摘要:

Intermittent photic stimulation can induce epileptic seizures in some patients. These seizures may take various forms which are characterized by overt phenomena or atypical EEG signals. Many adventitious stimuli in the environment have been found to be capable of producing these attacks. The neuropbysiological mechanisms underlying this condition are only partially understood, and are the subject of considerable research effort at the present time. Various therapies have been proposed including some involving spectacle devices.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Four college students, ranging in age from 18 to 21 years, were tested on their dynamic, monocular accommodation responses to a square wave stimulus and sine waves of two frequencies. The tests were conducted over a period of seven days in a controlled environment, each subject being tested once every three hours. Latency, magnitude, velocity, gain and phase lag of the responses were measured, and means and standard deviations were computed. The latency of response was stable throughout and agreed fairly well with previous studies. The response magnitude was relatively stable. Three of the subjects had higher velocities on receding targets; one was faster on approaching targets. The group mean velocity increased over the seven days of the study. In keeping with the trend to faster dynamics over the seven days, both gain and phase lag improved.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Using a direct acting sympatbomimetic drug, the pupillary response with and without prior instillation of a topical anesthetic was studied. When a topical anesthetic is applied prior to instilling a mydriatic, the pupillary response is greater than the use of a mydriatic alone. The increased pupillary response resulting from use of an anesthetic has certain clinical implications with regard to optimum dose and paradoxical drug reactions.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Determining a neurophysiology code for color from single cell studies meets with some difficulty, because most visual neurons in primates change their activity as a result of a change in stimulus intensity, spectral composition, form or position. It is argued in the present paper that the activity of a single neuron cannot be considered as the neural representation of a stimulus, but instead, stimulus encoding must be viewed in terms of the relative amounts of neural activity produced in many parallel neurons at various stages of the visual pathway. This “across-neuron pattern” code for color is used to account for color sensations and bue discriminations in normal trichromats and dicbromats. The neural basis of brightness and saturation are all discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

This paper contains a brief analysis of the drawbacks manifested by presently available near acuity test cards for preschool children. Expanding upon a recently proposed design, the production of a new near point card is discussed with consideration given to the factors in the card's design as well as the methods of production.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Fabrication of an inexpensive, easy-to-use prism bar using Fresnel Press-onTMprisms is discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Subjective determinations were made of the refractive error before, during, and after the presence of chalazia on the upper and lower lids of one eye of a 37-year-old female subject. Ophthalmometric corneal measurements were made during and after. Spherical and cylindrical power changes were not significant, but the subjectively determined cylindrical axis was shifted significantly counter-clockwise, and the corneal cylindrical axis was shifted significantly clockwise, while the chalazia were present.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Three persons (five eyes) fitted with B&L Softens™ contact lenses, wore them continuously, except for brief periods when they were removed for cleaning or other reasons. Condition of the corneas was frequently monitored, and no adverse effect on the eyes or lenses was noted. Minimal surface coating and discoloration was observed, and all subjects felt that lenses performed in a superior manner when they were undisturbed for extended periods of time.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

Validity coefficients of astigmatic techniques were obtained from two experiments which consisted of (1) crossed cylinders and parabolic chart with 18 subjects, and (2) regular clock dial, polarized clock dial, and crossed cylinders with 26 subjects. Results showed almost perfect correspondence between crossed cylinders and parabolic chart, and high correlation for adjusted values among the two clock dials and crossed cylinders. The significant difference between the nearly perfect correlation from (1), and high correlation from (2), suggested that either the crossed cylinders or parabolic chart would serve better than the regular or polarized clock dials in the final determination of astigmatism, and that in the confirmation of patients with small degrees of astigmatism, the parabolic chart would perform better than the regular clock dial.

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1974

数据来源: OVID