Top 10 Used OCT for Glaucoma as a Screening Tool

OCT technology was invented in 1991 to aid in the early detection and diagnosis of retinal diseases. Over the years, Optical coherence technology for glaucoma has been debated in the medical industry. Below we explore the significant concepts of Optical Coherence Topography.

Have you been eager to learn more about the most commonly used OCT for Glaucoma as a screening tool? Then, you have come to the right place. In this article, you will learn about them and much more. But first, let us look at the basics for a better understanding.

What is the OCT test for glaucoma?

 

OCT is a non-invasive imaging test that utilizes light waves to take cross-section pictures of the Retina. OCT reveals the distinctive layers of the Retina, enabling the mapping and measurement of their thickness. The measurements enable testing and also provide treatment guidance for Glaucoma. 

OCT stands for Optical Coherence Topography. OCT is a test to obtain a topographical map of the optic nerve. Non-invasive light waves used during this test take cross-section pictures of the retina. An OCT test will measure the nerve fiber layer. This eye portion is considered most vulnerable to eye pressure elevation.

Why is OCT used in glaucoma?

Optical coherence tomography for glaucoma scans will help assess all the macular glaucoma regions. Assessing the macular glaucoma regions is crucial because almost 50% of the retinal ganglion cells are in the macular region. This makes macular glaucoma regions ideal for detecting any early cell loss.

What is the OCT test used for?

OCT is an imaging method that generates the back of the eye’s or retina’s picture. The picture measures the total dim red light reflecting off one’s retina. This makes OCT a routinely used imaging method for testing glaucoma.

How do you detect glaucoma?

To detect glaucoma, an individual is required to do a complete eye examination. The ophthalmologist will measure the pressure of an individual’s eye to detect glaucoma. He will also inspect the drainage angle of the eye. He will also examine an individual’s optic nerve for damage and test the peripheral (side) vision. The ophthalmologist will also take a picture or the computer measurement of the optic nerve and measure the thickness of the cornea. 

OCT in the Diagnosis and Management of Glaucoma

Optical coherence tomography imaging technology is used to evaluate glaucomatous structural damage. The non-invasive optical technique enables in vivo cross-sectional imaging of the ONH and retina.

The current iteration of the OCT technology spectral-domain (SD)-OCT has proven to have theoretical advantages as regards glaucoma assessment. It offers increased axial resolution and enables faster-scanning speed, leading to lower susceptibility to eye movement artifacts. 

After diagnosing glaucoma through OCT, the disease can be managed by lowering the pressure on an individual’s eye. However, this situation varies from person to person, and the management options may include taking oral medications, using prescription eye drops, surgery, or laser treatment. 

The Role of OCT in glaucoma diagnosis

OCT provides objective quantitative measurements that complement eye examination. By using OCT for glaucoma, ophthalmologists are better placed to detect glaucoma early, given that the progression of glaucoma causes irreversible loss of vision. Thus by using OCT, glaucoma can be detected before any visual loss. 

Oct also provides a baseline for looking for a change over time; what’s more, the changes on OCT predict future functional losses. Important to note is that OCT cannot be used to detect glaucoma in every patient; individuals with pre-existing conditions, among other risk factors, as we will explicate later, do not need OCT to detect glaucoma. But still, OCT might be needed to detect progression. 

Images from the OCT scans are usually examined from top to bottom and left to right within eight steps. The interpretation of the SD-OCT images takes on various aspects to ensure accurate detection of the condition. 

How Does Glaucoma Happen

When fluid builds up in the front part of the eye, it causes an increase in eye pressure, subsequently damaging the optic nerve. And you will not want your optic nerve damaged because it carries information from your eye to the brain. Thus once the optic nerve is damaged, it could lead to serious eye problems. 

Importance of Carrying Out Glaucoma Testing 

To diagnose glaucoma, a couple of tests are usually carried out. The advantage of doing the tests early enough is that if glaucoma is diagnosed early enough, the individual can take steps to prevent vision loss. 

How Many Types Of Glaucoma Are There? 

There are several types of Glaucoma; we will, however, look at the main types of glaucoma, the first one being

Closed-angle glaucoma

closed-angle glaucoma has two aka’s and can be referred to as narrow-angle glaucoma or angle-closure glaucoma. It is a type of glaucoma that affects one eye at a time; if an individual gets this type of glaucoma, their drainage canals will be covered. The above is why closed-angle glaucoma can be categorized as acute or chronic. 

Individuals who suffer from acute closed-angle glaucoma will be subjected to a rapid increase in eye pressure. The individuals could lose their vision in hours if the condition is not treated promptly. Acute angle glaucoma is therefore categorized as a medical emergency. 

Chronic closed-angle glaucoma is known to develop slowly; the individual will not experience any symptoms up until the damage is severe. 

The second primary type of glaucoma is open-angle glaucoma, which is called primary open-angle glaucoma.

Many people have been found to suffer from this type of glaucoma, which usually occurs when the eyes cannot drain fluid properly via the eye’s drainage canals. The fluid then gets backed up in the canals, consequently causing an increase in eye pressure. 

Open-angle glaucoma has been established to develop slowly and can ultimately take years or months to manifest. Individuals who suffer from this glaucoma never have any symptoms or vision changes at the beginning. But once infected, open-angle glaucoma will present in both eyes simultaneously. 

Another type of glaucoma that people must be familiar with is normal-tension glaucoma, which does not fall under the two main types. Thus people with this type of glaucoma tend to experience eye pressure within the normal range but still show signs of glaucoma. Individuals suffering from normal-tension glaucoma might experience optic nerve damage or have blind spots in their field of vision. 

Importance of Glaucoma Testing

As mentioned earlier, individuals who suffer from open-angle glaucoma may not exhibit any symptoms until the disease has developed into a more serious stage. And that is why individuals who have certain risk factors must be tested. The above brings us to the next big question what are some of the risk factors of glaucoma? 

Individuals with glaucoma in their family history are at risk of developing complications. Glaucoma has also been found to affect older people; thus, individuals aged 60 and above are at risk of developing eye complications. Also, Hispanics aged 60 and above have a higher risk of developing glaucoma when compared to native Europeans. 

African Americans are also at a greater risk of developing glaucoma, while individuals of Asian descent have a much higher risk of developing closed-angle glaucoma. Individuals who have had eye injuries are at risk of developing glaucoma. The same applies to people who are far and nearsighted. 

The long-term use of steroid medication can lead to the development of glaucoma. Individuals with conditions such as high blood pressure, diabetes, and migraines, among other health problems that affect the entire body, are at a high risk of contracting glaucoma.  

What Is a Comprehensive Eye Exam in Glaucoma Testing?

Given the severity of the two main types of glaucoma, it is natural to want to know the eye exam that an ophthalmologist is likely to carry out. Below is an outline of the exams carried out by an ophthalmologist when testing for glaucoma. 

• Tonometry

  the tonometry test will require an individual to sit in an exam chair next to a slit lamp (special microscope). The ophthalmologist will then numb the eyes using eye drops, and the individual will be required to rest their chin and forehead on the slit lamp. And while leaning into the slit lamp, the eye specialist will use a tonometer to measure eye pressure. During this examination, the individual will experience a small puff of air but nothing painful. 

• Pachymetry

  – when performing the tonometry test, the first step involves numbing the eyes using eye drops. The eye specialist will then use the pachymetry device to measure the thickness of the cornea, which is known to predispose individuals to a higher risk of developing glaucoma. 

• Perimetry

  is better referred to as the visual field test and is used to measure peripheral (side) vision. Under the perimetry test, an individual must stare straight ahead at a screen. And light or image will then move in from one side of the screen. The patient’s job is to let the eye specialist know when they detect the light or image while looking straight ahead. 

• Dilated eye test

  when conducting this test, the specialist will first put eye drops into the eyes, dilating the pupils. And with a device with a light and a magnifying lens, he/she will examine the optic nerve to check for damage. 

• Gonioscopy

  under this test, the ophthalmologist will put drops in the patient’s eyes to numb and dilate them. He/she will then place a special handheld contact lens on the patient’s eyes. The lens is usually designed with a mirror, enabling the specialist to view the inside of the eye from different angles. The lens can show if the angle between the iris and the cornea is too wide, indicating the possibility of open-angle glaucoma. And if the angle is too narrow, it would be a possible sign of closed-angle glaucoma.  

How to Prepare For a Glaucoma Test

If you have never done any eye test, it is not uncommon to wonder what might transpire. So what you need to know is that when your eyes are dilated, your vision may be blurred, and there are chances that you might become extra sensitive when exposed to both natural and artificial light. This particular condition might persist for a few hours, and the severity will vary from person to person. 

So to be safe and protect your eyes from bright light, you might want to invest in sunglasses, which you will put on after your appointment with the ophthalmologist. Most importantly, you might not be able to take yourself back home, and as such, you should bring along a company that will drive you back home because your vision will be too impaired to enable you to drive safely. 

Are there any risks associated with the Glaucoma Test? 

There haven’t been any known risks associated with Glaucoma testing; however, some of the tests described above could be uncomfortable and could temporarily blur your vision. 

Can the Damage Cause By Glaucoma Be Reverse? 

No, the damage caused by glaucoma cannot be reversed, which means the condition will be permanent. However, further damage can be halted through surgery and the prescribed medicine. 

Can OCT Diagnose Other Conditions? 

Apart from glaucoma, OCT can also diagnose diabetic retinopathy, vitreous traction, macular edema, macular pucker, macula hole, central serous retinopathy, vitreous traction, and age-related macular degeneration. OCT has been instrumental in diagnosing optic nerve disorders, but it cannot be relied upon to diagnose conditions that interfere with light passing through the eye.

What Follows If Diagnosed With Glaucoma? 

Given the outcome of the tests and the determination that you indeed suffer from glaucoma, one or more of the following treatments will be recommended. 

The Ophthalmologist may recommend that you undergo surgery, creating a new opening that will enable the fluid to leave the eye. The specialist might also recommend some medicines, which can lower an individual’s eye pressure or even cause the eye to generate less fluid. Regarding prescriptions, some medicines could be in the form of pills and others in the form of eye drops. 

The ophthalmologist could also recommend the implantation of a drainage tube implant, a type of surgery where a flexible plastic tube will be placed in the eye to help to assist in draining the excess fluid. 

Here are the Top 10 commonly used OCT for Glaucoma as a Screening Tool.

1. Optovue Avanti ($19,999.00)

Optovue Avanti is a wide-field device OCT. This test offers multi-layered peripheral pathology assessment at various choroid and retina levels. Thus, establishing a new OCT imaging standard.

Few Features of Optovue Avanti:

• Wide Field En-Face OCT: Eyecare practitioners can use Optovue Avanti OCD to avoid all clinical challenges as it uses the most current technology. 
• Establishes New OCT Imaging Standards: Optovue Avanti offers En Face OCT with a 40° wide field. The OCT test will assess peripheral pathologies giving rise to advance OCT platforms.
• Motion Correction Technology data proprietary algorithms applied by the motion correction technology help reduce artifacts caused due to motion eye motion while scanning.
• 2-Phase Noise Reduction: The 2-Phase noise reduction feature helps reduce signal noise during scan acquisition and capture data post-processing.
• Deep Choroidal Imaging: The deep choroidal imaging feature or DCI helps push signal strength into the retina’s choroidal area with a button.
• Retina Module: The feature will enable specialists to assess the retina’s parts and evaluate change over time.

2. Optovue iFusion ($8,888.00)

Fundus and OCT imaging in one instrument is made possible with the Optovue iFusion. This tool combines the best of Fundus imaging and Spectral-Domain OCT.

Features of Optovue iFusion:

• Complete Solution For Retinal Imaging: Optovue iFusion makes the complete solution for retinal imaging as its modularity provides one with numerous upgrade pathways that one can choose from.
• Range Of Retinal Scans: This tool helps take a range of retinal scans such as 3D retina cube, real-time en face, retina map, and radial line.
• Extensive Scans For Glaucoma: Some extensive OCT and more offered by iFusion include the following:
  • 3D Disc Cube: In-depth analysis of one’s optic disc structure is possible with iFusion’s 3D disc cube scans.
  • Nerve Fibre Layer Analysis: Quantification and visualization of RNFL thinning occurring in glaucoma patients can be done with a nerve fiber thickness map.
  • Ganglion Cell Complex Analysis: Ganglion cell loss due to glaucoma can be measured and identified with GCC thickness map analysis delivered by this tool.
  • Comprehensive Reports: Comprehensive analysis of the patient can be done using the combo, GCC, and RNFL analysis reports.

3. Wavelight Topolyzer Vario ($19,999.00)

Wavelight Topolyzer Vario diagnostic device helps take precision measurements, enabling doctors to offer personalized treatments. From navigating corneal scans to viewing and measuring them, one can do it as efficiently as possible with just a few clicks.

Features of Wavelight Topolyzer Vario:

• Keeps It Simple: This diagnostic device has a refined navigation system, a one-click printing feature, intuitive image selection, and pupil detection, simplified drop-down menus, smooth export functions, and WaveNet™ integration.
• Easily Compare Scans: One can easily compare scans through automatically ordered exams, side-by-side on-screen positioning, and ease of switching between ‘excluded’ and ‘preferred’ scans.
• Helps Perform Advanced Diagnostics: Advanced diagnostics is possible with the advanced Vario platform, Contoura® Vision. Thus providing a more personalized and satisfactory experience to all the engaging patients.
• Get The Whole Picture: This navigation device makes the whole picture of a glaucoma patient’s eye possible. This device’s scan covers the screen more than the previous version. It provides one-click toggles between topography, camera, and Placido imaging views.

4. Nidek Mirante ($25,999.00)

Nidek Mirante is the ultimate multimodal imaging platform with state-of-the-art OCT or SLO combo. The tool offers ultra-wide HD images along with FlexTrack technology.

Features of Nidek Mirante:

• Unsurpassed Clarity & Color: Nidek Mirante offers unsurpassed clarity and color for every detail. In refine mode, one can make detailed pathology evaluations using its 163°ultra-wide-field color image. The tool also provides panorama image composition.
• FlexTrack Technology: The new FlexTrack technology can enhance average image quality. This helps doctors correct a distorted image taken due to poor fixation and correct it through this technology.
• Simple Interface & Easy Operations: The Nidek Mirante tool has multiple functions and modalities. However, the unique interface software of this testing tool makes it pretty simple and easy to use. Presenting all the multimodal images directly in the summary screen allows for more comprehensive and faster disease evaluation.
• Glaucoma Analysis: This Mirante tool also incorporates 16.5 to 12mm thickness maps. This map clearly and visually represents all the significant pathological changes from the periphery to the central retina.
• Tilt & Swing Features: This tool’s optical head’s tilt and swing features enable it to take images of the fundus periphery. This feature also helps the tool acquire panorama patients. Thus, helping all those patients with unstable fixation pretty much.

5. Optopol REVO FC ($12,999.00)

Optopol REVO FC is a real-time eye-tracking hardware device. It is an all-in-one fundus and OCT camera. This tool comprises full-fledged features, accurate fundus color imaging, high-resolution hardware tracking OCT, and more.

Features of Optopol Revo FC

• Fundus Camera With OCT Functionality: This all-in-one device with OCT technology is one compact system that offers high-quality and detailed OCT images with detailed fundus photos enabling multipurpose diagnosis.
• Offers Proven REVO System Advantages: This device provides proven REVO system advantages with cutting-edge color fundus imaging. Diagnostic certainty becomes achievable with high-quality, comprehensive OCT scanning analysis of the eye’s retinal layer.
• All-In-One Device: This OCT technology-rich device is all-in-one with a full-color fundus camera within one compact system. Its ability to capture fundus color images and OCT scans in a shot makes it a significant space saver.
• New Linking Function: The new linking feature present in this device makes linking a single photo of the fundus to several OCT exams. This helps to reduce the total shots number per eye significantly.

6. ZEISS CIRRUS 6000 ($49,999.00)

Zeiss Cirrus 6000 is another OCT for glaucoma testing tool that can deliver up to 100,000 scans in one second. This next-generation OCT device from ZEISS can deliver high-speed image capturing and HD detailed imaging. Thus, helping one make more informed decisions.

Features of ZEISS CIRRUS 6000:

• Faster & Wider Level Of Detailing: ZEISS CIRRUS 6000 enables clinicians to take over 100,000 scans in less than one second. It captures high-definition OCT scans and OCT Angiography scans. Thus, providing them with more insights into the condition of the patient.
• Makes Revolution Routinely: The ZEISS AngioPlex OCT Angiography helps take non-invasive retina microvasculature imaging. This aids in taking retinal and glaucoma disease management and treatment to the next level by assessing and analyzing a good range of pathologies.
• CIRRUS-Powered Treatment Decisions: This CIRRUS-powered OCT technology device provides clinically validated and extensive applications for glaucoma, anterior, and retina segments. Thus, allowing for faster throughput, precise analysis, and more intelligent decision-making.

7. ZEISS PLEX Elite 9000 ($30,999.00)

ZEISS PLEX Elite 9000 is a swept-source OCT Angiography device that aims to cover the undiscovered. This device uses transformational imaging OCT technology. Thus, helping glaucoma and retina researchers get microvascular and structural clarity.

Features of ZEISS PLEX Elite 9000:

• Swept Source Dual-Speed OCT: Deeper, faster, higher resolution, and dual-speed new PLEX Elite 9000 takes clinical research and ophthalmic imaging to the next level. Clinicians can use the information derived from this dual-speed OCT device to investigate any clinical scan benefits acquired at a scan speed of 200kHz.
• Helps Explore Deeper Meanings: Exploring deeper meaning is made possible with the ZEISS PLEX Elite 9000. This device helps clinical researchers see profoundly and widely the potential disease. This device explores retinal progression to evaluate choroid and retina response. This device can even explore choroidal pathology.

8. Optos Silverstone ($20,555.00)

Optos Silverstone is one of the most powerful tools for examining one’s retina. This ultra-widefield imaging retinal has been integrated with swept-source UWF-guided optomap images.

Features of Optos Silverstone:

• Combines UWF & SS-OCT: The Optos Silverstone device combines the optomap-guided OCT swept source with ultra-widefield or UWF fundus capture. Thus, aiding in the improved management of patients and also in making impactful treatment decisions.
• Significant Peripheral OCT Imaging: This device can capture peripheral pathologies using optomap integrated imaging and the swept-source full field. In most cases, this enables clinicians to get anatomical and guided media insight essential for crucial surgery management. Thus, providing significant clinical peripheral OCT imaging.
• Direct Contribution In Plans For Patient Management: In a few cases, the navigated optomap SSC-OCT aids incredibly much when it comes to patient management plans such as surgical, laser, or injection treatment.

9. Ziemer Galilei G6 ($15,555.00)

Galilei G6 combines the benefits of Optical Biometry, Tomography, and Topography. The device provides access to the total corneal wavefront, pachymetry, astigmatism data, and curvature. Thus, providing surgeons with complete data set for planning cataract and refractive surgery.

Features of Galilei G6:

• All-In-One Unit: This device is an all-in-one unit as it combines the benefits of Scheimpflug tomography, optical biometry, and Placido-disc–based topography.
• Offers Comprehensive Screening: The above-mentioned all-in-one combination allows Galilei G6 to provide comprehensive screening for refractive surgery or cataracts by providing complete data.
• Improves Work Maintenance, Efficiency, & Optimisation: This device helps store and gather data on a single device. Thus, improving the clinician or practitioner’s workflow efficiency, reducing maintenance costs, and optimizing office space utilization.
• Complete Data Set For Planning & Surgery: This device provides surgeons access to the total corneal wavefront, high-definition pachymetry, astigmatism data, and curvature. Thus, helping medical practitioners plan reflective and cataract surgery. 

10. Canon Xephilio oct-a1 ($15,999.00)

One device taking OCTA to the next level is the Canon Xephilio OCT-A1 device. This device provides fast and easy acquisition of essential data and incredible detailing.

Features of Canon Xephilio oct-a1

• New Retinal Imaging Reality: Canon Xephilio OCT-A1 device provides multiple opportunities to operate this device to examine the patient safely.
• Outstanding Imaging Quality: Due to Canon’s recognized expertise in optical, one can expect superb image quality from this device. Thus, enabling excellent individual layers and structure differentiations of the retina. 
• Consistent & Automatic High-Quality Images: Most of the time, involuntary eye movement becomes unavoidable during examinations. But with the device’s integrated real-time SLO retinal tracking maintaining the same position during scanning provides automatic results.

Conclusion 

Optical Coherence Topography is a valuable clinical helpful tool for diagnosing and detecting glaucoma progression in patients. Getting OCT for glaucoma done with the correct method will provide accurate information for diagnosing glaucoma. From detecting moderate glaucoma to late disease conditions, early detection of glaucoma is certainly possible with the best OCT test tool.

Of the two types of glaucoma, closed-angle glaucoma requires immediate treatment because it can potentially cause blindness. Some symptoms that individuals should, therefore, watch out for include severe eye pain, red eyes, sudden blurring of vision, colored halos around lights, severe eye pain, and nausea and vomiting. 

Once diagnosed with glaucoma, the ophthalmologist will want to monitor your vision regularly and ensure that the recommended treatment prevents additional vision loss. Important to note is that glaucoma cannot be cured, and the instituted treatment measures will not restore vision, but if detected early, significant vision loss can be stopped.