Purpose of Dilation/ B-Scan Allied Ophthalmic Training Program

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

http://morancore.utah.edu/section-15-ultrasound/b-scan-technique/

• An eye and orbit ultrasound used to visualize ocular anatomy as well as measure the size and structures of the eye

• 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

• 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

• Permits assessment of gross intraocular pathologies that distort architecture • Detailed assessment of pathology is very limited

• 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

• 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

Moran-Axis

• Patients with suspected ocular globe rupture • Trauma patients • Patients who recently underwent surgery

• 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

• 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/

• Project Administrator: James Gilman, CRA, FOPS • Roger Harrie , MD