Ming-Ling Tsai

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.

Independent Effects of the Broccoli-Derived Compound Sulforaphane on Ca(superscript 2+) Influx and Apoptosis in Madin-Darby Canine Renal Tubular Cells

This study explored whether sulforaphane changed basal [Ca²⁺]i levels in suspended Madin-Darby canine kidney (MDCK) cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. Sulforaphane at concentrations between 2.5-10 microM increased [Ca²⁺]i in a concentration-dependent manner. This Ca²⁺ influx was inhibited by phospholipase A2 inhibitor aristolochic acid but not by Ca²⁺ channel blockers such as nifedipine, nimodipine, nicardipine, diltiazem, verapamil, econazole and SK&F96365. The Ca²⁺ signal was abolished by removing extracellular Ca²⁺. In Ca²⁺-free medium, pretreatment with sulforaphane did not alter the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin-induced Ca²⁺ release suggesting sulforaphane did not induce slow Ca²⁺ release from endoplasmic reticulum. At concentrations between 1 and 20 microM, sulforaphane induced concentration-dependent decrease in cell viability which was not affected by pre-chelation of cytosolic Ca²⁺ with BAPTA/AM. Flow cytometry data suggest that 20 (but not 5 and 10) microM sulforaphane induced significant increase in sub G1 phase indicating involvement of apoptosis. Collectively, in MDCK cells, sulforaphane induced [Ca²⁺]i rises by causing Ca²⁺ entry through phospholipase A2-sensitive pathways without inducing Ca²⁺ release from the endoplasmic reticulum. Sulforaphane also induced Ca²⁺-independent cell death that might involve apoptosis.

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.

Effects of Horizontal Acceleration on Human Visual Acuity and Stereopsis

The effect of horizontal acceleration on human visual acuity and stereopsis is demonstrated in this study. Twenty participants (mean age 22.6 years) were enrolled in the experiment. Acceleration from two different directions was performed at the Taiwan High-Speed Rail Laboratory. Gx and Gy (< and >0.1 g) were produced on an accelerating platform where the subjects stood. The visual acuity and stereopsis of the right eye were measured before and during the acceleration. Acceleration <0.1 g in the X- or Y-axis did not affect dynamic vision and stereopsis. Vision decreased (mean from 0.02 logMAR to 0.25 logMAR) and stereopsis declined significantly (mean from 40 s to 60.2 s of arc) when Gx > 0.1 g. Visual acuity worsened (mean from 0.02 logMAR to 0.19 logMAR) and poor stereopsis was noted (mean from 40 s to 50.2 s of arc) when Gy > 0.1 g. The effect of acceleration from the X-axis on the visual system was higher than that from the Y-axis. During acceleration, most subjects complained of ocular strain when reading. To our knowledge, this study is the first to report the exact levels of visual function loss during Gx and Gy.

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.

Multiple preretinal yellowish dots in a patient with syphilis

Contrary to yellowish dots located mostly at perivascular retina in previous reports, our case revealed even and discrete distribution on retinitis region. Our observations also suggested that perivasculitis seem not to explain completely the pathogenesis of retinal precipitations. Further studies are required. Besides, similar epiretinal lesions have been described in the absence of retinitis in patients with sarcoidosis. Small intraretinal lesions may mimic epiretinal precipitates in patients with herpetic retinitis, Behcet’s disease, etc [1-4]. Cautiously, the differential diagnosis is necessary. A male visited our hospital for the evaluation of uveitis for 6-month duration. On examination, the best-corrected visual acuity (BCVA) was 6/60 on the right eye and 6/60 on the left eye. Fundus examination revealed moderate vitritis and an area of retinitis in the superior midperiphery associated with yellowish retinal precipitates on the both eyes [Figure 1a and b]. Laboratory examination shows a positive finding of rapid plasma reagin and treponema pallidum hemagglutination (TPHA). A positive result on the ELISA and Western blot test confirmed the infection of the human immunodeficiency virus (HIV). The patient had a homosexual history with CD4 T-cell count around 64 cells/mL. Under the impression of ocular syphilis coinfected with HIV, the patient was treated with intravenous penicillin for 14 days. Rapid resolution of the vitritis and retinal precipitation were noted. Two months later, BCVA recovered to 6/7.5 and retina showed minimal retinal pigment epithelial changes [Figure 1c and d].

Significant Tumor Reduction of Extensive Conjunctival Squamous Cell Carcinoma by Radiotherapy with Adjuvant Topical 0.04% Mitomycin C Treatment

Purpose: To report a Taiwanese female with extensive conjunctival squamous cell carcinoma significantly reduced by radiotherapy and adjuvant topical mitomycin C. Methods: Case report Result: A 79-year-old Taiwanese woman with a history of lymphoma visited our uveitis service due to suspected ocular metastasis. On examination, an extensive papilliform conjunctival mass (24 mm×19mm×11 mm) with periorbital region involvement was observed over the left eye. Orbital computed tomography (CT) scan and positron emission tomography (PET) demonstrated a massive suspected malignant mass lesion over the peribulbar region without intraocular invasion. Under impression of conjunctival lymphoma, incisional biopsy was performed, revealing squamous cell carcinoma. Focal radiotherapy was applied but showed limited response. Therefore, adjuvant topical 0.04% mitomycin C was prescribed. Dramatic tumor reduction was observed with visual acuity of 6/20 achieved after radiation and adjuvant topical chemotherapy. Conclusions: Radiotherapy with adjuvant topical chemotherapy shows potential in the management of extensive conjunctival squamous cell carcinoma.

Bilateral Cataracts after Psoralen and Long-Wave Ultraviolent Radiation (PUVA) Treatment for Psoriasis

Purpose: To report a case of bilateral cataracts in one young patient of psoriasis treated with PUVA which induced severe impairment of visual acuity. Method: Case report. Results: A 35-year-old male of psoriasis received oral 8-MOP (8-methoxypsoralen) photo-chemotherapy and exposed to ultravilolet A for 8 years. Recently his best corrected vision were 6/60 in the both eyes on ocular examination. The slit lamp microscopy showed bilateral dense posterior sub-capsular opacity. Clear cornea incision wound of phacoemulsification combined with foldable IOL implantation was performed one by one. Three months later, his bilateral bare visual acuity returned to 6/6 and no other ocular complications were found during the 6 months follow-up. Conclusion: The efficacy of oral psoralen and long wave ultraviolent A radiation (known as PUVA) were popularly used as the treatment for psoriasis. Unfortunately, UVA is largely absorbed by the lens. Oral administered 8-MOP also diffuses in the lens and binds irreversible with DNA molecules and lens proteins. Long-term risks of PUVA including cataracts are relatively rare found in young people. The ocular symptoms may be neglected by the patients of psoriasis. The best method of minimizing the cataract formation is reminding them of the importance of wearing UVA-block protective sunglasses.

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.