PURPOSE: To assess the clinical usefulness of the pressure phosphene tonometer (Proview(R)) compared with the Goldmann applanation tonometer. METHODS: Ninety four eyes of 50 patients, aged from 3rd decade to 6th decade and with intraocular pressure (IOP) ranging from 9 to 21 mmHg, were measured by Proview(R) 5 times each. The average of these values was compared with the value measured with the Goldmann applanation tonometer. Twenty eyes of 10 patients, aged from 3rd decade to 4th decade, were trained repeatedly and measured again by the same method after 1 month. RESULTS: IOP measured by Proview(R) was statistically higher than that with the Goldmann applanation tonometer (p<0.05). The difference between the two measurements for patients in their 5th and 6th decades was more than in their 3rd and 4th decades. Nevertheless, the measurement difference decreased and the correlation coefficient increased between the devices in the repeatedly trained group (r=0.923). CONCLUSIONS: In measuring IOP, the pressure phosphene tonometer (Proview(R)) is not suitable in elderly or newly adapted patients, but it provides significant values in young and repeatedly trained group.
Aged ; Humans ; Intraocular Pressure ; Phosphenes*

This paper introduces the current research progress on effect factors of mobility performance based on simulated prosthetic vision.
Phosphenes ; Prostheses and Implants ; Vision, Ocular

PURPOSE: To compare the intraocular pressure (IOP) measured by the pressure phosphene tonometer (PPT) and the Goldmann applanation tonometer (GAT) according to the feedback of the IOP measured by GAT and the use of the dominant hand during the measurement. METHODS: In a group of 40 eyes of 40 normal subjects in their twenties and thirties without diagnostic specificity, IOP was measured with PPT three times by themselves and with the GAT by one examiner on 3 different days. In 20 eyes of the feedback group, the subjects were informed of their IOP measured by GAT and were allowed to measure with PPT again. In each group, half of the eyes (20 eyes) were assigned to use the dominant hand to measure the IOP (dominant group) and the other half (20 eyes) were assigned in the other way (nondominant group). RESULTS: In feedback, nonfeedback and dominant groups, comparison of the first day showed statistically significant differences of mean IOP. But on the third day, there were no significant differences among all 4 groups and there were significant correlations. There was a stronger correlation between the two methods in the feedback group (r=0.721) than in the nonfeedback group. The correlation coefficient of all 40 eyes was 0.605 (p<0.001). CONCLUSIONS: PPT has a strong correlation with GAT in the range of normal IOP and is thought to be more useful as a self tonometer for the measurement of both eyes with the periodical measurement of IOP by GAT in clinics.
Hand ; Intraocular Pressure* ; Phosphenes* ; Sensitivity and Specificity

BACKGROUND: The physiological change of positive acceleration is primarily focused on the hydrostatic column effects that are associated with acceleration exposures. IOP values during positive acceleration is reduced according to this theory. However, the first trial of IOP measurement during positive acceleration showed that there were no significant changes in IOP values during the +2G phase of parabolic flight. In addition, IOP study during centrifuge exposures showed that there were significant increases in IOP during +2Gz and +3Gz. Therefore, the purpose of this study is to investigate the effect of positive acceleration on IOP. METHODS: The data from 4 normal subjects (2 men and 2 women) were included in this study. The baseline IOPs of subjects were within normal range. The subjects did not wear anti-G suits and use anti-G maneuver during the acceleration exposure. Pressure phosphene tonometer was used to measure IOP. To minimize the difference between the Goldmann tonometer and the pressure phosphene tonometer, IOPs were measured in subjects for 1 week prior to this study. IOP measurements of protocol 1 were obtained with pressure phosphene tonometer at +1Gz (baseline), +2Gz, +3Gz, +4Gz, and again at +1Gz (post). IOP measurements of protocol 2 were obtained at + 1Gz (baseline), +3Gz, and again at +1Gz (post). IOP measurements of protocol 3 were obtained at + 1Gz (baseline), +4Gz, and again at +1Gz (post). A total of 55 IOP measurements for each subject were made. RESULTS: The result showed that there was a significant difference in the means of IOP in protocol 1, 2, and 3 (P<0.05). But, they did not show an increasing or decreasing trend according to increase in acceleration. In particular, subject 1 showed that there was significant decrease of IOP in protocol 1, 2, and 3 compared to the baseline IOP measurements during positive acceleration(P<0.05). Based on symptom questionnaire and VTR review, variable body contractions may affect the IOP measurements during acceleration. There were significant differences in the means of IOP among variable body contractions in subject 1 when compared to the baseline IOP measurements. CONCLUSIONS:Persistent decreases of IOP in subject 1 suggest that the mechanism of IOP changes under positive acceleration could be explained by the hydrostatic column effect. In addition, interpretation for IOP measurements under positive acceleration should be cautious due to variable muscle contraction.
Acceleration* ; Humans ; Intraocular Pressure* ; Male ; Muscle Contraction ; Phosphenes ; Reference Values ; Surveys and Questionnaires

BACKGROUND: The pathophysiology of migraine has not been fully understood. One of the hypotheses is cortical hyperexcitability. Transcranial magnetic stimulation (TMS) is a noninvasive electrophysiologic tool for the investigation of cortical excitability. Divalproex sodium may prevent migraine attacks by increasing the GABA-ergic tone. We examined the phosphene generation using TMS in migraine patients in order to investigate the cortical excitability and its response by valproate prophylaxis. METHODS: We applied TMS to 27 migraineurs and 27 control subjects. TMS was performed by a Magstim Rapid Stimulator connected to a 70 mm figure-of-eight coil to examine the phosphene threshold between migraineurs and controls on primary (V1) and bilateral secondary (V5) visual cortices. Twelve migraine patients completed a one month administration of divalproex sodium 500 mg/day. We compared the phosphene threshold between pre- and post-treatment with devalproex sodium in these patients. RESULTS: The prevalence of the phosphene generation was significantly higher in migraineurs compared with controls in V1 and V5. The phosphene average thresholds were significantly lower in migraineurs compared with controls in V1 and V5. The phosphene average thresholds in the same areas were significantly higher in post-treatment compared with pre-treatment in migraineurs. CONCLUSIONS: The differences of the phosphene threshold in the visual cortex between migraineurs and controls comply with the theory of cortical hyperexcitability for the pathophysiology of migraine. Valproate might play a significant role in the prophylaxis of migraine by decreasing cortical hyperexcitability.
Humans ; Migraine Disorders* ; Phosphenes ; Prevalence ; Sodium ; Transcranial Magnetic Stimulation* ; Valproic Acid* ; Visual Cortex*