Tumor necrosis factor alpha induces a serotonin dependent early increase in ciliary beat frequency and epithelial transport velocity in murine tracheae

The tracheal epithelium prevents via its highly effective clearance mechanism the contamination of the lower airways by pathogens. This mechanism is driven by ciliary bearing cells which are not only in contact with the gas phase; in addition they are also influenced by inflammatory mediators. These mediators can alter the protective function of the epithelium. Since the pro-inflammatoric cytokine tumor necrosis factor-α (TNF-α) plays a pivotal role within the inflammatory cascade, we investigated its effect onto the tracheal epithelium measured by its ciliary beat frequency and the particle transport velocity. In organ explant experiments the ciliary beat frequency and the particle transport velocity were measured under the application of TNF-α using tracheae from male C57BL6J mice. We observed a dose dependent TNF-α induced increase of both particle transport velocity and ciliary beat frequency. Knock out mice experiments made evident that the increase was depended on the expression of tumor necrosis factor receptor 1 (TNF-R1). The increases in ciliary beat frequency as well as the accelerated particle transport velocity were either inhibited by the unspecific serotonin antagonist methysergide or by cyproheptadine a specific 5-HT2 receptor antagonist. Thus, acetylcholine antagonists or nitric oxide synthase (NOS) inhibitors failed to inhibit the TNF-α induced activation. In conclusion, TNF-α may play a pivotal role in the protection of lower airways by inducing ciliary activity and increase in particle transport velocity via TNF-R1 and 5-HT2 receptor.

[Spasm of accommodation]

Spasm of accommodation refers to prolonged contraction of the ciliary muscle, most commonly causing pseudomyopia to varying degrees in both eyes by keeping the lens in a state of short sightedness. It may also be manifested as inability to allow the adaptation spasticity prevailing in the ciliary muscle relax without measurable myopia. As a rule, this is a functional ailment triggered by prolonged near work and stress. The most common symptoms include blurring of distance vision, varying visual acuity as well as pains in the orbital region and the head, progressing into a chronic state. Cycloplegic eye drops are used as the treatment.

Ghrelin in ocular pathophysiology: from the anterior to the posterior segment

Ghrelin is a 28 amino acid acylated peptide produced in several organs that binds the growth hormone secretagogues receptor type 1a (GHSR-1a). It acts over a wide range of systems, e.g. the endocrine, cardiovascular, musculoskeletal and immune systems and the eye. The aim of this work is to review the physiologic and pathologic implications of the ghrelin-GHSR-1a in the eye. A systematic revision of studies published between 2000 and 2013 in English, Spanish or Portuguese in MEDLINE, EMBASE and Scopus was performed. Search words used included: ghrelin, GHSR-1a, ocular production, iris muscular kinetics, ciliary body, glaucoma, retinopathy and uvea. The production of ghrelin by the ocular tissue has been detected both in the anterior and posterior segments, as well as the presence of GHSR-1a. This peptide promotes the relaxation of the iris sphincter and dilator muscles, being this effect independent from GHSR-1a and dependent on prostaglandins release in the first case and dependent on GHSR-1a in the second. Regarding ocular pathology, ghrelin levels in the aqueous humor appear to be decreased in individuals with glaucoma. Moreover, ghrelin has been shown to decrease the intraocular pressure in animal models of ocular hypertension through GHSR-1a. In the posterior segment, the ghrelin-GHSR-1a system interferes with the development of oxygen-induced retinopathy, being protective in the vaso-obliterative phase and deleterious in the vaso-proliferative stage of the disease. Thus, the ghrelin-GHSR-1a system presents as a possible local regulatory mechanism in the eye, with pathophysiological implications, constituting a target for future clinical and therapeutic research and interventions.

[Accommodation examination in myopia associated with nondifferentiated connective tissue dysplasia]

Features of accommodative response in children with myopia associated with nondifferentiated connective tissue dysplasia (NCTD) were studied using computered accommodography. A variety of accommodative response patterns were found in myopia associated with NCTD, that is indicative of a great functional potential of ciliary muscle. Theoretic side is discussed for normal accommodative response and for muscle fibers hyperfunction as well.

[Multifocal, toric, and aspheric intraocular lenses for glaucoma patients]

Cataract surgery has greatly developed over recent years, mainly due to the introduction and availability of newer intraocular lenses (IOLs) with modern platforms and better visual outcomes. Aspheric, multifocal, and toric lenses are among these new lenses. Glaucomatous eyes have a number of particularities that can influence the way these implants are indicated and used. Contrast sensitivity is usually reduced in eyes with glaucoma and, sometimes, a poor IOL choice can aggravate the disease. Small pupils and zonular weakness are frequently associated with certain types of glaucoma (e.g. pseudoexfoliative glaucoma) and can limit the indication of some of the newer IOLs. Lastly, in some cases of combined surgery, the postoperative axial length and anterior chamber depth can change after surgery, requiring adjustments in the IOL power calculation. The purpose of this article is to quickly review some of the specific features of cataract surgery in the glaucomatous eye, some of the IOL choices, and the necessary precautions for these eyes.

Emmetropization in the primate eye

A theory to explain the mechanism of emmetropization of the human eye is reviewed and updated. The theory is probably also valid for the primate eye. It is proposed that the ciliary muscle-choroid layer behaves like a solid sheet of smooth muscle, so that it is able to resist part of the intraocular pressure and to regulate scleral stretch in the growing eye. It is suggested that the autonomic nervous system and stress play a role in the development of ametropia and that interference with the cortical-subcortical control of the ciliary muscle may prevent emmetropization.

Presbyopietherapie mit Femtosekundenlaser

Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Accommodation and presbyopia: the ciliary neuromuscular view

Presbyopia (literally, "old eye"), the age-related loss of the ability to accommodate, is the most common ocular affliction in the world. Although the lens no doubt has a major role in presbyopia, altered lens function could be in part secondary to extralenticular age-related changes, such as loss of ciliary body forward movement. Centripetal ciliary muscle movement does not seem to decrease significantly with age. Loss of elasticity of the ciliary muscle posterior attachments may be an important factor contributing to presbyopia. Even if loss of ciliary muscle mobility is not causally related to presbyopia, it may limit the performance of putatively accommodating intraocular lenses now being developed by academic and industrial groups.

The influence of cycloplegia in objective refraction

The purpose of this study was to compare refractions measured with an autorefractor and by retinoscopy with and without cycloplegia. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 +/- 2.66 years. The measurements were performed first without cycloplegia and repeated 30 min later with cycloplegia. Data were analysed using Fourier decomposition of the power profile. More negative values of component M and J(0) were given by non-cycloplegic autorefraction compared with cycloplegic autorefraction (p < 0.0001). However more positive values for the J(45) vector were given by non-cycloplegic autorefraction, although this difference was not statistically significant (p = 0.233). By retinoscopy, more negative values of component M were obtained with non-cycloplegic retinoscopy (p < 0.0001); for the cylindrical vectors J(0) and J(45) the retinoscopy without cycloplegia yields more negative values (p = 0.234; p = 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to the accommodative response, the present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain the objective starting point for refraction under non-cycloplegic conditions.

Sympathetic innervation of ciliary muscle and oculomotor function in emmetropic and myopic young adults

PURPOSE

Evidence exists for an additional inhibitory accommodative control system mediated by the sympathetic branch of the autonomic nervous system (ANS). This work aims to show the relative prevalence of sympathetic inhibition in young emmetropic and myopic adults, and to evaluate the effect of sympathetic facility on accommodative and oculomotor function.

METHODS

Profiling of ciliary muscle innervation was carried out in 58 young adult subjects (30 emmetropes, 14 early onset myopes, 14 late onset myopes) by examining post-task open-loop accommodation responses, recorded continuously by a modified open-view infrared optometer. Measurements of amplitude of accommodation, tonic accommodation, accommodative lag at near, AC/A ratio, and heterophoria at distance and near were made to establish a profile of oculomotor function.

RESULTS

Evidence of sympathetic inhibitory facility in ciliary smooth muscle was observed in 27% of emmetropes, 21% of early-onset myopes and 29% of late-onset myopes. Twenty-six percent of all subjects demonstrated access to sympathetic facility. Closed-loop oculomotor function did not differ significantly between subjects with sympathetic facility, and those with sympathetic deficit.

CONCLUSIONS

Emmetropic and myopic groups cannot be distinguished in terms of the relative proportions having access to sympathetic inhibition. Presence of sympathetic innervation does not have a significant effect on accommodative function under closed-loop viewing conditions.

[Study of an accommodational response after surgical correction of myopia with an ICL intraocular lens]

The paper analyzes the nature of an accommodational response in 11 patients (19 eyes) before and after surgical correction of myopia with ICL intraocular lenses (IOLs). Rapid and slow accommodational responses were studied to different values of an accommodation stimulus (from 1.0 to 3.0 diopters). The implanted IOLs were found to have no effect on the performance of the ciliary muscle. Its compensatory enhancement occurs after implantation, which ensures the normal performance of the accommodation apparatus.

Changes in the shape of the anterior and posterior corneal surfaces caused by mydriasis and miosis

PURPOSE

To evaluate changes in the anterior and posterior corneal shape, corneal thickness, and anterior chamber depth (ACD) caused by mydriasis or miosis using scanning-slit corneal topography.

SETTING

Department of Ophthalmology, Iwate Medical University School of Medicine, Iwate, Morioka, Japan.

METHODS

Twenty-eight eyes of 28 healthy volunteers with refractive errors of -6.00 to +0.25 diopters were studied. One eye of each subject had instillation of tropicamide-phenylephrine hydrochloride (Mydrin P) to obtain mydriasis and of pilocarpine hydrochloride 2% (Sanpilo) to obtain miosis. To assess the corneal shape, the best-fit sphere (BFS), axial power, and tangential power were measured for the anterior and posterior corneal surfaces before and after mydriasis and before and after miosis using scanning-slit corneal topography (Orbscan version 3.0, Orbtek, Inc.). The pupil size, corneal thickness, and ACD were also examined before and after mydriasis and before and after miosis.

RESULTS

The mean age of the patients was 31.1 years +/- 5.6 (SD) (range 20 to 46 years). The anterior BFS changed from a mean of 8.04 +/- 0.3 mm at the time of mydriasis to a mean of 8.00 +/- 0.3 mm at the time of miosis. The posterior BFS changed from 6.53 +/- 0.3 mm to 6.46 +/- 0.3 mm, respectively. Thus, the anterior and posterior cornea became significantly steeper after miosis (P<.01). The ACD was significantly more shallow after miosis than after mydriasis. However, there was no significant difference in corneal thickness after mydriasis or miosis.

CONCLUSIONS

The anterior and posterior corneal shapes changed as a result of mydriasis and miosis, and the refractive power of the cornea significantly increased after miosis. To date, changes in refractive power from changes in pupil size have been attributed to a change in the refractive power of the crystalline lens; however, it is now thought that changes in corneal refractive power also occur.

Ciliary staphyloma: very rare sequelae of conjunctival rhinosporiodosis

The main ocular manifestation of rhinosporiosis is lid or conjunctival infection. Conjunctival rhinosporiodosis is very rately causing sclera necrosis. A patient named Shumi (8 years), D/O.- Rukan Uddin of Rupchandrapur, Atpara, Netrokona admitted on 09/03/2003 in the department of Ophtalmology, Mymensingh Medical College Hospital with complains of mass in right eye looks externally like a growth in upper lid and mild dimness of vision of right eye. On examination, it was found that she got VAR : 6/24 and having a shaphyloma near 12-00 O'clock position with a mass adjacent to it which was identified as rhinosporiodosis after excisional biopsy. No history of ocular trauma or any other ocular disease was found.

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.

Angle-closure glaucoma: impact, etiology, diagnosis, and treatment

PURPOSE OF REVIEW

Recent studies underscore the importance of angle-closure glaucoma (ACG) as a cause of world blindness. A major contribution in assessing the true impact of this disease has been an article estimating the number of persons with occludable angles, angle closure, and blindness from ACG in China as 28.2 million, 9.1 million, and 1.7 million, respectively. Although these numbers are based on data from Singapore and Mongolia, which may be applied to China only with caution, they emphasize the blinding potential of ACG, which is three times as likely to be associated with blindness as open-angle glaucoma (OAG).

RECENT FINDINGS

Recent reports in the Chinese literature on ACG prevalence suffer from definitional problems that would appear to lead to systematic overestimates of ACG prevalence and underestimates of OAG prevalence. Nonetheless, data from studies by Chinese investigators further emphasize the strong association between ACG and blindness, with fully 16% of subjects with ACG blind in one report-a far higher proportion than for OAG in China and elsewhere. The importance of topiramate as a cause of secondary angle closure has recently been understood, in part, because of a series of 19 such cases reported by investigators at the Food and Drug Administration.

SUMMARY

Angle closure in this setting appears to be caused by uveal effusion and anterior rotation of the ciliary body with resultant closure of the angle. The condition is not always responsive to laser iridectomy, and elimination of the causative agent appears to be critical. Ultrasonic biomicroscopy is a potential new diagnostic modality for ACG, allowing the measurement of novel parameters, such as the angle opening distance (AOD) at 500 microm (AOD 500). The efficacy of such parameters in improving screening for ACG can only be established by prospective studies of potentially at-risk eyes. A number of novel treatments for AC and angle closure have recently been proposed, including cataract extraction, paracentesis, and argon laser iridoplasty. As with proposed new diagnostic modalities, the efficacy of these treatments remains to be demonstrated with prospective studies, ideally organized in a controlled, randomized fashion.

Incidence of elderly eye injuries in automobile crashes: the effects of lens stiffness as a function of age

The purpose of this paper is to elucidate the incidence of eye injuries with respect to occupant age in frontal automobile crashes as well as to investigate possible injury mechanisms of the elderly eye and the effects of lens stiffness. The National Automotive Sampling System was searched from years 1993-2000 for three separate occupant age groups of 16-35 years old, 36-65 years old, and 66 years old and greater in order to compare the total number of weighted occupants who sustained an eye injury to the number of occupants who sustained an eye injury per age group. Three separate impact scenarios simulating a foam particle (30 m/s), a steering wheel (15 m/s), and an air bag (67 m/s), were applied to a finite element eye model in order to elucidate the effects of aging on the eye when subjected to blunt trauma. The lens stiffness of the model was varied according to human lens stiffness values determined for each age group. Occupants aged 66 years old and greater were two to three times more likely to incur an eye injury than younger occupants. The computational eye model demonstrated that increased risk was related to the increasing stiffness of the lens, producing up to a 120% larger stress in the ciliary body.

Modelling the mechanics of accommodation and presbyopia

Finite element methods have been used to compute the expected relationship between changes in ciliary body diameter and the change in refractive power implied by the change in geometry of the human ocular lens, using values for the material properties and initial geometry taken from the literature (notably the slit lamp photography of Brown (1973) and the studies by Fisher (1969) of the lens material properties). The results show that if the non-linearity associated with the changing geometry is taken into account the lens does not respond to ciliary body stretch by an increase in power [as recently claimed by Schachar et al. (1993), but in the conventional way with a decrease in power. The models show a decrease in the amplitude of accommodation between the age of 29 and 45 years (using Brown's data, 1973), but using Brown's data for the 11-year-old eye leads to the paradoxical conclusion that accommodation amplitude in this eye would have been small. In the process of carrying out the modelling, we have examined the consistency of the published measurements and also the validity of the mathematical methods used in interpreting them, and this analysis suggests that further work is needed before one can be confident that the assumptions about geometry and material properties on which the modelling is based are sound.