摘要:

The author shows that the wetting of contact lens on the eye is a complex process. Measuring the contact angle is possible by several techniques but knowing the contact angles (advancing and receding) is not enough to define wettability in scientific terms. A contact lens on the eye, bathed in lacrimal fluids and subjected to a number of pressures, presents a challenging problem in physics as well as in clinical vision care.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

As optometry advances in this modern age, adjacent disciplines make increasingly greater contributions. It is at the interfaces of physiology, optics, chemistry, and other basic sciences that the answers to new and more complex contact lens problems will be found—answers which will aid in balancing the needs of the eye with the care systems and requirements of new materials in order to assure the best visual performance.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This paper was presented as the Caret C. Koch Memorial Award Lecture at the American Academy of Optometry meeting in Houston on December 11, 1983. Dr. Koch's commitment to interprofessional affairs is recognized and examples of interaction between optometrists and medical, educational, and psychological personnel are highlighted. A challenge is presented to enhance interprofessional cooperation for the future.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This paper discusses contact lenses in a military environment and reports the results of (1) a literature survey, (2) an extensive questionnaire sent to 1400 spectacle and contact lens wearers, and (3) a short questionnaire given to soldiers taking part in a large scale and long military maneuver. Only a small number of publications were found concerning the relation between adverse environmental conditions and contact lens wearing. In Vietnam dust and poor hygiene often led to eye irritations that precluded the wearing of contact lenses by soldiers. Nevertheless, persons in the army are often in favor of contact lenses. In the air force and navy, wearing contact lenses seems compatible with nearly all military duties. A questionnaire was sent to all known contact lens wearers in the Dutch army and air force and to about an equal number of spectacle wearers. The responses indicate that the proportion of contact lens wearers is 1.8%. The distribution of hard vs. soft lenses was 60 and 40%, respectively. Military personnel wore their lenses during nearly all daily activities. Most contact lens wearers were of the opinion that in military conditions contact lenses have advantages over spectacles. To obtain more information on field exercises, a second questionnaire was handed out immediately after a large-scale NATO field maneuver. Twenty percent of the contact lens wearers had decided in advance not to wear their lenses, but another 30% ceased wearing their lenses during the exercise. It was recommended that for nearly all functions and/or conditions, wearing of contact lenses should be allowed, but that during extended field exercises wearing of hard contact lenses should be discouraged.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

In a single masked experiment qualitative vision (QV) and qualitative over-keratometry (QK) were determined in 10 patients wearing a variety of hydrogel lenses. Better QV (right eye vs. left eye) was reported by the patients. Better OK was judged by the author using a modified Bausch & Lomb keratometer. The two measures correlated in all 10 patients. Slitlamp observations confirmed the supposition that the variable quality of the over-keratometry (over-K) images was due to alterations of the prelens tear film. Over-K revealed a secondary image due to reflection at the concave surface of the contact lens. Observations of the nature of the primary and secondary images lead to the conclusion that the lenses do not buckle; hence, the quality of vision in the 10 patients studied was dependent upon the quality of the prelens tear film. Photographic examples of over-K images are shown.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Ten steady-state visual evoked responses (VER's) were recorded from each of 47 normal, adult subjects. For each subject, the mean and SD for the 10 VER amplitudes were calculated and used to determine amplitude variability. Although some subjects produced extremely reliable VER's, data from the majority showed a considerable degree of variability. A number of factors including trend (the tendency of the VER amplitudes to increase or decrease with repeated measurements), noise, attention, binocularity, accommodation, eye movements, artifacts, and electrode placement were evaluated to determine their relative contributions to this variability. Noise and trend factors produced a large proportion of the variability (75%) whereas the other factors were found to be relatively insignificant.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We use a new model for describing the flexure of hydrogel lenses in situ to evaluate toric hydrogel lenses. The mathematical development of the model precludes use of prism ballasted lenses (because of differential thickness in the vertical meridian and possible lenticulation in the midperiphery), and so double-thin zone lenses were used here. Our results suggest that such lenses (low-minus power) align almost perfectly with the anterior corneal surface creating minimal tear layers.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Traditionally, the components of ocular refraction are analyzed in surface powers and their linear separations in the eye. More recently it has been suggested that the refractive effects of these components are better studied in terms of their vergence contributions. This study presents an improved method of vergence analysis which takes into account the refractive status of the eye. Results show a significant interaction of all components and indicate that their relative contributions are dependent on refractive status.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Direct in vivo observation of acute ultraviolet (UV)-induced corneal endothelial damage is not possible due to the more severe damage produced in the epithelium. In order to quantify damage and evaluate endothelial recovery an indirect method was used. Eyes of pigmented rabbits were irradiated with UV-B (290 to 320 nm) isolated from the output of a high-pressure 1000 W reflectorized Xenon arc lamp by a grating monochromator and appropriate filters. The peak wavelength of the radiation used was 305 nm, with a 18 nm bandwidth at half-maximum. Corneal thickness variations measured with a modified Zeiss (Oberkochen) pachometer were used to follow alterations in epithelial and endothelial function. Epithelial damage alone resulted in a maximum thickness increase of 13.5% within 24 hr with recovery within a further 24 hr. Greater increases in corneal thickness, in the absence of anterior uveal involvement, were taken to indicate endothelial damage, and reached maximum at 2 days, with recovery occurring in 7 days. The threshold for endothelial damage sufficient to disturb corneal deturgescence was 0.12 cm-2.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Refractive data obtained by means of the Dioptron Nova Diagnostic Eye Computer were compared to data obtained by conventional clinical refraction on a group of 236 clinic patients. Spherical equivalent power data were found to average –0.32 D more for Dioptron Nova data than for clinical data, whereas spherical power data averaged –0.25 D more for Dioptron Nova data than for clinical data, and cylinder power averaged –0.12 D more for Dioptron Nova data. Dioptron and clinical data were found to be within 0.50 D of each other for 74% of eyes for spherical equivalent power, for 83% of eyes for spherical power, and for 91% of eyes for cylinder power. Cylinder axis data were found to be within 10 degrees for the two methods for 78% of eyes.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID