Thicknesses of the Fovea and Retinal Nerve Fiber Layer in Amblyopic and Normal Eyes in Children

PURPOSE: This study was designed to assess and compare the thicknesses of the fovea and the retinal nerve fiber layer in normal children and children with amblyopia. METHODS: Optical Coherence Tomography (OCT) was performed on 26 children (52 eyes total) with unilateral amblyopia that was due to anisometropia or strabismus. OCT was also performed on 42 normal children (84 eyes), for a total of 136 eyes. Retinal thickness measurements were taken from the fovea, and the retinal nerve fiber layer thickness measurements were taken from the superior, inferior, nasal and temporal quadrants in the peripapillary region. RESULTS: The average age of the normal children was 8.5 years, and the average age of the children with amblyopia was 8.0 years. The average thickness of the fovea was 157.4 micrometer in normal eyes and was 158.8 micrometer in amblyopic eyes. The difference between the two groups was not statistically significant (p=0.551). The thicknesses of the superior, inferior, nasal and temporal quadrants of the retinal nerve fiber layer between the normal children and the children with amblyopia were also not statistically significant (p=0.751, 0.228, 0.696 and 0.228, respectively). However, for the children with anisometropic amblyopia and the children with strabismic amblyopia, the average thicknesses of the fovea were 146.5 micrometer and 173.1 micrometer, respectively, and the retinal nerve fiber layer thicknesses were measured to be 112.9 micrometer and 92.8 micrometer, respectively, and these were statistically significant differences (p=0.046, 0.034, respectively). CONCLUSIONS: Normal thicknesses of the fovea and the retinal nerve fiber layers were established, and there were no differences in the fovea and the retinal nerve fiber layer thickness found between normal children and children with amblyopia.

Change of Muscle Insertion Position after Disinsertion of Extraocular Muscles

PURPOSE: This study examines the change in distance from the corneal limbus to the insertion of the rectus muscles before and after disinsertion and retraction with a pair of fixation forceps during strabismus surgery. METHODS: In 38 strabismus patients, on 30 medial rectus muscles and 38 lateral rectus muscles, before and after disinsertion and retraction with a pair of fixation forceps, the distances from the corneal limbus to the upper, middle and lower parts of the insertion of the medial and lateral rectus muscles marked with methylene blue solution were measured. RESULTS: The distances between the corneal limbus and upper, middle and lower parts of the insertion after the disinsertion were reduced on, average 0.23 mm, 0.28 mm, and 0.18 mm, for the medial rectus muscle, respectively, and 0.21 mm, 0.28 mm, and 0.15 mm, for the lateral rectus muscle, respectively (P<0.05). The percentage of cases in which the advance from the corneal limbus to the insertion was greater than 0.5 mm was 33.3% for the medial rectus muscle, and 21.1% for the lateral rectus muscle. The lateral rectus muscle was disinserted, fixed with a pair of forceps, and subsequently, the distance from the upper, middle and lower parts to the corneal limbus were reduced to 0.36 mm, 0.43 mm, and 0.30 mm, respectively (P<0.05). The percentage of cases that advanced more than 1.0 mm was 13.2 %. The changes in distance from the upper, middle, and lower parts of insertion toward the limbus after disinsertion and retraction were 0.15 mm 0.15 mm, 0.16 mm, respectively (P<0.05). CONCLUSIONS: When performing the recession of the lateral rectus muscle, disinsertion of the rectus muscle, may result in a change of the site of insertion, which in turn might influence the outcome of strabismus surgery.

Type 3 Waardenburg Syndrome

PURPOSE: We report a case of Type 3 Waardenburg syndrome accompanied by intermittent exotropia, which had not previously been encountered in Korea along with the literature study. METHODS: A 5-year-old boy visited as a result of hypochromic heterochromic iridum in the right eye. Suspecting Type 3 Waardenburg syndrome, plain radiography, a hearing test, an alternate prism cover test and fundus examinations were performed and the presence of lateral displacement of the lacrimal puntum was evaluated. RESULTS: The presence of hypochromic heterochromic iridum, dysplasia of the left thumb, sensorineural deafness, dystopia canthorum along with a lateral displacement of the lacrimal puntum, albinism of the posterior pole upon a fundus examination, and intermittent exotropia with a 20 prism diopters of deviation were found. CONCLUSIONS: This patient showed the 4 criteria for a diagnosis of Type 3 Waardenburg syndrome including hypochromic heterochromic iridum, dystopia canthorum along with lateral displacement of the lacrimal puntum, sensorineural deafness, and a muscular system abnormality, i.e., dysplasia of the left thumb. He also showed intermittent exotropia.