Ulnar Neuropathy as a Complication of Retinal Detachment Surgery

PURPOSE: To report a case of ulnar neuropathy as an extraocular complication following retinal detachment surgery and face-down positioning. CASE SUMMARY: A 65-year-old woman was referred to our hospital with decreased visual acuity in the left eye. Fundus examination revealed a rhegmatogenous retinal detachment not involving the macula in the left eye. A vitrectomy with scleral encircling and 18% SF6 gas tamponade was performed. The patient was instructed to assume a face-down position. After 5 days, the patient reported having paresthesia and numbness of the left 4th and 5th fingers. Neurologic exams were performed and the results indicated ulnar neuropathy. There was no improvement in the neurologic symptoms during the 6-month follow-up. CONCLUSIONS: Surgeons performing retinal surgery should caution their patients of ulnar neuropathy when face-down positioning is required. The patients should be instructed to minimize the time spent with their elbows flexed in a stationary position. Additionally, the pressure loaded on the bent elbow should be minimized.

Multifocal Electroretinograms in Amblyopic Patients

PURPOSE: To evaluate the results of amblyopia on multifocal electroretinogram (mfERG). METHODS: The mfERG procedure was performed on nineteen monocular amblyopic patients (age ranged from 7 to 42 years) using the VERIS(TM) (EDI, San Mateo, CA) system. The central 30 degrees of ocular fundus were stimulated by an array of 103 hexagonal elements for four minutes. The responses of six concentric rings (rings 1 to 6) radiating from the foveal center were averaged, and the latencies and amplitudes of N1, P1 and N2 were compared with the findings of the normal contralateral eyes. The mfERG procedure was recorded again after improvement of vision in one patient (No. 4) who underwent occlusion treatment for one month. RESULTS: There were no significant differences of N1, P1 and N2 latencies between normal contralateral and amblyopic eyes (P>0.05). However, P1 amplitudes of the amblyopic eyes were reduced significantly compared with those of the normal contralateral eyes on rings 1 and 2 (P<0.05). N1 and N2 amplitudes of the amblyopic eyes were also reduced, but not significantly. After the successful occlusion treatment of patient No. 4, the responses of the amblyopic eye were improved but not the level of the contralateral normal eye. CONCLUSIONS: These results suggest that amblyopia may cause some changes in mfERG responses, especially in terms of amplitudes of the central retina. Further investigation is needed to determine whether these results are due to the physiologic change(s) of the amblyopia itself or to fixation instability during the test.

Effect of Refractive Error on the Multifocal Electroretinogram

PURPOSE: To evaluate the influence of refractive blur on the results of mfERG. METHODS: mfERG was performed on 10 healthy volunteers with a refractive error within +/- 1 diopter. The central 30 degrees of the ocular fundus were stimulated by an array of 103 hexagonal elements, for four minutes, using VERISTM. To change the refractive status, 6-cm diameter corrective lens, of -6, -4, -2, plano, +2, +4, and +6 diopters, were placed in front of the eyes, and the examination distance adjusted to compensate retinal image size changes due to corrective lens. The mfERG responses were grouped by 6 concentric rings, and then averaged. For each ring, the latencies and amplitudes of the N1, P1 and N2 were analyzed. The 6 rings were divided into the central (ring 1, 2) and peripheral (ring 3~6) retina, and the latencies and amplitudes of the N1, P1 and N2 were then also analyzed. RESULTS: Refractive blur can affect the results of the mfERG. Latency delay was more common at the peripheral than central retina, but had no statistically significant correlations with the refractive power increase. CONCLUSIONS: When the viewing distance was adjusted to create a constant retinal image size, the influence of refractive blur may cause some changes in the mfERG results. Therefore, when evaluating the results of an mfERG, the effects of the refractive error should be borne in mind.

Relationship between Uncorrected Visual Acuity and Refractive Error in Visual Acuity Test of Children

PURPOSE: To evaluate the relationship of uncorrected visual acuity and refractive error in children. METHODS: Visual acuity testing was performed, using LogMAR chart without optical aids, in children between 4 and 11 years old. Cycloplegic refraction was carried out to check the refractive error. Correlation indices between uncorrected visual acuity (UCVA) and refractive error were obtained by regression analysis with SPSS according to the sex, age, and refractive error type, myopia, or hyperopia. RESULTS: One hundred and one children were enrolled in this study. Spherical refractive error range was -13.00D~+6.25D and cylinder range was -4.50D~0D. In the older age group, correlation indices of UCVA and refractive error increased. In addition, female patient and myopia were other components that increased the correlation indices. The formulae for the UCVA regression line and refractive error were; y=0.491e0.1492x (x=refractive error, y=UCVA), R2=0.4319. Based on the regression line, a prediction table to calculate the refractive error from the UCVA and UCVA prediction table of refractive error was made. CONCLUSIONS: For the children who are not cooperative, the prediction table of this study will be helpful to reduce the test error in visual acuity and refractive error tests.

Electroretinograms in Cataract Patients: Changes in Electroretinographic Responses According to the Cataract Type and Severity

PURPOSE: To evaluate the changes of electroretinographic responses according to the lens opacity type and severity in cataract patients with normal retina. METHODS: Retrospective study was performed on 79 eyes of 79 patients who had undergone electroretinograms (ERG) before cataract surgery. The patients with high myopia, diabetes mellitus, hypertension or glaucoma were excluded. Cataracts were classified using Lens Opacities Classification System III (LOCS III). Whether the ERG results are different according to the location and severity of lens opacity was analyzed. RESULTS: Marked reduction in amplitude and delay in implicit time were observed in mature cataracts. Amplitudes of a- and b-wave were reduced significantly, especially a-wave in maximal combined response and b-wave in rod response (P<0.01). Among the 4 groups, excluding the mature opacity, amplitude was reduced in posterior subcapsular opacity. Implicit times were also delayed, but not significant. CONCLUSIONS: Lens opacity, especially posterior subcapsular opacity affects the ERG results significantly. These findings should be considered in evaluating the retinal abnormalities in patients with cataract.

Visual Field Changes in Children with Vigabatrin Treatment

PURPOSE: Recently, several reports have documented persistent visual field changes associated with long-term use of Vigabatrin, an antiepileptic drug. Epilepsy is a common disease in children, therefore we investigated perimetric changes in children who were on Vigabatrin treatment. METHODS: Total 36 eyes of 18 patients who had been treated with Vigabatrin were tested with Humphrey Field Analyzer. The visual fields were assessed using central 30-2 threshold test and peripheral 60-4 threshold test. RESULTS: In central 30-2 threshold tests, 13 eyes(40.6%) showed mild visual field constrictions and 4 eyes(12.5%) showed severe visual field constrictions. In peripheral 60-4 threshold tests, 23 eyes(71.8%) showed visual field changes. CONCLUSIONS: Asymptomatic visual field loss may develop in Vigabatrin-treated children. Regular examinations of the visual field is warranted for Vigabatrin-teated children.