ObjectiveTo observe the changes in blood flow density of radial retinal peripapillary capillary (RPC) around the optic disc in patients with non-arteritic anterior ischemic optic neuropathy (NAION) at different stages of the continuous course of the disease. MethodsA prospective cohort study. From January to December 2020, 29 cases of 29 eyes of NAION patients diagnosed in the Eye Center of the Second Affiliated Hospital of Zhejiang University School of Medicine were included in the study. Among them, there were 18 males with 18 eyes and 11 females with 11 eyes. The average age was 53.62±6.67 years old. The affected eye underwent routine eye examination and visual field, optic cohenrence tomography angiography (OCTA) examination. Visual field inspection was performed to obtain the average visual mean defect (MD) value. OCTA was used to measure the thickness of the peripapillary retinal nerve flayer (pRNFL) around the optic disc, the whole en face image vessel density (wiVD), intro disc vessel density (diVD), RPC blood flow density around the optic disc, and macular ganglion cell complex (GCC). The course of disease ≤3 weeks was defined as the acute phase; 4-12 weeks was defined as the subacute phase; ＞12 weeks was defined as the chronic phase. The changes of visual field MD, optic disc RPC blood flow density, pRNFL thickness and macular GCC thickness were observed in the acute, subacute and chronic phases (12-24, ＞24 weeks). A completely randomized design of variance analysis was used to compare the differences in visual field MD, RPC blood flow density, GCC, and pRNFL thickness in different courses. Pearson correlation analysis was used to analyze the correlation between pRNFL thickness, macular GCC thickness, visual field MD changes and RPC blood flow density around the optic disc sex. ResultsThe wiVD of the eyes in the acute phase, subacute phase, and chronic phase (12-24 weeks, ＞24 weeks) were (44.96±2.76)%, (41.50±3.49)%, (39.08±5.43)%, (38.56±6.48)%. There was a statistically significant difference in wiVD of eyes with different disease courses (F=8.939, P＜0.001). The average difference of wiVD between 12-24 weeks and ＞24 weeks in the chronic phase was －0.984, and the difference was not statistically significant (P＞0.05). There was no statistically significant difference in diVD of patients with different courses of disease (F=1.079, P=0.365). The blood flow density of RPC around the optic disc of the affected eye, except for the lower part, the blood flow density of the nasal side, the temporal side, and the upper quadrant, decreased significantly with the progression of the disease, and the difference was statistically significant (F=8.816, 6.069, 8.943; P＜0.05). In the chronic phase, the average difference of blood flow density between the nasal, temporal, and upper sides of the eyes between 12-24 weeks and more than 24 weeks in the chronic phase was －0.984, －0.230, －0.198, and the difference was not statistically significant (P＞0.05). There was no statistically significant difference in the visual field MD of patients with different courses of disease (F=0.277, P=0.842); the overall pRNFL thickness and average macular GCC thickness were compared with statistical significance (F=47.122, 14.954; P＜0.001, ＜0.001), all became significantly thinner with the progression of the disease. The results of Pearson correlation analysis showed that the blood flow density of the entire optic disc wiVD, the blood flow density of RPC in the temporal quadrant around the optic disc and the visual field MD (r=－0.225, －0.268; P＜0.05), and the average thickness of GCC (r=0.480, 0.436; P＜0.01) were all related. ConclusionThe blood flow density of RPC in the entire optic disc and around the optic disc (except the lower quadrant) of NAION eyes gradually decrease with the progression of the disease, and stabilize after 12 weeks of the disease.
ObjectiveTo observe the clinical features and visual prognostic factors of ethambutol-induced optic neuropathy (EON).MethodsA cohort study. Twenty-four inpatients (46 eyes) identified as EON in Neuro-Ophthalmology Department of Chinese PLA General Hospital from January 2014 to December 2017 were enrolled, including 14 males (26 eyes) and 10 females (20 eyes) with a ratio of 1.4/1 male/female. The average age was 42.79±15.12 years and the average weight was 62.46±12.31 kg. The average time duration between oral administration of ethambutol and occurrence of EON was 9.94±16.49 months. The average time of ethambutol duration was 7.06±11.68 months, with an average accumulative dose of 156.7±1 779.0 g and the average daily dose of 15.07±8.95 mg/(kg·d). All patients were tested with visual acuity, fundus photos, colour vision, OCT, visual field, VEP, orbital MRI and the gene of OPA1 and mitochondrial deoxyribonucleic acid (mtDNA). All the patients accepted drug withdrawal immediately after diagnosis, and were given the treatment of systemic nerve nutrition and improvement of microcirculation for 2 weeks. The time of follow-up was more than 12 months. According to whether the visual acuity (VA) in any of eyes was over than 0.1 at the last follow-up, all the patients were divided into two groups: the bad VA group (VA less than or equal to 0.1) and the better VA group (VA over than 0.1) group. The χ2 test and Fisher's exact probabilistic method test were used to compare the counting data between groups, and the Wlincox rank sum test was used to compare the measurement data. Multiple factors of VA outcome between the patients with bad or better va were analyzed by logistic regression.ResultsThirty eyes (65.2%) had VA less than or equal to 0.1 and 5 eyes (10.9%) had VA over than 0.5 at EON onset. The VA of the rest 11 eyes (23.9%) was higher than 0.1 and lower than 0.5. At the last follow-up, 20 eyes (43.5%) had VA less than or equal to 0.1 and 9 eyes (19.6%) had VA over than 0.5, the VA of the rest 17 eyes (36.9%) was higher than 0.1 and lower than 0.5. Fundus examination revealed 7 eyes (15.3%) with optic disc edema. OCT revealed significant loss of the retinal nerve fiber layer (RNFL) in the affected eyes, mainly in the temporal RNFL of the optic disc. All patients had dyschromasia, mainly in distinguishing the color of red and green. The types of visual field defect was as following: central dark spot (52.2%), diffuse visual acuity decreased (30.4%), temporal hemianopsia (17.4%). Orbital MRI revealed that 12/24 (50.0%) patients had T2 lesions with T1 enhancement in 6/24 patients (25.0%). Genetic test showed that 4 patients (16.7%) had gene mutation. Among them, there were 2 patients with OPA1 mutation, 1 with mtDNA 14340 point mutation and 1 with the mtDNA 11778 point mutation. Thirteen patients showed better VA outcomes (over than 0.1) while 11 showed bad VA outcomes after discontinuation of ethambutol. Between the better VA group and the bad VA group, there were statistically significant differences in the daily dose of ethambutol and gene mutation (P=0.031, 0.023). The daily dose was related to visual prognosis of EON while only the daily dose of more than 18 mg/(kg·d) may lead to bad VA outcomes according to the logistic analysis (95% CI 0.007-0.736, OR=0.069, P=0.027).ConclusionsEON may have OPA1 and mtDNA mutation with more bilateral eyes involved and less optic edema, which about 43.5% of the patients showed irreversible visual impact. The daily dose of ethambutol is related to the vision recovery.