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Accommodative and binocular vision disorders associated with video display terminals: diagnosis and management issues.

BACKGROUND: With the rapid computerization of the workplace, school and home office, it is likely that a vast majority of Americans will be using computers for significant amounts of time in the near future. Research has demonstrated a high prevalence of accommodative and binocular vision disorders in symptomatic VDT users, which underscores the importance of the assessment and management of accommodation and binocular vision for patients working with computers. METHODS/RESULTS: This paper presents a simplified approach for the diagnosis and management of accommodative and binocular vision disorders in VDT users. The emphasis is on modifications of the traditional examination routine to make the assessment as sensitive as possible to the vision problems associated with VDT use. CONCLUSIONS: To meet the needs of symptomatic VDT users, optometrists must perform a comprehensive assessment of accommodation and binocular vision. The use of appropriate testing, when combined with attention to the environmental factors associated with VDT use, will enable optometrists to understand the reasons for symptoms and design an effective treatment program.

Accommodation, Ocular↗

Transsphenoidal management of 28 symptomatic Rathke's cleft cysts, with special reference to visual and hormonal recovery.

OBJECTIVE: This is a retrospective study of a series of 28 Rathke's cleft cysts operated on transsphenoidally that was undertaken for the following reasons: 1) to study the presentation, with particular reference to hormonal and visual disturbances; 2) to study postoperative improvements in endocrine function and vision; 3) to record postoperative complications; and 4) to assess the efficacy of a minor modification of the standard transsphenoidal surgical technique, whereby the cyst is allowed to drain directly into the sphenoid air sinus without fossa floor repair when there is no intraoperative cerebrospinal fluid leak. METHODS: A retrospective study was made of case notes, radiological findings, and operative notes in the series. RESULTS: There were 16 female and 12 male patients, with a mean age of 45 years. Endocrine disturbance was the most common presentation (50%), followed by headaches (32.1%) and visual impairment (14.3%). Neuroophthalmological assessment showed central visual acuity and field deficits in 32.1 and 44.6% of eyes, respectively. Biochemically, 85.7% of patients showed hormonal disturbances. Magnetic resonance imaging was used for 84.7% of cases, and 60.7% of cases showed suprasellar extension. Four magnetic resonance imaging patterns were noted. All cases were operated on transsphenoidally. Postoperative complications included cerebrospinal fluid rhinorrhea (7.1%), diabetes insipidus (3.6%), and meningitis (3.6%). Recovery of visual acuity and field was seen in 66.6 and 68% of eyes, respectively. Postoperative prolactin levels declined to normal or nearly normal values in 62.5% of cases, 20% of cases with low preoperative gonadotrophin levels achieved normal levels, and 15.4% of cases with preoperative pan-hypopituitarism achieved normal serum cortisol levels postoperatively. Within the study period there were no recurrences; although a relatively short time interval is presented for this series, a patient with a similar lesion operated on by the same method 7 years previously remains well, without radiological evidence of recurrence. CONCLUSION: Although comparatively rare and benign lesions, Rathke's cleft cysts are an important cause of hormonal and visual disturbances. Transsphenoidal surgery is safe and efficacious and leads to excellent improvement of function in the majority of cases. The surgical modification described seems safe and satisfactory and is extremely easy to perform.

Adolescent↗

3-D vision and figure-ground separation by visual cortex.

A neural network theory of three-dimensional (3-D) vision, called FACADE theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a boundary contour system (BCS) and a feature contour system (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that are mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object parts are separated, completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by context-sensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity; partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, Da Vinci stereopsis, 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analyzed. The BCS and FCS subsystems model aspects of how the two parvocellular cortical processing streams that join the lateral geniculate nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-DEpth, or FACADE, within area V4. Area V4 is suggested to support figure-ground separation and to interact with cortical mechanisms of spatial attention, attentive object learning, and visual search. Adaptive resonance theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal (IT) cortex for purposes of attentive object learning and categorization. Object attention mechanisms of the What cortical processing stream through IT cortex are distinguished from spatial attention mechanisms of the Where cortical processing stream through parietal cortex. Parvocellular BCS and FCS signals interact with the model What stream. Parvocellular FCS and magnocellular motion BCS signals interact with the model Where stream.(ABSTRACT TRUNCATED AT 400 WORDS)

Depth Perception↗

Fast and slow recovery phases of goldfish behavior after transection of the optic nerve revealed by a computer image processing system.

As the goldfish is a common experimental animal for vision research, including psychophysical behavior, it is very important to quantitatively score fish behavior. We have previously developed a computer image processing system which can acquire the positional coordinates of goldfish moving freely in an aquarium and determine turning directions (go straight, right or left turn). In the present study, an algorithm to determine tilting angles of moving goldfish was constructed. We also made histograms for quantifying the interaction between pairs of goldfish (two-point distance). By using these histograms, we estimated the time-course of behavioral regeneration after optic nerve transection in goldfish. Control goldfish showed an equal percentage of right or left turns and maintained an upright position in a dorsoventral axis. When the optic nerve of a goldfish was unilaterally sectioned, the goldfish showed predominant turning and slight tilting toward the intact eye. The abnormal turning and tilting behaviors lasted for 10-14 days and then gradually decreased, returning to control behaviors by one month after the unilateral transection. When the optic nerve of a single goldfish was bilaterally sectioned, it did not show any preferential turning and tilting behavior, which is similar to what was observed in control goldfish. However, the trace maps showed that, after bilateral sectioning, fish preferred to cross the center of the tank, which was unlike control fish. In control pairs, one goldfish chased the other with a fixed small range of two-point distances. However, in pairs of goldfish with bilateral transection of the optic nerve, the blind goldfish behaved independently of each other, with a long two-point distance. The long two-point distance of the blind goldfish lasted for at least two months and then slowly returned to control two-point distance by four months after bilateral transection. Such fast and slow recovery in goldfish behaviors evoked after unilateral and bilateral transection of the optic nerve is discussed with respect to reconnection of regenerating optic nerves in the fish central nervous system. This computer image processing system is a useful tool with which we can quickly and easily quantify fish behavior.

Algorithms↗

Discrete analysis of spatial-sensitivity models.

The visual representation of spatial patterns begins with a series of linear transformations: the stimulus is blurred by the optics, spatially sampled by the photoreceptor array, spatially pooled by the ganglion-cell receptive fields, and so forth. Models of human spatial-pattern vision commonly summarize the initial transformations by a single linear transformation that maps the stimulus into an array of sensor responses. Some components of the initial linear transformations (e.g., lens blurring, photoreceptor sampling) have been estimated empirically; others have not. A computable model must include some assumptions concerning the unknown components of the initial linear encoding. Even a modest sketch of the initial visual encoding requires the specification of a large number of sensors, making the calculations required for performance predictions quite large. We describe procedures for reducing the computational burden of current models of spatial vision that ensure that the simplifications are consistent with the predictions of the complete model. We also describe a method for using pattern-sensitivity measurements to estimate the initial linear transformation. The method is based on the assumption that detection performance is monotonic with the vector length of the sensor responses. We show how contrast-threshold data can be used to estimate the linear transformation needed to characterize threshold performance.

Humans↗

Moyamoya disease. Posterior cerebral artery occlusion and pattern-reversal visual-evoked potential.

Although vascular abnormality in moyamoya disease predominates in the anterior and middle cerebral arteries, the posterior cerebral artery (PCA) has been found to be involved in the course of the disease. To explore PCA occlusion by noninvasive means, we studied visual-evoked potentials in the patients with PCA occlusion (occlusive group), as well as in those without PCA occlusion (nonocclusive group). The results were compared with those of other examinations that also detected an occipital lobe pathologic condition. Abnormalities of those examinations were highly specific to PCA occlusion. Positron emission tomography and pattern-reversal visual-evoked potentials yielded high incidence of abnormality in the occlusive group (86% and 75%, respectively), and expressed the side of PCA occlusion if the occlusion was unilateral. Since pattern-reversal visual-evoked potentials is popular and a low-cost examination compared with positron emission tomography, we conclude that pattern-reversal visual-evoked potentials is the most practical mean to explore PCA occlusion in the course of moyamoya disease.

Arterial Occlusive Diseases↗

Proptosis from maxillary sinus inverted papilloma with malignant transformation.

We describe a 58-year-old woman who presented with proptosis, upward displacement, and decreased vision in her right eye. A computed tomography scan revealed a mass filling the right maxillary sinus, destroying bone and invading the inferolateral orbit. The tumor proved to be an inverted squamous papilloma with focal transformation to squamous cell carcinoma. Although a rare cause of proptosis, inverted papilloma with orbital invasion must be considered when a patient describes associated nasal or sinus disease.

Biopsy↗

Skew deviation with ocular torsion: a vestibular brainstem sign of topographic diagnostic value.

Fifty-six patients with unilateral brainstem infarctions presenting with skew deviation of the eyes were analyzed for static vestibular function in the roll plane. Ischemic lesions were allocated to the level and side of the brainstem by the clinical syndrome and neuroimaging. Two findings of clinical relevance were obtained: (1) All skew deviations were ipsiversive (ipsilateral eye was undermost) with caudal pontomedullary lesions and contraversive (contralateral eye was lowermost) with rostral pontomesencephalic lesions. (2) All skew deviations were associated with concomitant ocular torsion and tilts of subjective visual vertical toward the undermost eye. Thus, skew deviation or more correctly, ocular skew torsion is a sensitive brainstem sign of localizing and lateralizing value. Evidence is presented that the ocular skew torsion sign indicates a vestibular tone imbalance in the roll plane secondary to graviceptive pathway lesions.

Adolescent↗

Reversible posterior leukoencephalopathy syndrome in children undergoing induction therapy for acute lymphoblastic leukemia.

We present three cases of children with acute neurologic changes while undergoing induction chemotherapy for acute lymphoblastic leukemia (ALL). These cases fall into the spectrum of reversible posterior leukoencephalopathy syndrome (RPLS), including abrupt alterations in mental status, headache, seizures, visual changes, hypertension, and characteristic findings on magnetic resonance imaging. Although the underlying mechanism of RPLS is still under investigation, the appropriate treatment and management of the acute event is becoming clearer. Early treatment of hypertension, control of seizure activity, and withdrawal of inciting agents can lead to rapid reversal of symptoms and return to baseline functioning.

Adolescent↗

Ocular findings in trigonocephaly.

BACKGROUND: Trigonocephaly, caused by premature closure of the metopic suture, is a rare form of craniosynostosis. The aim of this study was to assess the visual outcome in children operated on for trigonocephaly. METHODS: We present eight cases of children with trigonocephaly surgically corrected by the same craniofacial technique. CT with 3D reconstruction was performed in all cases. Genitori defined three types of trigonocephaly according to the severity of the deformity of the skull base only types II and III were included in this study directed at evaluation of the ocular disorder. A complete eye examination was performed on all children by the same observer, with a follow-up of 2-6 years. RESULTS: 3D-CT reconstruction of the skull base showed that the frontozygomatic region was affected by the deformation. Ocular examination showed considerable astigmatism in most children with late operation. A low degree of strabismus was observed in most children. CONCLUSION: This study demonstrated that reconstructive surgery should be performed by the age of 6 months, given the immaturity of the visual system up to that time. Close cooperation between neurosurgeons, pediatricians and ophthalmologists is of paramount importance in order to prevent this bone deformation exerting an adverse effect on visual development. The ophthalmologist must possess a basic understanding of the various craniosynostoses.

Astigmatism↗

Long-term outcome in aqueductal stenosis.

In this study, 78 patients with aqueductal stenosis were submitted to detailed neurodevelopmental assessment with a follow-up of 5-25 years. Sixty-eight percent of patients were categorized as normal; they either attended normal school courses or had regular jobs. Among these, 34% had some motor abnormalities (ataxia, mild hemiparesis, visual disturbances). Twenty-four percent (19 cases) were moderately disabled (trainable retardation) and 8% (6 cases) were severely handicapped. Epilepsy was observed in 13% of the cases. Incidence of recurrent and generalized seizures paralleled neurodevelopmental outcome (5% in normal, 16% in moderately disabled and 50% in severely disabled patients). Endocrine dysfunctions were evident in 28% of the cases and were characterized by precocious or delayed puberty, amenorrhea and somatic underdevelopment. No patient with ventricular enlargement and a cortical mantle width below 20 mm showed a good outcome. Large ventricles were compatible with normal mental development when compensated with a corresponding cranial vault enlargement. In patients with normal mental status and motor abnormalities, long-term CT scan findings revealed the presence of focal brain abnormalities (poroencephaly, brain atrophy, calcifications, extracerebral collections).

Adolescent↗

Sensory strategies in human postural control before and after unilateral vestibular neurotomy.

Vestibular inputs tonically activate the anti-gravitative leg muscles during normal standing in humans, and visual information and proprioceptive inputs from the legs are very sensitive sensory loops for body sway control. This study investigated the postural control in a homogeneous population of 50 unilateral vestibular-deficient patients (Ménière's disease patients). It analyzed the postural deficits of the patients before and after surgical treatment (unilateral vestibular neurotomy) of their diseases and it focused on the visual contribution to the fine regulation of body sway. Static posturographic recordings on a stable force-plate were done with patients with eyes open (EO) and eyes closed (EC). Body sway and visual stabilization of posture were evaluated by computing sway area with and without vision and by calculating the percentage difference of sway between EC and EO conditions. Ménière's patients were examined when asymptomatic, 1 day before unilateral vestibular neurotomy, and during the time-course of recovery (1 week, 2 weeks, 1 month, 3 months, and 1 year). Data from the patients were compared with those recorded in 26 healthy, age- and sex-matched participants. Patients before neurotomy exhibited significantly greater sway area than controls with both EO (+52%) and EC (+93%). Healthy participants and Ménière's patients, however, displayed two different behaviors with EC. In both populations, 54% of the subjects significantly increased their body sway upon eye closure, whereas 46% exhibited no change or significantly swayed less without vision. This was statistically confirmed by the cluster analysis, which clearly split the controls and the patients into two well-identified subgroups, relying heavily on vision (visual strategy, V) or not (non-visual strategy, NV). The percentage difference of sway averaged +36.7%+/-10.9% and -6.2%+/-16.5% for the V and NV controls, respectively; +45.9%+/-16.8% and -4.2%+/-14.9% for the V and NV patients, respectively. These two distinct V and NV strategies seemed consistent over time in individual subjects. Body sway area was strongly increased in all patients with EO early after neurotomy (1 and 2 weeks) and regained preoperative values later on. In contrast, sway area as well as the percentage difference of sway were differently modified in the two subgroups of patients with EC during the early stage of recovery. The NV patients swayed more, whereas the V patients swayed less without vision. This surprising finding, indicating that patients switched strategies with respect to their preoperative behavior, was consistently observed in 45 out of the 50 Ménière's patients during the whole postoperative period, up to 1 year. We concluded that there is a differential weighting of visual inputs for the fine regulation of posture in both healthy participants and Ménière's patients before surgical treatment. This differential weighting was correlated neither with age or sex factors, nor with the clinical variables at our disposal in the patients. It can be accounted for by a different selection of sensory orientation references depending on the personal experience of the subjects, leading to a more or less heavy dependence on vision. The change of sensory strategy in the patients who had undergone neurotomy might reflect a reweighting of the visual and somatosensory cues controlling balance. Switching strategy by means of a new sensory selection of orientation references may be a fast adaptive response to the lesion-induced postural instability.

Adult↗

Long-term results of the surgical treatment of craniopharyngioma: the experience at the Policlinico Gemelli, Catholic University, Rome.

BACKGROUND: Craniopharyngioma (CP) is the most common intracranial non-glial tumour observed in pediatric age. Although histologically benign and amenable to surgical treatment, its location and relation with vital nervous and vascular structures makes the feasibility of a radical resection difficult even in the microneurosurgery era. Beside the difficulties experienced when performing tumour resection, post-operative complications, such as endocrinological imbalance, represent another point that makes CP total excision a challenge. In order to avoid such complications, some authors have suggested to renounce to radical resection and to rely on post-operative radiation therapy to minimise the risk of residual tumour progression. METHODS: We report our experience with 52 children and adolescents operated on for CP at the Department of Pediatrics, Section of Pediatric Neurosurgery, Catholic University Medical School, Rome, between January 1985 and December 2002. The study included 14 children <5 years old (five less than 2 years of age), 25 between 6 and 10 years old, and 13 more than 10 years old. The most common presenting signs were related to endocrinological imbalance (35 cases), increased intracranial pressure (32 cases), and to a lesser extent, visual compromise (17 cases). Concerning location, CP was intrasellar in three cases; sellar/suprasellar with prominent prechiasmatic growth in 24 cases; retrochiasmatic/3rd ventricular in 14 cases, and giant (with an extension into the middle and/or posterior cranial fossae) in 11 cases. The tumour was managed by means of a single surgical approach in 47 cases and with a two-stage operation in the remaining five cases. In 11 cases of intrasellar or intra/suprasellar midline location, the first surgical approach was done through the transsphenoidal route (which represented the first step of a staged operation in five instances); in the remaining 41 patients, craniotomy was the first surgical procedure. Radical tumour resection was achieved in 40 cases, subtotal (only small tumour remnants adherent to the carotid arteries, 3rd ventricle floor or visual pathways) in nine, and only partial in the remaining three cases RESULTS: Histology demonstrated the adamantinous variant in all cases. Two surgical deaths were recorded in this series (both following a transsphenoidal approach): one secondary to uncontrollable intra-operative bleeding from the carotid artery, and the other to fulminating bacterial meningoencephalitis. Morbidity included endocrinological disturbances, namely hypopituitarism and diabetes insipidus, in more than 80% of cases, worsening of pre-operative visual deficit in six cases, and transitory neurological deficits in five cases. One late death was recorded 2 years after surgery, secondary to electrolytic imbalance although favoured by a major head trauma with subacute subdural haematoma. Nine recurrences occurred 1-8 years after surgery (three true recurrences, and six re-growths of incompletely resected tumours) that required re-operation. Twelve patients underwent radiotherapy, six after an initially incomplete tumour resection and six following relapse. One patient presented with a malignant thalamic glioma 8 years after radiotherapy. At long-term follow-up, all survivors showed good clinical condition, even though approximately 60% relied on hormone replacement, and some patients presented obesity. Diabetes insipidus has subsided in about 80% of the cases; visual deficits improved or remained stable, whereas post-operative neurological deficits subsided in all but one patient. CONCLUSION: In our experience, radical resection of CP represented the first and almost unique treatment modality. Although not insignificant, post-operative mortality and morbidity do not seem to represent a major contraindication in attempting a radical tumour resection whenever possible. On the other hand, extensive hypothalamic involvement should suggest a less aggressive attitude.

Adolescent↗

Hydatidosis of the orbit in Turkey: results from review of the literature 1963-2001.

Hydatidosis can involve almost every organ or tissue in the body via the systemic circulation, but hydatid infestation of the orbit comprises far less than 1% of the total incidence. This study investigated the data on all patients of orbital hydatid disease reported in Turkey since 1963. In this meta-analysis, a total of 25 patients were included and slowly progressive unilateral proptosis, with or without pain, was the most frequent clinical manifestation (80%). The other presenting symptoms were visual loss (48%), periorbital pain (24%), chemosis (16%), and headache (12%). The presumptive diagnosis of hydatid cyst was made on the images obtained from ultrasonography (US), computed tomography (CT) and/or magnetic resonance imaging (MRI) examinations. These diagnostic studies demonstrated a well-circumscribed cystic mass in almost all patients. Total surgical removal without rupture remains the best mode of therapy for orbital hydatid disease. The study indicates that in Turkey hydatidosis remains a serious problem, causing blindness. Orbital hydatid cyst should be included in the differential diagnosis of unilateral proptosis and visual handicap in patients from countries where hydatidosis is endemic.

Conjunctival Diseases↗

Pituitary apoplexy: a review of clinical presentation, management and outcome in 45 cases.

OBJECTIVE: To review clinical presentation, management and outcomes following different therapies in patients with pituitary apoplexy. METHODS: Retrospective analysis of case-records of patients with classical pituitary apoplexy treated in our hospitals between 1983-2004. RESULTS: Forty-five patients (28 men; mean age 49 years, range 16-72 years) were identified. Only 8 (18%) were known to have pituitary adenomas at presentation. Thirty-four (81%) patients had hypopituitarism at presentation. CT and MRI identified pituitary apoplexy in 28% and 91% cases, respectively. Twenty-seven (60%) patients underwent surgical decompression, whilst 18 (40%) were managed conservatively. Median time from presentation to surgery was 6 days (range 1-121 days). Patients with visual field defects were more likely than those without these signs to be managed surgically (p = 0.01). Complete or near-complete resolution occurred in 93% (13/14), 94% (15/16) and 93% (13/14) of the surgically treated patients with reduced visual acuity, visual field deficit and ocular palsy, respectively. All patients with reduced visual acuity (4/4), visual field deficit (4/4) and ocular palsy (8/8) in the conservative group had complete or near-complete recovery. Only 5 (19%) patients in the surgical group and 2 (11%) in the conservative group had normal pituitary function at follow up. One (4%) patient in the surgical group and 4 (22%) in the conservative group had a recurrence of pituitary adenoma. CONCLUSIONS: This large series suggests that the patients with classical pituitary apoplexy, who are without neuro-ophthalmic signs or exhibit mild and non-progressive signs, can be managed conservatively in the acute stage.

Acute Disease↗

An automated visual acuity testing computer program using the Apple II system.

We developed an automated visual acuity testing program that uses an E optotype with surrounding confusion bars. The computer software program runs on Apple II equipment and a black-and-white monitor with a five-inch screen. The program is available in response box and joystick versions. The test is suitable for children older than 31/2 to 4 years of age and for adults. A t-test on the same floppy disk as the visual acuity programs is used to test the probability that the differences in test results are greater than chance. Visual acuities of 20 normal subjects were reduced by means of plus lenses. Test-retest acuity correlation coefficients were similar for letter charts and computer-generated E optotypes, suggesting approximately equal reliability under the test conditions employed. Visual acuities of 12 amblyopic eyes were obtained by a Ferris-type letter chart and computer-generated E optotypes. The correlation coefficient was +0.93, suggesting similar test results by these two methods.

Adult↗

Computer generated visual assistance during retroperitoneoscopy.

In this paper we present a system of computer assisted surgery, the function of which is to enhance the real time feedback between the patient's body, the surgical tools and the surgeon. We show using such a system during some surgical operations--in our case, retroperitoneoscopy. After giving the requirements for such a system, we describe the components currently used in our experiments. We detail the different problems and our current solutions; photographs of an experiment carried out on a cadaver and of classical operations are shown in this paper.

Computer Simulation↗

Quantitative studies of fly visual sustained neurons.

We present a quantitative study of a neural network model [1] proposed for the sustained neurons in the fly visual system. Electrophysiological recordings of sustained neurons [2] are digitized and transferred to a computer. A numerical ordinary differential equation solver is used to simulate the model. In order to obtain an initial set of parameters, we introduce approximations to the model and obtain fits to parts of the response characteristics. These initial parameter values are then refined by optimization routines. The model is compared to data in 4 different experimental paradigms and in general is in good agreement with data. We conclude that the simplified versions of temporal and spatial adaptation mechanisms of the model capture the essential features of the dynamics of sustained neurons and that the refinement of the model requires further experimental studies to elucidate the number of stages involved in temporal adaptation as well as the precise shape of the relationship between the membrane potentials and the spike frequency for the sustained neurons.

Action Potentials↗