Peripheral neural circuits regulating IOP?

The peripheral nervous system is classically separated into a somatic division containing both afferent and efferent pathways and an autonomic division composed of efferents only. The somatic afferent division is divided in A- and B-neurons. The B-neurons are supposed to be autonomic afferents as part of a reflex system involved in homeostasis. Recent data obtained by neuronal tracing and immunohistochemical experiments concerning the eye related peripheral nervous system endorse the existence of these peripheral reflex systems. Somatic afferents of trigeminal origin synaptically innervate parasympathetic neurons in the pterygopalatine ganglion. This probably represents a pathway mediating autonomically regulated ocular activity in response to sensory stimulation. In addition, it has been hypothesized that trigeminal sensory nerve fibres have an efferent function in response to noxious stimuli e.g. the ocular injury response. Sympathetic nerve fibres originating in the superior cervical ganglion course through the trigeminal and pterygopalatine ganglion without forming direct synaptic contacts. These fibres, however, contain clusters of vesicles suggesting some kind of interneural communication. Parasympathetic nerve fibres of pterygopalatine origin course through the ciliary ganglion. These nerve fibre terminals also contain clusters of vesicles without direct synaptic contacts. Experimental data concerning the distribution of neuropeptides revealed a more detailed knowledge of the anterior eye segment innervation. These experimental data are subject to some debate. The pros and cons of different techniques are discussed. Neural circuits regulating IOP have long been postulated. The possible role of peripheral reflex systems in the regulation of IOP is discussed.     

Classic Triad of Ross Syndrome with Diffuse Autonomic Dysfunction and Positive Antinuclear Antibody Titre

A 23-year-old woman presented with left-sided hemifacial flushing and hyperhidrosis with right-sided anhidrosis. Examination showed a dilated right pupil and a slightly constricted left pupil with bilateral sluggish vermiform movements and light-near dissociation. A neurological examination showed absent deep tendon reflexes. Magnetic resonance imaging of the brain, neck, and spine was normal. These features are consistent with Ross syndrome. Ross syndrome is characterized by Holmes-Adie syndrome (tonic pupil, areflexia of deep tendon reflexes) and segmental anhidrosis and lies within the spectrum of peripheral, partial autonomic dysfunction syndromes together with harlequin and Horner syndromes. In addition to the classic triad of Ross syndrome, the patient had diffuse, systemic autonomic dysfunction with a positive antinuclear antibody test and a positive ribonucleoprotein antibody titre.     

A follow-up study of pupillary dynamics in patients with ocular hypertension and primary open angle glaucoma

The authors previously reported light reflex abnormalities and adrenergic supersensitivity to topical epinephrine (DPE; dipivalyl epinephrine) of the pupils in patients with ocular hypertension (OH) and those with primary open angle glaucoma (POAG). In this investigation, we attempted to reconfirm pupillary light reflex abnormalities we reported previously, and to investigate the relationship between the normotensive effect of 0.1% DPE and the pupillary light reflex abnormalities in OHs and POAGs. A total of 11 OHs and 11 POAGs under good oculotensive control with neither mydriatics nor miotics were examined. They were measured by an open-loop photically stimulated infrared videopupilogram, and were neurologically diagnosed by comparing the simulated patterns of the light reflex made by topical autonomic agents. When we considered the progress of the stage of POAG, both OHs and POAGs showed satisfactory reproducibility of pupillary light reflex abnormalities. Other cases in which light reflexes altered, showed worsening of the visual field deficit, which was prominent when OHs developed into POAG. OHs with significant reduction of intraocular pressure (IOP) after topical administration of 0.1% DPE showed various kinds of abnormal pupillary light reflexes. On the contrary, cases with little reduction of IOP after 0.1% DPE instillation showed normal pupillary light reflexes in OHs and afferent pupillary defect on POAGs.     

The nature of reverse phase reflex eye movement

The unusual phenomenon of reverse phase reflex eye movement was first described by Ishikawa. In this study the reflex frequency response was examined by electrooculography. In typical cases a reflex was observed by repeated forced duction up to 9 Hz. As a result it was postulated that proprioception is usually involved in reverse phase reflex eye movement, because visual eye movement cannot respond to a movement beyond 1 Hz. When the lag-times between the peaks of forced duction in one eye and those of the reflex movement in the other were measured, they were almost zero or even negative at high frequencies of forced duction as 6 and 9 Hz. This phase advance of the reflex movement was explained only when the receptor of the reflex had a dynamic response, because 90 degrees phase advance results in a reflex through such a receptor. The primary ending of muscle spindle represents such a receptor. The magician's forceps phenomenon as first discovered by Mitsui in exotropia is supposed to be a blocking reflex through the tendon organ. The transmission lag-times of both reflexes can be as short as 20 msec, but must be slightly longer to consider them to be monosynaptic.     

Skiaskopie Multimediales Lernprogramm auf CD

INTRODUCTION: Retinoscopy is a classical method to determine the refraction of the eye by observing the dynamics of reflexes and varying the experimental parameters until a specific reflex (neutralisation point) is observed. Until now photographs and geometrical drawings of the different ray tracings have been commonly used to visualise the pathways. We intend to use new media such as video and CD to offer the students a better understanding of retinoscopy. METHODS: With the aid of appropriate experimental devices, retinoscopal reflexes of artificial and human eyes are recorded on video. The video sequences are converted in computer files and together with computer animations of the geometrical ray tracings, text files and audio sequences, they are stored in a suitable CBT-programme. RESULTS: The systematically prepared computer compatible contents offer a modern individually controllable method to perform the instruction programme by multimedia. The CBT-program and the specific files are stored on CDs or can be distributed on the internet. A collection of retinoscopy records of patients, some with extraordinary reflex phenomena is also available. DISCUSSION: Video and animation procedures are more suitable for matching the dynamic phenomena on retinoscopy than photographs or drawings as they offer a more direct basis for understanding of the sometimes difficult processes of retinoscopy. The collection of recorded reflexes also offers the direct visualised experience of particular patient findings such as the appearance in context of implanted spherical and aspherical intraocular lenses or the irregularities of the optic system of eyes with keratokonus.     

眼外伤与眼心反射

目的　了解眼外伤对心脏的间接影响 ,评估创伤性眼心反射的临床意义。方法　回顾性分析 65 7例眼外伤住院患者的血压、脉博及部分心电图变化。结果　伤后 1小时内首次平均动脉压低于 70mmHg者 7例 ( 2 2 7% ) ( 1mmHg =0 13 3kPa) ;首次脉搏较基础频率减慢者 14例 ( 4 5 4% ) ,二者同步 1例。异常心电图 2 17例 ( 5 6 66% ) ,眼挫伤比眼烧伤发生异位心律失常明显增多 (P <0 0 5 ) ;窦性心动过缓 ,异位心律失常与ST -T异常心电图以 40岁以上年龄段多见 (P <0 0 5 )。结论　眼外伤导致血压下降甚微且与脉搏减慢无同步关系 ;心脏植物神经功能的稳定性受到伤情影响 ;窦性心动过缓、异位心律失常及ST -T异常发生与年龄段密切相关。应加强创伤性眼心反射的防治 ,注重 40岁以上年龄段     

The light that leaks: Brückner and the red reflex

The Brückner test utilizes the ophthalmoscope to assess symmetry of binocular fixation by qualitative comparison of the red reflexes. Accurate fixation by the patient's eye on the ophthalmoscope light causes darkening of the red reflex, previously believed due to macular pigmentation. By desgning and experimenting with a beamsplitter ophthalmoscope, we have demonstrated that if the patient's fovea is not exactly conjugate to the light source, light from the retina spills past the light source at the ophthalmoscope mirror into the examiner's eye, creating the red reflex. Therefore, binocular asymmetry of this conjugate relationship, whether due to anisometropia or strabismus, creates asymmetrical red reflexes. Understanding this principle of conjugacy is critical to optimal utilization of the red reflex in routine clinical examination as well as in microsurgery.     

Unusual Presentation of Spasm of Near Reflex Mimicking Large-Angle Acute Acquired Comitant Esotropia

We report the case of an 11-year-old boy who presented with sudden esotropia, binocular diplopia, and blurred vision. The patient was neurologically normal. He had a large, constant, comitant, alternating esotropia associated with minimal accommodative spasm. Ocular motility and pupillary reactions were normal. He was diagnosed to have spasm of the near reflex presenting as acute onset of esotropia. The esotropia was persistent despite treatment and eventually resolved with prolonged cycloplegic therapy. This unusual case illustrates that spasm of the near reflex can have unique and variable presentations. Spasm of the near reflex needs to be considered in the differential diagnosis of every case of acute, acquired, comitant esotropia. This is the first case of spasm of the near reflex where persistent esotropia is reported in the absence of any neurological disorder.     

The autonomic control of accommodation and implications for human myopia development: a review

Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork-induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression.     

Relative Afferent Pupillary Defects in Homonymous Visual Field Defects Caused by Stroke of the Occipital Lobe Using Pupillometer

Relative afferent pupillary defects (RAPD) may be detected in patients with occipital lobe lesions. However, no previous report has used an objective technique to record the abnormal pupillary light reflex in such cases. Therefore, we measured the pupillary light reflex objectively in 15 patients with homonymous visual field defects (HVFD) due to occipital stroke using a new pupillometer. This study detected significantly smaller and slower pupillary light reflexes in the contralateral eyes than in the other eyes, which is equivalent to the presence of RAPD in patients with HVFDs caused by retrogeniculate lesions using an objective technique. Our results confirmed those of the previous reports using the swinging flashlight test more objectively.     

Tonic accommodation: a review I. Basic aspects

In the absence of an adequate visual stimulus, accommodation adopts an intermediate position of ∼ I D. Since this position was believed to reflect the level of tonic innervation to the ciliary muscle, this response has been termed tonic accommodation (TA). Part 1 of this review will consider various aspects of this parameter, including its reference to closed-loop accommodative function and autonomic physiology. In addition, both the methods of measurement and appropriate terminology for this function will be discussed. It is concluded that the response, which becomes apparent under so-called 'stimulus-free' conditions, in fact probably represents an aggregate response resulting from multiple, non-optical stimuli. Thus the designation tonic accommodation may not be appropriate, since it fails to describe accurately the heterogeneous composition of the stimulus-free accommodative response. An associated paper (to be published as part II of this review) will examine accommodative adaptation and both clinical aspects of TA and adaptation of TA.     

Chronic bilateral common carotid artery occlusion: a model for ocular ischemic syndrome in the rat

Background Ocular ischemic syndrome is a devastating eye disease caused by severe carotid artery stenosis. The reduction of blood flow produced by bilateral common carotid artery occlusion (BCCAO) of rats for 7 days induces events related to gliosis with no evident histological damage. However, retinal degeneration and cellular death occur after 90 days of BCCAO. Our purpose has been to investigate the effects of BCCAO for 30 days in the retina of adult rats. Methods Adult Wistar rats were submitted to BCCAO or sham surgery. Both direct and consensual pupillary light reflexes were investigated before and after surgery, everyday for the first week and weekly for 30 days. After 1 month, eyes were enucleated and embedded in paraffin. The retinal ganglion cell (RGC) density and thickness of the internal plexiform (IPL), internal nuclear, outer plexiform, and outer nuclear layers were estimated. Results Four rats of the BCCAO group (50%) lost the direct pupillary reflex in both eyes, three rats (37%) lost this reflex in one eye, and only one (13%) maintained it in both eyes. RGC density (cells/mm) was diminished in the BCCAO group, and a significant decrease was found in the total retina and IPL thickness; however, no changes were evident in the other layers. BCCAO pupillary-reflex-negative rats presented with a significant decrease in total retinal thickness and retinal ganglion cell density compared with the sham group. Both BCCAO pupillary-reflex-positive) and -negative rats showed a decrease in IPL compared with the sham group. Conclusion This study demonstrates that BCCAO for 30 days induces functional and morphological damage to the retina with loss of the pupillary reflex and a decrease in IPL thickness and RGC number. We suggest that this protocol might be used as a model for ocular ischemic syndrome in the rat.     

BOOK REVIEWS

Book reviewed in this article: Dictionary of Eye Terminology (2nd Edition): B Cassin, SAB Solomon. ML Rubin (ed) Atlas of Primary Eyecare Procedures: M Fingeret L Casser HT Woodcome The Ocular Fundus: Methods of Examination and Typical Findings (5th Edition) Professor Arno Nover Clinical Procedures for Ocular Examination: NB Carlson D Kurtz DA Heath C Hines Differential Diagnosis of Eye Diseases Hans Pau New methods of sensory visual testing M Walland AA Sadun     

The influence of ocular surgery for lacrimal secretion

Dry eye syndrome remains a constant health problem while more and more patients are being involved and final data concerning the etiopathology is still missing. This study investigates the hypothesis that ocular surgery inflicts damage on the tear production (regarding quantity, quality or the compositional aspect). Ocular symptoms were registered with the help of a questionnaire. Lacrimal tests were applied before and after surgery at 6 weeks. Basic and reflex tear secretion was differentiated through Schirmer tests and tear quality was assessed with BUT. Proteomic analysis (global proteins, electrophoresis) and conjunctival biopsy was realized before surgery. Open eye surgery altered tear secretion in 91% of the 22 patients examined.     

Anterior segment manifestations of human immunodeficiency virus/acquired immune deficiency syndrome

Ocular complications are known to occur as a result of human immunodeficiency virus (HIV) disease. They can be severe leading to ocular morbidity and visual handicap. Cytomegalovirus (CMV) retinitis is the commonest ocular opportunistic infection seen in acquired immune deficiency syndrome (AIDS). Though posterior segment lesions can be more vision-threatening, there are varied anterior segment manifestations which can also lead to ocular morbidity and more so can affect the quality of life of a HIV-positive person. Effective antiretroviral therapy and improved prophylaxis and treatment of opportunistic infections have led to an increase in the survival of an individual afflicted with AIDS. This in turn has led to an increase in the prevalence of anterior segment and adnexal disorders. Common lesions include relatively benign conditions such as blepharitis and dry eye, to infections such as herpes zoster ophthalmicus and molluscum contagiosum and malignancies such as squamous cell carcinoma and Kaposi's sarcoma. With the advent of highly active antiretroviral therapy, a new phenomenon known as immune recovery uveitis which presents with increased inflammation, has been noted to be on the rise. Several drugs used in the management of AIDS such as nevirapine or indinavir can themselves lead to severe inflammation in the anterior segment and adnexa of the eye. This article is a comprehensive update of the important anterior segment and adnexal manifestations in HIV-positive patients with special reference to their prevalence in the Indian population.     

Macular reflexes in optic atrophy

We investigated the annular reflex of the macula and the foveal reflex in 14 eyes with various degrees of optic atrophy by means of red-free fundus photographs. The patients ranged in age from 13 to 34 years (mean age, 25.9 years). We compared our observations with data obtained from 51 age-matched normal eyes. Optic atrophy was found to be associated with changes in the reflexes of the macular area. Alterations occurred in all eight eyes that had visual acuities of 20/50 or worse. Changes in the annular reflex of the macula were more significant in younger patients (less than or equal to 25 years of age) than in older patients. In the younger group, the annular reflex was blunt, distorted, and fragmented, and showed an irregular extension toward the foveal area, whereas in the old group it showed less specific attenuation. Fading of the foveal reflex was observed in both groups. Changes in the retinal reflexes of these patients result from alterations in the ganglion cell and nerve fiber layer and should be included among the signs of optic atrophy. They can help determine the extent of optic atrophy and can be useful clinical clues in children whose optic disks are difficult to examine. They should not be mistaken for signs of associated primary retinal disorders.     

Visual signs and symptoms of multiple system atrophy

Multiple system atrophy (MSA) is a rare movement disorder and a member of the ‘parkinsonian syndromes’, which also include Parkinson's disease (PD), progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB) and corticobasal degeneration (CBD). Multiple system atrophy is a complex syndrome, in which patients exhibit a variety of signs and symptoms, including parkinsonism, ataxia and autonomic dysfunction. It can be difficult to separate MSA from the other parkinsonian syndromes but if ocular signs and symptoms are present, they may aid differential diagnosis. Typical ocular features of MSA include blepharospasm, excessive square‐wave jerks, mild to moderate hypometria of saccades, impaired vestibular‐ocular reflex (VOR), nystagmus and impaired event‐related evoked potentials. Less typical features include slowing of saccadic eye movements, the presence of vertical gaze palsy, visual hallucinations and an impaired electroretinogram (ERG). Aspects of primary vision such as visual acuity, colour vision or visual fields are usually unaffected. Management of the disease to deal with problems of walking, movement, daily tasks and speech problems is important in MSA. Optometrists can work in collaboration with the patient and health‐care providers to identify and manage the patient's visual deficits. A more specific role for the optometrist is to correct vision to prevent falls and to monitor the anterior eye to prevent dry eye and control blepharospasm.     

Pupil cycle time and early autonomic involvement in ocular leprosy.

Ocular complications of leprosy patients often develop insidiously and with few if any symptoms. This study involves measurement of the pupil cycle time (PCT) to evaluate the autonomic nerve system of the iris to determine the presence of subclinical intraocular involvement. The study included 19 lepromatous (LL), 19 borderline lepromatous (BL), and five borderline tuberculoid (BT) leprosy patients and involved 25 healthy volunteers, 10 patients with pulmonary tuberculosis and eight with Duhring disease. The PCT was measured in these groups. In all leprosy groups included in the study the PCT was higher than in the control groups. Moreover, the PCT of the leprosy patients without any intraocular involvement was higher than in the controls. These results show that in the ophthalmic examination of leprosy patients without any symptoms the fact that autonomic nerve system of the eye is affected by the leprosy can often be determined by measuring the PCT.     

Study of ocular hemodynamics and general somatic status of patients with primary open-angle glaucoma

Ocular hemodynamics and general somatic status were studied in 50 patients with primary open-angle glaucoma. Complex ophthalmological and therapeutic examinations were carried out, macro- and microcirculatory hemodynamics of the eye was examined, case histories and therapeutic status of patients were analyzed with due regard for previous local hypotensive and general vascular therapy. Revised recommendations for glaucoma patients aimed at correcting their life style include diet, regular vascular and metabolic therapy, normalization of orbital circulation in order to improve ocular hemodynamics and increase the tolerance of the optic nerve to intraocular pressure fluctuations.