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A B Safran

Publications and source records attributed to A B Safran.

At least 19 recordsLinked to original sources
PubMed1995

Role of the completion phenomenon in the evaluation of Amsler grid results.

PURPOSE: To evaluate the limitations, particularly those related to the perceptual completion phenomenon, of Amsler grid tests in patients with central scotomas caused by macular disorders. METHODS: We tested 15 affected eyes of 15 patients with macular lesions. In each subject, the central visual field was assessed by using four different types of Amsler grid testing and a tangent screen. Tests were conducted in a random order, and the sequence of tests was repeated once. The distance between the fixation point and the closet border of the plotted scotoma was assessed. For each patient, reproducibility in repeated examinations was evaluated by assessing changes in location of the computed center of the defects and by measuring changes in the position of the center of the scotoma. RESULTS: The tangent screen was more sensitive than Amsler grids in delineating the borders of the scotoma, and the results were more reproducible. Furthermore, by using a tangent screen, the fixation point was found adjacent to the scotoma. CONCLUSION: Poor sensitivity and intraindividual variations found with Amsler grid testing are at least partly a result of the perceptual completion phenomenon. This phenomenon proved to be a dynamic and fluctuating process, as the results of two successive Amsler grid tests were not comparable, even when the technique was identical and the time between tests was no more than two to 15 minutes.

Aged↗
PubMed1995

[Vestibular neuritis: a frequently unrecognized cause of diplopia].

The vestibular function plays an essential role in the stabilization of the image on the retina. In addition, when the head is tilted, it contributes to maintain horizontally the plane of the gaze. Vestibular changes can result in oscillopsia and/or diplopia. The latter is related to occurrence of a skew deviation. The authors emphasize the frequent occurrence of diplopia following disorders of the vestibular nerve, specially after vestibular neuritis. In clinical practice, the causal relationship between vestibular neuritis and diplopia is often unrecognized.

Adult↗
PubMed1995

[Automated static perimetry in the child: methodologic and practical problems].

PURPOSE: In a pediatric population, the use of computerized static perimetry is known as particularly difficult. The specific difficulties which may occur when testing young subjects are stability of fixation, ability to maintain concentration, resistance throughout the procedure, and reliability of the answers. It seems important to investigate and to develop appropriate strategies for the examination of children aged 8 years and younger according to their ability to undergo visual field evaluation using automated static perimetry. PATIENTS AND METHODS: Eighty normal children aged 5 to 8 years old were evaluated using an Octopus 2000R perimeter, with a one-level strategy. Adaptation of the procedure were included. RESULTS: The analysis of answers and false-positive catch-trials showed that children as young as five years old did remarkably well regarding both the duration of the examination and the reliability of answers. CONCLUSIONS: Automated static perimetry examination can provide reliable results in children as young as five years old once a familiarization procedure has been conducted and if the duration of examination does not exceed the child's capacity to remain task focused.

Child↗
PubMed1995

Angioscotomata and morphological features of related vessels in automated perimetry.

AIMS: To determine principles which regulate the occurrence of angioscotomata in automated static perimetry, variations in light sensitivity were correlated with the location and diameter of neighbouring retinal vessels. METHODS: Ten normal eyes were tested with the Octopus 2000R, using a 0.431 degree light stimulus. Sensitivity was quantified in points located around the blind spot, according to a regular, 0.5 degree constant, grid pattern. From 336 to 443 locations were tested in each eye. The resulting printouts were superimposed on corresponding fundus photographs. At each tested point, the following five additional variables were evaluated: the diameters of the closest and the second closest vessel (in 0.1 degree units); the distances of the apparent location of the tested point to the closest and the second closest vessel (in 0.25 degree units); and the distance between the two closest vessels (in 0.25 degree units). Altogether, 3869 locations were tested and 23,214 values were quantified. RESULTS: The following two conditions were found to be related to a reduction in sensitivity: (1) proximity (< 0.25 degree) to a large vessel (> or = 0.5 degree in diameter); (2) proximity (< 0.25 degree) to one of two adjacent (< 0.5 degree distant), moderately large vessels (0.3 degree to 0.4 degree in diameter). In condition 1, sensitivity was 51.3% and specificity was 92.2%; in condition 2, sensitivity was 16.2% and specificity was 98.3%; and with a combination of conditions 1 and 2, sensitivity was 67.6% and specificity was 90.5%. Increase by 0.1 degree of an adjacent vessel which was 0.4 degree in diameter markedly affected light sensitivity. CONCLUSION: Modifications in vessel diameter are observed in a number of circumstances, including adaptive vascular response to changes in ambient conditions and obstructive disorders of retinal vessels. These findings indicate that changes in vessel diameter over time can result in fluctuation of sensitivity. It is concluded that, in contrast with what is commonly stated, when ocular media are unaltered and the subject's collaboration is adequate, temporal variations in measured thresholds do not necessarily reflect functional changes in nervous tissues in the visual pathways.

Adult↗
PubMed1994

Skew deviation after vestibular neuritis.

We treated five patients with vestibular neuritis who had strabismus. Three of them spontaneously noted vertical diplopia. During the following weeks and months, strabismus progressively resolved, indicating the recently acquired nature of the oculomotor condition. In three of these individuals, a change in visual vertical and cyclo-torsion of the globes suggested that strabismus was a form of skew deviation that occurred as a part of an ocular tilt reaction resulting from the peripheral vestibular lesion. Strabismus appears to occur frequently in this common vestibular condition.

Adult↗
PubMed1994

[Occlusion of the ophthalmic artery in Crohn disease].

BACKGROUND: Nearly 10% of patients with Crohn's disease develop ocular complications. Most complications are inflammatory in nature, and involve both the anterior and the posterior segments of the eye. Episcleritis, uveitis and keratopathies are the most frequently described. Occlusions of retinal and optic nerve vessel are less common. We believe this to be an important observation as the ocular involvement was the patients primary complaint, thus allowing the correct diagnosis to be made. PATIENT: We report a case of a 44-year-old woman, who presented with an occlusion of the ophthalmic artery, before the diagnose of Crohn's disease was established.

Adult↗
PubMed1994

Anterior ischemic optic neuropathy in Graves' disease.

Optic neuropathy occurred in two patients suffering from Graves' disease with marked limitation of eye movement. Optic nerve changes were moderate. They consisted of parapapillary flame-shaped hemorrhages, swelling of the disc, and bundle defects in the visual field on the involved side. This clinical pattern suggested that the optic neuropathy was anterior and ischemic in nature. In one patient, symptoms of optic neuropathy were noted 3 days after starting stretching exercises with the ocular muscles, performed following a friend's advice in an attempt to prevent increase in restrictive myopathy. In patients with Graves' disease, it is conceivable that mild optic neuropathy occasionally occurs as a result of elevation in intraocular pressure, and stretching exercises of the ocular muscles might consequently favor such ischemic events. In the mechanisms of optic nerve involvement associated with Graves' disease, the role of ischemia should be considered in addition to the widely accepted role of optic nerve compression by enlarged extraocular muscles, at the level of the orbital apex.

Female↗
PubMed1993

[Clinical evaluation of otolithic function by the measurement of ocular cyclotorsion and skew deviation].

The ocular tilt reaction (OTR) consists in an association of an eye-head postural reaction, alteration of vertical perception, conjugated eye cyclotorsion, skew deviation and head tilt. We observed this condition following unilateral vestibular neurectomy and labyrinthectomy performed in patients suffering from severe Meniere's disease. All patients described postoperative vertical diplopia and vertical perception tilt. One illustrative case is reported in detail here. Changes in visual vertical were measured using a vertical frame with a pivoting pointer and the Maddox rod calibrated with a spirit level. The actual eye torsion was measured by a photography of eye-fundus. In the follow-up, it was found that vertical diplopia disappeared within a few days while conjugated eye cyclotorsion lasted weeks to months. Mechanisms involved in the OTR could be the consequence of a unilateral deafferentation of the utricular and saccular organs. We feel that the techniques of examination which we used with this patient might be a useful measurement for the clinical evaluation of unilateral otolithic dysfunction.

Adult↗
PubMed1992

Increasing short-term fluctuation by increasing the intensity of the fixation aid during perimetry.

An increase in short-term fluctuation is a clinically useful clue in the diagnosis of acquired disorders of the visual pathways. However, short-term fluctuation can also be increased in normal subjects by several factors. We found an increase in short-term fluctuation occurred in normal subjects when the visual field was tested using a bright fixation aid. Eight normal subjects underwent automated perimetry with the Octopus 2000R, in which the dimmest (12.5 candelas/m2) and brightest (435 cd/m2) available fixation aids were used. Mean short-term fluctuation values were 1.63 +/- 0.27 dB with the dimmest aid, and were 2.65 +/- 1.26 dB with the brightest aid. The difference was significant using the paired t-test (P = .037). Moreover, mean sensitivity was reduced from 35.67 +/- 2.26 dB to 33.66 +/- 1.71 dB when the brightest fixation aid was used (P = .004). In six of eight subjects, the relative changes in short-term fluctuation after an increase in brightness of the fixation aid were more pronounced than those in mean sensitivity. An increase in intensity of the fixation aid may cause visual changes in normal subjects that resemble those induced by disorders in the visual pathways. Whenever possible, minimal intensity of the fixation aid should be used to allow for an adequate interpretation of short-term fluctuation values.

Adult↗
PubMed1992

[Strabismus induced by peripheral vestibular lesions].

Little attention has been paid in the ophthalmological literature to strabismus resulting from lesions located in the peripheral vestibular system. However, this phenomenon is commonly encountered in clinical practice. As a rule, this kind of strabismus shows a prominent vertical component. It is generally combined with a change in perception of verticality, conjugate cyclotorsion of the eyes, and head tilt. This association is known as "ocular tilt reaction". It occurs in a number of clinical settings which are believed to be related with alteration in the otolithical and/or vertical semicircular canal pathways. Strabismus occurring as a feature of ocular tilt reaction might result from different mechanisms according to the location of the lesion, e.g. in the utricles, in the midbrain tegmentum, and in the dorso-lateral medulla oblongata. This phenomenon is illustrated here with the report of a patient suffering from Ménière disease, who underwent selective vestibular neurectomy. Methods of ophthalmological evaluation in such cases is described.

Aged↗
PubMed1992

Congenital nystagmus: rebound phenomenon following removal of contact lenses.

Symptoms resulting from congenital nystagmus can be significantly reduced by wearing corneal contact lenses. A 90 minute therapeutic trial with contact lenses was performed on a 20-year-old affected patient and produced a beneficial effect. Upon removal of the lenses however the patient showed a transient rebound phenomenon with oscillopsia lasting about 20 minutes. This phenomenon, although it might be expected in theory, has apparently not previously been observed either because it is rare or because in most patients it is not clinically apparent. The purpose of this report is not to discourage treating patients with congenital nystagmus by means of contact lenses, but rather to draw attention to the occasional occurrence of such a rebound phenomenon and to discuss its theoretical significance.

Adult↗
PubMed1992

Pain upon eye movement following digoxin absorption.

A patient who had received digoxin for 6 months experienced glare and ocular pain induced by eye movement. The symptoms lasted for 2 days and disappeared within hours after the treatment was discontinued. Four months later, digoxin was readministered. After 2 days, the symptoms reappeared but disappeared again within hours of stopping treatment. The origin of the pain is uncertain, although mechanisms related to optic nerve or ocular muscle involvement should be considered. Digoxin toxicity should be included in the differential diagnosis of pain evoked by ocular movements.

Adult↗
PubMed1991

[Multiple evanescent white dot syndrome].

MEWDS is a benign acquired disorder of the retinal pigment epithelium of unknown etiology which has been first described in 1984. Actually more than 50 cases have been reported worldwide but only 5 cases from Europe. We report 10 other cases of MEWDS, seen in the past 5 years. Their clinical presentation, perimetric and electroretinographic results, as well as their differential diagnosis will be reported.

Diagnosis, Differential↗