A Case of Atypical Leber Hereditary Optic Neuropathy Associated with MT-TL1 Gene Mutation Misdiagnosed with Glaucoma

PURPOSE: Leber hereditary optic neuropathy (LHON) is one of the most common hereditary optic neuropathies caused by mutations of mitochondrial DNA. Three common mitochondrial mutations causing LHON are m.3460, m.11778, and m.14484. We report a rare mutation of the mitochondrial tRNA (Leu [UUR]) gene (MT-TL1) (m.3268 A > G) in a patient with bilateral optic atrophy. CASE SUMMARY: A 59-year-old female diagnosed with glaucoma 3 years earlier at a community eye clinic presented to our neuro-ophthalmology clinic. On examination, her best corrected visual acuity was 0.4 in the right eye and 0.7 in the left eye, and optic atrophy was noticed in both eyes. Optical coherence tomography revealed retinal nerve fiber layer (RNFL) thinning in both eyes; average RNFL thickness was 52 µm in the right eye and 44 µm in the left eye, but the papillomacular bundle was relatively preserved in both eyes. Goldmann perimetry demonstrated peripheral visual field defects, mostly involving superotemporal visual field in both eyes. Mitochondrial DNA mutation test showed an unusual mutation in MT-TL1 gene seemingly related to this optic neuropathy. CONCLUSIONS: We found a rare mutation (m.3268 A > G) of the mitochondrial DNA in a patient having bilateral optic atrophy, which led to the diagnosis of LHON. There have been previous reports about mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and infantile myopathy caused by MT-TL1 mutation, but this is the first case of LHON associated with the same mutation. In this case of LHON associated with MT-TL1 mutation, atypical clinical features were observed with a relatively mild phenotype and peripheral visual field defects.

Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes

PURPOSE: To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes. METHODS: For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry. The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation formula built into the tono-pachymetry. Bland-Altman plot and paired t-test were conducted to evaluate the between-method agreements. RESULTS: The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 µm in non-surgical eyes (p < 0.001) and 17.8 µm in post-PRK eyes (p < 0.001) compared with US pachymetry. Differences were significant in both Bland-Altman plotand paired t-test. The mean difference of corrected IOP values obtained by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87 mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot were not significant. CONCLUSIONS: The CCT measurement determined using tono-pachymetrywas significantly thicker than that of US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from US pachymetry and GAT measurements.

Clinical Features and Molecular Characteristics of Korean Patients with Congenital Aniridia

PURPOSE: To introduce clinical features and molecular characteristics of Korean patients with congenital aniridia. METHODS: Patients with iris hypoplasia were diagnosed clinically as congenital aniridia and were included in the study. Best corrected visual acuity (BCVA) and associated ocular abnormalities (including severity of iris hypoplasia, nystagmus, keratopathy, and foveal hypoplasia), and findings in optical coherence tomography were analyzed. PAX6 analysis,multiplex ligation-dependent probe amplification (MLPA), genomic molecular karyotyping, and candidate gene sequencing were performed to detect genetic abnormalities. RESULTS: 28 patients from 18 families were included in the study. BCVA varied from hand motion to 20/25. No manifest nystagmus was found in 3 patients, but the rest of the patients had pendular horizontal nystagmus. Keratopathy was found in 23 patients, cataracts in 12 patients, and glaucoma in 4 patients. All patients had foveal hypoplasia, including one case with a subtle phenotype. The PAX6 mutation was detected in 13 families out of 18;2 (p.Trp162Leufs*38,p.Gly409Arg) were novel,3 families had the miss ensemutation, and 3 families had alargedeletion in the PAX6 gene. CONCLUSIONS: This study adds 2 novel PAX6 mutations related to congenital aniridia to those previously reported. Congenital aniridia is a serious, sight-threatening ocular malformation, but central vision and the degree of iris hypoplasia were highly variable. The PAX6 mutation was detected in 72% of the patients in this study, and there were no specific clinical features differentiating aniridia with and without PAX6 mutations.