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Biomedical subjects

D Safra

Publications and source records attributed to D Safra.

At least 19 recordsLinked to original sources
PubMed1995

[The F-L test for determining alternating central scotoma].

BACKGROUND: Based on their experiences several authors consider an alternating central scotoma as the main reason for reading difficulties due to dyslexia. METHODS: Searching for a simple and reliable method for determination of an alternating central scotoma we used a pair of synoptophore fusion images, in the center of which we added the letter F respectively L as central control signs. A spontaneously perceived and persisting E means a perfect and stable orthophoria. A persisting F or L with fusion of the images means a one sided central scotoma. Alternation of F and L with fusion of the images means an alternating central scotoma. RESULTS: By examining normal readers, untreated asthenopic and untreated dyslexic patients, we found mostly rapid alternation of F and L in the latter two groups, whereas most of the normal readers saw F, L and E alternating at longer intervals. CONCLUSIONS: Thus undisturbed reading seems not to demand perfect orthophoria. On the other hand a rapidly alternating central scotoma may be considered as an important factor causing reading difficulties.

Adolescent↗
PubMed1994

[The 30 prism test].

The 30-prism-test is a relatively quick and simple method for many-sided testing binocular behaviour in near distance in patients with reading difficulties and asthenopic symptoms, respecting well known and assumed causes of the disturbances. Therefore indications for treatment are given.

Asthenopia↗
PubMed1992

[Orthoptic treatment of dyslexia].

It is assumed that dyslexia is due to a brain-organic syndrome, either congenital or acquired in infancy, with specific gnostic deficiencies and faulty controlled binocular vision. The latter is expressed by an intermittent alternating central scotoma which is thought to be responsible for impaired visual perception during reading. The aim of the orthoptic treatment of dyslexia must therefore be to eliminate the alternating central scotoma by stabilizing the binocular vision, and thus to improve reading ability by achieving unimpaired visual perception.

Child↗
PubMed1990

[The accommodation-convergence bar (A=C bar)].

The accommodation-convergence bar was developed as a simple measuring and exercise instrument. For the ophthalmologist, it is a convenient means of measuring accommodation and convergence in the office, while patients can use it for home convergence and fixation exercises which they can monitor themselves. The A = C bar has also been used experimentally to eliminate the functional central scotoma in dyslexic children.

Accommodation, Ocular↗
PubMed1989

[The "Ring Test" for evaluating eye dominance].

A horizontal diplopia is produced with prisms whose bases are nasal or temporal. The subject has to fixate a circle, now seen double, alternately with his left and right eye and touch the center of the circle with a finger. Of one hundred subjects thus examined, 85 located the circle accurately every time when the one eye was fixating it and always missed when fixating with the other eye. This appears to prove that dominance of one eye also means that it is preferred for binocular spatial orientation.

Child↗
PubMed1977

[Results of objective accommodation determination in eyes with alternating functional central scotoma (alternating strabismus) (author's transl)].

Objective determination of monocular accommodation in young eyes revealed a different behaviour in strabismus alternans from that in normal binocular vision. This manifested itself by strongly differing individual responses, less correct values in physiological and unphysiological accommodation tests, and different reactions on hindering clear vision that cannot be compensated by refraction changes. The possibility of central scotoma, persisting during fixation and varying in density, occurring in alternating strabismus, is discussed.

Accommodation, Ocular↗
PubMed1976

[Objective determination of the consensual accommodation (author's transl)].

The direct and consensual accommodation of both eyes were determined by a modified coincidence refractometer. Young individuals with normal monocular and binocular vision revealed a close quantitative correspondence between the direct and the ipsi- and contralateral consensual accommodation. Experimental impairment of the function of the ciliary muscle by medical means caused disturbed consensual accommodation of both eyes. The weakening of the function of the ciliary muscle of one eye by instillation of, for example Homatropin leads to an important increase of the contralateral and diminution of the ipsilateral consensual accommodation. By the results of the investigations it was concluded: 1. that the regulation of the direct accommodation reflex is influenced also by the function of the ciliary muscle in the fixating eye and has stimulating and depressing components, 2. that the innervation of the nonfixating eye passes through an efferent neuron, from where the accommodation impulse emerges to both eyes. - The anatomically based relation between the direct and the ipsilateral and contralateral consensual accommodation allows one to use its quantitative determination in both eyes as a diagnostic test in afferent and efferent disturbances of the accommodation reflex.

Accommodation, Ocular↗
PubMed1975

[Objective determination of accommodation in eyes with permanent central scotoma due to amblyopia (author's transl)].

Objective determination of accommodation in 38 children with permanent central scotoma due to amblyopia on one side (with central and eccentric fixation) revealed: 1. The physiological adaptation of refraction for far and near distances did not serve its purpose. 2. There was either no or an irregular response on hyperopia, which was produced by placing concave lenses in front of the eye while fixing a far object, or on myopia produced by placing convex lenses in front of the eye while fixing a near object. 3. On hindering clear vision which could not be compensated by accommodation there was contrary to normal eyes no reactive change of refraction at all or only a poor one. The accommodation behavior in eyes with permanent central scotoma due to amblyopia does not differ from that in eyes with permanent central scotoma due to organic lesions when using the same test methods.

Accommodation, Ocular↗
PubMed1975

[Visual training of partial blinds due to organic lesions (author's transl)].

The immanent sense of optic orientation in space is related to the unchangeable line of principal visual direction and its collaterals. Therefore in patients with loss of central vision due to organic lesion the orientation in space is impaired as well. as a result of a vicious circle of indistinct vision, eccentric fixation and suppresion of foveal perception. By a systematic training the normal sense of direction may be restored and thereby relatively good orientation and by reactivation of the suppressed macular perceptions some reading ability may be regained. Based on experience during 15 years the special diagnostic, the training course and the results of the method are reported and the possibility of rehabilitation of patients with to a high degree impaired central vision due to organic lesions is shown.

Adolescent↗