摘要:

AbstractA technique is described which seems to permit accommodative convergence, and thus heterophoria and AC/A, to be measured while binocular fusion with stereopsis is active. The results obtained by this technique are compared with those obtained with conventional dissociation.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractOculomotor functions and information processing systems form a complex interaction in the achievement of reading skills. This study was designed to determine the relation between oculomotor functions and reading ability in fourth and sixth grade children. Four oculomotor functions were measured during the reading of digits and prose. The oculomotor functions were used independently and collectively to predict reading ability under both reading conditions. These relations were then examined with and without removal of the influence of verbal intelligence. The results indicate that when examined collectively, oculomotor functions are related to reading ability, but when oculomotor functions are examined independently, only marginally significant relations appear. Similar relations were found for both age groups. Verbal intelligence influenced some of the individual relations. The individual oculomotor functions that appeared responsible for the collective relation were frequency of fixations and lag of accommodation. A reciprocal-causation model between reading ability and oculomotor functions is proposed.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractThe graded balls test of Sheridan is used to screen for vision problems in infants and poorly communicative patients. To simulate what the infant with a refractive error may see, we photographed black and white spheres of identical size through various plus lenses. The results show that the white ball becomes progressively easier to identify with increasing blur. The size of the blur circle is shown to be directly related to background contrast. Because the white balls are viewed against a black cloth at 10 ft to enhance contrast, this may significantly bias the test results. Consequently, a neutral background may be a more appropriate surface upon which to assess the visual acuity by this technique.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractTwo psychophysical methods for monitoring retinal defocus are compared. One method, spatial frequency thresholds with sine wave grids, is well known. The second method is relatively new: it uses the effect of defocus on the width of the perceptually enhanced region of brightness or darkness generated next to a luminance edge. Both methods produce characteristic functions as the retinal image is thrown out of focus. However, spatial frequency thresholds appear relatively unchanged until a certain level of defocus has been introduced, whereas border enhancement spread is affected even by very small deviations from focus. It is suggested that variations in the frequency threshold are dampened in the near-focus range by aberrations and by the nonlinear relation between contrast and defocus, but chiefly by the resolution limit of the retina and visual pathways. However, it is found that the apparent lack of response to small deviations from focus is due to a drastic compression rather than absence of threshold changes. If responses through this region are shown on a greatly expanded scale in relation to the rest of the function, fluctuations appear that often match those generated by border enhancement.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractIn a patient with constant concomitant alternating exotropia at distance and near, the angle of anomaly varied in concert with the objective angle as the objective angle was altered by stimulating accommodative convergence using concave lenses to stimulate accommodation. The angle of anomaly was found to vary up to 31 as the objective angle was varied up to 37. The correlation coefficient (r) between the two variables was 1.00. The implications of this finding are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractCalculations are made of the effects of base curvature on squeeze pressures in hard contact lenses during blinking. An axisymmetrical model with parabolic profile is used of a cylindrical body (the lens) moving along its axis toward a rigid surface (the eye), from which it is separated by a tear film. The results are compared with those obtained from a two-dimensional model having the same parabolic profile. It is found that the maximum pressures in the axisymmetric case are precisely one-half of those in the corresponding two-dimensional one, irrespective of the base curvature. Thus, estimated pressures using the latter model are likely to be too large. A simple formula is also obtained which shows the effect of base curvature on the force. The calculated pressures (and hence forces) will be further reduced if lens deformation occurs as is the case in soft contact lenses.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractWhen observers with normal binocularity view reversing black and white checkerboard patterns, the amplitude of the resulting binocular visual-evoked response (VER) is significantly greater than the amplitude of either corresponding monocular response. When the same checkerboard pattern is dichoptically presented with an interocular luminance difference (1.3 to 2.0 log units), the amplitude of the dichoptic VER is significantly less than either monocular response. In a previous study, we attributed this effect to interference between the monocular components of the binocular response resulting from a phase shift induced by the interocular luminance difference. To test this hypothesis, dichoptic VER's were recorded for three temporal frequencies (1.88, 3.75, and 7.5 Hz). The results obtained support the phase shift interpretation.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractComplications from mydriatic and cycloplegic drugs are rare compared with their extensive use. Adverse effects are often related to dosage or other factors. The ocular complications include increased intraocular pressure, pigmentation of the conjunctiva and cornea, pigment in the anterior chamber, lacrimal duct blockage, macular edema, corneal endothelium damage, hyperemia, allergy, discomfort, and blurred vision. The systemic complications are those common to sympathomimetic and parasympatholytic drugs and include tachycardia, hypertension, headache, faintness, pallor, trembling, excessive sweating, palpitations, arrhythmias, confusion, hallucinations, drowsiness, ataxia, flushed skin, high fever, dysarthria, thirst, dry mouth, convulsions, disorientation, nervousness, coma, and death. An understanding of all possible side effects is of paramount importance to those using these drugs in the treatment of anticholinesterase poisoning. This review is intended as a ready reference to the adverse effects of mydriatic and cycloplegic drugs.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractFitting a comfortable and cosmetically attractive prosthetic device is a challenge, one which many people in the ophthalmic field seem to hesitate to undertake. Based on my experience, I provide practical guidelines for this important task. Artificial eyes which are required after enucleation are not discussed, but contact lenses and shells for disfigured blind or seeing eyes are.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

AbstractThe central visual fields of 44 optometric patients with known or suspected field defects were measured with the Friedmann Visual Field Analyser (FVA) and a 2-m tangent screen. The clinical correlation of visual field characteristics was at least adequate in more than 90% of eyes. Statistically significant correlations were also found between the area of scotoma found on the tangent screen and (1) the number of locations with reduced sensitivity and (2) the average reduction in sensitivity of the stimulated locations as determined by the FVA.

ISSN:0093-7002    

出版商:OVID    

年代:1982

数据来源: OVID