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Delayed visual maturation: pupillary responses implicate subcortical and cortical visual systems.

Vision in very early infancy is probably subserved by subcortical pathways, with many cortical processes only fully emerging by 3 months of age. The improvement of vision in delayed visual maturation (DVM) occurs around this time, and this has given rise to the suggestion that the condition may have a subcortical basis that resolves with the appearance of cortical function. To explore further the role of cortical and subcortical visual systems in DVM we studied the visual development in identical twins, one of whom had type 1b DVM. Two non-invasive methods of investigating visual pathway function were employed: the acuity card procedure (a behavioural response) and luminance and grating pupillometry. While the former reflects both subcortical and cortical function and can be detected at birth, pupil responses to gratings reflect cortical activity alone and normally become measurable at 1 month of age. Development of both behavioural and pupillary responses was delayed in DVM, indicating that although the underlying defect is primarily subcortical, secondarily it delays the emergence of cortically mediated responses. The observed rapidity of improvement--over a very few days and within a narrow age range--suggests a discrete rather than a widespread structural abnormality, the improvement of which is closely linked to postmenstrual age.

Failure to Thrive↗

Using 3D computer simulations to enhance ophthalmic training.

PURPOSE: To develop more effective methods of demonstrating and teaching complex topics in ophthalmology with the use of computer aided three-dimensional (3D) animation and interactive multimedia technologies. METHODS: We created 3D animations and interactive computer programmes demonstrating the neuroophthalmological nature of the oculomotor system, including the anatomy, physiology and pathophysiology of the extra-ocular eye muscles and the oculomotor cranial nerves, as well as pupillary symptoms of neurological diseases. At the University of Vienna we compared their teaching effectiveness to conventional teaching methods in a comparative study involving 100 medical students, a multiple choice exam and a survey. RESULTS: The comparative study showed that our students achieved significantly better test results (80%) than the control group (63%) (diff. = 17 +/- 5%, p = 0.004). The survey showed a positive reaction to the software and a strong preference to have more subjects and techniques demonstrated in this fashion. CONCLUSION: Three-dimensional computer animation technology can significantly increase the quality and efficiency of the education and demonstration of complex topics in ophthalmology.

Computer Simulation↗

"Hemicrania episodica"--a new type of headache or a pre-chronic stage of hemicrania continua?

For seventeen years, a young man suffered from headaches of one to three days duration occurring once every six or seven days and totally disappearing between episodes. These were strictly unilateral (always on the left side), and were absolutely responsive to indomethacin. They differ clinically from the other two indomethacin-responsive headaches described up to now: Hemicrania Continua (HC) and Chronic Paroxysmal Hemicrania (CPH). He has a sister suffering from HC. Similar to HC, but unlike CPH, topical tyramine in our patient's eyes resulted in anisocoria before, but not after, indomethacin treatment. Our case differs from HC, however, in its time pattern; it could either be a pre-chronic stage of HC or a new type of headache. It seems unlikely that a time pattern that has remained unchanged for 17 years will become continuous, as in HC, in the future, and thus it is possible that our patient represents a case of a new type of headache that we propose to name "Hemicrania Episodica." In any case, it seems probable that this type of headache, although clinically different, may share a common pathogenic basis with HC.

Adult↗

Oculocephalic sympathetic dysfunction in posttraumatic headaches.

Oculocephalic sympathetic functions were assessed in five patients with posttraumatic headaches using the thermoregulatory sweat test and biochemical pupillary responses. Four patients demonstrated bilateral sympathetic dysfunction following whiplash injury, and one patient demonstrated unilateral sympathetic dysfunction following forehead injury. Biochemical pupillary responses were diagnostic in the early posttraumatic period, while the thermoregulatory sweat test was abnormal up to 56 months following the injury. This study documents serious injury to the cervical sympathetic nerves in patients with posttraumatic headaches following whiplash injury, and shows the reliability of the thermoregulatory sweat test in identifying patients with long-term oculocephalic sympathetic dysfunction. It also shows dissociated postganglionic cranial sympathetic dysfunction. Our experience and a review of the pertinent literature shows no convincing clinical or experimental evidence to establish oculocephalic sympathetic dysfunction as a direct cause of head pain, but it may exert an effect on cephalic pain through the trigeminovascular system.

Adult↗

Pupillary function in multiple sclerosis.

Eighteen MS patients with visual acuity of 20/30 or better and without recent visual complaints, and 14 age- and sex-matched controls were studied by TV pupillography. The response amplitude and the maximum rate of pupillary constriction or dilation of the light, dark, accommodation and ciliospinal reflexes were unchanged. The latency of the pupillary light response (PLR), however, was prolonged and closely related to walking performance (R = 0.76; p less than 0.001). No relationship was established between PLR latency and previous history of optic neuritis or latency of the VEP. It is concluded that MS patients with preserved visual acuity have only discrete autonomic pupillary disturbances and that the PLR delay is related to disease progression.

Adult↗

Acute zonal occult outer retinopathy.

Retinal photoreceptor dysfunction is an uncommon and often unrecognized cause of acute visual loss. Acute zonal occult outer retinopathy (AZOOR) has been reported to cause cone and rod dysfunction. Patients with AZOOR may present with normal visual acuity, normal fluorescein angiography, and a normal fundus examination despite severe loss of visual field. A healthy young white female presented with acute, unilateral loss of visual field and an afferent pupillary defect, but normal visual acuity, color vision, fundus examination, and fluorescein angiogram. A pattern visual evoked potential was normal, but an electroretinogram showed a unilateral peripheral photoreceptor dysfunction consistent with the diagnosis of AZOOR. Ophthalmologists should be aware of the diagnosis of AZOOR and should consider an ERG in the evaluation of any patient with unexplained visual field loss even in the presence of normal visual acuity, color vision, fluorescein angiography, or retinal examination.

Acute Disease↗

The use of pupillometry in joint and connective tissue diseases.

The central and peripheral nervous systems are variably affected in the rheumatic diseases. Automated standardized infrared pupillometry allows the safe, noninvasive assessment of the pupillary innervation. Pupillometry has already been used in studying the autonomic nervous system (ANS) in various rheumatic diseases. In systemic lupus erythematosus, the irideal parasympathetic branch of ANS was more affected then the sympathetic branch. In Sjögren's syndrome, signs of pupillary parasympathetic denervation have been reported. In rheumatoid arthritis, pupil parasympathetic dysfunction has been shown to correlate with ocular dryness. In systemic sclerosis (SSc), both sympathetic and parasympathetic irideal impairment have been demonstrated. Beside providing autonomic innervation, sensory nerves fibers are able to control iris diameter. Exogenous ocular instillation of substance P (SP), a sensory neuropeptide, can determine an omathropine-resistant, non-cholinergic myosis, acting on specific receptors present on the iris sphincter muscle. We first studied pupillary SP-ergic responsiveness in SSc, evaluating substance P (SP)-stimulated pupillary diameters by pupillometry. A higher basal and SP-stimulated myosis was found in lSSc versus both dSSc and controls, whereas no differences existed between dSSc and controls. From the literature, the pupillary parasympathetic nervous system seems to be more affected than the sympathetic branch of ANS in the rheumatic diseases characterized by an inflammatory status. However, we found in SSc both sympathetic and parasympathetic pupil control to be equally impaired. From our experience, we conclude that pupillary nervous control is differently affected in the two subsets of SSc, and that the SP-ergic system seems to be impaired only in lSSc.

Autoimmune Diseases↗

Neurological problems presenting to an ophthalmic casualty department.

All patients presenting with neurological problems to an eye hospital casualty department over one year were prospectively studied. A total of 119 patients were identified. The most frequent diagnoses were retrobulbar neuritis (34; 28.5%), sixth cranial nerve palsy (22; 18.5%), third cranial nerve palsy (15; 12.6%) and Adie's tonic pupil (11; 9%). Cranial nerve palsies were most commonly due to diabetes or hypertension (16; 43.2%). Only one intracranial aneurysm was found. Symptoms included blurred vision (52; 43.7%), binocular diplopia (51; 42.8%), and eye pain (27; 22.7%). Fifty patients (42.0%) were referred by a general medical practitioner. Twenty-two (18.5%) were admitted to hospital. Forty-nine skull X-rays were requested and all were normal. Twenty-nine chest X-rays were requested. One (3.4%) showed an abnormality (carcinoma of the bronchus). Neurological patients present to ophthalmic casualty departments because of ophthalmic symptoms. Ophthalmic casualty officers are able to make working diagnoses and to direct patients appropriately. The use of investigations in the casualty department, however, is unlikely to be productive.

Adolescent↗

Active iris mechanics and pupillary block: steady-state analysis and comparison with anatomical risk factors.

Primary angle-closure glaucoma arises when the iris physically obstructs outflow of aqueous humor, increasing the intraocular pressure and damaging the optic nerve. Pupillary block, the predominant mechanism for angle closure, is believed to be driven by mechanical interaction between the aqueous humor and the iris. We performed steady-state simulations of this coupled fluid-solid system, including an active sphincter to control pupil constriction. Model results compared favorably against Mapstone's pupil-blocking force analysis. We also evaluated anatomical risk factors and quantified their contributions to pupillary block and angle closure. The results showed that greater lens curvature and shorter iris-zonule distance contribute significantly to pupillary block and the associated narrowing of the angle. Surprisingly, the model predicted that maximum pupillary block and angle closure occur at the minimum pupil dilation, contradicting the clinical observation that angle closure is most severe in dark conditions. This discrepancy suggests the involvement of one or more phenomena not captured by our current model.

Animals↗

Consistency of microvascular and autonomic abnormalities in diabetes.

The progression of early measures of microvascular disease and autonomic neuropathy were studied in a group of 81 children with insulin dependent diabetes mellitus over a mean interval of 4.2 years. Repeated measurements were made of blood pressure, albumin excretion, joint mobility, and pupillary dilatation in darkness. Over the years between the first and the second study, systolic and diastolic blood pressure showed positive tracking correlations (r = 0.38 and r = 0.32) with a small but significant deviation from normality; albumin/creatinine ratio was significantly increased (0.79 v 0.55); a greater number of children were identified in the second study as having limitation of mobility of the fifth metacarpophalangeal joint; and pupillary dilatation in darkness significantly decreased (61.5% v 62.9%); 62% of the children with one or more abnormal measurements in the first study were found to have measurements outside the normal ranges in the second study, indicating a consistency in observations over time. It remains to be seen with what accuracy these measurements predict adult onset clinical disease.

Adolescent↗