ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractContact lenses are worn by many individuals in military and civilian populations. Anecdotal reports have described contact lenses “sticking” and “freezing” to the eye during extreme cold conditions. However, some articles indicate the advantages of wearing contact lenses in cold environments. Military operations frequently take place in cold regions; therefore, we need to know whether contact lenses can be worn safely in extreme cold. Rabbits were fitted with hard (polymethyl methacrylate) contact lenses and exposed to −28.9°C temperatures with winds up to 78 mph (125 km/hr) for 3-hr periods. The wind-chill factor in these conditions exceeded −67.8°C. No effects of the cold or contact lenses were seen in 85% of the eyes. A few of the eyes, both with contact lenses and without, showed mild superficial fluorescein staining of the cornea which cleared within a few hours after exposure. Histologic examination of the corneas revealed no abnormalities attributable to the cold. Inasmuch as this study showed that rabbits wearing contact lenses in extreme cold suffered no acute deleterious effects to the eyes, the research can be expanded to include human subjects.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractA mathematical model for calculating the sagittal height of the anterior eye is used to study the effect of variation in ocular dimensions on the sagittal height of the eye. Examination of the relation between sagittal height and contact lens fitting reveals that the three-point touch theory is not inconsistent with normal fitting procedures for semiscleral soft lenses.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractTwelve exotropes of various types received oculomotor biofeedback therapy at State College of New York (SUNY) University Optometric Center. Feedback of a variable pitch tone which reflected changes in ocular vergence reinforced motor control of eye posture. Patients were trained to achieve and sustain alignment in a variety of viewing situations. The six intermittent exotropes in the study who did not have amblyopia or prior history of unsuccessful surgical or orthoptic therapy achieved the highest recovery rating after training. The amblyope and those who had orthoptic training learned to voluntarily correct their eye position, although they did not achieve as acute a sensitivity to loss of alignment as did the others. Therapy restored eye control at near in a young constant exotrope whose condition resulted from severe neurological dysfunction. A constant postsurgical exotrope who had no ability for sensory fusion made little progress. Advantages of oculomotor biofeedback therapy are shorter treatment time, elimination of lengthy home training exercises, and enhanced patient motivation.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractA dichoptic viewing device was used to present sinusoidal gratings with interocular asynchrony. The persistence of various spatial frequencies was then determined psychophysically by using blank detection, for near-threshold and suprathreshold contrast conditions and across the contrast range. Greater persistence was evident for higher spatial frequencies, and across all spatial frequencies the values were higher for near-threshold contrast conditions. Contrast specificity was evident, with the low spatial frequencies showing flat contrast functions while the higher spatial frequencies showed a steeper monotonic curve. Intermediate spatial frequencies displayed biphasic properties. In view of the different neural persistence for different spatial frequencies, we investigated the degree of binocular summation for different interocular asynchronies. Binocular summation was predominant for all spatial frequencies where the dichoptic asynchrony was within 25 msec. Binocular summation decreased as a function of asynchrony. The binocular/monocular ratio decreased to a greater extent and earlier for low than for high spatial frequencies.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractOcular hypertension was found in 54 (5.4%) of 1000 consecutive patients of an optometrist. In a separate trial, 50 ocular hypertensive subjects were followed for a mean follow-up time of 6.9 years. Five of the ocular hypertensive subjects (10%) developed primary open angle glaucoma and 2 (4%) developed primary angle-closure glaucoma. No single test could have enabled diagnosis in all five cases that developed open-angle glaucoma. Guidelines are recommended for the optometric management of patients having ocular hypertension.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractA procedure is proposed for computing the visual effectiveness of light incident on the retina considering the directional sensitivity of the underlying photoreceptor population. A half-sensitivity half-width measurement of the retinal directional sensitivity provides the basis for integrating a parabolic approximation to the directional sensitivity over the pupillary area penetrated by the incident light.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractIntraocular pressure measurements were made on 30 normal eyes using seven noncontact tonometers. The instruments were from 4 to 8 years old. Results show that pressures indicated by most noncontact tonometers are not significantly different. In the most extreme case, differences in mean pressures of 3.48 mm Hg were obtained. A difference of this magnitude may be important when following a patient over a period of time, and could be the result of measurements being made on a different tonometer.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractThis paper reports a survey of the lantern tests that have been or are used to evaluate the color vision of people who wish to enter occupations that require the ability to recognize colored signal lights reliably. The origin of each lantern is traced and the principal features of each are described. The available data concerning failure rate of normals, the failure rate of people with defective color vision, and the extent to which scores on lantern tests correlate with field trials are summarized. Despite the fact that lantern tests have been used since the turn of the century and that some lanterns have been in use for more than 30 years and some for much longer periods, the available validation data are incomplete and sometimes conflicting. However, the data do indicate that some lanterns may fail a significant proportion of normals and that there is considerable variation between lanterns in the proportion of color vision defectives that will fail. It is noted that most lanterns will pass some protanomals despite their reduced sensitivity to red light and correspondingly short visual range for red signals. The view of Cameron is supported that a more rational approach would be to make a clinical diagnosis of the type of color vision defect, to reject protanopes, deuteranopes, and protanomals and to use a lantern test only to determine which deuteranomals should be accepted.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID