USG IN OPHTHALMOLOGY

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A SCAN B SCAN UBM

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ULTRASONOGRAPHY IN OPHTHALMOLOGY: 

ULTRASONOGRAPHY IN OPHTHALMOLOGY DR. ANUJA DESAI FIRST YEAR RESIDENT DHIRAJ HOSPITAL

PowerPoint Presentation: 

Diagnostic ocular ultrasonography allows the detection of intraocular abnormalities not visualized clinically because of opacification of the cornea, anterior chamber, lens or vitreous, as well as pathologic processes involving the periorbital tissues .

A BRIEF HISTORY OF ULTRASOUND: 

A BRIEF HISTORY OF ULTRASOUND

PowerPoint Presentation: 

In 1793 Lazzaro Spallanzani (Italy) discovered that bats orient themselves with the help of sound whistles while flying in darkness. This was the basis of modern ultrasound application. In 1956 Mundt and Hughes used A scan (time/amplitude) technique to detect intraocular tumour . In 1960 Baum & Greenwood first introduced B scan (intensity modulation) USG to ophthalmology. A water bath was used as coupling agent between the globe & probe In 1972 First use of hand held B scan by Bronston & workers ,which was applied directly to the closed lid without a water bath.

BASIC PHYSICAL PRINCIPLES OF ULTRASOUND: 

BASIC PHYSICAL PRINCIPLES OF ULTRASOUND

Ultrasound is an acoustic wave with a frequency above the audible range of 20 KHz: 

Ultrasound is an acoustic wave with a frequency above the audible range of 20 KHz The first is a Piezoelectric phenomenon, which is really a phenomenon where crystals or materials can be bent and will send electricity, and if you put electricty into them they will bend. Transducing electricity into sound and then sound back into electricity.

PowerPoint Presentation: 

The second principle is called acoustic impedance. It means how difficult it is for sound to get through something, how much the material can impede the movement of sound and basically comes down to how close the molecules are, one to another. If two materials are next to each other, with a different acoustic impedance in each one, the reflection that occurs at the interface between one material and the other really determines how much echo comes back.

PowerPoint Presentation: 

The angle of incidence is an important factor in the strength of the returning echoes. To accurately access structures based on the intensity of the returning echoes, the sound beam needs to be directed perpendicular to the desired structure. Frequencies currently used in ophthalmic ultrasound machines range from 8 to 80 MHz, compared with 2 to 6 MHz typically used in other fields of diagnostic ultrasound. The use of higher frequencies allows for increased resolution

INSTRUMENTATION: 

INSTRUMENTATION A-SCAN B-SCAN ULTRASOUND BIOMICROSCOPY

A-SCAN: 

A-SCAN A-scan is a one-dimensional display of echo strength over time. Vertical spikes correspond to echo intensity and are shown on the horizontal axis as a function of time. Two primary types of A-scan: biometric A-scan and standardized diagnostic A-scan.

A-scan: 

A-scan Biometric A-scan is optimized for axial eye length measurements. It uses a probe with an operating frequency of 10 to 12 MHz and a linear amplification curve. The sound velocity in ocular structures along the visual axis at physiologic temperatures results in highly accurate measurements. Used in cataract surgeries for IOL calculations. An error in axial length measurement of 1 mm can cause an error in IOL power of 2.5 D (approximately)

A-scan: 

A-scan Standardized A-scan uses a probe with an operating frequency of 8 MHz and an S-shaped amplification curve. Primary feature is the tissue sensitivity or standardized decibel setting used for the detection and differentiation of abnormal intraocular tissues. It is designed to display an echo spike for retina that is 100% on the echo intensity scale. In combination with B-scan, diagnostic A-scan is essential in the differentiation of vitreoretinal membranes

PowerPoint Presentation: 

S, sclera; V, vitreous; R, retina; O, orbital tissue.

B-scan: 

B-scan Contact B-scan is a two-dimensional display of echoes using horizontal and vertical orientations to show shape, location, and extension. Dots on the screen represent echoes, and the strength of the echo is determined by the brightness of the dot. Frequency in the range of 10 MHz. The term ‘‘contact’’ refers to the direct application of the probe to the surface of the eye with methycellulose as a coupling agent.

B-scan: 

B-scan Examination Technique : All B scan probe contains a marker that contains a transducer that moves rapidly back and forth near the tip of the probe. The probe tip is oval in shape with the back and forth motion of the transducer corresponding to the longest diameter of the probe tip. Each probe has a marker (dot or line) that indicates the side of the probe that is represented on the upper portion of the B scan screen. Methylcellulose is used as a coupling medium. The probe is then placed directly on the globe ( i,e conjunctiva or cornea). Examination through the lid is generally avoided because of sound attenuation by the lids and also with the lids closed, one can never be certain which position of the globe is being evaluated. Closed lid examination technique minimizes the discomfort for patient and allows better visualization of the peripheral fundus .

B-scan probe orientations: 

B-scan probe orientations Axial scan is obtained by placing the probe face directly over the center of the cornea. The resulting B-scan image includes the lens and is bisected by the optic nerve. However, the sound attenuation from the lens often limits the diagnostic use of this view.

PowerPoint Presentation: 

Baum’s Bump- The lens refracts light as well as sound waves, which results in distortion of the echography . Resultant demarcation produces bulges known as Baum’s Bump. In axial view of the phakic eye, posterior lens capsule is the 1 st intraocular structure to appear in the screen  vitreous gel retina, choroid and sclera .

PowerPoint Presentation: 

Axial scan obtained by directing the sound beam across the visual axis through the cornea and lens. L, lens; V, vitreous; R, retina; S, sclera; ON, optic nerve; O, orbital tissue.

B-scan probe orientations: 

B-scan probe orientations 2. Longitudinal B-scan require the probe to be placed on the conjunctiva overlying the sclera and directed through the vitreous bypassing the lens. It produce a cross-section of the eye along a specific clock hour, displaying the anterior portion of the eye at the top of the screen and the optic nerve at the bottom.

PowerPoint Presentation: 

Longitudinal scan- V, vitreous; R, retina; S, sclera; ON, optic nerve; O, orbital tissue.

B-scan probe orientations: 

B-scan probe orientations 3. Transverse B-scan  probe placed on the globe with marker parallel to the limbus in 2 directions either nasally or superiorly It produces a lateral cross-section of the eye that results in an image with the superior or nasal aspect displayed at the top of the screen and the inferior or temporal aspect displayed at the bottom of the screen.

PowerPoint Presentation: 

Designation of transverse scan is determined by the meridian that lies in the middle of the scanning section. For eg .-If probe is held horizontally with its face centered on the 6 0’ clock meridian, the middle of the echogram will display the 12 0’ clock meridian of the fundus , this probe position is called a transverse scan of 12 0’ clock meridian

PowerPoint Presentation: 

Transverse B-scan obtained by directing the sound beam transsclerally at a 90 angle to the structure of interest to evaluate a superior to inferior or a nasal to temporal cross-section. L, lens; V, vitreous; R, retina; S, sclera; ON, optic nerve; O, orbital tissue.

ULTRASOUND BIOMICROSCOPY: 

ULTRASOUND BIOMICROSCOPY It is an ultrasound instrument introduced by Pavlin and colleagues that uses frequencies from 35 to 80 MHz for the acoustic evaluation of anterior segment of the eye. A plastic eyecup of the appropriate size is inserted between the lids, holding methylcellulose or normal saline coupling medium. The real-time image is displayed on a video monitor

ULTRASOUND BIOMICROSCOPY: 

ULTRASOUND BIOMICROSCOPY ANTERIOR CHAMBER AC DEPTH- axial distance from the internal corneal surface to the lens surface.

ULTRASOUND BIOMICROSCOPY: 

ULTRASOUND BIOMICROSCOPY CORNEA CORNEAL LAYERS-The first highly reflective line is the surface of the corneal epithelium . H ighly reflective line below this is the Bowman’s layer. S troma reveals a low internal reflectivity The endothelium and Descemet’s membrane form a single highly reflective line at the posterior corneal margin.

ULTRASOUND BIOMICROSCOPY: 

ULTRASOUND BIOMICROSCOPY ANTERIOR CHAMBER ANGLE REGION

PowerPoint Presentation: 

ANTERIOR CHAMBER ANGLE DEPTH:- The corneoscleral junction and scleral spur can be distinguished The iris epithelium forms a constant highly reflective layer on the posterior iris surface. This line defines the posterior iris border and can be useful when one is differentiating intra-iris lesions from lesions behind the iris.

ANTERIOR SEGMENT DISORDERS: 

ANTERIOR SEGMENT DISORDERS

ANGLE CLOSURE GLAUCOMA: 

ANGLE CLOSURE GLAUCOMA I ris is not in a flat plane but is bowed anteriorly (anterior convexity) secondary to relative pupillary block.

ANGLE CLOSURE GLAUCOMA: 

ANGLE CLOSURE GLAUCOMA After peripheral iridotomy (arrowhead), the angle (arrow) has opened.

COMPLETE PUPILLARY BLOCK: 

COMPLETE PUPILLARY BLOCK Adherence of the posterior surface of the peripupillary iris to the anterior lens capsule causes pupillary block (arrows)

IRIS BOMBE: 

IRIS BOMBE The peripheral iris is pushed forward closing the anterior chamber angle (arrow).

PIGMENTARY GLAUCOMA: 

PIGMENTARY GLAUCOMA P igment accumulation on the corneal endothelial surface ( Kruckenberg spindle) (arrow)

PIGMENTARY GLAUCOMA: 

PIGMENTARY GLAUCOMA Posterior bowing of the iris

PERIPHERAL ANTERIOR SYNECHIA: 

PERIPHERAL ANTERIOR SYNECHIA

VITREORETINAL DISORDERS: 

VITREORETINAL DISORDERS

VITREOUS HEMORRHAGE: 

VITREOUS HEMORRHAGE A fresh VH appears as diffuse opacities of low to medium reflectivity on B-scan, with multiple low intensity spikes on A-scan

VITREOUS HEMORRHAGE: 

VITREOUS HEMORRHAGE As the blood organizes, it forms pseudomembranous surfaces on B-scan, corresponding to slightly higher intensity spikes on A-scan

VITREOUS HEMORRHAGE: 

VITREOUS HEMORRHAGE Layering of blood inferiorly results in very high reflectivity on B-scan and in a static examination may be mistaken for a RD

VITREOUS HEMORRHAGE: 

VITREOUS HEMORRHAGE In a vitrectomized eye, blood can remain in a liquefied state and often requires the use of high-gain settings to visualize the Hemorrhage.

VITREOUS HEMORRHAGE: 

VITREOUS HEMORRHAGE Same patient on low gain. The vitreous hemorrhage is not visible, as it does not organize in a vitrectomized eye.

POSTERIOR VITREOUS DETACHMENT: 

POSTERIOR VITREOUS DETACHMENT The vitreous is attached (vitreous base) in a band extending 360 around the ora serrata and weakly adherent to the macula and optic disc. Thus the site of detachment is usually located in the posterior pole. Retinal tears often occur just posterior to the vitreous base, because of traction placed on the retina as the vitreous pulls away from the retina.

POSTERIOR VITREOUS DETACHMENT: 

POSTERIOR VITREOUS DETACHMENT Posterior vitreous detachment (PVD) adherent to the optic disc (arrowhead).

POSTERIOR VITREOUS DETACHMENT: 

POSTERIOR VITREOUS DETACHMENT PVD at high gain (90dB) PVD (arrowheads) and retina (arrow)

POSTERIOR VITREOUS DETACHMENT: 

POSTERIOR VITREOUS DETACHMENT PVD at low gain (39 dB) As the gain is reduced, the PVD (arrowheads) disappears in contrast to the retina (arrow), which remains visible even at low gain settings

POSTERIOR VITREOUS DETACHMENT: 

POSTERIOR VITREOUS DETACHMENT Layering of blood along the surface of a PVD may result in a thickened appearance on B-scan

RHEGMATOGENOUS RD: 

RHEGMATOGENOUS RD Thickened rope like appearance and attachment to the optic disc.

TRACTIONAL RD: 

TRACTIONAL RD T hin posterior vitreous detachment (arrows) adherent to tent-like tractional retinal detachments (arrowheads).

EXUDATIVE RD: 

EXUDATIVE RD S mooth convex surface and absence of rugae and retinal breaks. A s the patient’s head position is changed, the subretinal fluid will shift to the most dependant portion.

TOTAL RD: 

TOTAL RD T-shaped chronic retinal detachment appears as a thickened, highly reflective membrane with complete loss of mobility

CHOROIDAL DETACHMENT WITH VITREOUS H’AGE: 

CHOROIDAL DETACHMENT WITH VITREOUS H’AGE B -scan shows posterior vitreous detachment ( arrow ), choroidal detachment (arrowhead), and vitreous hemorrhage

SEROUS CHOROIDAL DETACHMENT: 

SEROUS CHOROIDAL DETACHMENT B -scan shows two choroidal detachments (arrowheads) with subchoroidal serous fluid (SF)

HEMORRHAGIC CD: 

HEMORRHAGIC CD Note appositional choroidal detachment (arrowheads) with dense opacities in the suprachoroidal space indicative of subchoroidal hemorrhage (SH).

CHOROIDAL DETACHMENT WITH RD: 

CHOROIDAL DETACHMENT WITH RD B -scan showing choroidal detachment (arrowhead) with SH and retinal detachment (arrow).

RETINOSCHISIS: 

RETINOSCHISIS B -scan transverse view demonstrates a smooth, thin, dome shaped membrane.

INTRAOCULAR TUMOURS: 

INTRAOCULAR TUMOURS

RETINOBLASTOMA: 

RETINOBLASTOMA

RETINOBLASTOMA: 

RETINOBLASTOMA Transverse B-scans demonstrate a large, dome- shaped lesion with marked internal calcification.

RETINOBLASTOMA WITH RD: 

RETINOBLASTOMA WITH RD

RETINOBLASTOMA WITH RD: 

RETINOBLASTOMA WITH RD Longitudinal B-scan demonstrates a large, dome-shaped lesion with internal calcification (back arrow) and RD ( white arrow) over the apex of the lesion and extending peripherally.

RETINOPATHY OF PREMATURITY: 

RETINOPATHY OF PREMATURITY Longitudinal B-scan demonstrates a highly reflective, closed funnel -shaped retinal detachment (arrows) inserting into the disc.

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS: 

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS: 

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS Longitudinal B-scan demonstrates taunt, thickened vitreous band adherent to the slightly elevated optic disc.

CHOROIDAL MELANOMA: 

CHOROIDAL MELANOMA C onfined to the subretinal space, are dome-shaped, lobulated, and diffuse.Longitudinal B-scan demonstrates a dome-shaped lesion with slightly sloping shoulders

CHOROIDAL MELANOMA: 

CHOROIDAL MELANOMA The pathognomonic appearance of choroidal melanoma is the collar button shape that results from a break in the Bruch’s membrane

CHOROIDAL MELANOMA: 

CHOROIDAL MELANOMA Longitudinal B-scan demonstrates a collar button-shaped choroidal lesion with a defined segmentation corresponding to Bruch’s membrane

CHOROIDAL HEMANGIOMA: 

CHOROIDAL HEMANGIOMA P resents as a circumscribed or diffuse orange-red, mildly elevated lesion. Circumscribed tumors are sporadic, usually located in the posterior pole, and dome-shaped with a thickness less than 6 mm.

CHOROIDAL HEMANGIOMA: 

CHOROIDAL HEMANGIOMA H yperechoic on B-scan with regular internal structure and little internal blood flow

OPTIC NERVE DISORDERS: 

OPTIC NERVE DISORDERS

NORMAL RETROBULBAR OPTIC NERVE MEASUREMENTS: 

NORMAL RETROBULBAR OPTIC NERVE MEASUREMENTS The optic nerves are usually symmetric and measure the same thickness both anteriorly and posteriorly. The optic nerve sheath diameter is measured in two locations, 3 mm posterior to the optic nerve head and as close as possible to the orbital apex . Normal retrobulbar optic nerves measured at the arachnoid sheath are 2.2 to 3.3 mm in diameter . A difference of 0.5 mm between eyes frequently indicates an abnormal thickness in one eye.

PowerPoint Presentation: 

30 o TEST- Increased subarachnoid fluid can be differentiated from thickening of the parenchyma or perineural sheaths with a 30 o test. The patient fixates in primary gaze (straight ahead position), and the optic nerve perineural sheaths are measured anteriorly and posteriorly. The patient’s gaze then is directed 30 o laterally. W hen the eye is fixated laterally, the optic nerve sheaths are stretched and the subarachnoid fluid is spread over a larger area. A decrease in sheath diameter of greater than 10% in lateral gaze, as compared with primary gaze, is considered a positive 30 o test and thus indicative of increased subarachnoid fluid.

PAPILLOEDEMA: 

PAPILLOEDEMA

PAPILLOEDEMA: 

PAPILLOEDEMA Transverse B-scan shows marked elevation of the optic disc.

PAPILLOEDEMA: 

PAPILLOEDEMA Transverse B-scan shows a cross section of the retrobulbar optic nerve (arrow) and low reflective crescent-shaped echolucent area behind the nerve indicative of increased subarachnoid fluid (arrowheads)

PAPILLOEDEMA: 

PAPILLOEDEMA Positive 30° test with diagnostic A-scan while the eye is in primary gaze (straight ahead) position with an enlarged retrobulbar optic nerve (diameter =4.8 mm)

PAPILLOEDEMA: 

PAPILLOEDEMA When the eye is fixated 30° laterally, note a marked decrease in the size of the retrobulbar optic nerve (diameter = 3.5 )

BURIED OPTIC DISC DRUSEN: 

BURIED OPTIC DISC DRUSEN Fundus photograph shows optic nerve head elevation and absence of optic cup mimicking the appearance of papilledema .

BURIED OPTIC DISC DRUSEN: 

BURIED OPTIC DISC DRUSEN Longitudinal B-scan shows highly calcified, round drusen at the optic nerve head with shadowing .

BURIED OPTIC DISC DRUSEN: 

BURIED OPTIC DISC DRUSEN Diagnostic A-scan shows normal retrobulbar optic nerve diameter measuring 3.2 mm

VISIBLE OPTIC DISC DRUSEN: 

VISIBLE OPTIC DISC DRUSEN

VISIBLE OPTIC DISC DRUSEN: 

VISIBLE OPTIC DISC DRUSEN Transverse B-scan shows two round, highly calcified drusen at the optic nerve head without optic disc edema

TILTED OPTIC DISC: 

TILTED OPTIC DISC A pparent elevation of the nasal rim (arrow) of the optic disc right eye.

TILTED OPTIC DISC: 

TILTED OPTIC DISC Axial B-scan images show mild optic disc elevation without buried drusen or optic disc edema of the right eye.

POSTERIOR SEGMENT TRAUMA: 

POSTERIOR SEGMENT TRAUMA

PowerPoint Presentation: 

Ocular trauma is a major cause of vision loss, particularly among younger patient. Vitreoretinal involvement is present in nearly 50% of all severe eye injuries secondary to blunt or penetrating trauma . E xamination of the posterior segment is limited due to coexisting anterior segment injury.

RETINAL DETACHMENT: 

RETINAL DETACHMENT Retinal detachment after blunt trauma may develop as a result of retinal dialysis, flap tears , or giant retinal tears through rapid compression- decompression forces that result in transient anteroposterior shortening and equatorial elongation of the globe.

RETINAL DETACHMENT: 

RETINAL DETACHMENT Peripheral Retinal Tear-Longitudinal B-scan at a low gain displays small, highly reflective flap (arrow).

RETINAL DETACHMENT: 

RETINAL DETACHMENT Giant retinal tear. Transverse B-scan shows discontinous , folded, hyperechoic retina.

RETINAL DETACHMENT: 

RETINAL DETACHMENT Combined tractional and rhegmatogenous retinal detachment at the site of globe penetration.

CHOROIDAL DETACHMENT: 

CHOROIDAL DETACHMENT Serous choroidal detachment. Transverse B-scan demonstrates scalloped appearance of choroid with absence of opacities in the suprachoroidal space.

CHOROIDAL DETACHMENT: 

CHOROIDAL DETACHMENT Hemorrhagic choroidal detachment. Transverse B-scan demonstrates scalloped appearance of choroid with dense opacities in the suprachoroidal space.

LENS DISLOCATION: 

LENS DISLOCATION Blunt trauma can lead to the subluxation or dislocation of the crystalline lens or intraocular lens implants through the disruption of zonular fibers. B lunt trauma, including seizure-related injury , airbag deployment ,paint -ball injuries ,bottle corks ,and elastic cord–related injuries.

LENS DISLOCATION: 

LENS DISLOCATION Posteriorly dislocated normal crystalline lens. Longitudinal B-scan demonstrates smooth, oval mass with foci of high reflectivity and mobility.

LENS DISLOCATION: 

LENS DISLOCATION Posteriorly dislocated intraocular lens implant. Oblique transverse B-scan shows a highly reflective echo source causing marked shadowing of the posterior orbit.

INTRAOCULAR FOREIGN BODY: 

INTRAOCULAR FOREIGN BODY IOFBs are encountered in 18% to 41% of cases that involve open globe trauma. Young men are the most frequently affected, and hammering is the most frequent predisposing activity . CT scans have a much higher sensitivity. MRI imaging is contraindicated when metallic IOFB is suspected.

INTRAOCULAR FOREIGN BODY: 

INTRAOCULAR FOREIGN BODY Extremely thin IOFBs (< 100 mm ) can be differentiated, localized . Metallic IOFBs are echo dense—even at low gain settings—and often produce shadowing of intraocular structures and the orbit.

ENDOPHTHALMITIS: 

ENDOPHTHALMITIS Endophthalmitis can occur in the setting of open- globe injury. Retained foreign body composed of vegetative material, delayed repair (> 24 hours), lens capsule disruption, and the presence of a contaminated wound are important risk factors for development of endophthalmitis

ENDOPHTHALMITIS: 

ENDOPHTHALMITIS Transverse B-scan shows marked vitreous opacities and membrane formation consistent with endophthalmitis .

THANK U: 

THANK U