摘要:

The effects of base-in (BI) and base-out (BO) prism upon performance of four occupational-like tasks were measured on a group of 10 subjects who had normal binocular vision. Performance on tasks which required depth perception was significantly poorer when subjects wore prism glasses with 8 and 12 Δ BI and BO, whereas 4 A BI and BO did not significantly affect performance. The performance decrements with prism (3.0 to 6.7%) were considerably less than those induced by denial of binocularity (20 to 30%) as measured in a previous study. Thus, vergence-inducing prism does impair task performance but not as much as does the denial of binocularity. The reading and counting tasks did not require critical depth judgment and were much less affected by the prism than the needle-threading and pointers-and-straws tasks.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The general use of enzymatic cleaners for soft contact lenses has led to reports of incidents of allergic reactions in previously sensitized patients. In light of this, experiments were performed to assess the relative allergenic potential of four such enzymes: papain, subtilisin A, subtilisin B, and pancreatin. Mice immunized intraperitoneally (i.p.) with either subtilisin A or papain exhibited little serum immunoglobulin E (IgE), even after tertiary doses of protein. Primates immunized intradermally (i.d.) with the four enzymes showed various levels of response to challenges: none to papain, mild to moderate to subtilisin A and pancreatin, and severe to subtilisin B. Finally, guinea pigs instilled ocularly with enzymes weekly for 15 weeks exhibited significant hyperemia and chemosis only to the positive control protein, ovalbumin, and not to any of the enzymes tested. We conclude that three of the four enzymes tested have low potential to sensitize human beings, and, further, that animal models may find increased use in screening products of biotechnology.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Until recently, convergence limits have been measured only in the primary position of gaze. A new instrument permits such measurements in all directions of gaze and at various angular distances from the primary straight-ahead position. Aberration and distortion-free stimuli based on Heine's principle were incorporated in the apparatus. For each of the nine subjects participating, convergence limits were obtained in the primary straight-ahead position, secondary, and tertiary positions and in varying degrees of obliquity of these directions of gaze. The convergence limits were measured in 10° steps away from the straight-ahead position of gaze in 18 different meridians. It was found that convergence limits vary markedly with the direction of gaze, the maximal vergence range usually being found between 10 to 20° below the primary horizontal plane in the lower right-half field, possibly because subjects spend most of their time looking in this direction.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

To determine if there are any corneal endothelial cell size and shape changes in subjects wearing rigid gas-permeable contact lenses for cosmetic extended wear, six unadapted lens wearers were fitted using four different lens materials. Each subject wore one lens extended-wear and the other daily-wear for 3 months. Before lens wear and after 3 months, noncontact endothelial photographs were taken. Cell tracings were analyzed by a digitizing computer. This study showed significant endothelial polymegathism, an increase in maximum cell area to minimum cell area, and a significant decrease in percent frequency of hexagonal cells in the extended-wear eyes. There existed in these subjects a significant correlation between changes in cell size (polymegathism) and cell shape (pleomorphism).

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A controlled, randomized, double-masked study was conducted on eight human subjects to determine the threshold level of hydrogen peroxide, which is toxic when introduced into the eye via a high water content (75%; Dura-soft 4) hydrogel contact lens. Subjective comfort, conjunctival hyperemia, corneal and conjunctival epithelial staining, and corneal oxygen uptake were assessed in response to 5-min wear of lenses that were presoaked in isotonic saline solutions of physiologic pH containing 0, 25, 50,100, 200, 400, and 800 parts per million (ppm) hydrogen peroxide. Higher levels of hydrogen peroxide were associated with greater discomfort (p < 0.05) and increased conjunctival hyperemia (p < 0.001). The highest level of hydrogen peroxide tested (800 ppm) did not induce significant corneal or conjunctival epithelial staining or alter the corneal aerobic response. We conclude that residual concentrations of hydrogen peroxide in contact lens care systems should not exceed 100 ppm. Practitioners can use these data to estimate the level of residual hydrogen peroxide to which a patient may have been exposed upon lens application after neutralization.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The wavelength in focus on the retina was determined for 14 observers from measurements of the longitudinal chromatic aberration of the eye. Measurements were made at two viewing distances: 3 m and 40 cm. The results show a large amount of individual variability for the wavelength in focus at each distance. The range of values at 3 m was 457 to 593 nm with a mean of 518 nm, and 375 to 548 nm with a mean of 468 nm at 40 cm. The chromatic aberration measured at 3 m is the same as previously reported data by other investigators for distant viewing. The average results of this study indicate very little difference for the chromatic aberration measured at near compared to distant viewing but, again, considerable individual variability exists.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Visually guided, spatially oriented behavior involves an ongoing integration of signals regarding the loci of the retinal images and the position and orientation of the eye. In the strabismic this requires an altered spatial metric resulting from a functional readaptation to avoid confusion and diplopia. A comparator mechanism for evaluating these two signals is presented. A case report using “disruptive” therapeutic procedures that deliberately alter the strabismic's visual-postural control system is presented. A treatment plan for altering the anomalous binocular link, a characteristic of the well adapted strabismic, is described and related to the comparator mechanism

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Pre- and post-task measures of dark focus (DF) were used to assess the response of the accommodative system to within-task disparity-vergence in 10 late-onset myopes (LOM's) and 10 emmetropes. Disparity was induced by 3 and 6 A base-out prisms imposed during a 3 D near-vision task undertaken for 3− and 10-min periods. Accommodation was measured after the task at 1-s intervals over a 90-s period using an objective infrared optometer to determine post-task regression of DF toward pre-task values. After the 3-min task both groups show a reduction in DF adaptation with increasing disparity-vergence. After the 10-min task, disparity continues to have a significant effect on accommodative adaptation in LOM's but not in emmetropes, suggesting diminished prism adaptation in LOM's. The implications of these findings are discussed with regard to both current models of accommodation-vergence interaction and the etiology of late-onset myopia

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Although accommodative facility testing is used widely in the evaluation of accommodation in children, published normative data are not available for this age group. Current values being used are based upon studies of adult populations. In order to establish norms, 542 elementary schoolchildren were screened. Those that passed a specific set of criteria were included in the accommodative facility assessment. We used a new target and instructional set, which took into consideration the problems associated with subjective testing of young children. The results revealed lower mean accommodative facility values for both monocular and binocular accommodative facility than the values obtained previously from adult populations. These new findings can be used as a clinical guide to evaluate accommodative facility in young children

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Surveys were sent to family physicians in Illinois to determine knowledge and attitude concerning optometry. The respondents were knowledgeable in certain aspects of optometry. However, many need to become more aware of the optometrist as a health care provider

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID