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At least 721 records · Page 40Linked to original sources
PubMed2003

Quality of vision after laser in situ keratomileusis: influence of dioptric correction and pupil size on visual function.

PURPOSE: To determine the influence of pupil size and the amount of ablation on visual performance and on the patient's perception of glare or halo after laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This study included a random cross-section of 50 eyes of 32 patients with "uniform" topography at least 6 months after LASIK and 51 eyes of 28 patients who had normal corneas. Each LASIK patient completed a survey rating adverse effects such as symptoms of night glare and halo. Pupil diameter and best spectacle-corrected visual acuity (BSCVA) were measured under photopic and scotopic conditions. Contrast sensitivity was measured with an MCT 8000 (Vistech Consultants, Inc.) under daytime and nighttime and with night glare conditions. A Technomed C-scan (Technomed Technology) was performed, and the potential corneal visual acuity (PCVA) was calculated after the settings for the pupil size were changed to the values measured under bright-light or dim-light conditions. RESULTS: No significant difference was found between the post-LASIK and normal cornea groups in photopic or scotopic BSCVA (P>.05). In cases of moderate myopia, the post-LASIK group had decreased PCVA and contrast sensitivity (P<.05). In cases of high myopia, the post-LASIK group had decreased contrast sensitivity at spatial frequencies of 1.5 cycles per degree (cpd) under daytime conditions and 3 cpd under nighttime conditions (P<.05). Glare or halo symptoms did not correlate with scotopic BSCVA, PCVA, or nighttime contrast sensitivity with or without glare (P>.05). Pupil size was not significantly correlated with glare or halo symptoms, BSCVA, or contrast sensitivity under scotopic or photopic conditions (P>.05). In moderate myopia, the amount of attempted correction of the spherical equivalent (SE) was correlated with halo symptoms (P<.05; adjusted r(2) = 0.17). In high myopia, the amount of attempted astigmatism correction was correlated with the development of glare symptoms (P<.05; adjusted r(2) = 0.16). CONCLUSIONS: There was a decrease in contrast sensitivity in post-LASIK eyes. The amount of attempted correction of the SE or astigmatism was correlated with the development of glare and halo symptoms. Pupil size was not significantly correlated with glare or halo symptoms, BSCVA, or contrast sensitivity in post-LASIK patients with "uniform" topography who had scotopic pupils not larger than 7.0 mm.

Adult↗
PubMed1993

[Possibility of detecting visual functional disturbance in rats by the open-field test].

In order to determine whether visual disturbance in small rodents is detectable by means of the open-field test, the ambulation scores of enucleated and intact rats in an open-field were measured. In a 30-min test of Slc:Wistar/ST rats, there were significant differences in ambulation scores between enucleated and intact rats in the first 10-min. In addition, the effects of observation times (09:00-11:00, 13:00-15:00 and 17:00-19:00 hr) and strains on the open-field test were studied using a 10-min test. Regardless of observation times, ambulation scores of enucleated rats of the Slc:Wistar/ST and F344/N Slc strains were significantly elevated as compared with those of intact rats from both strains. When tested during the 13:00-15:00 hr period, there were significant differences in the Slc:SD rats. These findings indicate that the changes in ambulation are due to visual disturbance. However, significant ambulatory changes in F344/N Slc rats were documented at the three different observation times. Based on these results, Slc:Wistar/ST rats appear to be suitable for detecting visual disturbance by the open-field test.

Animals↗
PubMed2004

Visual functional magnetic resonance imaging in patients with Sturge-Weber syndrome.

The purpose of this study is to report different patterns of visual cortex activation in patients with Sturge-Weber syndrome as compared with healthy control subjects. Utilizing a visual paradigm of flashing lights, three children with Sturge-Weber syndrome were studied with functional magnetic resonance imaging. The results are compared with those documented in eight normal sedated children, and six young adult awake volunteers, using the same paradigms. All adult volunteers manifested bilateral activation in primary visual cortex (Brodmann's 17 and 18 areas). Two of them also had activation in secondary visual cortex (Brodmann's 19 area). In the eight sedated normal children, seven manifested activation in primary visual areas. The last exhibited no activation. The patients with Sturge-Weber syndrome demonstrated in the affected occipital lobe increased activation in one patient (11 months old), no activation in the second (12 years of age), and abnormal distribution of the activation in the third (11 months old). This report demonstrates that the vascular malformation of Sturge-Weber syndrome does not necessarily prevent cortical activation in the expected occipital cortex and may be associated with different patterns of abnormal activation. Assessing cortical function with functional magnetic resonance imaging in patients with Sturge-Weber syndrome may be helpful in decisions of surgical management and counseling.

Adolescent↗
PubMed2000

A randomized trial of different ratios of linoleic to alpha-linolenic acid in the diet of term infants: effects on visual function and growth.

BACKGROUND: There are nutritional recommendations that the ratio of linoleic to alpha-linolenic acid (LA:ALA) in formula for term infants be between 5:1 and 15:1. These recommendations were made in the absence of data on functional or clinical outcomes. OBJECTIVE: We compared the fatty acid status, visual evoked potential (VEP) acuity, and growth of term infants fed formula containing an LA:ALA of 10:1 or 5:1 with those of a breast-fed reference cohort. DESIGN: Formula-fed infants were allocated randomly in a double-blind fashion to receive formula with an LA:ALA of either 10:1 (16.9:1.7; n = 36) or 5:1 (16.3:3.3; n = 37) from near birth to 34 wk of age. Increased ALA was attained by replacing soy oil with low-erucic acid cannola oil. A parallel group of breast-fed infants was also recruited. Infant growth and fatty acid status were assessed at 6, 16, and 34 wk of age. VEP acuity was assessed at 16 and 34 wk. RESULTS: Infants fed the 5:1 formula had greater docosahexaenoic acid (DHA) concentrations in plasma and erythrocyte phospholipids than did infants fed the 10:1 formula, but DHA concentrations of infants fed the 5:1 formula remained less than those in breast-fed infants. The VEP acuity of all formula-fed and breast-fed infants was not significantly different at 16 and 34 wk of age. At birth, infants fed the 5:1 formula were heavier, were longer, and had a greater head circumference than infants assigned to the 10:1 formula group; this differential was maintained throughout the trial. The rate of gain in weight, length, and head circumference was not significantly different between the 2 formula-fed groups, although breast-fed infants had lower weight and length gains than did formula-fed infants between 16 and 34 wk of age. CONCLUSION: Lowering the LA:ALA in formula from 10:1 to 5:1 by using low-erucic acid canola oil resulted in a modest increase in plasma DHA but had no effect on VEP acuity or growth rate.

Dietary Fats↗
PubMed1994

Visual function following enucleation or episcleral plaque radiotherapy for posterior uveal melanoma.

OBJECTIVE: To evaluate the posttreatment visual performance of patients with a primary posterior uveal melanoma treated by enucleation or plaque radiotherapy. DESIGN: Standardized interview using previously reported interview instrument. SETTING: Referral center. PATIENTS: One hundred two patients with malignant melanoma of choroid or ciliary body, 51 of whom had been treated by primary enucleation and 51 of whom had been treated by plaque radiotherapy. MAIN OUTCOME MEASURES: Vision-related changes in employment status, driving status, reading ability, and television-watching ability during available posttreatment follow-up. RESULTS: Forty-eight (94.1%) of the patients who had undergone enucleation and 46 (90.2%) of the patients who had undergone irradiation reported no vision-related change in any of four evaluated areas. CONCLUSIONS: The great majority of patients with posterior uveal melanoma retain satisfactory visual performance status for many years after initial treatment, regardless of whether that treatment was enucleation or plaque radiotherapy.

Activities of Daily Living↗
PubMed1981

Recovery of visual functions in patients with cerebral blindness. Effect of specific practice with saccadic localization.

Patients with homonymous visual field defects after damage to the geniculo-striate pathway were forced to make saccadic eye movements to light targets presented briefly in their perimetrically blind regions. This specific type of saccadic localization led to an increase in visual field size in the region subjected to this practice. Visual acuity and color identification also improved in the restored region, provided that the lesion was mainly limited to the striate cortex. The enlargement of the visual field strongly depended on a specific practice. The degree of recovery was related to the sharpness of the visual field border. In patients with a rather shallow gradient of light sensitivity in the area between the intact visual field and the scotoma, a fairly good recovery was obtained, whereas in patients with a steeper gradient the enlargement of the visual field was small. It is suggested that recovery takes place at the level of the striate cortex and is probably mediated by the retino-tectal pathway.

Adult↗
PubMed1989

Central visual function in patients with resolved central serous retinopathy. A long term follow-up study.

The visual acuity, central retinal sensitivity, macular thresholds, contrast sensitivity and temporal visual acuity were employed to assess the long term visual outcome in 23 patients with a history of central serous retinopathy (CSR). Twenty patients had unilateral CSR, and 3 had had bilateral disease. The unaffected eyes had significantly better visual acuities (P less than 0.014), better retinal sensitivities (P less than 0.006) and lower macular thresholds (P less than 0.008) when compared with affected eyes. The eyes with CSR whose visual acuities were mildly affected (6/9) showed lower sensitivity for the high spatial frequency (P less than 0.0072). There was no significant difference in the temporal visual acuity between eyes with CSR and the non-affected eyes.

Follow-Up Studies↗
PubMed2001

Brain activation in sedated children: auditory and visual functional MR imaging.

PURPOSE: To map developing areas of activation with functional magnetic resonance (MR) imaging in sedated children by using passive auditory and visual tasks. MATERIALS AND METHODS: Forty children between 2 months and 9 years old were examined and grouped according to age. Children were selected from patients referred to undergo brain MR imaging. Patients received pentobarbital (3.0-7.0 mg per kilogram of body weight) or chloral hydrate (50-75 mg/kg). The functional MR imaging study was performed at the end of the examination. Paradigms consisted of flashing lights at 8 Hz displayed on special goggles and a prerecorded mother's voice presented through headphones. Activation maps were obtained from a paired t test with a P value of.0005 (uncorrected). RESULTS: The visual stimulus produced statistically significant negative values in the rostral aspect of the primary visual area (28 [90%] of 31 patients). The auditory paradigm activated either temporal or frontal areas in 26 (68%) of 31 patients. There was more frontal activation in the older children. CONCLUSION: Visual and auditory cortices can be activated in children who have been sedated. Visual responses show negative values in the rostral visual cortex, independent of age. Auditory activation is seen in temporal and frontal lobes.

Auditory Perception↗
PubMed2000

Disorders of higher visual function and hemi-spatial neglect.

Lesions of the extrastriate cerebral cortex result in disorders of vision, which reveal two cortical processing streams extending ventrally and dorsally from the primary visual cortex. Current theories emphasize the visual perceptual and visuomotor specialization of the ventral and dorsal streams, respectively. Recent investigations of hemi-spatial neglect suggest that the inferior parietal region may lie at the junction of the visual and motor processing pathways.

Agnosia↗
PubMed1998

Retinal ganglion cell layer and visual function in a patient with optic disc drusen.

BACKGROUND: To correlate the retinal ganglion cell pattern to visual acuity and visual field data in a patient with bilateral optic disc drusen, a quantitative clinicopathological study was carried out. METHODS: Both retinae of a patient with optic drusen were whole-mounted. Retinal ganglion cell counts were made using a sampling scheme covering the whole retina and compared to the findings in 10 normal retinae. Relative ganglion cell reduction in the drusen retinae was correlated to clinical data. RESULTS: The total retinal ganglion cell count was reduced from 1244858+/-98736 in normal retinae to 305319 on the right and 527571 on the left eye with optic disc drusen. Large ganglion cells had a better chance of survival. Parafoveal ganglion cell loss was 57% for the right and 36% for the left eye, while visual acuity was 0.8 and 1.0 respectively. The mean light sensitivity loss increased from the centre (6.2 dB) to paracentral (9.9 dB), mid-peripheral (13.7 dB) and outer peripheral (15.0 dB) retina, while ganglion cell losses were smallest in outer peripheral retina (21.9%), followed by central (53.0%), mid-peripheral (70.9%) and paracentral retina (87.7%). CONCLUSION: These data validate Frisén's theory on central retinal resolution and provide the structural basis for the clinical rule that low visual acuity should not be attributed to disc drusen. Automated light sense perimetry gives an inadequate picture of retinal damage caused by optic disc drusen.

Adolescent↗
PubMed1991

Contribution of striate cortex and the superior colliculus to visual function in area MT, the superior temporal polysensory area and the inferior temporal cortex.

We studied the visual responses of single neurons in three extra-striate visual areas of the macaque following lesions of striate cortex, lesions of the tecto-pulvinar system or both. After striate lesions, there was (a) considerable specific activity remaining in area MT including direction selectivity, (b) only non-specific activity in the superior temporal polysensory area (STP), and (c) no visual responsiveness at all in inferior temporal cortex (IT). In animals with striate lesions, interruption of the tecto-pulvinar pathway eliminated the residual visual activity in MT and STP that survived the striate lesions. Interruption of the tecto-pulvinar pathway alone had little or no effect on visual evoked activity in any of the three areas. These results are related to the relative dependence of visual responsiveness in MT, STP and IT on striate cortex and the superior colliculus, to differences between the dorsal and ventral cortical processing streams, and to neural mechanisms underlying blind sight.

Animals↗