Breakthrough in Ophthalmology 

      Optical coherence tomography (OCT), first widely available in the mid 1990s  provides unprecedented, high-resolution, cross-sectional imaging of the retinal cells and anatomy of the optic nerve head.  OCT gives clinicians the capability of microscopic examination of living retinal cells while histology only allows for microscopic examination of preserved retinal cells from a non-living tissue sample. OCT imaging is real time, quick, noncontact, noninvasive, and avoids patient sensation. This technology can image both transparent and non-transparent ocular tissue with 10-100 times finer detail than ultrasound and scans are viewable as two or three-dimensional data sets with resolution approaching histopathological detail. OCT scans also allow for real time identification of cellular features in individual retinal layers.

      Major Optical Coherence Tomography benefits:

      1

      Non-invasive and non-contact

      No surgery required and nothing touches the eye
      2

      Quick and convenient

      Lasts only a few minutes and no dilation is needed

      3

      Comfortable and painless

      Uses invisible light and no sensation is felt

      4

      Effective and reliable

      Obtainable in low vision and pediatric patients, provides detailed and valid data 
      5

      Accurate and repeatable

      Measures within a few micrometers and exact locations can be scanned at subsequent exams

      6

      Objective and Scientific

      Does not require subjective feedback and is the standard of care in the field of ophthalmology

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      When OCT examination is required:

      • Your eye care provider needs more information (such as OCT scans) to determine if you are suffering from an optic nerve or retinal disorder 
      • You have been diagnosed with a progressive eye condition (such as glaucoma or retinitis pigmentosa) which needs close monitoring 
      •  The exact diagnosis of your eye condition will not be known until OCT scans are performed to rule out other optic nerve or retinal disorders 
      • You need an explanation for the concerning changes in your vision 
      • You have a neurological medical condition known to affect vision or the optic nerve (multiple sclerosis, pituitary tumor, brain trauma, etc...)
      • You have a condition like retinitis pigmentosa with associated complications like cystoid macular edema
      • You know your vision is off, but you can’t describe why exactly

      When OCT exam is recommended: 

      • To ensure vision loss is actually from a neurological complication (ex. stroke, trauma, tumors) rather than an optic nerve problem
      • To monitor for optic nerve or retinal changes in (likely) non-progressive eye conditions such as past ischemia or traumatic optic nerve damage
      • To evaluate if your multiple sclerosis (with relapses) is  affecting your optic nerve or retinal health and treat if necessary
      • You have been diagnosed with papilledema and need your optic nerve health monitored 
      • You have family member(s) diagnosed with a hereditary eye condition and you are concerned about the health of your eyes 
      • You had an eye surgery (ex. cataracts) and you want to ensure your retina and optic nerve is healthy afterwards

      When you can spare on OCT exams

      • If you vision problems are due to cataract or refractive problems (according to your eye care provider) 
      • If your visual complaints do not relate to optic nerve or retinal damage (must be confirmed by your eye care provider)
      • If your visual field limitations result from a droopy eyelid (and your eye care provider states no other problems exist)
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      Not sure if you need
      electrophysiologic testing?

      Ask our physicians for evaluation

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      Ophthalmological Diagnosis

      Prior to OCT technology, retinal conditions were only described and diagnosed clinically. These cross-sectional scans have provided crucial insight into the pathogenesis of ocular conditions by deciphering which specific layers are involved and better visualizing the disease process.

      Clinical studies have demonstrated usefulness and feasibility of OCT in ocular conditions such as glaucoma, retinitis pigmentosa, macular degeneration, optic neuritis, drusen of the optic nerve and macula, diabetic retinopathy, macular edema, epiretinal membranes,, and choroidal tumors.

      OCT scans are performed with a patient sitting upright with their chin in a chin rest and forehead against a bar. Unlike ultrasound, OCT can be utilized with air as the medium rather than gel. This form of imaging is noncontact, noninvasive, and takes only a few minutes. A harmless and invisible laser painlessly scans the retina and optic nerve head. Vision remains unaffected and no dilation of the pupil is required. The data is calculated and analyzed through a computer system. The new recordings and measurements are automatically saved and compared with previous scans to assess potential changes. Even the slightest value discrepancies of the retina and optic nerve head will be identified. The course of progression is graphically plotted to easily visualize changes over time.

       

      Basic OCT Interpretation
      (for non-professionals)

      While diagnosis and interpretation using OCT takes intimate familiarity, experience, and training, non-professionals can use some basic principles for rudimentary interpretation. 

      Depending on the type of OCT instrument being used, analysis of the scans may clearly state if thickness measurements of the RNFL, GCL, or macula are normal, abnormally thin, or abnormally thick. Color indicators may also be used to depict the relative thickness or an area or layer compared to age-matched controls. Careful attention to the color key is necessary as color scales may vary (and even be opposite) depending on which ocular structure is being viewed.

      OCT undamaged optic nerve and thickness map

      Healthy Optic Nerve

      Generally, a healthy posterior segment of an eye displays no clinical or OCT abnormalities. The extraordinary sensitivity of OCT  allows for visualization of individual ocular structures of the such as the optic nerve as optic nerve head, retinal nerve fiber layer (RNFL) and axons of retinal ganglion cells as  different retinal layers as well.

      With OCT, a large devoid space is visible where axons exit the eye and edema is not observed at the surface along the edge margins. The vitreous appears dark and absent while the internal limiting membrane (ILM) and retinal nerve fiber layer (RNFL) are highly reflective. The RNFL will be thicker nasally than temporally, corresponding to the papillomacular bundle.

      OCT healthy retina

      Healthy Retina

      Retinal layers will appear distinguishable, smooth (no breaks), and  even while a small dip in contour is observed at the fovea. The posterior cortical vitreous may be delicately attached to the macula or floating above the macula. 

      The inner and outer nuclear layers as well as the ganglion cell layer (GCL) have minimal reflectivity. The external limiting membrane (ELM), photoreceptor integrity line (PIL), and retinal pigment epithelium (RPE) are hyper-reflective. Posterior to these layers is the less reflective choroid.



      Diseases Of The Optic Nerve

      Bildschirmfoto 2020-04-13 um 13.27.27

      Along with perimetry (visual field testing), the OCT has become the standard of care for glaucoma diagnosis and management over the last decade. The strongest indicator of glaucoma is progressive thinning of the RNFL along the papillomacular bundle over a given time. ONH structural changes in the form of excavation or cupping are quantifiable using OCT. Atrophy (thinning) of the retinal ganglion cell layer (GCL) and total macular thickness are also measurable.

      Bildschirmfoto 2020-04-13 um 13.28.04Typically, initial ischemic optic nerve damage causes moderate or severe swelling of the ONH due to lack of oxygen. Treatment with steroids remains controversial as no benefits have been confirmed. Usually this swelling resolves in 8-12 months after NAION onset, but without vision recovery. Chronic NAION demonstrates RNFL and GCL thinning. OCT angiography is a particularly useful diagnostic tool in the diagnosis of NAION as it is capable of revealing reduced capillary density or attenuation of patent vessels.

      Bildschirmfoto 2020-04-15 um 05.21.21Leber Hereditary Optic Neuropathy: In LHON, primary damage occurs at the level of the retinal ganglion cells with secondary involvement of the optic nerve. OCT plays a key role in diagnosis and stage determination of LHON as OCT patterns differ greatly by disease state. In early or acute episodes of LHON, the RNFL may demonstrate thickening due to axonal edema. In general, chronic LHON demonstrates primarily temporal thinning of the RNFL and severe GCL loss due to progressive atrophy.

      Bildschirmfoto 2020-04-13 um 13.27.01The optic nerve is known to be vulnerable to systemic autoimmune inflammation. Clinical OCT findings demonstrate that the temporal aspect of the RNFL is most affected in optic neuritis which reflects not just local pathological characteristics, but brain axonal degeneration processes. Macular scans reveal prominent reduction of GCL thickness from cellular damage and subsequent atrophy. Chronic optic neuritis demonstrates significantly thinner RNFL beginning a few months after onset. Similar to other conditions, during acute episodes, ONH swelling may cause a thicker than normal RNFL.

      Bildschirmfoto 2020-04-13 um 13.28.53In optic nerve hypoplasia, OCT scans of the ONH accurately measure a physically smaller optic disc also observable with dilated fundus examination. Hypoplastic optic discs have decreased horizontal width, lessened cup depth, and a thin peripapillary RNFL. Foveal hypoplasia may be seen with reduced overall macular thickness, decreased GCL thickness, and RNFL thinning.

      Bildschirmfoto 2020-04-13 um 13.29.33

      OCT has demonstrated usefulness in differentiating ONH edema from buried drusen. While edema presents with altered RNFL and GCL thickness, drusen leaves these layers unaffected. With edema, the anterior ONH may reveal an abnormal RNFL swelling, yet the posterior ONH will have a smooth contour. However, with small or moderate buried ONH drusen, the anterior ONH usually remains unaffected while the posterior ONH demonstrates “bumps” evident of buried ONH drusen. Severe ONH drusen may cause RNFL atrophy and mild vision loss.

      Retinal Changes Secondary
      To The Optic Nerve Damage.

      Healthy
      Retina
      OCT undamaged retina retinal ganglion cells mapping
      Retinal ganglion cell (RGC) layer based on color mapping in microns (red=thick, blue=thin).
      Early
      Glaucoma
      OCT inital  atrophy ofretinal ganglion cells glaucoma
      Early glaucomatous neuropathy as evidenced by slight superior thinning of the RGC layer
      Advanced
      Glaucoma
      OCT half atrophy of retinal ganglion cells by ischemic optic neuropathy
      Advanced glaucoma with severe inferior RGC loss. Cupping is visible on the ONH.
      Severe
      Glaucoma
      OCT severily atrophied  retinal ganglion cells by glaucoma
      Severe and diffuse RGC loss. Thinning more pronounced superiorly and temporally.
      Optic
      Neuritis
      OCT moderate  atrophy of retinal ganglion cells optic neuritis
      Diffuse and severe RGC loss of the macula with complete RGC loss in the fovea.
      Leber Optic
      Atrophy
      OCT moderate  atrophy of retinal ganglion cells Leber Hereditary Optic Neuropathy
      Diffuse, moderate central and complete foveal  loss of RGC due to LHON.
      Traumatic Optic Neuropathy
      OCT complete  atrophy of retinal ganglion cells traumatic optic neuropathy
      Severe and diffuse macular RGC thinning with small intact islands of RGCs due to trauma
      Ischemic Optic Neuropathy
      Severe ischemic optic neuropathy (NAION) Fedorov Restore Vision Clinic
      Almost complete loss RGCs of the macula  due to ischemic damage of the nerve.

      OCT Patterns Of The
      Optic Nerve Damage

      Healthy Optic Nerve Head
      Healthy optic nerve. OCT scan Restore Vision Clinic
      Normal retinal nerve fiber thickness adjacent to the ONH. (layer between red and blue lines)
      Advanced 
      Glaucoma
      OCT mild optic nerve damage13
      Severe RNFL atrophy due to advanced glaucoma (glaucomatous optic neuropathy)
      Leber Optic
      Atrophy
      OCT Temporal optic nerve atrophy leber hereditary optic neuropathy Fedorov Restore Vision Clinic
      Temporal RNFL thinning in case of Leber Hereditary Optic Neuropathy
      Traumatic Optic Neuropathy
      Severe optic nerve atrophy
      End-stage (near complete) RNFL atrophy due to trauma optic neuropathy
      ONH Glaucoma
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      Typical pattern of advanced glaucomatous excavation of the optic disk head.
      ONH NAION
      Severe optic nerve atrophy caused by ischemic optic neuropathy. NAION Fedorov Restore Vision Clinic
      Severe optic nerve atrophy caused by ischemic optic neuropathy. NAION 
      Optic Nerve Head
      Bildschirmfoto 2020-04-13 um 20.14.30
      RNFL and Optic Nerve Head edema due to Idiopathic Intracranial Hypertension
      ONH Drusen
      OCT scan over optic nerve head with inintial drusen
      Buried ONH drusen. Initial stage. Pseudopapilledema

      Diseases Of The Retina

      Bildschirmfoto 2020-04-13 um 13.42.36

      RP is a progressive retinal dystrophy emerging in the peripheral retina before advancing centrally. OCT will reveal loss of the photoreceptor integrity line (PIL) throughout the retina as well as choroidal thinning. In the macula, both foveal thinning and thickening may be observed and cystic macular changes may be noted. In later stages, foveal atrophy occurs due to cone degeneration in the macula (center retina). Cystoid macular edema (CME) accompanies up to 20-30% of RP cases and can cause a disruption of central vision due to structural abnormalities of the macula. OCT imaging is extremely important to diagnose, manage, and initiate therapeutic intervention.

      Bildschirmfoto 2020-04-13 um 13.43.09With cone-rod dystrophy, abnormalities in the PIL are observed especially at the outer segment of the photoreceptor layer and primarily affect the fovea (part of the central retina responsible for sharp vision). Additionally, OCT autofluorescence may reveal a perifoveal hyperfluorescent ring due to photoreceptor disorganization and RPE changes/atrophy. Increased lipofuscin may be seen within the RPE.

      Bildschirmfoto 2020-04-13 um 13.43.42Macular drusen is the hallmark of age-related macular degeneration (AMD). Clinically, drusen appear as yellow or white deposits in the retina. With OCT, drusen are observed as focal deposits in the outer retina, between the RPE and Bruch’s Membrane. In early and intermediate AMD, no associated choroidal thinning is typically observed. However, in advanced AMD, thinning of the choroid may also be noted. In advanced AMD, other retinal abnormalities are also visible with OCT.

      Bildschirmfoto 2020-04-13 um 13.44.46Retinal Pigment Epithelium (RPE) atrophy: With RPE atrophy, pigment migration is observable as an accumulation of material in some areas of the RPE and a lack of pigment in other areas. The RPE may thicken in areas of material accumulation and thin in other areas due to atrophy. Such changes result in an irregular morphology of the RPE. The RPE can also exhibit porosity, observable as gaps or holes in the layer itself.  Less often, a choroidal neovascular membrane may form, pushing the RPE anteriorly.

       

      OCT Patterns Of
      Retinal Dystrophies

      Healthy
      Retina

      OCT healthy retina
      Even and smooth laters. Right side thicker RNFL consistent with the nasal papillomacula bundle.
      Early Retinitis Pigmentosa
      OCT Retinitis Pigmentosa. Advanced stage Rod-Cone Dystrophy Fedorov Restoration Therapy
      Loss of the photoreceptor integrity line (PIL) peripherally. PIL present centrally. Epiretinal membrane likely forming temporal to the fovea.
      Advanced Stage
      of  RP
      OCT Retinitis Pigmentosa. moderate stage Rod Dystrophy Restore Vision Clinic Germany
      Complete photoreceptor integrity line (PIL) loss. Diffuse RPE loss. . Fovea is still intact. Mild macular posterior staphyloma from myopia.
      Advanced RP /
      RPE Atrophy
      OCT Retinitis Pigmentosa. Advanced stage Severe rod atrophy Retinal RPE retinal pigment epithelium atrophy
      Complete loss of photoreceptor integrity line (PIL). Extensive RPE atrophy. Generalized retinal atrophy. Fovea intact, but losing contour.
      Cone Rod
      Dystrophy
      OCT Retinitis Pigmentosa. Severe stage Rod Dystrophy Fedorov Restore Vision Clinic
      Advanced stage with loss of the cones integrity and cells death. Diffuse RPE atrophy. Generalized retinal thinning.
      Cone Rod
      Dystrophy
      OCT Retinitis Pigmentosa. Advanced stage Cone Rod Dystrophy Severe cone atrophy
      Abnormal foveal contour due to generalized retinal and foveal atrophy. Almost complete RPE loss. 
      Stargardt
      Disease
      OCT Cone Dystrophy Stargardt Disease
      Stargardt Disease. Severe loss of photoreceptors. Generalized retinal and foveal atrophy. Almost complete RPE loss. 

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