domain optical coherence tomography (SD-OCT) scans of the fovea were taken in patients with unilateral TON. The main outcome measure was thickness of the entire retina, fRNFL, and GCIPL in eight areas. Thickness of each retinal layer was compared between affected and unaffected eyes. The correlation between the thickness of each retinal layer and visual function parameters, including best corrected visual acuity, color vision, P100 latency, and P100 amplitude in visual evoked potential (VEP), mean deviation (MD) and visual field index (VFI) in Humphrey visual field analysis in TON eyes was analyzed. Thicknesses of the entire retina, fRNFL, and GCIPL in SD-OCT were significantly thinner (3–36%) in all measurement areas of TON eyes compared to those in healthy eyes (all p<0.05). Whereas, only GCIPL in the outer nasal, superior, and inferior areas was significantly thinner (5–10%) in the early TON eyes than that in the control eyes (all p<0.01). A significant correlation was detected between retinal layer thicknesses and visual function parameters including color vision, P100 latency and P100 amplitude in VEP, MD, and VFI (particularly P100 latency, MD, and VFI) (r = -0.70 to 0.84). Among the retinal layers analyzed in this study, GCIPL (particularly in the superior and inferior areas) was most correlated with these five visual function parameters (r = -0.70 to 0.71). Therefore, evaluation of morphological change of each retinal layer using SD-OCT can help in understanding TON pathophysiology and indirectly assessing visual function. Moreover, evaluation of the morphological change of the GCIPL in TON eyes may be useful to assess visual function in patients with early TON.

Ganglion Cell Layer and Inner Plexiform Layer as Predictors of Vision Recovery in Ethambutol-Induced Optic Neuropathy: A Longitudinal OCT Analysis

Purpose To describe changes in the retina during ethambutol-induced optic neuropathy (EON) progression, and determine the retinal layer thickness as a predictive factor for vision recovery after stoppage of ethambutol (EMB) in EON. Methods A total of 42 eyes in 21 patients with EON underwent Spectralis optical coherence tomography after the onset of symptoms. Peripapillary and macular retinal nerve fiber layer as well as ganglion cell layer plus inner plexus layer (GCIPL) thickness was measured using Early Treatment Diabetic Retinopathy Study (ETDRS) circles. Data on best-corrected visual acuity at first visit and 1, 3, 6, and 12 months after stoppage of drug were collected. The longitudinal change of each retinal layer was described, and the association between retinal thickness at the first visit and the degree of vision recovery at each visit was analyzed. Results In inner temporal GCIPL, a 10-μm-thickness loss in the initial OCT was associated with a 0.5 decrease in the amount of logMAR visual acuity recovery at 12 months (P < 0.001, 95% confidence interval [CI]: 0.2-0.7), and a 10-μm-thickness reduction between follow-up visits was associated with a 0.5 decrease in the amount of logMAR visual acuity recovery (P < 0.001, 95% CI: 0.3-0.7). Conclusions We described a structure-function relationship between the retinal changes that occur in early EON and vision recovery. Temporal GCIPL could be used to predict vision recovery at 12 months after stoppage of EMB. Careful evaluation for GCIPL damage is required for visual prognosis in early EON.

Choroidal thickness in traumatic optic neuropathy

ABSTRACT Purpose: To examine the choroidal thickness in patients with indirect traumatic optic neuropathy (TON) Methods: Patients with unilateral traumatic optic neuropathy over a period of 4 years were included in this study. Horizontal and vertical enhanced-depth imaging (EDI) from spectral-domain optical coherence tomography (SD-OCT) scans of the fovea were obtained in patients with unilateral TON within 2 weeks of injury. The main outcome measure was the choroidal thickness at nine locations. The choroidal thickness was compared between affected and unaffected eyes in the TON group, and the mean difference in the choroidal thickness in both eyes was compared between TON and control groups. Results: A total of 16 patients and 20 control subjects were included. The choroidal thickness at horizontal, vertical and average subfoveal, inner temporal, and outer inferior locations was significantly thicker (13–23%) in affected eyes than in unaffected fellow eyes (p = 0.042, 0.046, 0.024, 0.013, 0.018, and 0.027, respectively). The mean difference value between choroidal thickness measurements in both eyes was significantly larger in the TON group than in the control group at the horizontal, vertical and average subfoveal, inner temporal, inner nasal, inner superior, inner inferior, and outer superior locations (p = 0.001, 0.011, <0.001, 0.001, 0.033, 0.014, 0.011, and 0.014, respectively). The choroidal thickness at subfoveal locations showed no statistical difference between TON and control eyes (p > 0.05). Conclusion: Eyes affected by TON showed a regionally thicker choroid than unaffected fellow eye. This thick choroid might be due to impaired blood circulation and vascular remodeling of the optic nerve head and choroid. These results help to better understand the pathophysiology of TON.

Correlation between the Limbus-Insertion Distance of the Lateral Rectus Muscle and Lateral Rectus Recession Surgery in Intermittent Exotropia.

The aim of this study was to investigate whether the limbus-insertion distance (LID) of the lateral rectus (LR) muscle can be a useful indicator for predicting the surgical effect of recession surgery in intermittent exotropia (IXT). Patients who underwent unilateral or bilateral LR recession for the basic type of IXT were included. The distance between the corneal limbus and the posterior edge of the insertion of LR muscle (limbus-insertion distance) was measured intraoperatively using surgical calipers (graded with 0.25 mm precision). We calculated the actual dose-response effect as the difference between the angle of preoperative deviation and the angle of postoperative deviation, and then divided the figure by the total amount of recession at postoperative months 1, 3, and 6. The correlation between the limbus-insertion distance (LID) of LR muscle and each dose-response effect was statistically analyzed. A total of 60 subjects were enrolled in this study. The mean LID of LR muscle was 5.8±0.7 mm. The dose-response effect was 3.2±1.0 prism diopters (PD)/mm at postoperative month 1, 3.4±1.0 PD/mm at postoperative month 3, and 3.4±1.1 PD/mm at postoperative month 6. The LID of the LR muscle was significantly correlated with dose-response effects in cases of unilateral and bilateral LR recession at postoperative months 3 and 6 (P = 0.01, <0.01, 0.04 and <0.01 respectively). As the LID of the LR muscle increased by 1 mm, the dose-response effect increased by 0.2PD/mm in unilateral LR recession, and by 0.4 PD/mm in bilateral LR recession at postoperative month 6. In conclusion, the LID of the LR muscle can be used as one predictor of the recession effect to assist in surgical planning for IXT. Moreover, undercorrection at the time of LR recession might be considered in patients with long LID of the LR muscle.

Comparison of the efficiency of various muscle transposition procedures using a novel three-dimensional model

Aim To investigate the performance of a newly developed three-dimensional (3D) biomechanical model in various transposition procedures for correction of complete sixth nerve palsy with educational purpose. Methods A 3D biomechanical eye model was created using Hyperworks software based on geometry data and the biochemical properties of the eyeball and extraocular muscles. A complete sixth nerve palsy model was achieved via modification of lateral rectus muscle strength. Four different muscle transposition procedures (the Hummelsheim, Jensen, Foster, and muscle union procedures) were set up, and the objective surgical effect of each procedure was calculated using 3D model simulation. Results In the 3D simulation, sixth nerve palsy was modeled by rotating the eye 34.16 degrees in the medial direction, consistent with 70 prism diopter (PD) esotropia. In surgical model simulation, the Hummelsheim procedure resulted in a 28 PD reduction of total deviation, the Jensen procedure achieved a 34 PD reduction, the Foster procedure led to a 57 PD reduction, the muscle union procedure yielded a 57 PD reduction in esotropia in sixth nerve palsy. Conclusion The 3D simulation provided a consistent model of sixth nerve palsy and objective data excluding the potential for variation of surgical skill. It could also help predict surgical outcomes.

Lateral rectus muscle recession for intermittent exotropia with anomalous head position in type 1 Duane’s retraction syndrome

BackgroundWe questioned how to treat for intermittent exotropia in type 1 Duane’s retraction syndrome (DRS). To avoid secondary abduction deficit and late overcorrection on the affected eye following ipsilateral lateral rectus (LR) recession, we performed less correction of the lateral rectus (LR) recession to correct exodeviation and anomalous head position (AHP). We report the surgical outcomes of LR recession in patients with unilateral type 1 DRS.MethodsFour patients who underwent less correction of LR recession in the affected eye to correct intermittent exotropia and AHP to the contralateral side in type 1 DRS were enrolled. Data on preoperative and postoperative angle of exodeviation, degree of AHP, ocular motility, global retraction, palpebral fissure change, and complications were retrospectively obtained. Success was defined as postoperative deviation within 8 prism diopters (PD) and AHP < 5°.ResultsThe preoperative angles of exodeviation and AHP were significantly improved after LR recession. The median grade of abduction limitation was improved from − 1.3 to − 0.8 postoperatively. Final median value of deviation was orthotropia in the primary position of the eye with the normal motility. All patients had successful outcomes without overcorrection or further abduction limitation in DRS eyes.ConclusionsLess correction of ipsilateral LR recession may be useful for correcting intermittent exotropia and AHP in patients with type 1 DRS.

Prevalence and incidence of non-arteritic anterior ischaemic optic neuropathy in South Korea: a nationwide population-based study

Aims To determine the age and sex-specific prevalence and incidence of non-arteritic anterior ischaemic optic neuropathy (NAION) in South Korea. Methods This is a nationwide population-based study using data from the Korean national health claims database to identify patients with NAION using the registration programme database, which comprises ophthalmologist-confirmed NAION from 2011 through 2015. We evaluated prevalence and incidence rates using these data. Results Among 25 816 797 of entire population 40 years of age or older, 26 167 patients had NAION (47.8% men) during the 5-year study period. The prevalence in the general population 40 years of age or older was 102.87 (95% CI 95.22 to 110.53) per 100 000 people. In men, it was 111.10 (95% CI 101.19 to 121.02), and in women, it was 94.64 (95% CI 89.25 to 100.03) per 100 000 people. The prevalence increased with advancing age and peaked at 70–74 years in men and 65–69 years in women. The incidence in the general population 40 years of age or older was 11.35 (95% CI 10.37 to 12.33) per 100 000 person-years. In men, it was 14.89 (95% CI 12.26 to 16.91), and in women, it was 9.92 (95% CI 8.85 to 10.99) per 100 000 person-years. The incidence increased with advancing age and peaked at 80–84 years in men and 70–74 years in women. Conclusions The prevalence and incidence estimates of NAION are comparable with those of Caucasians. These detailed estimates could promote understanding of the disease’s pathophysiology and allow for appropriate planning within the healthcare system.

Diagnostic value of ganglion cell-inner plexiform layer for early detection of ethambutol-induced optic neuropathy

Aim To evaluate the diagnostic value of macular ganglion cell-inner plexiform layer (mGCIPL) thickness versus peripapillary retinal nerve fibre layer (pRNFL) thickness for the early detection of ethambutol-induced optic neuropathy (EON). Methods Twenty-eight eyes of 15 patients in the EON group and 100 eyes of 53 healthy subjects in the control group were included. All patients with EON demonstrated the onset of visual symptoms within 3 weeks. Diagnostic power for pRNFL and mGCIPL thicknesses measured by Cirrus spectral-domain optical coherence tomography was assessed by area under the receiver operating characteristic (AUROC) curves and sensitivity. Results All of the mGCIPL thickness measurements were thinner in the EON group than in the control group in early EON (p<0.001). All of pRNFL thicknesses except inferior RNFL showed AUROC curves above 0.5, and all of the mGCIPL thicknesses showed AUROC curves above 0.5. The AUROC of the average mGCIPL (0.812) thickness was significantly greater than that of the average pRNFL (0.507) thickness (p<0.001). Of all the mGCIPL-related parameters considered, the minimum thickness showed the greatest AUROC value (0.863). The average mGCIPL thickness showed a weak correlation with visual field pattern standard deviations (r2=0.158, p<0.001). Conclusions In challenging cases of EON, the mGCIPL thickness has better diagnostic performance in detecting early-onset EON as compared with using pRNFL thickness. Among the early detection ability of mGCIPL thickness, minimum GCIPL thickness has high diagnostic ability.