Ophthalmic Nerve
Meridians
Acupuncture
Lacrimal Duct Obstruction
Estimation of the retinal nerve fibre layer thickness in the papillomacular area of long standing stage IV macular holes. (1/109)
AIM: To compare the thickness of the retinal nerve fibre layer (RNFL) in the papillomacular area of patients with long standing stage IV macular holes with age matched controls, using a scanning laser polarimeter. METHODS: The nerve fibre analyser (NFA) was used to measure the mean thickness of the RNFL around the optic nerve head, the thickness values of temporal and nasal 45 degrees sectors and the integral values in 10 patients with macular holes and in 10 age matched controls. RESULTS: The mean RNFL thickness around the optic nerve head was 79.71 (SD 15.06) microm in the macular hole group and 75.1 (10.8) microm in the control group (p = 0.44). The mean thickness in the temporal sector was 63.69 (12.08) microm in the macular hole group and 58.65 (8.9) microm in the control group (p = 0.3). The mean ratio between the temporal and nasal sector thickness values was 0.8441 in the macular hole group and 0.7819 in the controls (p = 0.42). CONCLUSIONS: There was no significant difference in the thickness of the RNFL in the papillomacular area in the two groups. This suggests that there may be no changes in the thickness of the RNFL in patients with long standing macular holes. (+info)Behavioral modulation of tactile responses in the rat somatosensory system. (2/109)
We investigated the influence of four different behavioral states on tactile responses recorded simultaneously via arrays of microwires chronically implanted in the vibrissal representations of the rat ventral posterior medial nucleus (VPM) of the thalamus and the primary somatosensory cortex (SI). Brief (100 microsecond) electrical stimuli delivered via a cuff electrode to the infraorbital nerve yielded robust sensory responses in VPM and SI during states of quiet immobility. However, significant reductions in tactile response magnitude and latency were observed in VPM and SI during large-amplitude, exploratory movements of the whiskers (at approximately 4-6 Hz). During small-amplitude, 7-12 Hz whisker-twitching movements, a significant reduction in SI response magnitude and an increase in VPM and SI response latencies were observed as well. When pairs of stimuli with interstimulus intervals <100 msec were delivered during quiet immobility, the response to the second stimulus in the pair was reduced and occurred at a longer latency compared with the response to the first stimulus. In contrast, during large-amplitude whisker movements and general motor activity, paired stimuli yielded similar sensory responses at interstimulus intervals >25 msec. These response patterns were correlated with the amount and duration of postexcitatory firing suppression observed in VPM and SI during each of these behaviors. On the basis of these results, we propose that sensory responses are dynamically modulated during active tactile exploration to optimize detection of different types of stimuli. During quiet immobility, the somatosensory system seems to be optimally tuned to detect the presence of single stimuli. In contrast, during whisker movements and other exploratory behaviors, the system is primed to detect the occurrence of rapid sequences of tactile stimuli, which are likely to be generated by multiple whisker contacts with objects during exploratory activity. (+info)Corneal stromal changes induced by myopic LASIK. (3/109)
PURPOSE. Despite the rapidly growing popularity of laser in situ keratomileusis (LASIK) in correction of myopia, the tissue responses have not been thoroughly investigated. The aim was to characterize morphologic changes induced by myopic LASIK in human corneal stroma. METHODS: Sixty-two myopic eyes were examined once at 3 days to 2 years after LASIK using in vivo confocal microscopy for measurement of flap thickness, keratocyte response zones, and objective grading of haze. RESULTS: Confocal microscopy revealed corneal flap interface particles in 100% of eyes and microfolds at the Bowman's layer in 96.8%. The flaps were thinner (112 +/- 25 microm) than intended (160 microm). The keratocyte activation in the stromal bed was greatest on the third postoperative day. Patients with increased interface reflectivity due to abnormal extracellular matrix or activated keratocytes at > or = 1 month (n = 9) had significantly thinner flaps than patients with normal interface reflectivity (n = 18; 114 +/- 12 versus 132 +/- 22 microm, P = 0.027). After 6 months the mean density of the most anterior layer of flap keratocytes was decreased. CONCLUSIONS: Keratocyte activation induced by LASIK was of short duration compared with that reported after photorefractive keratectomy. The flaps were thinner than expected, and microfolds and interface particles were common complications. The new findings such as increased interface reflectivity associated with thin flaps and the apparent loss of keratocytes in the most anterior flap 6 months to 2 years after surgery may have important clinical relevance. (+info)Effect of myopic LASIK on corneal sensitivity and morphology of subbasal nerves. (4/109)
PURPOSE: To investigate whether the morphology of the subbasal nerves corresponds to corneal sensitivity after laser in situ keratomileusis (LASIK). METHODS: In a case series study, 59 patients were examined at 2 to 4 hours, 3 days, 1 to 2 weeks, 1 to 2 months, 3 months, or 6 or more months after undergoing LASIK for myopia, by using a Cochet-Bonnet esthesiometer and an in vivo confocal microscope, and were compared with control subjects. Corneal sensitivity and confocal images of subbasal nerves were obtained centrally and 2 mm nasally and temporally. Subbasal nerve fiber bundles (NFBs) were grouped as follows: corneas with no nerve images; corneas with short (<200 microm), unconnected NFBs; corneas with long (> or =200 microm) NFBs without interconnections; and corneas with long NFBs with interconnections. RESULTS: Corneal sensitivity was at its lowest at 1 to 2 weeks after LASIK. Sensitivity of the hinge area was higher than temporal or central areas at every time point. At 6 or more months the sensitivity values were comparable with the values observed in control subjects. The central area showed mainly short, unconnected subbasal NFBs, even at 6 months. In general, the temporal area presented with long NFBs from 3 months onward, whereas the nasal area showed long NFBs at every time point. CONCLUSIONS: The results suggest that the corneal areas with no nerve images or short, unconnected NFBs are associated with lower sensitivities than corneal areas with long NFBs with or without interconnections. In vivo confocal microscopy reveals LASIK-induced alterations of subbasal nerve morphology and thus enables a direct comparison of corneal sensory innervation and sensitivity. (+info)Autosomal recessive cornea plana: in vivo corneal morphology and corneal sensitivity. (5/109)
PURPOSE: Autosomal recessive corneal plana (RCP) is a rare corneal anomaly with unknown pathogenesis and a high incidence in Finland. The aim was to examine corneal sensitivity and the morphology of different corneal layers and subbasal nerves in RCP patients. METHODS: Three patients with a diagnosed autosomal recessive cornea plana were examined. Corneal sensitivity to different modalities of stimulation was tested in four corneas using noncontact esthesiometry. Tissue morphology of three corneas was evaluated, and in two corneas thickness of corneal layers was measured using in vivo confocal microscopy. RESULTS: Corneas of RCP patients appear to have mechanosensory, polymodal, and cold-sensitive nerve terminals. RCP patients had normal sensation thresholds for chemical, heat, and cold stimulation but a high threshold for mechanical stimulation. Their capacity to discriminate increasing intensities of stimulus was reduced, except for cold stimuli. Thickness of the epithelial layer was reduced, whereas total corneal and stromal thicknesses were slightly reduced or close to normal values. In all cases Bowman's layer was absent. Subbasal nerves had abnormal branching patterns. The arrangement of anterior keratocytes was altered, showing clustered and irregularly shaped nuclei. Increased backscattering of light in confocal microscopy through focusing (CMTF) profiles was observed throughout the stroma. Epithelial and endothelial cells appeared to be regular in shape. CONCLUSIONS: The present study revealed qualitative and quantitative alterations in corneal sensitivity, cellular morphology, and the thickness of corneal layers in RCP patients. (+info)Development of conjunctival goblet cells and their neuroreceptor subtype expression. (6/109)
PURPOSE: To investigate expression of muscarinic, cholinergic, and adrenergic receptors on developing conjunctival goblet cells. METHODS: Eyes were removed from rats 9 to 60 days old, fixed, and used for microscopy. For glycoconjugate expression, sections were stained with Alcian blue/periodic acid-Schiffs reagent (AB/PAS) and with the lectins Ulex europeus agglutinin I (UEA-I) and Helix pomatia agglutinin (HPA). Goblet cell bodies were identified using anti-cytokeratin 7 (CK7). Nerve fibers were localized using anti-protein gene product 9.5. Location of muscarinic and adrenergic receptors was investigated using anti-muscarinic and beta-adrenergic receptors. RESULTS: At days 9 and 13, single apical cells in conjunctival epithelium stained with AB/PAS, UEA-I, and CK7. At days 17 and 60, increasing numbers of goblet cells were identified by AB/PAS, UEA-I, HPA, and CK7. Nerve fibers were localized around stratified squamous cells and at the epithelial base at days 9 and 13, and around goblet cells and at the epithelial base at days 17 and 60. At days 9 and 13, M2- and M3-muscarinic and beta2-adrenergic receptors were found in stratified squamous cells, but M1-muscarinic and beta1-adrenergic receptors were not detected. At days 17 and 60, M2- and M3-muscarinic receptors were found in goblet cells, whereas M1-muscarinic receptors were in stratified squamous cells. Beta1- and beta2-adrenergic receptors were found on both cell types. Beta3-adrenergic receptors were not detected. CONCLUSIONS: In conjunctiva, nerves, M2- and M3-muscarinic, and beta1- and beta2-adrenergic receptors are present on developing goblet cells and could regulate secretion as eyelids open. (+info)Effects of oleoresin capsicum pepper spray on human corneal morphology and sensitivity. (7/109)
PURPOSE: To examine the potential harmful effects on corneal structure, innervation, and sensitivity of a spray containing the neurotoxin capsaicin (oleoresin capsicum, OC). METHODS: Ten police officers who volunteered for the study were exposed to OC. Clinical signs were assessed. Corneal sensitivity was measured using a Cochet-Bonnet or a noncontact esthesiometer that provides separate measurements of mechanical, chemical, and thermal sensitivity. Tear fluid nerve growth factor (NGF) was measured. Corneal cell layers and subbasal nerves were examined by in vivo confocal microscopy. The subjects were examined before application and 30 minutes, 1 day, 1 week, and 1 month after OC exposure. RESULTS: OC spray produced occasional areas of focal epithelial cell damage that healed within 1 day. Each eye showed conjunctival hyperemia and in two subjects, mild chemosis. All except one eye had unchanged best corrected visual acuity (BCVA). A transient decrease (day 1) of mechanical sensitivity was observed with the Cochet-Bonnet esthesiometer. With the gas esthesiometer, mechanical sensitivity remained below normal values for 7 days. Chemical sensitivity to CO2 was high for as much as 1 day and decreased below normal 1 week later, whereas sensitivity to cold was unaffected. Two subjects had measurable tear NGF that increased after exposure. Basal epithelial cell morphology suggested temporary corneal epithelial swelling, whereas keratocytes, endothelial cells, and subbasal nerves remained unchanged. CONCLUSIONS: Although OC causes immediate changes in mechanical and chemical sensitivity that may persist for a week, a single exposure to OC appears harmless to corneal tissues. The changes are possibly associated with damage of corneal nerve terminals of mainly unmyelinated polymodal nociceptor fibers. (+info)Corneal structure and sensitivity in type 1 diabetes mellitus. (8/109)
PURPOSE: Corneal wound healing is impaired in diabetic cornea. The purpose of this study was to examine patients with type 1 diabetes mellitus for changes in corneal morphology and to correlate corneal sensitivity, subbasal nerve morphology, and degree of polyneuropathy with each other. METHODS: Forty-four eyes of 23 patients with diabetes and nine control eyes were included. Corneal sensitivity was tested with a Cochet-Bonnet esthesiometer (Luneau, Paris, France), and corneal morphology and epithelial and corneal thickness were determined by in vivo confocal microscopy. The density of subbasal nerves was evaluated by calculating the number of long subbasal nerve fiber bundles per confocal microscopic field. The degree of polyneuropathy was evaluated using the clinical part of the Michigan Neuropathy Screening Instrument (MNSI) classification, and retinopathy was evaluated using fundus photographs. RESULTS: A reduction of long nerve fiber bundles per image was noted to have occurred already in patients with mild to moderate neuropathy, but corneal mechanical sensitivity was reduced only in patients with severe neuropathy. Compared with control subjects the corneal thickness was increased in patients with diabetes without neuropathy. The epithelium of patients with diabetes with severe neuropathy was significantly thinner than that of patients with diabetes without neuropathy. CONCLUSIONS: Confocal microscopy appears to allow early detection of beginning neuropathy, because decreases in nerve fiber bundle counts precede impairment of corneal sensitivity. Apparently, the cornea becomes thicker in a relatively early stage of diabetes but does not further change with the degree of neuropathy. A reduction in neurotrophic stimuli in severe neuropathy may induce a thin epithelium that may lead to recurrent erosions. (+info)The ophthalmic nerve, also known as the first cranial nerve or CN I, is a sensory nerve that primarily transmits information about vision, including light intensity and color, and sensation in the eye and surrounding areas. It is responsible for the sensory innervation of the upper eyelid, conjunctiva, cornea, iris, ciliary body, and nasal cavity. The ophthalmic nerve has three major branches: the lacrimal nerve, frontal nerve, and nasociliary nerve. Damage to this nerve can result in various visual disturbances and loss of sensation in the affected areas.
In the context of traditional Chinese medicine, meridians are believed to be energy pathways or channels within the body through which Qi (vital energy) flows. There are said to be 12 main meridians and eight extra meridians that connect various organs and systems in the body. According to this belief, blockages or imbalances in the flow of Qi through these meridians can lead to illness or disease.
It's important to note that this concept of meridians is not recognized by modern Western medicine. The anatomical structures and physiological functions of meridians have not been scientifically validated, and the theories surrounding them are considered alternative or complementary medicine approaches.
Osteology is the study of the skeleton, including the structure and function of bones, joints, and other connective tissues that make up the skeletal system. It involves the analysis of the anatomy, physiology, and pathology of bones, as well as their development, growth, and repair. Osteology is an important field in medicine, anthropology, and forensics, and has applications in the diagnosis and treatment of various musculoskeletal disorders and injuries.
Acupuncture is a form of traditional Chinese medicine that involves the insertion of thin needles into specific points on the body to stimulate the body's natural healing processes. According to traditional Chinese medicine theory, energy (known as "qi" or "chi") flows through the body along pathways called meridians. Acupuncture is believed to help restore the flow of qi and improve the balance of the body's energy.
In modern medical practice, acupuncture is often used to treat pain, including chronic pain, muscle stiffness, and headaches. It is also sometimes used to treat conditions such as nausea and vomiting, insomnia, and addiction. The precise mechanism by which acupuncture works is not fully understood, but it is thought to involve the release of natural pain-relieving chemicals called endorphins, as well as other physiological changes in the body. Acupuncture is generally considered safe when performed by a qualified practitioner, and side effects are typically mild and temporary.
In medical terms, the orbit refers to the bony cavity or socket in the skull that contains and protects the eye (eyeball) and its associated structures, including muscles, nerves, blood vessels, fat, and the lacrimal gland. The orbit is made up of several bones: the frontal bone, sphenoid bone, zygomatic bone, maxilla bone, and palatine bone. These bones form a pyramid-like shape that provides protection for the eye while also allowing for a range of movements.
Lacrimal duct obstruction is a blockage in the lacrimal duct, which is the passageway that drains tears from the eye into the nose. This condition can cause excessive tearing, pain, and swelling in the affected eye. In some cases, it may also lead to recurrent eye infections or inflammation. The obstruction can be caused by various factors such as age-related changes, injury, infection, inflammation, or congenital abnormalities. Treatment options for lacrimal duct obstruction depend on the underlying cause and severity of the condition and may include medications, minor surgical procedures, or more invasive surgeries.
The nasolacrimal duct is a medical term that refers to the passageway responsible for draining tears from the eye into the nasal cavity. This narrow tube, which is about 12 millimeters long, begins at the inner corner of the eyelid (near the nose) and ends in the inferior meatus of the nasal cavity, close to the inferior turbinate.
The nasolacrimal duct is part of the nasolacrimal system, which includes the puncta (small openings at the inner corner of the eyelids), canaliculi (tiny channels that connect the puncta to the nasolacrimal sac), and the nasolacrimal sac (a small pouch-like structure located between the eye and the nose).
The primary function of the nasolacrimal duct is to help maintain a healthy ocular surface by draining tears, which contain waste products, debris, and pathogens accumulated on the surface of the eye. The continuous flow of tears through the nasolacrimal duct also helps prevent bacterial growth and potential infections.
In some cases, the nasolacrimal duct can become obstructed due to various factors such as age-related changes, inflammation, or congenital abnormalities. This condition, known as nasolacrimal duct obstruction (NLDO), may result in watery eyes, discomfort, and an increased risk of eye infections. In severe cases, medical intervention or surgical procedures might be necessary to restore proper tear drainage.
Dacryocystorhinostomy (DCR) is a surgical procedure that creates a new passageway between the tear sac and the nasal cavity to allow for the drainage of tears. This procedure is typically performed to alleviate symptoms associated with blocked or obstructed tear ducts, such as watery eyes, chronic inflammation, or recurrent infections.
During a DCR procedure, an incision is made either externally on the side of the nose or endoscopically through the nasal passage. The surgeon then creates an opening between the tear sac and the nasal cavity, allowing tears to bypass any obstruction and drain directly into the nasal cavity.
There are two main types of DCR procedures: external DCR (EDCR) and endoscopic DCR (ENDCR). The choice of procedure depends on various factors, including the location and severity of the blockage, patient anatomy, and surgeon preference. Both procedures have been shown to be effective in relieving symptoms associated with blocked tear ducts, although ENDCR may result in fewer complications and a quicker recovery time.