Passive limitation of adduction after Cüppers's 'Fadenoperation' on medial recti.

In 40 eyes of 20 esotropic subjects in which a 'Fadenoperation' was performed on the medial recti we measured the resistance to ocular rotation in adduction before and after the operation. The difference between the two sets of force measurements demonstrates that the Fadenoperation on medial recti produces a mechanical restriction to adduction which can explain the effect of the surgical procedure on the strabismic deviation.

Millimetric cover test--a linear strabismometric technique.

In ten normal subjects we measured the angular rotations of the globe, both in adduction and in abduction, corresponding to limbus shifts from 1 to 7 mm. Our study demonstrated that to each millimeter of temporal limbus shift corresponds an average adduction of about 4.6 degrees and to each millimeter of nasal limbus shift an average abduction of about 4.8 degrees. These experimental results give a sound foundation to the clinical evaluation of the strabismic angle by measuring, with a millimeter ruler, the limbus shift of the nonfixating eye by assuming fixation. This technique appears particularly useful as a substitute for the simultaneous prism and cover test, in the evaluation of a squint with a variable angle, and in measurements in other positions of gaze.

[Contour interaction in the examination of visual acuity]. / L'interaction de contours dans l'examen de l'acuité visuelle.

The author discusses the problem of the interoptotype distance in visual acuity charts. A small interoptotype distance (5,5' minutes) kept constant throughout the chart enhances the sensitivity of the visual acuity measurement for the detection of a functional deficit, without decreasing its specificity. A specification of the distance between the last recognized optotypes should be given with the visual acuity in order to permit an estimate of the measurement's validity. A simple formula for the measurement in minutes of the angular interoptotype distance is presented.

[Some remarks on the precision of visual acuity measurements]. / Einige Anmerkungen zur Präzision der Sehschärfemessung.

BACKGROUND: Visual acuity measurements are used to determine the course of diseases, treatment outcomes, consequences of accidents, and the occupational ability of a patient. The fact, that visual acuity depends both on visual function as well as on the circumstances of examination, is often understood more intuitively than explicitly. Precision and accuracy of visual acuity measurements must be kept in mind, and occasionally need to be quantified and statistically evaluated, to avoid clinical errors. METHODS: Factors influencing acuity measurements are analyzed. Using appropriate examples the precision of acuity measurements is evaluated and quantified with standard vision test charts and threshold or staircase procedures. Limits of confidence and limits of tolerance are described for the statistical evaluation of consecutive visual acuity measurements. RESULTS AND CONCLUSIONS: The statistical evaluation of standard procedures is relatively time consuming, as 3 to 4 standardized measurements are needed on first examination and on follow-up. Threshold and staircase methods, however provide more feasible data, due to the examination technique. All evaluation procedures described here, can only be applied with logMAR acuity readings.

[Clinical application of millimetric cover test (author's transl)]. / Klinische Anwendung des Millimeter-Abdecktestes.

The strabismic angle can be evaluated by measuring, with a millimeter ruler, the limbus shift of the nonfixating eye by assuming fixation. Each millimeter of temporal limbus shift corresponds to an adduction of about 4.6 degrees, and each millimeter of nasal limbus shift to an abduction of about 4.8 degrees. This technique permits rapid evaluation of the strabismic deviation without disturbing the sensory situation. It is very useful in the estimation of large and variable deviations, of vertical deviations and of the amplitude of nystagmus movements, in cases where the "rebound-saccades" render the prism cover test unreliable, in measurements of horizontal deviation in up and down gaze.

Evaluation of a new E-optotype chart for measuring contrast sensitivity.

BACKGROUND: Clinical examinations of the contrast sensitivity (CS) are currently made by one-trial measurements of a restricted number of spatial frequencies around the peak of the CS function (CSF). These methods do not allow calculation of the confidence intervals of the single measurements, thus preventing examiners from evaluating the reliability of their data. We elaborated a new method of CS measurement at the peak of the CSF, aiming at economical clinical applicability together with enhanced reliability. Moreover, we tried to establish lower limits of normal CS that would allow classification of low test results as pathological. METHODS: A chart containing six columns of E optotypes of constant size and decreasing contrast (from about 16% to 0.5%) was used to perform six-fold contrast threshold determination (method of descending limits, forced choice). Optotype dimensions are intended to measure the CS at spatial frequencies corresponding to 3 and 6 cycles per degree (c/deg). The reference values were defined by testing 61 normal subjects: 31 "young" (16-35 years) and 30 "old" (56-81 years). RESULTS: The mean logCS found in the young group was 2.07 +/- 0.086 SD for 3 c/deg and 1.94 +/- 0.154 SD for 6 c/deg, while in the old group the mean logCS was 1.88 +/- 0.095 SD and 1.74 +/- 0.118 SD respectively. CONCLUSION: This simple method of measuring CS can provide a single CS value together with a confidence interval for the individual patient, thus allowing evaluation of measurement reliability.

[Ocular rotation and corneal reflexes (author's transl)]. / Rotations oculaires et reflets cornéens.

The location of the corneal reflex (Purkinje's first image) produced by an electronic flash was studied at various degrees of ocular rotation both in adduction and abduction. A statistical analysis of the results showed a good correlation between the decentration of the corneal reflex and the degrees of ocular rotation. The results thus obtained give an experimental basis to the clinical use of the so-called Hirschberg test for measuring the strabismus angle.