Jeong-Min Hwang

Optic Disc Change with Incipient Myopia of Childhood

PURPOSE To describe progressive tilting of the optic nerve head (ONH) and development/enlargement of parapapillary atrophy (PPA) observed in children with incipient myopia and to investigate factors associated with such changes. DESIGN Retrospective, observational study. PARTICIPANTS This study included 118 eyes of 118 Korean children who were assessed by serial disc photography at intervals of 1 year or more. METHODS All disc photographs were reviewed by 2 experienced ophthalmologists, and eyes were classified into 2 groups with respect to the change in the ONH appearance and development/enlargement of β-zone PPA: (1) ONH/PPA changed group and (2) ONH/PPA unchanged group. To quantify the ONH/PPA changes, the ratio of the horizontal to vertical disc diameter (HVDR) and the ratio of the maximum PPA width to vertical disc diameter (PVDR) were measured. Factors associated with ONH/PPA changes were evaluated using logistic regression analysis. Refractive errors were measured with cycloplegic refraction. MAIN OUTCOME MEASURES Morphologic changes of the ONH/PPA as observed in serial disc photographs and its association with myopic shift. RESULTS Mean subject age and refractive error at the time of initial fundus examination were 7.3 ± 3.7 years (range, 1-17 years) and -0.9 ± 1.9 diopters (range, -5.9 to +3.0 diopters), respectively. Mean follow-up period was 38.1 ± 19.6 months (range, 12-88 months). Fifty-one eyes (43%) were classified as the ONH/PPA change group. In the ONH/PPA change group, HVDR decreased from the initial value of 0.92 ± 0.08 to the final value of 0.86 ± 0.11, and the PVDR increased from the initial value of 0.08 ± 0.07 to the final value of 0.20 ± 0.11. The ONH/PPA changes were most remarkable in subjects between 7 and 9 years of age (odds ratio [OR] = 6.698; 95% confidence interval [CI], 2.296-19.546) and were associated with greater myopic shift during the follow-up period (OR = 0.483; 95% CI, 0.345-0.676). CONCLUSIONS We demonstrate progressive tilting of the ONH, which was observed with development/enlargement of PPA in children who exhibited myopic shift. These findings suggest that tilted disc, as well as PPA, may be an acquired feature in myopic eyes, arising from scleral stretching. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Risk factors associated with sclerotomy leakage and postoperative hypotony after 23-gauge transconjunctival sutureless vitrectomy.

Purpose: To investigate the incidence and risk factors of sclertomy leakage and postoperative hypotony after 23-gauge transconjunctival sutureless vitrectomy. Methods: This was a retrospective study including 322 eyes of 292 patients who underwent 23-gauge transconjunctival sutureless vitrectomy by a single surgeon with minimum follow-up period of 1 month. The incidence and risk factors of intraoperative suture placement for leaking sclerotomies and postoperative hypotony (≤5 mmHg) were analyzed in association with seven clinical factors. Results: Intraoperative suture placement was required for leaking sclerotomies in 36 cases (11.2%) and was related to prior vitrectomy (OR = 7.5), young age (<50 years) at operation (OR = 4.9), and vitreous base dissection (OR = 3.5). The incidences of postoperative hypotony were 11.3% at 2 hours, 6.5% at 5 hours, 3.8% at 1 day, and 0% at 1 week. Myopia and gas tamponade were associated with early postoperative hypotony. No complications developed related to sclerotomy leakage or postoperative hypotony. Conclusions: The risk factors of intraoperative sclerotomy leakage requiring suture placement after 23-gauge transconjunctival sutureless vitrectomy are prior vitrectomy, a young age at operation, and vitreous base dissection. Caution should be exercised to ensure the detection of sclerotomy leakage and hypotony in cases with these risk factors.

Differentiation of Optic Nerve Head Drusen and Optic Disc Edema with Spectral-Domain Optical Coherence Tomography

PURPOSE To evaluate the efficacy of spectral-domain optical coherence tomography (SD-OCT) in differentiating optic disc edema (ODE) and optic nerve head drusen (ONHD) and to reveal the differential points. DESIGN Comparative case series. PARTICIPANTS Forty-five patients with ONHD, 15 patients with ODE, and 32 normal controls. METHODS Spectral-domain optical coherence tomography was performed with scans on the optic nerve head and measurements of retinal nerve fiber layer thickness. MAIN OUTCOME MEASURES Qualitative findings of optic nerve head scans and retinal nerve fiber layer thickness profiles on SD-OCT. RESULTS Optic nerve head drusen was visualized as a focal, hyperreflective, subretinal mass with a discrete margin on SD-OCT. The retinal nerve fiber layer was deformed and showed pseudoedema and high reflectance. The outer nuclear layer smoothly covered the drusen, which led to a hyporeflective, boot-shaped area adjacent to the drusen. In ODE, peripapillary retinal nerve fiber layers were significantly thicker in all sections than ONHD (average thickness of ODE: 174.1±53.5 μm vs ONHD: 119.2±20.2 μm vs control: 103.4±19.1 μm, P<0.001). Retinal nerve fiber thickness in the nasal section provides a good differential marker for ODE from ONHD (area under receiver operating characteristic curve = 0.866). CONCLUSIONS With the use of SD-OCT, noninvasive and accurate differentiation of ONHD and ODE is possible.

Mitochondrial DNA content is decreased in autosomal dominant optic atrophy

Background: Autosomal dominant optic atrophy (ADOA) is the commonest form of inherited optic neuropathy. Mutations in the OPA1 gene encoding a dynamin-related mitochondrial protein underlie ADOA and may perturb the biogenesis and maintenance of mitochondria. Objective: To investigate the mutation spectrum of the OPA1 gene and assess alterations in mitochondrial content caused by OPA1 mutations. Methods: Sixteen Korean patients with clinically suspected ADOA were studied. The mutation spectrum of the OPA1 gene was analyzed by PCR single-strand conformation polymorphism and sequencing, and mitochondrial DNA (mtDNA) content was quantified by real-time PCR. Results: Eight different mutations were found, including five novel mutations. Quantitative real-time PCR analysis showed excellent linearity and precision for the determination of mtDNA copy numbers. The number of mtDNA copies per cell in patients with OPA1 gene mutations (ages 7 to 40) was significantly lower than those in all normal control subjects (p = 0.037), particularly lower than in normal control subjects ages 10 to 39 (p = 0.022). Conclusion: The mutation spectrum of the OPA1 gene disclosed marked genetic heterogeneity and the mitochondrial DNA content was found to be lower in autosomal dominant optic neuropathy, which provides direct evidence for a pathogenetic role of mutations of the OPA1 gene.

Comparison between anisometropic and strabismic amblyopia using functional magnetic resonance imaging.

AIMS To assess calcarine activation with functional magnetic resonance imaging (fMRI) in patients with anisometropic and strabismic amblyopia. METHODS 14 amblyopes (eight anisometropic and six strabismic) were studied with fMRI using stimuli of checkerboards of various checker sizes and temporal frequencies. While T2* weighted MRI were obtained every 3 seconds for 6 minutes, patients viewed the stimuli monocularly with either the amblyopic or sound eye. RESULTS Amblyopic eyes showed reduced calcarine activation compared with contralateral sound eyes in fMRI in all subjects. The calcarine activation from amblyopic eyes in anisometropic amblyopes was more suppressed at higher spatial frequencies, while that from amblyopic eyes in strabismic amblyopes was more suppressed at lower spatial frequencies. CONCLUSION These results suggest that fMRI is a useful tool for the study of amblyopia in humans. The calcarine activation via amblyopic eyes because of anisometropia or strabismus has different temporospatial characteristics, which suggests differences in the neurophysiological mechanisms between two types of amblyopia.

Morphologic photoreceptor abnormality in occult macular dystrophy on spectral-domain optical coherence tomography.

PURPOSE. To investigate morphologic photoreceptor layer abnormalities and their correlation with visual function in occult macular dystrophy (OMD), by using spectral-domain optical coherence tomography (SD-OCT). METHODS. This observational case series included 18 eyes of 9 patients with OMD. All patients underwent an ophthalmic evaluation, which included a fundus examination, fluorescein angiography, full-field electroretinography (ERG), multifocal ERG, time-domain optical coherence tomography (TD-OCT), and visual field testing. Morphologic photoreceptor layer abnormalities of the retinal layers were investigated with SD-OCT. The structure-function relationship was investigated regarding visual acuity, symptom duration, and multifocal ERG RESULTS: RESULTS. Best corrected visual acuity ranged from 20/200 to 20/20. Four patients had a symmetric decline of acuity in both eyes (20/200-20/100), and five had unilateral vision impairment (20/200-20/50). TD-OCT showed foveal thinning in all patients, but revealed no other retinal layer abnormality. In 15 eyes of 8 patients, SD-OCT demonstrated a well-defined disruption of the inner segment-outer segment (IS-OS) junction of the photoreceptors and of the Verhoeff membrane (cone outer segment tips). SD-OCT showed that three of five patients with presumed unilateral OMD had bilateral OMD after initial or follow-up examinations. Degrees of abnormality in the photoreceptor layer varied and correlated with visual acuity and symptom duration. CONCLUSIONS. SD-OCT can demonstrate the disruption of photoreceptors in most patients with OMD and the morphologic changes on SD-OCT correlate with visual function and disease progression. These morphologic abnormalities can be an important feature and cause of vision loss in patients with OMD.

Correlation between topographic profiles of localized retinal nerve fiber layer defects as determined by optical coherence tomography and red-free fundus photography.

PurposeTo evaluate the topographic relationship of localized retinal nerve fiber layer (RNFL) defects as determined by optical coherence tomography (OCT) and by red-free fundus photography. MethodsSixty-five eyes of 65 patients with localized, wedge-shaped RNFL defects identified in red-free fundus photographs and with matching visual field defects were scanned with the Stratus OCT. On the resulting RNFL thickness report printout, segments of the line graph outside of the 95 and 99% normal limits were defined as “5% OCT defect” and “1% OCT defect,” respectively. Correlations between the angular location and angular width of RNFL defects as determined by OCT (OCT defects) and by red-free fundus photography (red-free defects) were evaluated. ResultsAngular locations and widths of both 5 and 1% OCT defects were significantly correlated with corresponding red-free defects (all P values<0.001). ConclusionsThere is a strong topographic correlation between characteristics of localized RNFL defects as determined by OCT and red-free photography.

Childhood ocular myasthenia gravis

PURPOSE To investigate the clinical manifestations and ocular findings in children with ocular myasthenia gravis (MG) that rarely have been reported in the literature. DESIGN Retrospective, noncomparative case series. PARTICIPANTS Twenty-four consecutive patients less than 15 years of age with ocular MG treated between June 1988 and July 2001. METHODS The medical records of 6 boys and 18 girls with ocular MG were reviewed retrospectively. MAIN OUTCOME MEASURES Alternate prism cover and uncover test, examination of ductions and versions, and visual acuity. RESULTS Mean age at onset was 38 months. Ptosis was found in 23 patients (96%), strabismus in 21 patients (88%), and amblyopia in 5 patients (21%). Exotropia combined with vertical heterotropia was the most frequent type of strabismus. Ductions were limited in 17 patients (71%), among whom supraduction or infraduction limitations were most frequently observed. Contrary to previous reports, medial rectus underaction was less common than lateral rectus underaction. Manifestations of strabismus and limitation of duction were variable and changed frequently during the follow-up period. The combined use of prednisone and pyridostigmine was found to be the predominant form of maintenance therapy, and ptosis was more responsive to drug therapy than limited ocular motility. CONCLUSIONS Children with ocular MG were found to have a high incidence of ptosis (96%) and exotropia and vertical hyperdeviation. Limitation on adduction was less common than that on abduction. First reported incidence of amblyopia (21%) and a relative nonresponsiveness of the limitation of eye movement to treatment were also noted.

A Study on Hemorrhage Detection Using Hybrid Method in Fundus Images

Image processing of a fundus image is performed for the early detection of diabetic retinopathy. Recently, several studies have proposed that the use of a morphological filter may help extract hemorrhages from the fundus image; however, extraction of hemorrhages using template matching with templates of various shapes has not been reported. In our study, we applied hue saturation value brightness correction and contrast-limited adaptive histogram equalization to fundus images. Then, using template matching with normalized cross-correlation, the candidate hemorrhages were extracted. Region growing thereafter reconstructed the shape of the hemorrhages which enabled us to calculate the size of the hemorrhages. To reduce the number of false positives, compactness and the ratio of bounding boxes were used. We also used the 5 × 5 kernel value of the hemorrhage and a foveal filter as other methods of false positive reduction in our study. In addition, we analyzed the cause of false positive (FP) and false negative in the detection of retinal hemorrhage. Combining template matching in various ways, our program achieved a sensitivity of 85% at 4.0 FPs per image. The result of our research may help the clinician in the diagnosis of diabetic retinopathy and might be a useful tool for early detection of diabetic retinopathy progression especially in the telemedicine.

Congenital Superior Oblique Palsy and Trochlear Nerve Absence: A Clinical and Radiological Study

OBJECTIVE To evaluate patients with congenital superior oblique palsy (SOP) by classifying them according to their magnetic resonance imaging (MRI) findings and cross-comparing the clinical characteristics of each group. DESIGN Retrospective, observational study. PARTICIPANTS Ninety-seven consecutive patients diagnosed with congenital SOP. METHODS Medical records of patients who demonstrated typical signs of congenital SOP were reviewed. The presence or absence of the trochlear nerve was visualized with thin-section high-resolution MRI of the cranial nerves. MAIN OUTCOME MEASURES Presence of the trochlear nerve and superior oblique (SO) muscle hypoplasia on MRI, age at the onset of symptoms or signs, ocular motility examination results, objective ocular torsion, and surgical outcomes. RESULTS Of the 97 patients with congenital SOP, 73% of patients were identified with an ipsilateral absent trochlear nerve and variable degree of SO muscle hypoplasia (absent group), whereas the remaining 27% had a normal trochlear nerve and normal symmetric SO muscle (present group). Patients with an absent trochlear nerve showed more frequent head tilt (P = 0.030) that was manifest at an earlier onset before 1 year of age (P<0.001). Patients with a normal trochlear nerve had a more prominent overelevation in adduction (P = 0.008) and more frequently were associated with dissociated vertical deviation (DVD; P = 0.025). CONCLUSIONS Congenital SOP patients without a trochlear nerve had a hypoplastic SO muscle and frequently manifested head tilt at an earlier age, whereas patients with a normal trochlear nerve showed prominent overelevation in adduction and frequent DVD. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.