The regional variations of extrafoveal perception of form in the central visual fields (photopic vision) with special reference to lesions of the visual pathways.
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Color Vision↗
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Results for “OPTIC PATHWAY”
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Intraocular lens implants for uniocular cataracts in childhood.
We report the outcome of intraocular lens implantation in 20 children with visually significant cataracts (seven traumatic, 13 non-traumatic). Six patients had anterior and 14 had posterior chamber implants. The mean age of the whole group at the time of surgery was 5.9 years (range 0.3 to 15.1 years), while the mean period of follow-up was 2.4 years (range 0.8 to 5.9 years). Postoperatively 10 patients developed a transient fibrinous uveitis, four required lens repositioning, one needed lens removal, and eight required posterior capsulotomy. Complications warranting secondary surgical procedures occurred predominantly in eyes with posterior chamber implants. Co-operation with conventional amblyopia treatment was satisfactory in eight out of 16 patients. Postoperatively nine out of 18 patients had peripheral fusion, four patients regained visual acuities of better than 6/9, and visual acuity did not improve beyond 3/60 in six cases. In 19 eyes the optical pathway to the retina is clear and the implants are stable with no evidence of persisting inflammation. Contact lenses remain the initial treatment of choice in infancy, but modern intraocular lenses are well tolerated and have a role in the visual rehabilitation of patients with contact lens and probable contact lens failures and older children with uniocular cataracts.
Adolescent↗
Confusional state and cerebral infarcts.
Thirteen patients with confusional state and cerebral infarction were studied. Seven patients had optic pathway alterations. On computed tomographic scan, 2 patients had multiple infarctions and 10 had single infarctions, predominantly located in the temporo-occipital associative cortex. One patient had a normal scan. Reduction of 'selective attention', 'release' hallucinations, amnesic syndrome and secondary individual adjustment could explain the confusional state.
Aged↗
Orbit: initial experience with surface coil spin-echo MR imaging at 1.5 T.
Fifty-nine cases in which surface coil MR imaging of the orbit was performed were reviewed. MR imaging was performed with spin-echo techniques at 1.5 T with both short repetition time/echo time (TR/TE) and long TR/TE sequences in all cases. In all patients short TR/TE images were obtained with small-diameter surface coils; long TR/TE images were usually obtained with a standard head coil. Surface coil MR appears to be an important adjunct in state-of-the-art orbital imaging. Orbital MR imaging may be most useful, providing information not available on computed tomography (CT), in identifying lesions in the orbital apex, superior orbital fissure, and optic canal; differentiating inflammatory pseudotumor from malignancy in clinically similar patients; characterizing lesions containing hemorrhage or other paramagnetic material; defining the posterior extent of optic pathway gliomas; and detecting abnormal flow in intraorbital vascular structures. CT seems to be superior to MR imaging in the evaluation of small perioptic meningiomas, especially those that are calcified.
Eye Neoplasms↗
Visual cortical inputs to deep layers of cat's superior colliculus.
In the superior colliculi of cats anesthetized with ketamine, 84% of identified output cells of the deep layers could be driven by shocks to the contralateral optic disk, optic chiasm, or ipsilateral optic tract; 75% of these deep-layer cells had response latencies reflecting a polysynaptic influence of retinal Y-cells. Following large, acute lesions of the ipsilateral occipital cortex (including visual areas 17, 18, 19, and the posteromedial lateral suprasylvian area (PMLS), only 18% of deep-layer output cells were driven by electrical stimulation of the optic pathway and only 4% exhibited an indirect Y-cell influence. Thus, one or more of these visual areas may be important for the relay of retinal information, and particularly of Y-cell information, to the deep layers of the superior colliculus. This hypothesis is supported by the observation that intracortical stimulation in areas 17, 18, 19, and PMLS activated many cells of the ipsilateral, deep tectal layers at latencies consistent with those exhibited by the indirect Y-cell pathway. The distributions of activation latencies were similar to those observed in the superficial layers, raising the possibility that at least some of the cortical influence on the deep layers may be mediated by direct connections. Cells of the deep layers were more likely to be excited by a cortical stimulus that activated cells immediately above them in the superficial layers than by a stimulus that did not. This indicates that the functional connections between visual cortex and the deep collicular layers exhibit a topographic orderliness similar to that previously described for corticotectal projections to the superficial layers. These results provide further evidence that the visual cortex exerts a significant influence on cells of the deep collicular strata and that the pathways involved are capable of mediating the indirect, retinal Y-cell input to these neurons.
Animals↗
Scheimpflug records without distortion--a mythos?
The Scheimpflug principle was recommended as allowing distortion-free imaging; however, a detailed analysis reveals geometrical errors as well as distortions arising from absorption of light along the optical pathway. Correction formulas and factors will be presented and applied to the biometry of the eye.
Biometry↗
Pituitary adenomas treated by microsurgery with or without Gamma Knife surgery: experience in 122 cases.
The clinical outcome of 122 patients with pituitary adenomas treated by microsurgery and/or Gamma Knife radiosurgery (GKRS) was analyzed to evaluate patient selection criteria and the role of GKRS. Sixty-six resections were performed in 59 patients. All tumors were macroadenomas, except for 5 ACTH-producing adenomas. Twenty-four of the 31 hypersecreting adenomas showed normal serum hormone values after treatment. Postoperative complications were rhinorrhea, cranial nerve palsies, and a small thalamic infarct. GKRS was performed on 18 of the operated patients because of residual tumors, mostly in the cavernous sinus. Thirty-five of the 63 patients treated by GKRS were followed for more than 2 years. All adenomas except 2 were stable or had decreased in size. Eleven of 17 functioning adenomas showed normal serum hormone values after treatment. It is concluded that tumors that compress the optic pathway should be removed and that residual tumors in the cavernous sinus are good indications for radiosurgery.
Adenoma↗
Stereotactic radiosurgery for pituitary adenomas: a review of the literature and our experience.
Pituitary adenomas are not just one of the most common intracranial tumors but also one of the most difficult to cure. Neurosurgeons have adapted their tools to include precise ionizing radiation in the form of the gamma knife to treat pituitary adenomas. The use of the gamma knife in the management of pituitary adenomas following microsurgery or in selected cases as a primary treatment is safe. The combined application of transsphenoidal surgery and Gamma Knife surgery is beneficial in many difficult cases. However in some patients, optimal control of tumor growth and normalization of hypersecretory states are not achieved. Innovative improvements in operative and radiosurgical techniques are required to avoid pituitary insufficiency and to reduce the number of the cases in which optimal radiosurgery is not feasible because of close tumor proximity to the optic pathways.
Acromegaly↗
Magnetic resonance analysis of suprasellar tumors of childhood.
A retrospective analysis of the magnetic resonance (MR) images in 53 pediatric patients with pathologically proven suprasellar tumors was performed, in an attempt to identify the characteristic MR features of these tumors and assess the capability of MR to predict a histologic differentiation. The tumors analyzed included 29 astrocytomas, 11 craniopharyngiomas, 4 germinomas, 3 pituitary adenomas with suprasellar extension, 2 teratomas, 1 spindle cell tumor, 1 primitive neuroectodermal tumor, 1 arachnoid cyst and 1 chordoma of the clivus with suprasellar extension. Thirty patients received intravenous Gd-DTPA as part of their MR exam. Certain MR features, while not pathognomonic, are quite helpful in the differentiation of craniopharyngiomas from chiasmatic/hypothalamic astrocytomas. Presence of a high signal intensity component on T1-weighted images, cyst formation with macrocystic predominance, irregular, heterogeneous solid portion, and smooth ring cyst wall enhancement represent the key characteristics of craniopharyngiomas. Solid predominance with microcysts, long T1 and T2 relaxation times, intense enhancement after contrast administration and extension along the posterior optic pathways are the typical MR findings of chiasmatic/hypothalamic astrocytomas. Presence of diabetes insipidus in correlation with the MR findings of a well-marginated, round or lobular tumor with prolonged T1 and T2 relaxation times, which enhances strongly after Gd-DTPA administration may be the clue in the diagnosis of suprasellar germinomas. Teratomas can be separated from other pediatric suprasellar neoplasms on the basis of internal heterogeneity with presence of fat, calcium and various soft tissue densities. Tumors invading the suprasellar cistern by extension are easily differentiated by identification of the primary site of origin. The above features, while not pathognomonic, are quite helpful in making a specific diagnosis.
Adenoma↗
Stereotactic gamma radiosurgery of craniopharyngiomas.
Ten cases of solid craniopharyngioma have been treated safely and effectively by gamma knife for a mean follow-up time of 13.9 months. Gamma radiosurgery was done as an initial radiotherapy to the residual or recurrent tumor after surgery in 8 cases. One recurrent tumor from surgery and conventional radiotherapy, and another tumor without previous treatment, have also been treated. Dose planning and dosimetry were performed using both axial and coronal MRIs. The tumor had a mean diameter of 21.1 mm and volume of 6.14 cm3. The tumor was treated with a mean maximum and marginal dose of 27.6 and 14.2 Gy respectively. The dose to the optic pathways is critical and was kept as low as possible which was calculated to be < 13.0 Gy on average. As a result, marked shrinkage of the tumor in 7 and central necrosis in 3 tumors have been obtained without significant side effects.
Adult↗
Suprasellar tuberculoma causing endocrinologic disorders and imitating craniopharyngioma.
A patient is reported with a suprasellar tuberculoma which imitated a craniopharyngioma on computed tomography scan and magnetic resonance imaging of the brain. This lesion developed during irregularly used antituberculous therapy and caused endocrinologic disorders 3 years after the original diagnosis of tuberculous meningitis. Surgery was performed to confirm the diagnosis and also to decompress the optic pathways. Five months later, the lesion disappeared completely after appropriate antituberculous treatment.
Antitubercular Agents↗
Some aspects of neurotoxicity associated with central nervous system prophylaxis in childhood leukemia.
Late effects of central nervous system (CNS) prophylaxis with cranial radiation (CR) and intrathecal chemotherapy encompass a broad spectrum of phenomena, ranging from fatal leukoencephalopathy to subclinical dysfunctions. Therefore, we studied 55 asymptomatic children with leukemia or solid tumors by means of visual-evoked potentials (VEP) in order to detect subclinical demyelination of the optic pathway after CNS prophylaxis. Ten of the 11 patients showed increased VEP latency after CR with 1,800 cGy, as compared with previous values. One third of our 34 children treated months to years before the study, with 2,400 cGy CR also showed increased VEP latency which was normal in children treated with intrathecal methotrexate only. Growth hormone secretion was investigated using sequential arginine (ARG) and insulin (INS) tolerance tests in 7 leukemic children treated with 1,800 cGy CR. At diagnosis all patients were responsive to both tests; after CNS prophylaxis, 2 patients were still responsive to ARG and INS, whereas the other 5 were responsive to ARG test only. These results are at variance with our previous experience in a series of 22 children treated with 2,400 cGy CR where 2 patients responded to ARG only and 5 did not respond to either stimulus. These data indicate that, even after a reduction of the CR dose, CNS prophylaxis is still associated with subclinical dysfunctions.
Antineoplastic Combined Chemotherapy Protocols↗
Visually impaired infants in the 1980s. A survey of etiologic factors and additional handicapping conditions in a school population.
To identify etiologic factors and ophthalmologic diagnoses related to visual impairment in young infants, a survey was carried out within the 22 school districts providing educational services to all visually impaired infants, birth to 3 years of age, in Harris County, Texas. Review of 102 records revealed that 51 percent had impaired vision associated with prenatal factors, and 31 percent were associated with perinatal events. The most frequent ophthalmologic diagnoses were lesions of the optic nerve, optic pathway, and visual centers of the brain (cortical blindness). A majority of the infants had multiple handicaps: 17 percent had hearing loss, 48 percent had cerebral palsy, 46 percent had seizures, and 78 percent had severe developmental delay. The high incidence of multiple handicaps and significant medical problems indicates the necessity for interface between physicians and educators who serve the visually impaired infant.
Child, Preschool↗
Development and implementation of a carboplatin desensitization protocol for children with neurofibromatosis, type 1 and hypersensitivity reactions in an outpatient oncology clinic.
Neurofibromatosis, type 1 (NF 1), is a relatively common disorder. Children with NF 1 are at much greater risk for the development of optic pathway tumors, which are sometimes treated with chemotherapy. As a result, many oncology centers and clinics are now seeing and treating NF patients. One of the most frequently used drugs is carboplatin. However, as many as 30% of NF patients may develop a reaction to carboplatin, which can include anaphylaxis. This often results in the cessation of the medication and treatment protocol. At the Children's Hospital of Philadelphia a desensitization protocol has been instituted with children who have had such reactions and whose tumors have demonstrated a positive response to the treatment. The desensitization process is quite complex and requires an interdisciplinary approach. However, it is the nursing personnel that are key to the successful coordination and delivery of such a protocol in an oncology outpatient clinic on a regular basis.
Ambulatory Care↗
Usefulness of systematic ophthalmologic investigations in neurofibromatosis 1: a cross-sectional study of 211 patients.
PURPOSE: To evaluate the usefulness of ophthalmologic examination for diagnosis and for detection of complications in adult patients with neurofibromatosis 1. METHODS: PATIENTS with at least one criterion of neurofibromatosis 1 (excluding ophthalmologic criteria) seen at a referral centre had a systematic ophthalmologic examination including best-corrected visual acuity, slit-lamp examination and dilated funduscopy. The ophthalmologist was unaware of all other anamnestic data. RESULTS PATIENTS: 211 patients with NF1 were included (mean age: 32 +/- 14 yr.). Ophthalmologic examination in neurofibromatosis 1 patients: Lisch nodules (n = 185) (87.7%); choroidal hamartomas (n = 61) (29%); enlarged corneal nerves (n = 1); 3 plexiform neurofibromas (n = 3); symptomatic optic pathway gliomas (n = 5). Diagnostic contribution of presence of Lisch nodules: 6 (3%) of 211 patients. Detection of complications: none. CONCLUSIONS: In adult patients with neurofibromatosis 1, the contribution of ophthalmologic examination to diagnosis and to the detection of complications is low. Ophthalmologic examination should be performed in patients for whom questioning and clinical examination failed to give evidence of NF1 or to determine the NF subtypes.
Adolescent↗
Dependence of wave front refraction on pupil size due to the presence of higher order aberrations.
PURPOSE: Propagation of light through the optical pathway within the eye can lead to a deformation of the wave front that might affect objective but also subjective refraction depending on pupil size. The aim of this study was to investigate the change in wave front refraction that is calculated on the basis of second order Zernike polynomials when varying the pupil size from 6 mm to 3 mm. The change was correlated with the amount of fourth and sixth order spherical aberration and fourth and sixth order astigmatism. METHODS: Wave front aberrations were measured in 130 eyes by means of a Tscherning wave front sensor at a pupil size of 6 mm. Wave front aberrations in terms of Zernike coefficients up to sixth order were approximated for 6 mm and 3 mm pupil size. The wave front refraction was calculated based on the second order Zernike coefficients for both pupil diameters. Resulting differences in wave front refraction (sphere or cylinder) due to the change in pupil size were correlated with the initial higher order aberrations determined for the 6.0 mm pupil by means of a linear regression (Spearman rank correlation coefficient). RESULTS: The correlation between the change in sphere and cylinder on one hand and the spherical aberration and higher order astigmatism on the other hand was found to be highly significant (p<0.001), with a correlation coefficient of R = 0.96 for sphere and R = 0.85 for cylinder. CONCLUSIONS: Calculating the wave front refraction on the basis of second order Zernike polynomials is plagued with the influence of the higher order aberration preexisting in the individual eye. This is one reason why this method does not represent precisely enough subjective refraction. Other methods that calculate the refraction based on wave front measurement independent from the pupil size should be established in the ophthalmic community.
Adolescent↗
Compound myopic astigmatism correction using a mask in-the-rail excimer laser delivery system. Preliminary results.
PURPOSE: The latest development in the erodible mask technology is an excimer laser containing the mask in the laser optical pathway. This paper reports the results of the first human series of consecutive treatments performed for the correction of compound myopic astigmatism. METHODS: We have treated 83 eyes. Spherical equivalent attempted correction ranged between -1.75 and -11.75 D (mean -7.07+/- 2.45 D), astigmatic attempted correction ranged between -1.00 and -5.00 D (mean -2.42+/- 1.02 D). The sphere correction was made by diaphragm using a multi-zone software with three ablation zones: 100% of the total attempted correction for the central 5.0 mm zone, 70% for the second 6.0 mm zone, 30% for the outer 6.5 mm zone. Cylinder correction was made sequentially after myopic correction using the appropriate mask. RESULTS: One month after treatment, mean refractive error was + 1.07 +/- 1.24 D (range + 4.50/-1.75 D) for spherical equivalent, and -0.49 +/- 0.57 D (range + 0.75/-2.00 D) for astigmatism. Forty-eight eyes (57.8%) had uncorrected visual acuity of 20/40 or better. At six months, mean refractive error was +0.42 +/- 0.97 D (range + 3.75/-1.00 D) for spherical equivalent, and -0.44 +/- 0.51 D (range +0.25/-3.00 D) for astigmatism. Vector analysis showed that 57 eyes (68.7%) had 5 or less degrees rotation. Seventy-two (86.7%) and 54 eyes (65.1%) had uncorrected visual acuity equal or better than 20/40 and 20/25 respectively. One eye (1.2%) showed a best corrected visual acuity loss of more than one line, but 8 eyes (9.6%) had a gain of more than one line. One-year results on a smaller series (33 eyes) overlap with the six-month results. CONCLUSIONS: The mask in-the-rail excimer laser delivery system appears to be effective and predictable in the correction of compound myopic astigmatism. We observed no significant regression of the astigmatic correction over time. Longer follow-up on larger series is necessary to draw final conclusions.
Adolescent↗
Hyperopia correction using an erodible mask excimer laser delivery system coupled to an axicon: preliminary results.
PURPOSE: This paper presents the results of the first human trial on the correction of hyperopia using an erodible mask excimer laser delivery system coupled to an axicon. METHODS: We treated 17 eyes of 17 patients (age range 34-62 years) for the correction of +3.21 +/- 1.04 D (range +1.00 to +4.00 D). The hyperopic correction was made using an erodible mask inserted on the laser optical pathway, to produce a circular ablation measuring 6.5 mm in diameter. An axicon was then used to create a blend transition zone from 6.5 mm up to 9.4 mm in diameter. Eyes were evaluated at one, three and six months after surgery. RESULTS: Reepithelization was always observed by the fifth postoperative day, despite the large area of deepithelization (diameter 9.5 mm). Mean refractive error one month after treatment was -2.44 +/- 1.59 D (range 0.00 to -6.50 D). Five eyes (29.4%) had a best corrected visual acuity loss more than two to three lines; all eyes showed mild annular haze not involving the central part of the cornea. Six months after treatment, mean refractive error was -0.88 +/- 0.99 D (range +0.50 to -3.00 D). Compared to preoperative status, 13 eyes (76.5%) showed an improvement in uncorrected distance visual acuity (1-8 lines), and 14 eyes (82.4%) showed an improvement in uncorrected vision at reading distance (3-7 lines). Two eyes (11.7%) showed a best corrected visual acuity loss of two of three lines. CONCLUSIONS: These preliminary results indicate this approach is effective in reducing hyperopia, while its predictability has still to be proved in a larger treatment group with longer follow-up. A cautious approach to this technique is still advisable, especially for higher hyperopic corrections, in view of the large best corrected visual acuity loss seen in two eyes at six months.
Adolescent↗