PURPOSE OF DILATION/ B-SCAN ALLIED OPHTHALMIC TRAINING PROGRAM Natalie K Modersitzki, Dustin J Randall, Alexandra S Vitale, Lydia Sauer MD, Sravanthi Vegunta MD ©UNIVERSITY OF UTAH HEALTH Normal Eye anatomy https://commons.wikimedia.org/ ©UNIVERSITY OF UTAH HEALTH IRIS ● The iris is the thin, pigmented contractile muscle that sits anterior to the lens ● The iris is surrounded by aqueous humor Moran-Axis ©UNIVERSITY OF UTAH HEALTH IRIS The amount of light entering the eye is controlled by the iris. This is analogous to a diaphragm of a camera. https://commons.wikimedia.org/wiki/File:Diaphragm_iris_types.svg ©UNIVERSITY OF UTAH HEALTH IRIS Contains • Melanocytes • Nerves • Clump cells • Collagen • Mucopolysaccharides • Two significant muscles ©UNIVERSITY OF UTAH HEALTH MUSCLES OF THE IRIS Dilator • Sphincter pupillae- Pupillae Sphincter contraction results in the pupillae constriction of the pupil (miosis) • Dilator pupillae- contraction results in the dilation of the pupil (mydriasis) ©UNIVERSITY OF UTAH HEALTH Parasympathetic vs Sympathetic Nervous System Parasympathetic Sympathetic Fight or Flight Rest and Digest TULA LAROCHELLE ©UNIVERSITY OF UTAH HEALTH SYMPATHETIC SYSTEM CONTROLS RADIAL(DILATOR) MUSCLES Iris Pupil ©UNIVERSITY OF UTAH HEALTH PARASYMPATHETIC SYSTEM CONTROLS CIRCULAR MUSCLES Pupil ©UNIVERSITY OF UTAH HEALTH Nondilated pupil Dilated pupil ©UNIVERSITY OF UTAH HEALTH DILATION • Specific eye drops called mydriatics contain medication that dilate the pupil The drops work in 3 ways: • Paralyzing the sphincter pupillae • Stimulating the dilator muscle • Preventing accommodation Source: https://www.aao.org/eye-health/drugs/dilating-eyedrops ©UNIVERSITY OF UTAH HEALTH DILATION • Sympathetic agonists- causes contraction of radial muscles • Example: Phenylephrine • Parasympathetic antagonists- causes relaxation of circular muscles of iris • Example: tropicamide, atropine, cyclopentolate ©UNIVERSITY OF UTAH HEALTH DILATION • It takes 20-30 minutes for an eye to fully dilate • The effects of the dilating drops can last from 4-6 hours (time may vary based on eye color) • Light colored eyes dilate faster than dark (brown) eyes ©UNIVERSITY OF UTAH HEALTH INDICATION- when to dilate ● People over the age of 60 should have a dilated eye exam every year ➢ Certain eye diseases and disorders that become more prevalent with old age: ○ Cataract ○ Diabetic retinopathy ○ Glaucoma ○ Age related macular degeneration (AMD) ○ Degenerative retinal Old age changes Jim Gilman ©UNIVERSITY OF UTAH HEALTH Age related- Macular Degeneration Moran-Axis ©UNIVERSITY OF UTAH HEALTH INDICATION Myopia ● Nearsighted patients have longer eyeballs, and as a result they can have abnormal blood vessel growth in the back of the eye Moran-Axis ©UNIVERSITY OF UTAH HEALTH INDICATION ● A premature birth occurs when a pregnancy lasts less than 37 weeks ● Retinopathy of Prematurity (ROP) ○ Blood vessels have the propensity to grow abnormally and uncontrollably which causes severe damage to the retina ○ Eventually the abnormal vessel growth can cause a retinal detachment and result in permanent blindness Prematurity Moran- Axis ©UNIVERSITY OF UTAH HEALTH INDICATION Systemic involvement ● There are many systemic diseases that affect the eye including both infectious and non-infectious conditions Non-infectious: Infectious: - Sarcoidosis - Toxoplasmosis - Diabetes - TB - Thyroid disease - Syphilis - Connective tissue disease - Leprosy - Behcet’s disease - HIV - Vogt Koyanagi Harada disease - CMV - Neuroretinitis ©UNIVERSITY OF UTAH HEALTH INDICATION • In order to accurately classify the stage and maturity of a cataract,the iris needs to be fully dilated – Dilation ensures a full view of the lens Moran-Axis ©UNIVERSITY OF UTAH HEALTH INDICATION A bigger pupil is necessary for cycloplegic retinoscopy: • This type of eye exam is often done on children – Children are very good at accommodating – It is necessary to temporarily relax the muscles that aid in focusing their lens to obtain an accurate measurement of their prescription ©UNIVERSITY OF UTAH HEALTH INDICATION • Dilation is necessary for proper examination of the retina, optic nerve, and blood vessels • It is also necessary if there is suspected retinal or uvetic conditions that could be affecting the peripheral retina Moran Eye Center - Axis Image ©UNIVERSITY OF UTAH HEALTH INDICATION • Dilation can not only • Dilation can be a treatment prevent but also break for amblyopia up scarring in the anterior chamber (like synechiae) Moran-Axis ©UNIVERSITY OF UTAH HEALTH Side Effects of Dilation • Sensitivity to light • Blurry vision • Pain or singing sensation when drops are put in the eye • Trouble focusing ©UNIVERSITY OF UTAH HEALTH B-SCAN http://morancore.utah.edu/section-15-ultrasound/b-scan-technique/ ©UNIVERSITY OF UTAH HEALTH WHAT IS A B-SCAN? • An eye and orbit ultrasound used to visualize ocular anatomy as well as measure the size and structures of the eye ©UNIVERSITY OF UTAH HEALTH B-SCAN - HOW DOES IT WORK? • High-frequency sound waves are utilized to advance through the eye • The waves are reflected by structures of the eye, forming a visual image of the structures ©UNIVERSITY OF UTAH HEALTH B-SCAN INDICATIONS • Used when the view into the eye is obscured due to opaque ocular media (e.g. cloudy cornea, dense cataract, vitreous hemorrhage) – When the view of the retina is inhibited we can not properly assess for intraocular pathologies, including retinal detachments, tumors, etc ©UNIVERSITY OF UTAH HEALTH B-SCAN BENEFITS and LIMITATIONS • Permits assessment of gross intraocular pathologies that distort architecture • Detailed assessment of pathology is very limited ©UNIVERSITY OF UTAH HEALTH B-SCAN - HOW IT IS PERFORMED • Anesthetic drops are applied to the eye for numbing • With the patient’s eyes closed, a gel is placed on the skin of the eyelids • Ultrasound transducer is carefully placed in contact with the eyelid • The test takes about 15 minutes ©UNIVERSITY OF UTAH HEALTH B-SCAN - ABNORMALITIES • Swelling (inflammation) • Foreign body • Bony socket (orbit) injuries or damage • Retinal detachment • Vitreous hemorrhage (blood in the vitreous, which is the clear gelatinous substance that fills the back of the eye) • Cancerous lesions ©UNIVERSITY OF UTAH HEALTH B-SCAN - FOREIGN BODY Moran-Axis ©UNIVERSITY OF UTAH HEALTH B-SCAN - RETINAL DETACHMENT Moran-Axis ©UNIVERSITY OF UTAH HEALTH Contraindications of B-Scan • Patients with suspected ocular globe rupture • Trauma patients • Patients who recently underwent surgery ©UNIVERSITY OF UTAH HEALTH Summary • Dilation increases the ● B- Scan gives a detailed size of pupils during an view of the posterior eye exam segment of the eye • Useful in fully examining ● Useful when opacifications the retina and optic obstruct the view of the nerve back of the eye • Critical for prevention ● Relatively fast and and treatment of vision- noninvasive scan that can threatening conditions be done on a non-dilated eye ©UNIVERSITY OF UTAH HEALTH SOURCES • https://www.flickr.com/photos/nihgov/28464844371 • https://pixabay.com/photos/foot-preemie-child-newborn-1689784/ • https://www.pikrepo.com/http://morancore.utah.edu/section-15-ultrasound/b- scan-technique/ • https://www.gograph.com/vector-clip-art/open-window.html • www.slideshar.net • www.Google/Clipart.eye//anatomy • https://ksumsc.com/download_center/Archive/4th/435/435%20TeamWork/Opht halmology/ • http://optometrist.com.au/dealing-degenerative-myopia/ • https://commons.wikimedia.org/ • https://commons.wikimedia.org/wiki/File:Diaphragm_iris_types.svg • https://www.needpix.com/ ©UNIVERSITY OF UTAH HEALTH Special Thanks for Moran axis Images • Project Administrator: James Gilman, CRA, FOPS • Roger Harrie , MD ©UNIVERSITY OF UTAH HEALTH Thank you.