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At least 199 records · Page 11Linked to original sources

Clinical applications of the Shack-Hartmann aberrometer.

The efficacy of the Shack-Hartmann technique for measuring the optical aberrations of the eye was evaluated for four classes of clinical conditions associated with optically abnormal eyes. These categories (with specific examples) are: anomalies of the tear film (dry eye), corneal disease (keratoconus), corneal refractive surgery [laser-assisted in situ keratomileusis (LASIK)], and lenticular cataract. We show that in each of these cases, it is possible to obtain at least a partial topographic map of the refractive aberrations of the patient's eyes, but severe losses of data integrity can occur. We further show that the Shack-Hartmann aberrometer provides additional information about the eye's imperfections on a very fine spatial scale (< 0.4 mm) which scatter light and further degrade the quality of the retinal image. Taken together, spatial maps of the variation of optical aberrations and scatter across the eye's entrance pupil represents an improved description of the optical imperfections of the abnormal eye.

Cataract↗

Multiple systemic and periocular malformations associated with the fetal hydantoin syndrome.

Anticonvulsants remain necessary during pregnancy and the removal of such drugs is not recommended. However, on the available evidence, the physician may expect an increased risk of malformation including eye abnormalities as has been outlined. The abnormalities include growth deficiencies and delayed motor/mental development together with dysmorphic features, the most common of which seems to be cleft lip/cleft palate. Additionally, many of these children suffer from eye abnormalities including hypertelorism, ptosis, strabismus, epicanthal folds, and in this case abnormalities of the lacrimal apparatus.

Abnormalities, Multiple↗

Eye movement abnormalities during reading in patients with Alzheimer disease.

OBJECTIVE: This goal of this study was to evaluate reading ability by assessing eye movements during reading among patients with Alzheimer disease (AD) compared with normal elderly controls. BACKGROUND: Reading is disturbed in patients with AD. These patients may have changes in reading ability early in the course of their disease before clinical alexia or abnormalities are apparent on standard reading tasks. METHOD: Reading competence was evaluated by recording eye movements during reading in 14 patients with mild to moderate clinically probable AD and 14 age- and education-matched controls. RESULTS: All patients with AD could recognize letters and words and could understand written material of similar difficulty. Despite successful reading comprehension among the patients with AD, their oculographs showed slowed reading and irregular eye movements. Compared with controls, the patients with AD did not differ in saccadic duration; however, they had significantly longer fixation times, more forward saccades per line of text, and more saccadic regressions. In addition, increased reading difficulty significantly correlated with a scale of dementia severity in the patients with AD. CONCLUSIONS: This pattern of eye movements corresponds to increased text difficulty and probably represents difficulty with lexical-semantic access in AD. These results suggest that disordered eye movements can signal difficulties in reading ability in AD even before complaints of reading difficulty or abnormalities on reading tests and may be a means of identifying linguistic impairment early in this disorder.

Aged↗

The Arden gratings in optometric practice.

The use of the Arden gratings (AO contrast sensitivity system) in optometric practice is evaluated. A total of 320 patients presenting for eye examination were screened with the gratings. Sixty-four eyes (10%) gave abnormal grating scores although results from conventional examination techniques revealed no abnormality. Of the 110 abnormal eyes detected by routine examination techniques, 8 presented with normal grating scores, 6 with "borderline suspect" scores and 96 with abnormal scores. Used in isolation, the failure rate of the Arden gratings to detect ocular abnormality in the patient population was 1.3% and the "false positive" referral rate was 10%.

Adolescent↗

Regional fine mapping of the beta crystallin genes on chromosome 22 excludes these genes as physically linked markers for neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disease, characterized by the development of bilateral vestibular schwannomas. The NF2 gene has been assigned to chromosome 22. Cataract and other eye abnormalities are frequently seen in NF2 patients. The specific association of eye abnormalities and NF2 might be caused by a genetic change on chromosome 22 that affects both the NF2 gene and a physically linked crystallin gene. In order to test this hypothesis, we regionally localized the known crystallin genes (i.e. CRYBB2, CRYBB2P1, CRYBB3, and CRYBA4) on chromosome 22. Crystallin gene-specific probes were hybridized to an extended panel of human x rodent somatic cell hybrids containing various portions of chromosome 22. It was found that all crystallin genes map to a very small region on chromosome 22 that is physically separate from the NF2 gene region by at least 160 kb of DNA. In addition, we found that the beta B crystallin genes (CRYBB2, CRYBB2P1, and CRYBB3) are clustered on a 300 kb SacII fragment and that the beta A4 crystallin gene (CRYBA4) is not part of this cluster. We conclude that the ocular manifestations in many NF2 patients are probably not the primary consequence of rearrangements on chromosome 22 that involve both the NF2 gene and a nearby beta crystallin gene.

Animals↗

Walker-Warburg syndrome.

Walker-Warburg Syndrome (WWS) is a rare form of autosomal recessive congenital muscular dystrophy associated with brain and eye abnormalities. WWS has a worldwide distribution. The overall incidence is unknown but a survey in North-eastern Italy has reported an incidence rate of 1.2 per 100,000 live births. It is the most severe form of congenital muscular dystrophy with most children dying before the age of three years. WWS presents at birth with generalized hypotonia, muscle weakness, developmental delay with mental retardation and occasional seizures. It is associated with type II cobblestone lissencephaly, hydrocephalus, cerebellar malformations, eye abnormalities and congenital muscular dystrophy characterized by hypoglycosylation of alpha-dystroglycan. Several genes have been implicated in the etiology of WWS, and others are as yet unknown. Several mutations were found in the Protein O-Mannosyltransferase 1 and 2 (POMT1 and POMT2) genes, and one mutation was found in each of the fukutin and fukutin-related protein (FKRP) genes. Laboratory investigations usually show elevated creatine kinase, myopathic/dystrophic muscle pathology and altered alpha-dystroglycan. Antenatal diagnosis is possible in families with known mutations. Prenatal ultrasound may be helpful for diagnosis in families where the molecular defect is unknown. No specific treatment is available. Management is only supportive and preventive.

Abnormalities, Multiple↗

[A case of "ping-pong ball eye movement (author's transl)].

We experienced a rare and peculiar eye movement in a comatose patient with ruptured intracranial aneurysm. The patient's eyes moved quickly and irregulary from one extreme position to the other with whirling and bounding components. Such abnormal eye movement occasionally halted, but abruptly reappeared. We named this abnormal eye movement which had never been reported before, "ping-pong eye movement". Neuropathological study revealed a subarachnoid hemorrhage and the diffuse infarction in the right remporal lobe, and a smal clot in the fourth ventricle without specific findings in the brainstem and the cerebellum. Consideration was made that the hemorrhage in the fourth ventricle resulted in a hyper-irritable state in the fastigial nuclei, from which the abnormal discharges were driven to the reticular formation, the vestibular nuclei, the MLF, and the oculomotor complexes. We conclude that this "ping-pong" ball eye movement" might be the appearance of epilepsy in the eyes, due to the epileptogenic focus of the fastigial nuclei.

Eye Movements↗

Multiple system atrophy manifested as dizziness and imbalance: a report of two cases.

Multiple system atrophy (MSA) is a progressive neurodegenerative disease of undetermined origin that occasionally manifests as dizziness and imbalance. It is not often considered in clinical situations, especially not by neuro-otological consultants. Hence, we report our recent experience with two cases of MSA. One is that of a 62-year-old man with MSA with a predominant cerebellar feature, and the other is that of a 72-year-old man with MSA with a predominant parkinsonian feature. The results of the syncopic study correlated with orthostatic hypotension. The neuro-otological study in both patients revealed an abnormal eye tracking test, abnormal optokinetic nystagmus test and loss of visual suppression in the caloric nystagmus. These indicate that the central vestibular system, e.g., the cerebellum or brain stem, is affected by MSA, contributing to dizziness and imbalance. Therefore, diagnosis of MSA should be kept in mind by neuro-otological consultants when dealing with patients with dizziness and imbalance, especially when this is accompanied by orthostatic hypotension.

Aged↗

Targeted disruption of Col8a1 and Col8a2 genes in mice leads to anterior segment abnormalities in the eye.

Collagen VIII is localized in subendothelial and subepithelial extracellular matrices. It is a major component of Descemet's membrane, a thick basement membrane under the corneal endothelium, where it forms a hexagonal lattice structure; a similar structure, albeit less extensive, may be formed in other basement membranes. We have examined the function of collagen VIII in mice by targeted inactivation of the genes encoding the two polypeptide subunits, Col8a1 and Col8a2. Analysis of these mice reveals no major structural defects in most organs, but demonstrates that type VIII collagen is required for normal anterior eye development, particularly the formation of a corneal stroma with the appropriate number of fibroblastic cell layers and Descemet's membrane of appropriate thickness. Complete lack of type VIII collagen leads to dysgenesis of the anterior segment of the eye: a globoid, keratoglobus-like protrusion of the anterior chamber with a thin corneal stroma. Descemet's membrane is markedly thinned. The corneal endothelial cells are enlarged and reduced in number, and show a decreased ability to proliferate in response to different growth factors in vitro. An important function of collagen VIII may therefore be to generate a peri- or subcellular matrix environment that permits or stimulates cell proliferation.

Animals↗

Childhood retinoblastoma.

Childhood retinoblastoma was studied in a period of January 1980 to December 1988. Forty six patients were included consisting of 21 males (45.65%) and 25 females (54.35%). Most of those patients (76.08%) were in the age group of 0-5 years. The main complaint was protrusion of eyes, found in 42 patients (91.30%). Bone marrow examination was done in 24 patients, and 52.17% of them showed sign of metastasis. Thirty seven cases had unilateral retinoblastoma (80.43%). The statistical analysis indicated no significant differences in sex and age, site of tumor (left or right eye), abnormality of the eyes, bone marrow involvement, protrusion of the eyes either unilateral or bilateral. Heredity was found in one patient (2.17%). The main treatment was radiation in 25 patients (50.43%).

Adolescent↗

[Three cases of involuntary movements following pontine hemorrhage].

We reported three cases with involuntary movements following pontine hemorrhage. All cases had various symptoms indicating brain-stem lesions, but the consciousness and motor functions were not severely disturbed. CT scans showed a small hematoma localized in unilateral pontine tegmentum in all cases. Intention tremor developed six to ten months after the hemorrhage when the initial neurological symptoms were almost relieved. Electromyogram (EMG) showed a rhythmic 3-4 Hz alternating or synchronized tremor pattern which was induced by finger-nose test and arm stretching. In one case which had showed bilateral horizontal gaze palsy indicating bilateral PPRF involvement in the acute stage, spontaneous vertical nystagmus was observed when the tremor developed. Electronystagmogram (ENG) and its differential calculus showed a pendular nature of the eye movement. This abnormal eye movement did not disappear while the patient was asleep. This case also developed a palatal myoclonus in the chronic stage. Magnetic resonance images (MRI's) obtained one to three years after the hemorrhage revealed a lesion localized in hemipontine tegmentum. The responsible lesion of these involuntary movements was thought to be located in pontine tegmentum from the MRI findings. The functional Prognosis of small hemorrhage in unilateral pontine tegmentum is generally good, but care should be taken for the possibility of late development of various types of involuntary movement.

Cerebral Hemorrhage↗