In view of previous evidence that area 17 and 18 cells in cats represent the first level contour abstraction, we decided to study the specific response pattern of these cells to shapes enriched with contours, such as animated objects (AO). AO (cat's body whole contours) and 4 levels of AO degraded patterns were presented monocularly and repeatedly to the same eye, within the cells' RF. The intact AO elicited stronger responses than degraded contours while the responses to various degradedAO were similar. We conclude that under monocular presentation of AO cells react mainly as "edge detectors": the best stimulus is closed, compared with open, contour.
PURPOSE:To report the use of preserved pericardium tissue in the treatment of scleral melt associated with uveal prolapse secondary to Wegener's granulomatosis. Wegener's granulomatosis may initially present with ophthalmic findings including scleral melting with uveal prolapse. In order to preserve the globe and treat this potentially fatal disease, prompt diagnosis, surgical correction of uveal prolapse, and subsequent immunosuppressive therapy are imperative. If advanced scleral melt associated with uveal prolapse is present, pericardium grafting with conjunctival advancement is a useful technique.METHODS:Case report of a 70-year-old white female who initially presented with a unilateral sderal melt associated with uveal prolapse involving 6 clock hours of the surgical limbus. Emergent pericardium grafting of the involved limbus with conjunctival advancement performed to correct the endangered globe. Laboratory data including sedimentation rate, cANCA, computerized tomography of the chest, and urinalysis confirmed the diagnosis of Wegener's granutomatosis.RESULTS:After pericardium grafting and immunosuppressive therapy the patient returned to baseline visual acuity, the sedimentation rate normalized, and the pulmonary lesions and renal failure resolved. The patient has been followed for 3 years since the initial diagnosis of Wegener's granulomatosis and there has been no recurrence.CONCLUSIONS:To the best of the author's knowledge, this is the first report using processed pericardium to emergently treat scleral melt associated with uveal prolapse, thereby allowing preservation of the globe. In addition to management of the scleral melt, systemic evaluation and treatment with immunosuppressive therapy are necessary.
We carried out an encephalic magnetic resonance (MR) study in a patient with thalassemia intermedia who complained about change of the visual acuity and of the visual field. Narrowing of the optical canal was present and it was related to the compression of hemopoietic tissue masses. We found a clear relationship between the elderly age, the irregular transfusions, and the optic neuropathy. RMN screening of patients w ith thalassemia intermedia should be mandatory if changes in visual function occur.
This article reports a spontaneous intracameral bleeding at the end of cataract surgery in both eyes of two patients with Lowe syndrome. Extracapsular cataract extraction with anterior vitrectomy and posterior capsulotomy, using the anterior chamber maintainer (ACM), was performed in both eyes of two patients. At the conclusion of the surgery, when the ACM was removed, spontaneous bleeding occurred into the anterior chamber and spread into the vitreous cavity. The hemorrhage resolved spontaneously over varying periods of time. We propose that bleeding occurred from damage to iris vessels in the abnormal angle in our patients with Lowe syndrome when the ACM was removed with a concomitant decrease in intraocular pressure.
We have studied whether the presence of an artificial metal conductor in the visual cortex has an effect on the responsiveness pattern of the cells there. The physiological properties of single cells have been characterized in the mammalian primary visual cortex, following the acute and chronic implantation of silver wire electrodes. The Experimental group was Chronic and Acute operated and implanted adult cats. The Control group consisted of operated, but not implanted, adult cats and intact (Normal) adult cats. A sagittal incision was unilaterally made in the primary visual cortex (area 17) and a silver wire was implanted. Single cells were extracellularly recorded in the pre- and postincision regions following anesthesia and paralysis, 4-8 weeks following the implantation in the Chronic and immediately in the Acute group. The responsiveness, ocular dominance, receptive field properties, orientation, and direction selectively of the cells were examined. The responsiveness level was different in the preincision (afferented) regions of all operated groups. I was consistently affected compared with their deafferented region. The main effect was found on the binocularity of cells in all operated groups. The following are the differences found between the preincision and postincision regions. Our findings show that although a metal wire conductor implanted in the mammalian visual cortex has an effect on the efficiency of the cells there, chemically inert metals may serve in the future as artificial conductors in the brain.
In this review we discuss the etiology of reading disturbances in children and adults. The majority of reading problems in children are either due to primary causes (dyslexia) or secondary to a variety of nonophthalmologic disorders or diseases. In adults the nature of reading difficulties is different to that in children and is defined as asthenopia. Asthenopia can develop as a result of uncorrected refractive errors or due to an imbalance of extraocular muscle action. The therapeutic approach to reading problems is reviewed and it will be seen to be different in children and in adults.
BACKGROUND:Precise evaluation of the iris vascular pattern in pseudoexfoliation syndrome (PXS) may be difficult with iris fluorescein angiography (IFA) because of the frequent presence of a heavily pigmented iris and conspicuous late leakage. However, iris indocyanine green videoangiography (IICGV) can precisely visualize details of the iris vascular pattern. This study analyzed the utility of IICGV in detecting microvascular changes in PXS and compared these findings with those of IFA.METHODS:Twenty-eight patients with PXS in both eyes underwent an ophthalmic examination including IFA and IICGV. IICGV was done with the IMAGEnet system H1024.RESULTS:IICGV gave better visualization of iris hypoperfusion and anastomotic vessels whereas iris microneovascularisation was far more clearly visible on IFA. IICGV also detected iris pigment epithelium defects.CONCLUSIONS:IICGV can be considered a useful tool for evaluation of the iris vascular pattern in PXS. Iris hypoperfusion did not appear to contribute to the development of iris microvascular changes.
During the last 5 years much discussion has occurred about the progressive anterior ischemic optic neuropathy of nonarteretic type and the usefulness of surgical optic nerve sheath decompression for its treatment. The description of cases with spontaneous recovery of the disease made some authors reserved or against this method and the whole subject has been debated with skeptisism. In this article three cases of progressive nonarteretic anterior ischemic optic neuropathy with spontaneous recovery are described. In all these cases visual acuity, as well as visual evoked responses, was spontaneously ameliorated and the optic disc swelling was resolved. Only the visual fields defects remained almost the same. The question arising from this study is whether or not surgical optic nerve sheath decompression in these cases was the only appropriate method of treatment, as some authors propose.
The purpose of this study was to compare visual evoked potentials (VEPs) of striate-peristriate and Cz to posterior parietal, especially IPL's supramarginal (Su) and angular (Ang, Ano, and Ant) leads in response to human face spatial attributes attend-task, to assess the concern of the former with basic features versus the latter's spatial attributes "rotated" rightwards, leftwards, or oblique (unusual angle of sight) or nodal one (eye)- and two-item, eye/mouth displacement. Monopolar cranially derived VEPs were recorded bihemispherically from six adults using 12 electrode arrays 1.5 to 2 cm apart. Subjects were instructed to fixate a marking on the monitor at a nodal eyebrow region, while attending the stimulus that was computer displayed for 200 or 300 ms, and followed by mask. Analysis was made on the first 240 ms of the records after stimulus onset; the test was compared to "full face," the hypothesized control. Localized VEP changes were observed task-bound and bihemispherically coherent in parietal leads, especially Ang, Ano, and Su. The early negativity of the "full face" control was replaced by an early positive wave with onset latencies of 70 +/- 15 ms, significantly shorter (p < 0.01) than the striate's 90 +/- 20 ms. The changes were observed for both rotation and displacement. The changes in the angular leads (Ano and Ang) are consistent with the encoding of spatial attributes of orientation and nodal face items displacement. Differentiation of direction and degree of rotation, "seen from above" versus "seen from below," largely encoded by the right Su. The composite double-item eye and displaced or obliquely rotated induced extended coherent activity in parietal leads. Oz, peristriate, and Cz showed no such changes. No attempt is made to imply source localization; we claim parietal localized and coherency of the VEP changes suggest high-order early processing of human face attributes. This occurs by a relatively fast pathway. The "triggers" for the changes are direction and degree of rotation or of displacement rather than actual geometry of the stimulus.
Hereditary optic atrophy is a significant cause of optic atrophy in children. We report two male siblings who suffered profound irreversible loss of vision over a 2-month period. Neither patient had any prior ophthalmic problems. Both siblings had a metabolic disorder characterized by transient episodes of ataxia and paresis, whereas in one brother a slight increase of lactate in blood and cerebrospinal fluid was detected during an acute episode. Respiratory chain defect in complex I was confirmed in one patient.
The purpose of this study was to test the objective and subjective performance of the Holo-Or Rigid Gas Permeable (RGP) Multifocal Contact Lens (MFCL), a new trifocal diffractive contact lens. Eleven experienced and two nonexperienced rigid gas permeable contact lens wearers participated in the study. Eleven patients were presbyopic (age 40-57) and two were aphakic (age 12 and 14). All patients were tested both with their best correction for distance and near and trifocal diffractive contact lenses. The follow-up period was 3-8 months. Subjective opinion was also assessed. Statistical analysis was performed using Student's t-test. We did not find any significant difference in visual acuity, measured at 6 m, 80 cm, and 40 cm, between best correction and Holo-Or diffractive contact lenses. Depth of focus improved to a statistically significant extent when using trifocal contact lenses. A small reduction in contrast sensitivity was observed when the patients used multifocal contact lenses. Overall satisfaction and comfort was good to excellent in 10 out of 13 patients. Two additional patients who used a bifocal model of the same contact lens design showed similar results. Holo-Or Trifocal Diffractive Contact Lenses are a satisfactory means of optical correction for patients with presbyopia or accommodative problems.
We wished to study in detail the time course of changes in the electroretinogram (ERG) that occur following lesioning of the cat retina by photocoagulation. The superior-temporal quadrant of one eye of 15 adult cats was photocoagulated by argon laser. The ERG was recorded at baseline and followed for up to 13 weeks postlaser. The retina was also observed ophthalmoscopically. Immediately after photocoagulation, the b-wave amplitude was markedly reduced. This was followed by a gradual recovery over the next 10 weeks. The ophthalmoscopic appearance of the lesions, however, appeared unchanged after 1 week. The ERG, which is reduced in amplitude immediately after retinal photocoagulation, shows recovery with time.
The purpose of the present study was to determine whether bromhexine (Solvex) affects the rate of tear secretion or the concentration of lysosyme in the tear fluid in healthy subjects. The rate of tear secretion and lysosyme concentration in tear fluid were estimated in 56 healthy volunteers before and after 3 weeks of oral administration of placebo (tablets of vitamin C, 200 mg per day) followed by bromhexine tablets, 32 mg per day. Shirmer's test I was performed to evaluate the tear secretion, and the lysosyme plate method was used to detect lysosyme concentration. Shirmer's test showed similar results before and after placebo and bromhexine administration. In conclusion, oral bromhexine was found to have no effect on the rate of tear secretion, nor on the concentration of lysosyme in the tear fluid of healthy subjects.
Intraocular calcification can rarely occur in Coats' disease. To our best knowledge, all previously reported cases with intraocular calcification had significant exudative detachment. We report an 11-year-old boy with unilateral Coats' disease who had only moderate, widespread subretinal exudation with a ridge located temporal to left macula without overt exudative retinal detachment. Ultrasonographic evaluation and orbital computed tomography revealed that the ridge was calcified. It should always be remembered that calcification may be present even in patients with a moderate form of Coats' disease.
Environmental factors such as solar radiation and drug treatment are potential cataractogenic agents. It is suggested that their damaging effects accumulate with age. The purpose of the study was to isolate the effect of one factor (UV-radiation) and find out the mechanism by which UV radiation causes damage to the eye lens. We irradiated bovine lenses with UV-A (365 nm) radiation for 50, 75, 90, 100, and 120 min and followed the optical changes of the lenses in a long-term organ culture. Enzyme activities were analyzed in lens epithelium after five days of incubation in organ culture. The enzymes analyzed were ATPase, which belongs to the transport mechanism in lens epithelium cells, hexokinase, the key enzyme of the glycolysis pathway, G6PD, which provides NADPH to the glutathione system and catalase, which protects the cells from H(2)O(2). Optical damage was observed even for the minimal radiation. The same amount of radiation also affected ATPase and hexokinase activities. G6PD and catalase were affected only in lenses which received radiation for 90 min, We can conclude that enzymes involved in the transport mechanism and metabolism are more sensitive to UV-A (365 nm) radiation than enzymes involved in the defense mechanism against oxidation.
Lesions of the posterior parietal system in humans and of the presumably homologous area 7 of the monkey cause impairment in high-order manipulative behavior. A specific "misreaching" observed prompted the outlook of dysfunction constrained to the perceptual, the comand/motor aspects excluded. To clarify the nature of normal functioning in this domain, a study was done by microelectrode recording from area 7 of the monkey of neural firing in relation to hand reaching to targets. The data obtained show that an area 7 neuron fires in relation to simple stimuli, such as a square of white light, and to composite stimuli, such as hand reaching by the monkey or by the trainer in the monkey's extrapersonal space, the response to complex stimuli characteristically multiduty. The firing patterns were presumably relatable to encoding of stimulus components with superposed situation variance. Selectivity of the stimulus was maintained along specific invariance, such as to hand used, to direction of outgoing reaching, to direction from which the rewarding hand of the trainer reached. It is proposed that functional linkage of cognate features, a consequent modular category encoding and "packaging" of information relevant for praxis schema, is thus achieved by area 7 cells specialized for integrating information in the time and space domains visual, tactile, proprioceptive/kinaesthetic, and other for the sake of behavior in extrapersonal space. Generalization without jeopardizing of differentiating is presumably enabled through the multiduty cell entity.
This study investigated the effect of antioxidants on cataract formation in galactosemic rats. Two antioxicants were compared: lycopene, a carotenoid derived from tomato, and butylated hydroxytoluene (BHT), a known antioxidant substance. The control group was fed with galactose 30%. The experimental groups received, in addition to galactose 30%, either lycopene 0.8% or BHT 0.2%. Cataractogenesis was evaluated by the incidence of cataract, grading of cataract, histology of the lenses, aldose reductase (AR) activity, protein levels, and reduced glutathione (GSH) contents in the lens. In both experiemtal groups: 1) the incidence and grading of cataract were lower, 2) the protein levels and GSH content were higher, and 3) the AR was decreased compared to the control group. In conclusion, "natural antioxidants" such as lycopene derived from tomato have a similar effect as BHT in delaying cataractogenesis in rats.
This is a cumulative clinical study of the effect of topical guanethidine sulfate solution. Two hundred fifty-six cases of patients with lid retraction secondary to thyroid orbitopathy or trauma were treated with guanethidine sulfate 5-10% solution before surgical intervention was considered. Eighty-five percent of thyroid-related lid retraction responded to guanethidine sulfate, whereas only 67% of the traumatic or iatrogenic cases responded to guanethidine sulfate. None of the patients showed overt reaction to guanethidine sulfate. The conservative management of lid retraction with topical guanethidine sulfate is relatively safe and mostly effective and should be considered before surgical intervention is considered.
We present a case of bilateral, primary, localized, corneal amyloid deposition with a unique appearance not, to our knowledge, previously described. The patient was a 73-year-old white man who complained of glare. Best corrected visual acuity was 20/25 in both eyes. Slit lamp examination revealed subepithelial/anterior stromal white-gray deposits in the peripheral cornea in both eyes. The corneal surface was smooth with no elevated areas. Superficial corneal scrapings showed focal deposits of an amorphous, glass-like material below the epithelial surface and within Bowman's membrane, which stained with Congo red. We examined the amyloid deposits using the confocal microscope to obtain high magnification images in vivo. The confocal microscopic views showed intercellular, cotton candy-like, fibrillar amyloid material scattered throughout the anterior stroma. The use of this instrument may permit clinical diagnosis of this rare disorder without the need for biopsy.
This report gives an overall view on the aspect of numerous diseases and symptom complexes affecting both eyes and teeth. The knowledge of these disorders enables the ophthalmologist to suspect and recognize certain types of dental malformation and enables the dentist to discover certain eye defects. Moreover, it is important that clinicians be aware that simultaneous eye and tooth defects may be the indication of possible disturbances in other, apparently unrelated, organs or systems. Because such disorders are frequently hereditary conditions, their early detection will aid in the diagnosis and treatment of other affected family members. This may also help the parents to cope with the disease and be of benefit to the infants because a cure may be forthcoming.
