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At least 1,027 records · Page 57Linked to original sources
PubMed2003

Relationship of optic disk topography and visual function in patients with large cup-to-disk ratios.

PURPOSE: To determine if topographic differences exist between large cup-to-disk ratio (C/D) eyes with standard achromatic automated perimetry (SAP) abnormalities and those with only short-wavelength automated perimetry (SWAP) abnormalities. DESIGN: Cross-sectional study. METHODS: The setting was a referral university-based clinical practice. We selected one eye of 72 patients with a vertical C/D of at least 0.8 by ophthalmoscopy. Patients performed SWAP, SAP, and confocal scanning laser ophthalmoscopy. We compared optic disk topography in eyes with and without visual field abnormalities and controlled for the influence of disk area. RESULTS: Disk area was a confounder of many topographic measures. After controlling for disk area, eyes with abnormal SAP had differences in rim volume, cup shape, rim area, retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area when compared with eyes with normal SAP (P <.05). Rim volume and rim area were different in the SWAP comparison (P <.05). CONCLUSIONS: Investigators should control for disk area when evaluating topographic measures by confocal scanning laser ophthalmoscopy. In eyes with a large C/D, optic disk topography is more glaucomatous in eyes with SAP abnormalities than in those with only SWAP abnormalities. Eyes with large C/D and only SWAP abnormalities may have fewer glaucomatous optic disk changes than such eyes with SAP abnormalities. This indicates that SWAP is likely to correspond to abnormalities in optic disk topography at an earlier stage of glaucomatous optic neuropathy than SAP. Therefore, clinicians should consider SWAP testing in glaucoma suspects to detect glaucomatous visual field loss at an earlier stage of structural loss.

Adult↗
PubMed2003

Dose-based duration adjustments for the effects of inhaled trichloroethylene on rat visual function.

Risk assessments often must consider exposures that vary over time or for which the exposure duration of concern differs from the available data, and a variety of extrapolation procedures have been devised accordingly. The present experiments explore the relationship(s) between exposure concentration (C) and time (t) to investigate procedures for assessing the risks of short-term solvent exposures. The first hypothesis tested was that the product of C x t would produce a constant health effect (Haber's rule). The second hypothesis tested was that exposure conditions produce effects in proportion to the tissue concentrations created. Awake, adult, male Long-Evans (LE) rats were exposed to trichloroethylene (TCE) vapor in a head-only exposure chamber while pattern onset/offset visual evoked potentials (VEPs) were recorded. Exposure conditions were designed to provide C x t products of 0 ppm/h (0 ppm for 4 h) or 4000 ppm/h created through four exposure scenarios: 1000 ppm for 4 h; 2000 ppm for 2 h; 3000 ppm for 1.3 h; or 4000 ppm for 1h (n = 9-10/concentration). The amplitude of the VEP frequency double component (F2) was decreased significantly by exposure; this decrease was related to C but not to t or to the C x t product, indicating that Haber's rule did not hold. The mean amplitude (+/- SEM in muV) of the F2 component in the control and treatment groups measured 4.4 +/- 0.5 (0 ppm/4 h), 3.1 +/- 0.5 (1000 ppm/4 h), 3.1 +/- 0.4 (2000 ppm/2 h), 2.3 +/- 0.3 (3000 ppm/1.3 h), and 1.9 +/- 0.4 (4000 ppm/1 h). A physiologically based pharmacokinetic (PBPK) model was used to estimate the concentrations of TCE in the brain achieved during each exposure condition. The F2 amplitude of the VEP decreased monotonically as a function of the estimated peak brain concentration but was not related to the area under the curve (AUC) of the brain TCE concentration. In comparison to estimates from the PBPK model, extrapolations based on Haber's rule yielded approximately a 6-fold error in estimated exposure duration when extrapolating across only a 4-fold change in exposure concentration. These results indicate that the use of a linear form of Haber's rule will not predict accurately the risks of acute exposure to TCE, nor will an estimate of AUC of brain TCE. However, an estimate of the brain TCE concentration at the time of VEP testing predicted the effects of TCE across exposure concentrations and durations.

Administration, Inhalation↗
PubMed2003

[Visual function in high myopia corrected with anterior chamber phakic lens (PK PIOL). Initial results].

20 eyes (12 women, 8 men) undergoing implantation of anterior chamber phakic IOL (PIOL) for correction of the refractive error were examined before and 1 and 6 months after surgery. Median of preoperative spherical equivalent of refraction was -9.75 D (range -19.00 to -6.00 D). Contrast sensitivity (CS) was tested on a computerized system of the Contrast sensitivity 8010 type in 6 spatial frequencies (range 0.74 to 29.55 c/deg) and using the Ginsburg's charts also in 6 spatial frequencies (range 1.15 to 27.25 c/deg), the best corrected visual acuity (BCVA) was measured on the normalized charts with Landolt rings, influence of glare of 342 cd/m2 was examined using Brightness Acuity Tester. At 6 months postoperatively, median of spherical equivalent of refraction was 0.00 (-1.00 to 0.00). BCVA increased from 0.79 (range 0.50 to 0.97) preoperatively onto 0.96 (range 0.83 to 1.00). Median of CS increased in all spatial frequencies tested using both methods, significantly in the middle and high frequencies and CS almost, reached lower border of CS normal range. Glare had only nonsignificant influence on both BCVA and CS. Quality of vision postoperatively improved significantly.

Adult↗
PubMed1989

Probing visual function with psychophysics and photochemistry.

New methods using computer based measurements and image analysis techniques can improve and expand our ability to investigate non-invasively the function of the retina in patients. These can provide insight into the underlying mechanism of an abnormality and further our understanding of disease processes.

Dark Adaptation↗
PubMed2003

Evaluation of visual functions in patients on ethambutol therapy for tuberculosis: a prospective study.

UNLABELLED: To study the incidence of clinical and subclinical optic nerve toxicity with ethambutol therapy in patients with tuberculosis and to evaluate the reversibility of its side effects after cessation of therapy. This prospective randomized controlled study included 60 newly diagnosed adult cases of tuberculosis, who were randomly assigned into two groups. The study group included 30 patients (60eyes) who received ethambutol as a part of their anti-tubercular treatment and the control group included 30 patients (60eyes) who did not receive ethambutol. The patients were examined on monthly basis. The visual parameters studied were best corrected visual acuity, pupillary reactions, optic disc changes, color vision, contrast sensitivity, pupil cycle time, visual field charting and visual evoked potential. Ethambutol was stopped in those patients in whom toxicity was detected and they were followed more frequently. Only one patient (3.3%) showed decrease in visual acuity, three patients (10%) developed visual field defects, two patients (6.7%) showed deterioration of contrast sensitivity, the pupil cycle time was prolonged in one eye and two patients (6.7%) showed abnormal visual evoked potential. During the therapy, all patients in the study group had normal pupillary reactions, fundus picture and color vision. CONCLUSIONS: Ethambutol induced ocular toxicity was seen in three patients (10%) in our study. The maximum visual recovery occurred in first six to eight weeks after stopping ethambutol. The visual recovery was complete in only one patient, but it was partial in two patients i.e. visual fields, contrast sensitivity and visual evoked potential remained abnormal.

Adult↗
PubMedDate not supplied

[Visual functional disorders in benign intracranial hypertension].

Seventy-two patients (69 women and 3 men) with benign intracranial hypertension were examined. Besides general clinical signs, such as headache in 71, giddiness in 29, vomiting in 19, poor health in general in 18, painful movements of the eyeballs in 11, unsteady walking in 10, ringing in the ears in 9, noise in the head in 3, all the patients developed changes in the organ of vision. Congestive optic disks were detected in all the cases. Obnubilations were detected in 34 (47.2%) patients, diplopia in 5 (6.9%). Vision acuity was reduced in 33 (45.8%) patients, visual field was limited in 23 (31.9%). Forty-three patients completely recovered, negligible residual symptoms of benign intracranial hypertension persisted in 16, and all symptoms of the condition were virtually unchanged in 13 patients. Vision acuity remained reduced in 10 (13.9%) patients, and one female patient developed amaurosis of both eyes.

Adolescent↗
PubMed2001

[Comparison of visual function in myopia over -6.0 dpt after photorefractive keratectomy and laser in situ keratomileusis].

1. 41 myopes undergoing PRK and 31 patients undergoing LASIK for correction of spherical refractive error were examined before and 1, 3, 6 a 12 months after surgery on Schwind Multiscan with ablation zone between 5 and 7 mm. Mean preoperative spherical equivalent of refraction was -8.0 +/- 1.7 D in PRK group and -9.2 +/- 2.1 D in LASIK one. 2. Contrast sensitivity (CS) was tested on a computerized system of the Contrast sensitivity 8010 type in 6 spatial frequencies (0.74; 1.97; 3.69; 7.39; 14.77; 29.55 c/deg) and the best corrected visual acuity (BCVA) was measured on the normalized charts with Landolt rings. 3. At 12 months postoperatively, mean spherical equivalent of refraction was -0.6 +/- 1.0 D (PRK) and -1.0 +/- 0.8 D (LASIK). A refractive error within +/- 0.5 D had 31.5% (PRK) and 57.5% (LASIK) patients. Increasing of BCVA was measured in 51.5% (PRK) and 41.9% (LASIK) patients about 1 optotype to 2.5 lines. Mean CS in 6 frequencies reached 99.4; 102; 105; 109; 115 and 140% of preoperative values in PRK group and only 96; 95.8; 96.3; 95.8; 97.8 and 94.6% in LASIK one. 4. At 12 months after surgery, mean spherical equivalent, CS was better and number of patients with increased BCVA was significantly higher after PRK, than those attained with LASIK. On the other hand, a number of patients with a refractive error within +/- 0.5 D was higher and percentage of reoperations was lower in LASIK group.

Adolescent↗
PubMed2001

Visual function in patients with cone-rod dystrophy (CRD) associated with mutations in the ABCA4(ABCR) gene.

Mutations in the ABCA4(ABCR) gene cause autosomal recessive Stargardt disease (STGD). ABCR mutations were identified in patients with cone-rod dystrophy (CRD) and retinitis pigmentosa (RP) by direct sequencing of all 50 exons in 40 patients. Of 10 patients with RP, one contained two ABCR mutations suggesting a compound heterozygote. This patient had a characteristic fundus appearance with attenuated vessels, pale disks and bone-spicule pigmentation. Rod electroretinograms (ERGs) were non-detectable, cone ERGs were greatly reduced in amplitude and delayed in implicit time, and visual fields were constricted to 10 degrees diameter. Eleven of 30 (37%) patients with CRD had mutations in ABCR. In general, these patients showed reduced but detectable rod ERG responses, reduced and delayed cone responses, and poor visual acuity. Rod photoresponses to high intensity flashes were of reduced maximum amplitude but showed normal values for the gain of phototransduction. Most CRD patients with mutations in ABCR showed delayed recovery of sensitivity (dark adaptation) following exposure to bright light. Pupils were also significantly smaller in these patients compared to controls at 30 min following light exposure, consistent with a persistent 'equivalent light' background due to the accumulation of a tentatively identified 'noisy' photoproduct.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

[The effect of noninvasive electrostimulation of the optic nerve and retina on visual functions in patients with primary open-angle glaucoma].

Electrostimulation courses with OEC-2 Ophthalmologic Electrostimulator were administered to 30 patients (36 eyes) with primary open-angle glaucoma and normal intraocular pressure. An active electrode was placed on the upper lid, an indifferent one on the forearm. Electric pulses (150-900 mcA) were grouped in several sessions, 30 sec each, divided by 30-45 sec intervals. Total duration of a procedure was 16 min, the course consisting of 10 procedures. Control group included 24 eyes of the same patients. The patients were examined before, immediately, and 4-5 months after the treatment. Noticeable changes in vision acuity and visual field were detected. Visual field was examined using Humphrey Field Analyzer and 120-point threshold related test. The treatment resulted in reduction of visual field deficit by 10% or more in 28 (78%) of 36 eyes, in its increase in 2 eyes, and in no changes in 2 cases. Visual field deficit decreased by 25% on an average as against the initial value. Four to five months after the treatment the changes in this parameter were negligible. Vision acuity increased after the treatment in 31 of 36 eyes by 0.17 diopters on an average; 4 to 5 months later no changes occurred. In control eyes no changes were detected either in vision acuity or visual field during and after the treatment.

Adult↗
PubMed2006

Human embryonic stem cell-derived cells rescue visual function in dystrophic RCS rats.

Embryonic stem cells promise to provide a well-characterized and reproducible source of replacement tissue for human clinical studies. An early potential application of this technology is the use of retinal pigment epithelium (RPE) for the treatment of retinal degenerative diseases such as macular degeneration. Here we show the reproducible generation of RPE (67 passageable cultures established from 18 different hES cell lines); batches of RPE derived from NIH-approved hES cells (H9) were tested and shown capable of extensive photoreceptor rescue in an animal model of retinal disease, the Royal College of Surgeons (RCS) rat, in which photoreceptor loss is caused by a defect in the adjacent retinal pigment epithelium. Improvement in visual performance was 100% over untreated controls (spatial acuity was approximately 70% that of normal nondystrophic rats) without evidence of untoward pathology. The use of somatic cell nuclear transfer (SCNT) and/or the creation of banks of reduced complexity human leucocyte antigen (HLA) hES-RPE lines could minimize or eliminate the need for immunosuppressive drugs and/or immunomodulatory protocols.

Animals↗
PubMed1989

Abnormal development of visual function following intrauterine growth retardation.

Vernier acuity was measured at 40 weeks post term in 18 infants born with symmetric intrauterine growth retardation (IUGR) and 32 normal (N) infants. Grating acuity was also measured in 12 IUGR and 26 N infants. The mean vernier detection threshold (V.min) was 0.4 octaves higher in the IUGR than in the N infants (P less than 0.04). The mean grating detection threshold (S.min) was 0.2 octaves lower in the IUGR infants (NS). The mean ratio of S.min to V.min was significantly lower in the IUGR infants (1.5 IUGR, 2.7 N, P less than 0.05). V.min was significantly negatively correlated with the head circumference of the IUGR infants at 40 weeks post term. Vernier acuity depends on visual processing at a cortical level. The normal grating acuity in the IUGR infants implies that cortical, rather than optical or retinal factors, underlie the reduced vernier acuity (high V.min). We suggest that the cortical representation of visual space is affected by IUGR.

Female↗
PubMed1975

Long-term effect of phototherapy on visual function.

Computer-averaged electroretinogram records were used to examine scotopic retinal functioning of a group of 4-year-old children who were treated for neonatal hyperbilirubinemia by exposure to at least 42 consecutive hours of continuous phototherapy. Dark adaptation functions of the children were similar to those previously found for control subjects, suggesting that no permanent damage to rod function had been incurred during exposure. Statistical analysis showed no significant differences in the final electroretinographic amplitudes of light-treated and control subjects. Ophthalmologic and neurologic examinations were also negative.

Birth Weight↗
PubMed1988

The effects of physostigmine sulphate eyedrops on human visual function.

Instillation of 0.25% physostigmine sulphate eyedrops in twelve subjects caused a sustained miosis, a transient reduction in near-point and a transient increase in the amplitude of accommodation. The latter had a peak at 30 min and had recovered by 90 min, though its amplitude varied widely between subjects. Contrast sensitivity to stationary grating patterns of 3-30 cycles/deg and phase-reversed grating patterns of 0.5-3 cycles/deg was reduced transiently with a time course similar to that of the increase in accommodation. The peak reduction in contrast sensitivity was correlated significantly with the peak amplitude of accommodation. Contrast sensitivity to laser interference fringes, observed in Maxwellian view where the effects of defocus are bypassed, was also reduced, indicating that physostigmine also had a direct deleterious action on the visual system.

Accommodation, Ocular↗
PubMed2003

Corneal thickness measurements and visual function abnormalities in ocular hypertensive patients.

PURPOSE: It has been suggested that a considerable subset of patients currently classified as having ocular hypertension may have thicker than average corneas that result in an overestimation of the true intraocular pressure (IOP). As a consequence, ocular hypertension patients with greater corneal thickness may be at a lower risk for functional damage, such as that detected by short-wavelength automated perimetry (SWAP). The purpose of this study was to evaluate the frequency of SWAP deficits in ocular hypertension patients and to correlate these findings with corneal thickness measurements in the same patients. DESIGN: Cross-sectional observational study. METHODS: Sixty-eight ocular hypertension patients with normal optic disks and 63 normal subjects were included in the study. All participants underwent standard automated perimetry (SAP), SWAP, and central corneal thickness measurements using ultrasound pachymeter. Central corneal thickness measurements in ocular hypertension patients with abnormal visual field test results were compared with central corneal thickness measurements in ocular hypertension patients with normal visual field results. In addition, central corneal thickness measurements in ocular hypertension patients were compared with central corneal thickness measurements in normal subjects. RESULTS: Sixteen of 68 patients with ocular hypertension (24%) demonstrated SWAP abnormalities, whereas four of 68 (6%) showed a deficit on SAP. The mean central corneal thickness in ocular hypertension patients with abnormal SWAP results was significantly lower than the mean central corneal thickness in ocular hypertension patients with normal SWAP results (545 +/- 25 microm vs 572 +/- 35 microm; P =.006). The mean central corneal thickness in the normal group was 557 +/- 33 microm. The mean central corneal thickness in ocular hypertension patients with normal SWAP results was significantly higher than in normal subjects (P =.02). There was no significant difference between mean central corneal thickness in normal subjects and in ocular hypertension patients with abnormal SWAP results (P =.19). CONCLUSIONS: The patients classified as having ocular hypertension but with visual field loss detected by SWAP had significantly lower central corneal thickness measurements than the ocular hypertension patients with normal visual field results. These results suggest that central corneal thickness should be taken into account when assessing risk for the development of glaucomatous damage among ocular hypertension patients.

Aged↗
PubMed2003

Impact of a modified optic design on visual function: clinical comparative study.

PURPOSE: To determine whether implantation of an intraocular lens (IOL) with a modified anterior surface designed to compensate for the positive spherical aberration of the cornea in eyes of cataract patients results in improved pseudophakic quality of vision. SETTING: Department of Ophthalmology, Bundesknappschaft's Hospital, Sulzbach, Germany. METHODS: In an intraindividual randomized study of 45 patients with bilateral cataract, an IOL with a modified anterior surface (Tecnis Z9000, Pharmacia) was compared with a biconvex lens with spherical surfaces (SI-40, Allergan). All patients had bilateral cataract surgery; in 1 eye the Z9000 IOL was implanted and in the other, the SI-40 IOL. After 1 and 3 months, the following investigations were performed: assessment of the anterior and posterior segments including IOL decentration and tilt, pupil size, high- and low-contrast visual acuities, photopic and mesopic contrast sensitivities, and wavefront aberration of the cornea and eye. RESULTS: Thirty-seven patients were examined at all follow-up visits. Although the eyes with the Z9000 IOL had significantly better best corrected visual acuity after 3 months, the improved quality of vision was more apparent when assessing low-contrast visual acuity and contrast sensitivity. Wavefront measurements revealed no significant spherical aberration in eyes with a Z9000 IOL but significantly positive spherical aberration in eyes with an SI-40 IOL. CONCLUSIONS: The clinical results confirm the theoretical preclinical calculations that the spherical aberration of the eye after cataract surgery can be eliminated by modifying the anterior surface of the IOL. The Tecnis Z9000 lens compensates for the positive spherical aberration in older eyes. This leads to a significant improvement, particularly in contrast sensitivity and mesopic visual quality.

Aged↗
PubMed2005

[Evaluation of visual function and changed quality of life among patients after excimer refractive surgery].

An anonymous wide-ranging questionnaire was forwarded to 60 patients (40 women and 20 men) who had a laser refractive surgery for myopia. The questionnaire was focused on 1. reasons for seeking a refractive surgery, 2. subjective complaints shortly after a surgery, 3. postoperative status: functionality, 4. satisfaction. The satisfaction with final outcome has reached 93% and that closely correlates to results of uncorrected VA (UCVA). However, some patients (17%) reported reduced vision under dim illumination and at night and also difficulty with nighttime driving.

Adolescent↗
PubMed2002

Functional visualization of the excretory system of adult Schistosoma mansoni by the fluorescent marker resorufin.

Excretion of metabolic wastes as well as xenobiotics is a major concern of all living organisms, and the Platyhelminthes including Schistosoma mansoni possess the protonephridial excretory system for their survival. Except for some ultra-structural and biochemical information, little is known about the protonephridium of platyhelminths due to a lack of established techniques for exploring the excretory activity. This study describes a new technique to assess the excretory activity of S. mansoni by use of the fluorescent marker resorufin, which is a potential substrate of the drug efflux pump, P-glycoprotein. After simple diffusion into the schistosome body, fluorescent resorufin was concentrated in the excretory tubules by an energy-dependent mechanism and excreted via the nephridiopore. The present technique of labelling functionally the excretory system was applicable to adult worms, but not schistosomula or cercariae. A variety of modulators known to interfere with mammalian P-glycoprotein function perturbed resorufin excretion from male adult schistosomes, including cyclosporin A, Ro11-2933, verapamil, or nifedipine. This technique of labelling the excretory system with fluorescent resorufin has enabled us to study aspects of the physiological function, hitherto unknown, of the protonephridial system of S. mansoni.

ATP Binding Cassette Transporter, Subfamily B↗