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At least 145 records · Page 8Linked to original sources
PubMed2006

Progression of visual field defects in leber hereditary optic neuropathy: experience of the LHON treatment trial.

PURPOSE: To describe the visual fields of patients with Leber hereditary optic neuropathy (LHON), a maternally inherited disorder characterized by bilateral, often sequential vision loss, before and during progressive visual deterioration. DESIGN: Prospective longitudinal follow-up of serial visual fields in patients enrolled onto an open-label, nonrandomized pilot study of topical brimonidine purite as prophylactic treatment after first eye involvement in LHON. METHODS: Nine molecularly confirmed primary mutation patients with LHON with monocular vision loss for less than six months and normal visual function in the other eye were followed prospectively for up to two years. Visual fields were performed on automated perimetry at baseline and on many follow-up visits. RESULTS: Despite normal visual acuity at baseline in all patients, seven patients had some minimal changes in the central visual field of the second eye. All patients had subsequent deterioration of visual acuity, mean deviation, and foveal sensitivity in their second eye. The earliest pattern of abnormality was typically a cecocentral defect enlarging to become a central defect, often with a superior or inferior predilection. The visual field defects in the two eyes of any given patient were remarkably similar. CONCLUSIONS: LHON may be a bilateral condition at onset more frequently than appreciated. Automated static perimetry of the "normal" eye may reveal subclinical findings that typically worsen rapidly over weeks to months to similar central scotomatous damage. Quantitative automated static perimetry is helpful in elucidating the natural history of LHON and in understanding the underlying pathology and pathophysiology of this disease.

Administration, Topical↗
PubMed2004

Indirect costs associated with accessing eye care services as a barrier to service use in Ethiopia.

BACKGROUND: The prevalence of blindness and visual impairment are high in Ethiopia and use of services is limited. Determining the barriers to use of eye care services is critical for planning strategies to prevent blindness. METHODS: A population-based survey of the magnitude and causes of blindness and visual impairment in adults 40 years and older in the Gurage Zone, central Ethiopia was conducted. Among those individuals who had binocular or monocular vision <6/18, an interview to assess use of eye care services and reasons for a failure to use such services was undertaken. RESULTS: Of 850 adults with visual impairment or blindness, 802 were interviewed. Cataract surgery accounted for the primary service currently needed by the blind, followed by trichiasis surgery; service needs were higher for women than for men. Use of services (27.8% of sample) was associated with being male, binocular vision loss, and blindness. The primary reason for a failure to use eye care services were indirect costs (overall, reported by 40% of respondents) associated with accessing the service. There were significant differences between men and women in the reasons for not using the services and between cataract and trichiasis cases but not when comparing binocular vs. monocular conditions, or patients with visual impairment vs. blindness. CONCLUSION: The majority of the causes of visual impairment and blindness are treatable (cataract) or preventable (trachomatous trichiasis). The main barrier for seeking service is related to the indirect medical costs of the service. This suggests that efforts are needed to create mechanisms that 'bridge' communities and eye care facilities. A holistic approach that deals both with the organization of services and the sociocultural factors in communities that affect use is needed. The organization of trichiasis surgery at peripheral health centres and screening programmes which identify and facilitate transport to hospital for cataract patients is one approach. The indirect burden of accessing eye care on the family may be lessened by encouraging patients to have surgery earlier (before they require assistance to reach the hospital), and by improving the efficiency of existing services. Promotion of services must be gender-sensitive, ensuring that specific characteristics of the sociocultural roles of women be considered in order to improve uptake among women. Training and placement of cataract surgeons in rural hospitals would also enhance provision of eye care for the rural population.

Adult↗
PubMed2004

Design of and normative data for a new computer based test of ocular torsion.

PURPOSE: To evaluate a new clinically practical and dynamic test for quantifying torsional binocular eye alignment changes which may occur in the change from monocular to binocular viewing conditions. METHODS: The test was developed using a computer with Lotus Freelance Software, binoculars with prisms and colored filters. The subject looks through binoculars at the computer screen two meters away. For monocular vision, six concentric blue circles, a blue horizontal line and a tilted red line were displayed on the screen. For binocular vision, white circles replaced blue circles. The subject was asked to orient the lines parallel to each other. The difference in tilt (degrees) between the subjective parallel and fixed horizontal position is the torsional alignment of the eye. The time to administer the test was approximately two minutes. RESULTS: In 70 Normal subjects, average age 16 years, the mean degree of cyclodeviation tilt in the right eye was 0.6 degrees for monocular viewing conditions and 0.7 degrees for binocular viewing conditions, with a standard deviation of approximately one degree. There was no "statistically significant" difference between monocular and binocular viewing. CONCLUSION: This computer based test is a simple, computerized, non-invasive test that has a potential for use in the diagnosis of cyclovertical strabismus. Currently, there is no commercially available test for this purpose.

Adolescent↗
PubMed1987

On the late invention of the stereoscope.

It was not until 1838, when Wheatstone published his account of the stereoscope, that stereoscopic depth perception entered into the body of binocular phenomena. It is argued that the stereoscope was not invented earlier because the phenomenon of stereopsis based on disparity had not been adequately described. This was the case despite the fact that there had been earlier descriptions of tasks that could be performed better with two eyes than with one; the perceptual deficits attendant upon the loss of one eye had been remarked upon; analyses of the projections to each eye were commonplace, and binocular disparities were accurately illustrated; moreover, binocular microscopes and telescopes had been made over a century earlier. Theories of binocular vision were generally confined to accounting for singleness of vision with two eyes, and the concepts employed to account for this were visible direction, corresponding retinal points, and union in the brain. The application of these concepts inhibited any consideration of disparities, other than for yielding diplopia. When perception of the third dimension was addressed by Berkeley at the beginning of the eighteenth century, it was in the context of monocular vision and binocular convergence. Thereafter visual direction became the province for binocular vision and it was analysed in terms of geometrical optics, whereas visual distance was examined in the context of learned associations between vision and touch. This artificial division was challenged initially with respect to visual direction and later with respect to stereopsis. An additional factor delaying the invention of the stereoscope was that experiments on binocular vision generally involved abnormal convergence on extended objects. Wheatstone's accidental observation of stereopsis was under artificial conditions in which disparity alone defined the binocular depth perceived. Once invented the stereoscope was enthusiastically embraced by students of vision. It is suggested that the ease with which retinal disparity could be manipulated in stereopairs has led to an exaggeration of its importance in space perception. "The appearances, which are by this simple instrument rendered so obvious, may be easily inferred from the established laws of perspective; for the same object in relief is, when viewed by a different eye, seen from the two points of sight at a distance from each other equal to the line joining the two eyes. Yet they seem to have escaped the attention of every philosopher and artist who has treated of the subjects of vision and perspective." (Wheatstone 1838, page 371).

Depth Perception↗
PubMed1998

Visual outcomes after surgery for unilateral cataract in children more than two years old: posterior chamber intraocular lens implantation versus contact lens correction of aphakia.

PURPOSE: We sought to determine whether posterior chamber intraocular lens implantation yields better visual acuity and binocular vision than does conventional contact lens correction of aphakia in similar groups of pediatric cataract patients. METHODS: We reviewed the medical records of children aged 2 to 16 years who had unilateral cataract surgery by a single pediatric ophthalmologist between 1986 and 1996. Before 1992 all patients underwent standard lensectomy with vitrectomy. Beginning in 1992 posterior chamber intraocular lens (IOL) implantation was offered as a choice to families and was performed on most patients. RESULTS: Monocular vision outcomes were not significantly different in 20 IOL and 31 lensectomy-vitrectomy patients, with 85% of the IOL group and 77% of the lensectomy-vitrectomy group showing better than 20/100 final acuity. Binocularity, however, was much better in the IOL group, with 90% demonstrating at least 400 seconds of arc stereopsis, as opposed to 39% in the lensectomy-vitrectomy group (p = 0.003). Subgroups of patients with traumatic or nontraumatic cataract origin, age at surgery less than 7 years, and preoperative visual acuity less than 20/100 compared very similarly. CONCLUSION: Posterior chamber IOL implantation appears to provide significantly better binocular function than conventional management of unilateral cataract in childhood but does not substantially improve visual acuity results.

Adolescent↗
PubMed1997

[Reference values in vision development of infants with clinical use of the Teller Acuity Cards].

BACKGROUND: Using Teller Acuity Cards (TAC) for clinical visual testing, the question arose how our measurements fitted in the different standard tables of the producer's hand-book. In addition, we wanted to investigate how reliable the measurements of newborn and infants were and what the examination success rate under clinical conditions was. METHODS: At the paediatric clinic of the University of Erlangen, we tested the binocular grating acuity of 98 infants up to the age of one year, using the complete set of Teller acuity cards. In addition, 41 of the children underwent a monocular vision test. RESULTS: 1. Theoretical: At first we calculated conversion data for our card set. Using this conversion scale from cy/cm in cy/deg and the corresponding vision equivalent we produced our own standards for the development of grating acuity up to the age of one year. 2. Clinical: In 3-5 min per clinical examination we could determine for 90.8% of the patients a vision equivalent. The reliability of the results was age dependent and was at its best at the age of 5-11 months. The reliability was also very dependent on the duration of the test and the number of test runs. This resulted in a limited card choice for each age group.

Age Factors↗
PubMed1976

[Facts for the muscle-reflex-hypothesis of squint. (The importance of asymmetry in the structure of the eyes for the pathogenesis of concomitant squint) (author's transl)].

Concomitant squint is regarded as result of a congenital dissymmetry in the structure of the eyes or of the oculomotor apparatus and of an insufficiency of the optomotor reflexes. Squint develops, when 1. the anomalies of the structure of the eye-muscles or of their insertions are so considerable that binocular vision cannot be maintained by fusional and convergence-reflexes; 2. the optomotor reflexes are too weak in order to compensate functionally even insignificant structural deviations of the extraocular muscles or 3. the optomotor reflex-mechanisms are disturbed to such a degree that binocular cooperation becomes impossible although the anatomical conditions are normal. Children with the symptoms of "potential squint" (ametropia, heterophoria, pseudo-ectopia of the macula) need special ophthalmological care. Using prisms early and operating in time one can stop the monocular vision becoming established.

Accommodation, Ocular↗
PubMed1998

Anteroposterior dynamic balance reactions to circular movement of the visual field without ocular pursuit.

It has been hypothesised that during natural vision, retinal image motion and eye motion information exert antagonistic effects on balance that cancel each other out. In a previous study, we found that pursuit movements of the eye unaccompanied by background slip on the retina induced strong, stereotyped anteroposterior sway in dynamic balance. In the present work, we investigated the influence of background retinal image slip alone on anteroposterior dynamic balance. We expected that retinal slip without ocular pursuit would induce large anteroposterior sway. Circular slip without rotation of the whole visual field image on the retina was obtained using a rotating prism. In this study, carried out on monocular vision, eye movement was prevented by fixating a stationary target seen through a small aperture in the prism. Anteroposterior dynamic balance conditions were elicited by a rocking platform. Strong, stereotyped anteroposterior sway accompanied by a visual illusion of target motion was observed. The induced sway was synchronised to the stimulus and led to a significant disturbance of balance. The similarity in magnitude of the effects of both retinal image motion studied here and eye motion information obtained previously, and their opposing phases, strongly support the initial hypothesis that the antagonistic effects of the two sources of information provided by normal ocular pursuit could interact in an additive algebraic mode.

Electrooculography↗
PubMed2005

Measurement of the visual contribution to postural steadiness from the COP movement: methodology and reliability.

We studied the reliability of different measures of the visual contribution to postural steadiness by recording the postural sway during standing with eyes open (EO) or eyes closed (EC). The COP trajectory was recorded in 21 subjects aged 42-61 standing on a firm or foam support. The improvement of postural steadiness due to vision was measured with a higher reliability (i.e. lower intra- and inter-subject variabilities) with the sway velocity V, than with the position RMS. Due to the increase of the variability of V and RMS with their own mean values, we quantified the visual contribution to posture by the stabilization ratio (SR), based on a logarithm transform of V or RMS. As compared to the Romberg quotient (EC/EO), SR improved the reliability of the measurement of the visual contribution to posture within individuals, across subjects, and even across different studies in the literature. Our method led to decrease the inter-subject coefficient of variation of this measurement to about 25%, using a foam support. It leads to a similar accuracy in binocular and monocular vision, and it also applies to the quantification of other non-visual sensory contributions to posture.

Adult↗
PubMed1999

Binocular function and patient satisfaction after monovision induced by myopic photorefractive keratectomy.

PURPOSE: To measure binocular function and patient satisfaction with monovision induced by photorefractive keratectomy (PRK) in myopic presbyopic patients. SETTING: Refractive Department, Cleveland Clinic, Cleveland, Ohio, USA. METHODS: This study comprised 21 myopic presbyopic patients with monovision induced by PRK. Sixteen emmetropic patients who had PRK served as a control group. Monovision was induced by undercorrecting the nondominant eye by 1.25 diopters for near vision and correcting the dominant eye with emmetropia for distance vision. Monocular and binocular uncorrected Snellen visual acuities at 20 feet and 13 inches, manifest refraction, ocular dominance, stereopsis at 20 feet and 13 inches, monocular and binocular contrast sensitivities, Worth-4-Dot test at 20 feet and 1/3 of a meter, and fusional convergence amplitudes were examined in each patient. RESULTS: In the monovision group at near and distance, 20 patients (95.3%) had binocular visual acuity of 20/25 or better. No patient in the monovision group used reading glasses postoperatively; 4 of 16 patients (25.0%) in the control group used such glasses. All patients maintained binocular fusion and stereo acuity ranging from 40 to 800 seconds of arc. Mean patient satisfaction was 86% (range 40% to 100%). In the control group, 12 patients (75.0%) had binocular distance visual acuity of 20/25 or better and 11 (68.8%) had binocular near visual acuity of 20/25 or better. CONCLUSION: Monovision PRK patients had better near vision than control PRK patients, with minimal compromise in stereo acuity and overall high patient satisfaction.

Adult↗
PubMed1998

Silicone oil tamponade to seal macular holes without position restrictions.

OBJECTIVE: The authors performed a study to determine the effectiveness and safety of silicone oil as a substitute for gas to fill the vitreous cavity to treat macular holes. DESIGN: Multicenter, nonrandomized, interventional trial. PARTICIPANTS: Thirty-seven consecutive patients chose vitrectomy with silicone tamponade instead of gas to treat 40 eyes with stage-2 to stage-4 idiopathic age-related macular holes. Stage-2 holes constituted 40% of the holes, and stage-3 and stage-4 holes made up 60%. INTERVENTION: All eyes were treated with vitrectomy, manual detachment of the posterior vitreous face (not done for stage-4 holes), autologous serum instillation, and silicone fill of the vitreous cavity. After insertion of the oil, the patients resumed normal activity with no restriction of head or eye position except to avoid faceup position. The oil was removed after approximately 6 weeks. MAIN OUTCOME MEASURES: The authors considered the seal of the macular hole and the preoperative and postoperative logarithm of the minimum angle of resolution (logMAR) visions the most significant measures for comparison to other studies. RESULTS: Eighty percent of all holes and 86% of holes not treated previously were sealed with a single silicone tamponade of the vitreous cavity. The logMAR value of visual acuity improved an average of 0.26 (2.6 lines) to 0.61 (20/81) for all eyes and 0.34 (3.4 lines) to 0.52 (20/66) when the macular hole sealed. Completeness of fill of the vitreous cavity with silicone affected seal of the macular hole. Three of eight eyes in which open holes developed after oil removal had less than 90% fill of the vitreous cavity by silicone. Sixty-nine percent of lenses increased opacity one grade or were removed after silicone tamponade. There were no significant adverse effects arising from silicone tamponade. CONCLUSIONS: Silicone oil tamponade of macular holes is effective and safe. Silicone may be optimal for the treatment of macular holes in persons who must travel, who cannot maintain facedown positioning, or who have monocular vision. The most important factor in the successful closure of the macular hole was the completeness of fill of the vitreous cavity with silicone oil.

Adult↗
PubMed1985

Horizontal optokinetic ocular nystagmus in the pigmented rat.

Horizontal optokinetic nystagmus was elicited in rats by rotation of a pattern of bright dots projected onto a cylinder surrounding the animal. Eye position was measured with the electromagnetic search coil technique. Optokinetic stimuli consisted either of velocity steps of pattern rotation or sinusoidal oscillations. Closed-loop gain (slow phase eye velocity/pattern velocity) of steady-stage step responses in binocular vision ranged between 0.8 and 1.0 for pattern velocities up to 20-40 degrees/s and decreased thereafter. Open-loop gain (steady-state slow phase velocity/retinal slip velocity) was dependent on retinal slip velocity and decreased linearly in double logarithmic plot from about 30 (at 0.5 degree/s) to about 9 (at 5 degrees/s). For retinal slip velocities larger than 5 degrees/s open-loop gain decayed faster and reached about 1 at 30 degrees/s. Step response profiles showed a gradual increase in slow phase eye velocity reaching steady-state after a time period roughly proportional to stimulus velocity. Initial slow phase velocity measured within 500 ms after stimulus onset reached between 2 and 4 degrees/s and was largely independent of stimulus amplitudes above 10 degrees/s. Occasionally rats showed fast rises in slow phase eye velocity at the onset of the step response profiles. Primary and secondary optokinetic afternystagmus were present. Duration of primary afternystagmus was largely independent of stimulus amplitude and lasted 8.0 +/- 4 s. Closed-loop gain of steady-state step responses in monocular vision was, for temporonasal stimuli, similar to that measured in binocular condition while for nasotemporal stimulation gain was much smaller even at low stimulus velocities. Sinusoidal modulation of slow phase velocity was linearly dependent on stimulus velocity; the linear range decreased as frequency of stimulation increased. Slow phase velocity gain was relatively constant (ca 0.8) between 0.05 and 0.3 Hz and showed only a small tendency to decrease at larger stimulus frequencies. Phase-lag increased strongly with stimulus frequency and could be fitted by assuming a response time delay of 100 ms. The results show that the rat's optokinetic system is qualitatively similar to that found in another lateral-eyed species, namely the rabbit. At a quantitative level, however, both fast and slow optokinetic response dynamics appear to be better developed in the rat than in the rabbit.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

Associations of presbyopia with vision-targeted health-related quality of life.

OBJECTIVE: To evaluate the associations of presbyopia and its correction, particularly monovision optical correction, with vision-targeted health-related quality of life. METHODS: The National Eye Institute Refractive Error Quality of Life (NEI-RQL) Instrument was prospectively self-administered by subjects from 6 medical centers in the following age and correction categories: subjects with emmetropia younger than 45 years (n = 75), subjects with emmetropia aged 45 years or older (n = 38), and subjects with ametropia aged 45 years or older without monovision (n = 486) or corrected with monovision (n = 38). Differences in the 13 NEI-RQL Instrument subscale scores among subjects in the 4 groups were examined. The age of 45 years or older was used as a surrogate for presbyopia. RESULTS: A comparison of older (age > or =45 years) vs younger (age <45 years) persons with emmetropia suggests that presbyopia was associated with reduced scores in 7 of 13 subscales (P<.05). In those aged 45 years or older, correction of presbyopia with monovision was associated with statistically significantly better scores on 3 subscales (expectations, dependence on correction, and appearance) compared with single-vision correction. One subscale (dependence on correction) showed worsening scores with increasing age without adjustment for need or type of correction. Older persons with monovision correction had significantly worse scores than younger subjects with emmetropia on all subscales except suboptimal correction and appearance. CONCLUSIONS: Presbyopia is associated with worse vision-targeted health-related quality of life compared with younger subjects with emmetropia. Monovision correction of presbyopia is related to some improvements in health-related quality of life, but it is still worse than that for younger subjects with emmetropia in several areas.

Adult↗
PubMed1983

Microscopic sinus surgery, transnasal ethmoidectomy and sphenoidectomy.

Intranasal ethmoid surgery has traditionally been a "blind procedure" using monocular vision, the delicate control of instruments being less than optimal. The addition of the operating microscope with a special self-retraining retractor speculum is presented in a series of 87 patients over 7 years, 49 of these having had transethmo-sphenoidectomy. Evaluation, anatomy, technique and results are discussed. Whereas the rate of serious complications is reported at 3% in large series, there were no complications in this series. The results of 181 microscopic antrostomies is also discussed. This technique offers considerable added safety to the patient, more self-confidence to the surgeon with binocular vision and much better control of instruments, and allows a more adequate procedure because of less fear of dreaded complications.

Adult↗
PubMed1984

Muscular activity and perimetric thresholds.

Static and kinetic peripheral luminance thresholds were measured by means of a Goldmann perimeter along oblique meridians in monocular vision. In a main group of 33 young and healthy subjects these measurements and visual reaction time assessments were made successively at rest, when cycling without load, when cycling with load using aerobic energy supply, when cycling with load using anaerobic energy supply and twice again at rest. Another group of subjects did not pedal and served as controls. The results show that peripheral visual sensitivity increases faintly but significantly during muscular exercise. When assessed by static perimetry the sensitivity increase is grossly proportional with load and is thus greatest in anaerobic condition, while kinetic sensitivity differs by a sensitivity decrease when passing from aerobic to anaerobic exercise. The reported modifications in perimetric sensitivity during dynamic muscular exercise seem related to changes in alertness.

Adolescent↗
PubMed1997

Adaptation to monocular torsion after macular translocation.

PURPOSE: To document the functional outcome of two patients following successful macular translocation for the treatment of severe subretinal hemorrhage in age-related maculopathy. METHODS: The retina was surgically rotated around the optic nerve with translocation of the fovea either upward or downward to an area of healthy retinal pigment epithelium. In the postoperative period, visual function was carefully studied with emphasis on adaptation to torsion. RESULTS: Visual acuity in one patient improved from 20/200 to 20/80 and the other patient remained at 20/200. Both patients developed horizontal and vertical strabismus with torsion of up to 55 degrees. After a prolonged period of occlusion of the unoperated eye, both patients were subjectively able to adapt to monocular torsion. However, adaptation under binocular conditions did not occur. CONCLUSION: Macular translocation was successful in improving visual acuity in one patient, with no improvement in the second. Both patients had significant ocular torsion and strabismus, but under monocular conditions they were successful in perceptually adapting to the change in the visual environment. Fear of cyclotorsion should not be a deterrent to considering macular translocation as a possible treatment option for severe subretinal macular hemorrhage if the patient is willing to accept monocular vision.

Adaptation, Ocular↗
PubMed1996

Lorazepam impairs perceptual integration of visual forms: a central effect.

Previous studies have shown a lorazepam effect on visual perception. We tested whether this impairment resulted from a peripheral effect induced by benzodiazepines. A first experiment showed that a single dose of lorazepam induces an oculomotor imbalance without impairing visual acuity or accommodation. In a second experiment, we tested whether the impairment induced by lorazepam on visual perception still occurred in monocular vision. Subjects matched incomplete forms controlled on the spacing and alignment of their local contour elements. A reference object was first displayed and followed by two laterally displayed objects, a target and a distractor. The distractor was the mirror-reversed version of the target. Performance was impaired in the lorazepam group when the reference was an incomplete form with a spacing of 10.8' or 22.2' of arc. These results were not correlated with sedation. They confirm that lorazepam has a central deleterious effect on visual perception. A post-hoc analysis also suggested that lorazepam-treated subjects used asymmetry in the stimuli as a compensatory strategy. This result is discussed in relation to previous hypotheses about the physiological mechanisms that determine the effects of lorazepam on visual perception.

Accommodation, Ocular↗