Review

Authors: Khizar Rana, Valerie Juniat, Sandy Patel...

Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.

Topics: Humans; Oculomotor Muscles; Tomography, X-Ray Computed; Graves Ophthalmopathy; Magnetic Resonance Imaging; Hypertrophy

PubMed: 35713708
DOI: 10.1007/s00417-022-05727-1

Authors: Grzegorz Zieliński, Anna Matysik-Woźniak, Anna Pankowska...

(1) Background: Myopia is one of the most common refractive errors in the world. The aim of this study was to evaluate the transverse dimensions of selected masticatory muscles (temporalis muscle and masseter muscle) versus the transverse dimensions of selected extraocular muscles (superior rectus, inferior rectus, medial rectus and lateral rectus) in emmetropic and high myopic subjects. (2) Methods: Twenty-seven individuals were included in the analysis, resulting in 24 eyeballs of patients with high myopia and 30 eyeballs of emmetropic subjects. A 7 Tesla resonance was used to analyze the described muscles. (3) Results: Statistical analysis showed differences in all analyzed extraocular muscles and all analyzed masticatory muscles between emmetropic subjects and high myopic subjects. In the high myopic subject group, statistical analysis showed four correlations. The three negative correlations were between the lateral rectus muscle and an axial length eyeball, refractive error and an axial length eyeball, and the inferior rectus muscle and visual acuity. The positive correlation was between the lateral rectus muscle and the medial rectus muscle. (4) Conclusions: The high myopic subjects are characterized by a larger cross-sectional area of extraocular muscles and masticatory muscles compared to the emmetropic subjects. Correlations were observed between the thickness of the extraocular muscles and the masticatory muscles. The lateral rectus muscle was related to the length of the eyeball. The phenomenon requires further study.

PubMed: 37373859
DOI: 10.3390/jcm12124166

Authors: Edith R Reshef, Suzanne K Freitag, Nahyoung Grace Lee...

Three patients presented with periorbital swelling, pain with extraocular movements, and binocular diplopia 1-4 days after receiving an mRNA Coronavirus Infectious Disease-19 (COVID-19) vaccine (BNT162b2, Pfizer/BioNTech; mRNA-1273, Moderna). All patients had a normal afferent function, unilateral limitation of extraocular motility, proptosis, and periorbital inflammation. Neuroimaging of the orbits with contrast revealed inflammation and enlargement of extraocular muscles in 2 cases and the lacrimal gland in 1 case. In all 3 cases, an extensive infectious and inflammatory laboratory work-up was unremarkable and signs and symptoms of orbital inflammation rapidly improved to complete resolution after treatment with high-dose oral prednisone. This is the first reported series of orbital inflammation occurring shortly after administration of the COVID-19 vaccine. Clinicians may consider an inflammatory postvaccine etiology as an alternative to presumed idiopathic diagnosis in such cases.

Topics: BNT162 Vaccine; COVID-19; COVID-19 Vaccines; Communicable Diseases; Humans; Inflammation; Vaccination

PubMed: 35323144
DOI: 10.1097/IOP.0000000000002161

Review

Authors: Roland Blumer, Génova Carrero-Rojas, Paula M Calvo...

Proprioception is the sense that lets us perceive the location, movement and action of the body parts. The proprioceptive apparatus includes specialized sense organs (proprioceptors) which are embedded in the skeletal muscles. The eyeballs are moved by six pairs of eye muscles and binocular vision depends on fine-tuned coordination of the optical axes of both eyes. Although experimental studies indicate that the brain has access to eye position information, both classical proprioceptors (muscle spindles and Golgi tendon organ) are absent in the extraocular muscles of most mammalian species. This paradox of monitoring extraocular muscle activity in the absence of typical proprioceptors seemed to be resolved when a particular nerve specialization (the palisade ending) was detected in the extraocular muscles of mammals. In fact, for decades there was consensus that palisade endings were sensory structures that provide eye position information. The sensory function was called into question when recent studies revealed the molecular phenotype and the origin of palisade endings. Today we are faced with the fact that palisade endings exhibit sensory as well as motor features. This review aims to evaluate the literature on extraocular muscle proprioceptors and palisade endings and to reconsider current knowledge of their structure and function.

Topics: Animals; Oculomotor Muscles; Sensory Receptor Cells; Mechanoreceptors; Proprioception; Muscle Spindles; Mammals

PubMed: 36869596
DOI: 10.1113/EP090765

Review

Authors: T Aguiar, A Morganho, V Passão...

Orbital myositis is a subgroup of the nonspecific inflammatory syndrome or orbital pseudotumor and is characterized by a primary inflammation of extraocular muscles. The authors describe a 70-year-old patient with acute proptosis, ocular pain and right ophthalmoplegia, whose orbital computed tomographic scan showed enlargement of the homolateral extraocular muscles. Clinical presentation and complementary tests were compatible with the diagnosis of orbital myositis however, because of the particular aspects, which included retinal central vein occlusion, optic nerve lesion, distension of the superior ophthalmic vein and the homolateral cavernous sinus, the differential diagnosis with cavernous sinus pathology and thyroid ophthalmopathy was considered. The importance of a rapid diagnosis and treatment is stressed.

Topics: Aged; Female; Glucocorticoids; Humans; Neurologic Examination; Orbit; Orbital Pseudotumor; Prednisolone; Tomography, X-Ray Computed

PubMed: 9446484
DOI: No ID Found

Review

Authors: J R Bruenech, I B Kjellevold Haugen

The sensory and motor control of human extraocular muscles (EOMs) have been subjected to considerable speculation in ophthalmic literature, often related to infranuclear structures such as the unique complement of muscle fibres and their associated sensory organs. The intrafusal fibres do not resemble their somatic counterparts and their peculiar morphology has raised questions about their proprioceptive capacity. No Golgi tendon organs have so far been observed and the myotendinous nerve endings, previously assumed to convey sensory information, have recently been argued to merely represent constituents of the efferent innervation serving the multiply innervated muscles fibres. These observations raise questions about the overall capacity to monitor the activity created by the generous efferent nerve supply observed in these muscles. Furthermore, the argued independent activity of muscular layers and compartments suggest that the required feedback must be highly structured and more specific than previously assumed. Yet, uncertainty about the source of such information remains. The purpose of this paper is to provide a short review of neuromuscular properties of human extraocular muscles. Their functional implications and the most reputable sources of proprioception will also be discussed. The promoted views are based on pertinent literature and previous research undertaken by the authors.

Topics: Eye Movements; Humans; Motor Neurons; Nerve Fibers, Myelinated; Nerve Fibers, Unmyelinated; Oculomotor Muscles; Proprioception; Tendons

PubMed: 25397785
DOI: 10.1038/eye.2014.269

Review

Authors: Mutahar Andrabi, Brian A Upton, Richard A Lang...

We live on a planet that is bathed in daily and seasonal sunlight cycles. In this context, terrestrial life forms have evolved mechanisms that directly harness light energy (plants) or decode light information for adaptive advantage. In animals, the main light sensors are a family of G protein-coupled receptors called opsins. Opsin function is best described for the visual sense. However, most animals also use opsins for extraocular light sensing for seasonal behavior and camouflage. While it has long been believed that mammals do not have an extraocular light sensing capacity, recent evidence suggests otherwise. Notably, encephalopsin (OPN3) and neuropsin (OPN5) are both known to mediate extraocular light sensing in mice. Examples of this mediation include photoentrainment of circadian clocks in skin (by OPN5) and acute light-dependent regulation of metabolic pathways (by OPN3 and OPN5). This review summarizes current findings in the expanding field of extraocular photoreception and their relevance for human physiology.

Topics: Mice; Humans; Animals; Opsins; Rod Opsins; Skin; Mammals; Membrane Proteins

PubMed: 37196422
DOI: 10.1146/annurev-vision-100820-094018