Edward Chang, MD · Ultrasound testing in 1930’s A-mode and B-mode scanning 1960’s 10 MHz to 50...

Edward Chang, MD Everett & Hurite Ophth Assoc

1887 – Photo of human retina on a live subject

1898 – Fundus camera developed allowing better fundus photography – Zeiss Jena

1909 – First stereo photograph - Thorner

Ultrasound testing in 1930’s

A-mode and B-mode scanning 1960’s 10 MHz to 50 MHz Ocular contents present a challenge Millimeters vs micrometers

IOL’s become available

Refractive surgery

Anterior Segment Anatomic evaluations Narrow angle Plateau Iris Tumors, cystic structures

Cataracts Biometry

Refractive

Trauma

Posterior Segment Retina Diabetic disease – rx and follow-up Cystoid macular edema Macular degeneration and similar Tumors

Glaucoma Nerve fiber layer Ganglion cell

Armament A-scan, B-scan

Ultrasound Biomicroscopy – UBM

CT/MRI

Confocal microscopy

Anterior Segment OCT – (AS-OCT)

IOL Master, Lenstar, Pentacam

Posterior segment OCT, GDx, Optovue

HD Photography

Cataracts Still the most commonly performed surgery within

Medicare

Population median age continues to rise

High expectations

Reimbursement stagnant

Technology advancements

A-scan, B-scan

IOL Master, Lenstar & Pentacam

AS-OCT

Posterior segment OCT

A-scan Immersion vs Applanation

Technology has improved over time

Portable

Accurate

Cost efficient

Comparative to other testing

Tech dependent;

IOL Master Approved in 2000

Non-contact optical device; measures distance from corneal vertex to retinal pigment epithelium by partial coherence interferometry

Accuracy to 0.02mm or better A-scan resolution 0.10mm to 0.12mm

500 version most commonly used

700v now available; swept source OCT

Lenstar Available in 2000

First biometer that can measure thickness of crystalline lens

Integrated formulas; easier data input

Dual zone keratometry; pachymetry, pupillometry, W to W, ACD

Pentacam Introduced in 2002

Rotating Scheimplug camera

Biometry added last year with AXL edition

Offers improved corneal data

Integration of data with IOL formulas

If you have one of the others, do you really needs this also??

Corneal rx uses such as crosslinking

B-scan

Glaucoma

Glaucoma - facts u 2.4 million people develop glaucoma throughout

world annually; 50% are unaware

u 2.6 million Americans with POAG

u >10 million with elevated IOP in U.S.

u Second leading cause of blindness overall in U.S. 80,000 to 116,000 blind from glaucoma

u Black pts. are 3X more likely to have glaucoma; 6-8x more likely to be blind from it

What is Glaucoma Family of ocular diseases characterized by

progressive optic neuropathy and visual field loss Gradual optic disk cupping Associated visual field deficits Progressive retinal ganglion cell loss

No longer defined alone by elevated intraocular pressure (IOP)

Disc Photography Fundus photography 1920’s

35mm disc photography starting in 1960’s

Digital photography

Stereo disc photos

Allowed baseline and ability for extended analysis of disc

Red-free nerve fiber layer photography

Quantitative Imaging Confocal Scanning Laser Ophthalmoscopy HRT

Scanning Laser Polarimetry GDx

Optical Coherence Tomography OCT

Heidelberg - HRT Developed in 1955

670-nm diode laser produces up to 64 transaxial scans of ONH

3-D topographical image

C/D ratio, rim area, disc parameters

HRT II and III versions available

?reproducibility

What do you do with data?

GDx measures peripapillary RNFL thickness by sending a

laser beam to the posterior retina and assessing the change in polarization (retardation) of the reflected beam. This retardation of the scanning beam results from the birefringent properties of the neurotubules contained within the ganglion cell axons.

780nm

Initial devices suffered from data affected by corneal birefringence; updated devices have variable corneal compensation

OCT Low-coherence interferometry, near infra-red light.

High resolution scanning within micrometers

Limited to 1-2 mm

Time domain, Frequency domain, Spectral domain, Swept source OCT

Becoming standard of care

Ultrahigh speed swept source OCT, ultrahigh resolution OCT, polarization sensitive OCT, and adaptive optics OCT are all on the horizon

Time vs Fourier domain OCT Time domain OCT

A scan generated sequentially, one pixel at a time of 1.6 seconds

Moving reference mirror

400 scans/sec

Resolution – 10 micron

Slower than eye movement

Fourier domain OCT Entire A scan is generated at

once based on Fourier transformation of spectrometer analysis

Stationary reference mirror

26,000 scans/sec

Resolution – 5 micron

Faster than eye movement

52

OCT image display,

Highest reflectivity - red nerve fiber layer retinal pigment epithelium and Choriocapillaris

Minimal reflectivity appear blue or black photoreceptor layer choroid vitreous fluid or blood

A 53 year old female patient : glaucoma suspect due to borderline IOP of 23 mm Hg

Right optic nerve: 0.5 cup with an infero-temporal RNFL loss (arrows)

The visual fields normal in both eyes along with the rest of the eye examination.

Circle Scan

Differences betweeen average thickness in sectors (along the calculation circle) in each eye

OCT Scan with automatic segmentation of RNFL

TSNIT RNFL thickness compared to normative database

RNFL Thickness in quadrants & sectors compared to normative database

Ultrasound Biomicroscopy UBM

Compared to regular ultrasound (A & B-scan 10Mhz), it uses higher frequency (35-100Mhz)

Resolution to 25 microns

Anterior segment pathology

Trauma Multiple modalities of imaging to be used for diagnosis

and follow-up

B-scan

Photography

AS-OCT

UBM

Post-segment imaging

Thank You