Jiann-Torng Chen

Visual fields during acute exposure to a simulated altitude of 7620 m.

BACKGROUND The hypoxia associated with sudden exposure to high altitude is known to impair vision and may thereby affect flight safety. However, no data were available regarding hypoxic effects on visual fields. The aim of this study was to evaluate black-and-white visual field sensitivity with acute hypoxia during acute exposure to a simulated altitude of 7620 m. METHODS Subjects were 15 male pilots 26-39 yr of age. We measured arterial oxygen saturation (S(aO2)%) using transdermal pulse oximetry while the visual field was measured within a 30 degrees eccentricity in the right eye by computerized perimetry. The subject breathed 100% O2 for 30 min before and during chamber ascent, then removed his mask while measurements were performed. RESULTS The S(aO2)% and visual field sensitivities (mean +/- SD) at ground level were 99.1 +/- 0.4% and 43.9 +/- 2.1 dB, respectively. During hypoxia, the S(aO2)% dropped to 64.0 +/- 5.4% within 3 min. Mean visual sensitivity was significantly reduced by 7.2 +/- 1.6 dB. Furthermore, peripheral sensitivity was slightly but significantly more diminished than central sensitivity. CONCLUSIONS Severe acute hypoxia reduces central and moderate peripheral black-and-white vision by a factor of two with the strongest effect in the periphery.

Regression of choroidal metastasis secondary to breast carcinoma with adjuvant intravitreal injection of bevacizumab.

Editor, T he choroid, which is supplied by rich vessels, is the most common site of intraocular metastasis. Choroidal metastases originate most commonly from a primary cancer of the breast or lung. Systemic chemotherapy is in widespread use and is efficient in the control of choroidal metastatic tumours. However, vision may be endangered or intolerable ocular pain may occur and progress despite systemic chemotherapy. Therefore, additional approaches are necessary. The treatment modalities for choroidal metastasis vary and include external beam radiotherapy, brachytherapy, laser photocoagulation and enucleation (Kanthan et al. 2007). However, current treatments have several drawbacks, such as limited facilities, the possibility of radiation-related ocular damage, loss of vision, etc. Bevacizumab, an anti-vascular endothelial growth factor therapy, has been proven to be effective in the treatment of metastatic carcinoma of the colon or rectum by the Food and Drug Administration (Giantonio et al. 2007). Moreover, previous research has shown that the choroidal metastastic lesion may manifest angiogenesis and its pathogenesis depends on the haematogenous dissemination of the primary malignancy. Thus, bevacizumab was considered to represent a promising approach to the treatment of choroidal metastasis. In December 2006, a 50-year-old woman with breast carcinoma was referred to our uveitis service with painful visual loss in the left eye. Previously, the patient had been diagnosed with breast carcinoma, grade 3, T2N0M0, stage IIA. Immunohistochemical stains expressed negative

Optic disc hemorrhages in a patient with hemophilia A

To report a hemophilia patient complicated with optic disc hemorrhages. A 13-year-old boy presented to our emergency room with a black shadow in the left eye for 1 day. The best-corrected visual acuity was 6/6 in both eyes. Peripapillary retinal and subretinal hemorrhages were found in the left eye. Result of the laboratory examination showed an extremely low level of coagulation factor VIII (1.9%). Factor VIII concentrate was given for 8 weeks. A follow-up 3 months later showed absorption of the hemorrhages, black shadow diminished, and the vision was 6/6.

Ocular Responses and Visual Performance after High-Acceleration Force Exposure

PURPOSE To evaluate ocular responses and visual performance after high-acceleration force exposure. METHODS Fourteen men were enrolled in the study. A human centrifuge was used to induce nine times the acceleration force in the head-to-toe (z-axis) direction (+9 Gz force). Visual performance was evaluated using the ETDRS (Early Treatment of Diabetic Retinopathy Study) visual chart, and contrast sensitivity (CS) was examined before and after centrifugation. Ocular responses were assessed with biomicroscopy and topographic mapping after gravitational stress. RESULTS Transient visual acuity reduction (0.02 +/- 0.04 logMar vs. 0.19 +/- 0.07 logMar VA; P < 0.05) and temporary ocular anterior segment reactions were observed immediately after centrifugation. These reactions included changes in corneal thickening (553.7 +/- 21.7 mum vs. 591.2 +/- 20.6 mum; P < 0.05), increasing anterior chamber depth (ACD; 3.19 +/- 0.26 mm vs. 4.53 +/- 0.34 mm; P < 0.05), and pupillary enlargement (3.54 +/- 0.73 mm vs. 5.76 +/- 0.61 mm; P < 0.05). The increase in ACD continued for 15 minutes after exposure to acceleration (3.19 +/- 0.26 mm vs. 4.39 +/- 0.27 mm; P < 0.05). Pupillary dilation was noted both 15 (3.54 +/- 0.73 mm vs. 5.56 +/- 0.67 mm; P < 0.05) and 30 (5.47 +/- 0.59 mm, P < 0.05) minutes after the gravitational stress. CS decreased significantly at low and medium spatial frequencies (1.5, 3, and 6 cyc/deg) and did not return to the baseline level by 30 minutes. CONCLUSIONS High-acceleration force may induce transient visual acuity reduction and temporary corneal thickening. Prolonged increase in ACD and pupillary dilation were also observed. The decrease in CS persisted for 30 minutes after centrifugation. The mechanisms underlying these observations are not clear, because there are no previous reports on this topic. Further studies are needed.

Changes in Visual Function During the Coriolis Illusion

BACKGROUND The Coriolis illusion produces spatial disorientation and is, therefore, dangerous for pilots. It is not known whether it also affects visual function (visual acuity and stereopsis). METHODS There were 18 subjects (15 men and 3 women, mean age 24.7 yr) enrolled in the study. A spatial disorientation simulator was used to produce Coriolis stimulation. The visual acuity of the subjects was evaluated with the Rosenbaum Vision Card before and during Coriolis stimulation. Stereopsis was measured with the Titmus stereo test. Throughout the experiments, eyeball movements were observed on a television monitor. Electrooculography (EOG) and electroencephalography (EEG) were also documented. RESULTS Before Coriolis stimulation, the visual acuity and stereopsis of all subjects were 20/20 and 40 s of arc, respectively. During the Coriolis illusion, the visual acuity of nine subjects (50%) remained 20/20, whereas the visual acuity of the others (50%) dropped by two lines. The stereopsis of most subjects (77.8%) decreased to 800 arc-seconds or less. Rhythmic nystagmus was observed, while EOG amplitudes were significantly elevated compared with those at baseline (9.41 +/- 0.26 microv2 and 8.45 +/- 0.36 microv2, respectively). EEG activity (frequency) was also greater than at baseline (13.15 +/- 0.84 Hz and 11.94 +/- 1.20 Hz, respectively; P < 0.05). CONCLUSIONS During Coriolis stimulation, the visual acuity of the subjects remained stable, but their stereopsis was reduced. Further study is warranted.

Preliminary Results of Changes in Refraction and Corneal Curvature Caused By+Gz Acceleration in Patients after Orthokeratology

Purpose: The aim of this study was to investigate the changes in visual acuity, refraction, and corneal curvature caused by sustained+Gz acceleration of patients in a human centrifuge after overnight orthokeratology. Methods: Five healthy men training to be aviation doctors, aged 25-26 years (mean=25.3 years), received overnight orthokeratology for two weeks. The human centrifuge at the Aviation Physiology Research Laboratory in Tainan, Taiwan, was used to expose the subjects to various acceleration profiles. Each subject experienced three centrifuge runs. Visual acuity, refraction, and corneal topography were measured before, and 1 min and 10 min after acceleration. We compared the study group findings with those of a control group of 13 subjects who had not undergone orthokeratology but experienced the same acceleration procedure. Results: In the orthokeratology group, nine eyes of five subjects completed the study. One eye was excluded because of keratitis. Visual acuity remained stable after human centrifugation. Refraction increased significantly at 1 min, but recovered at 10 min after centrifugation. There was a significant decrease in corneal thickness and a significant increase in anterior curvature at 1 min and 10 min after centrifugation. In the control group, best-corrected visual acuity was increased at 1 min and 10 min after centrifugation. Myopic shift was noted significantly at 1 min, but increased at 10 min after centrifugation. There was a significant decrease in corneal thickness and a significant increase in anterior curvature, at 1 min but this recovered 10 min after centrifugation. Conclusion: Visual acuity is stable, although some corneal topographic and refractive parameters change after centrifugation. Differences in the changes in refraction and anterior curvature between the orthokeratology and control groups may be due to the oblate shape of the cornea produced by the orthokeratology lens.

Acute Syphilitic Progression in an HIV-Positive Patient

The prevalence of syphilis dramatically decreased during the 1950s with the use of antibiotics.1 However, the incidence of syphilis has been rising, in part, because of increased HIV-related diseases.2 Diagnosing syphilis in HIV-positive patients remains challenging because syphilis in such patients frequently presents with atypical features and accelerated disease.1 We describe an HIV-positive patient who developed neurosyphilis in accelerated course within 1 year. Notably, primary syphilitic lesion was not observed. A 28-year-old man visited our hospital for evaluation of blurred vision of 1-month duration. The patient was diagnosed with HIV-1 infection 1 year earlier and had been treated with highly active antiretroviral therapy. Systemic opportunistic infections were not present 7 and 12 months ago. At admission, the patient presented with multiple symmetrical skin rashes but no evidence of genital lesions. Seborrheic dermatitis with nodular skin lesions were noted over the periorbital regions [Figure 1(A)]. Phthisis bulbi over the right eye was attributed to eyeball rupture previously. The left eye revealed impaired visual acuity of 6/12, and retinal examination showed multiple hemorrhages along the inferior temporal vessel [Figure 1(B)]. Rapid plasma reagin and Treponema pallidum hemagglutination of serum and cerebrospinal fluid confirmed neurosyphilis with syphilitic vasculitis. Administration of intramuscular benzathine penicillin achieved rapid resolution. After 5 months of treatment, visual acuity had recovered to 6/7.5, and only mild retinal vasculitis remained.

Using Bevacizumab in a Case of Poems Syndrome Related Bilateral Optic Disc Edema: A Case Report

Purpose: Intravitreal bevacizumab injection was tried in a case of POEMS syndrome with optic disc edema. The visual function and the OCT changes are reported. Methods: Case report. Result: A 40-year-old female complained of blurred vision in both eyes for 2 months. In the past 3 years, she had refractory ascites, hirsutism, hepatosplenomegaly, hypothyroidism, peripheral neuropathy, hyperpigmentation and monoclonal plasma cell disorder, and POEMS syndrome was diagnosed conclusively. The initial best-corrected visual acuity was 6/15 OU, fundus examination showed optic disc edema and cystoid macula edema OU. The average retinal thickness in the center of the fovea was 283μ OD and 267μ OS according to OCT after intravitreal bevacizumab injection. 7 months later, the best-corrected visual acuity improved to 6/8.6 OU. In addition, optic disc edema and cystoid macular edema had significantly subsided. Conclusion: Intravitreal bevacizumab injection may be a treatment option in the settings of optic disc edema and macular edema of POEMS syndrome.

Peri-Bulbar Injection of Triamcinolone in the Treatment of Bilateral Serous Retinal Detachment in Preeclampsia and Eclampsia

Purpose: To report two cases of preeclampsia and eclampsia with bilateral serous retinal detachment that received treatment with peri-bulbar steroid injection. Methods: Four eyes from two patients with bilateral serous retinal detachment were treated with a 40 mg peri-bulbar injection of triamcinolone acetonide (TA). Visual acuity, intraocular pressure, fundus photographs and B-scan ultrasonographs were evaluated. Results: Fundus photography and B-scan ultrasonography showed that retinal reattachment occurred two days after the injection and that normal visual acuity was subsequently regained in one week. There were no other ocular complications after 6 months follow-up. Conclusions: The occurrence of serous retinal detachment in pregnancy is relatively rare and complications unusual. Peri-bulbar injection of TA may result in rapid and sustained improvement of visual acuity and retinal attachment associated with preeclampsia and eclampsia. Although most of the symptoms and signs should improve gradually, the sudden onset of blindness may strike the younger women. Our method may be easier and safer for the early blind and anxious mothers.

Juxtapapillary Choroidal Melanoma-A Case Report

Purpose: To report a case of medium size of juxtapapillary choroidal melanoma. Method: Retrospective review of literatures. Result: Fundus examination of a 36-year-old female revealed a dome-shaped and pigmented subretinal lesion straddling the superonasal retina with disc insertion in the right eye. Ultrasonography showed an acoustically hollow lesion with initial high amplitude echoes and low-amplitude internal reflections. Based on clinical and ultrasonographic findings, the diagnosis was choroidal melanoma. The eye was enucleated. Histopathologic examination revealed a picture of malignant melanoma of choroid characterized by prominent nuclei and nucleoli (Spindle B cells). Conclusion: Treatment of melanomas should be directed toward minimizing the potential for recurrence and metastasis. However, few literatures have reported the treatment of jaxtapapillary choroidal melanoma. With the uncertain outcome of conservative treatment, the patient was treated with enucleation.