PalmScan A-Scan: The Ultimate Solution To Immersion Biometry

A-Scan Ultrasound Biometry
A-scan ultrasound biometry is a kind of diagnostic test that is commonly used in ophthalmology. It helps ophthalmologists determine the length of the eye, which is important for treating common eye diseases like cataract. This length calculation helps determine the intraocular lens that will perfectly fit the eye. Immersion biometry is used to conduct an A-scan to measure the axial length of an eyeball. The traditional method of immersion biometry requires direct intrusion with the eyeball. However, now thanks to medical advancements and research there is a safe device that can provide accurate results without having to insert anything in the eyeball. The PalmScan A-Scan from Micro Medical Devices (MMD) is revolutionizing the way A-scans are done.

What is the PalmScan A2000 A-Scan?
MMD has introduced the PalmScan A-Scan, which is a handheld device that has made immersion biometry fast and pain-free. It is also capable of performing applanation. PalmScan comes with an E-Z Tip Immersion Shell that makes conducting an A-scan extremely fast and easy. Let’s look at some of the benefits that it brings for ophthalmologists:

Innovative Benefits
• Portability: The PalmScan A-scan comes with amazing portability. It is so small in size and comes with a carrying case to safely store it and carry it with ease. It is a welcome change from the older A-scan machines that were huge in size and difficult to carry.
• Fast Results: The PalmScan produces results in mere seconds. This not only saves the doctor’s time, but also relieves the patient of pain of having a scanner in their eye. It has an average speed of 8,192 data-points per waveform.
• Ease of Use: there are no multiple tools needed to obtain a reading. The simple probe does everything. This means that the patient no longer has to be reclined to carry out an A-scan.
• Accuracy of Reading: The PalmScan uses ultrasonic waves to measure the thickness of anterior chamber, axial length and lens of the eye. All this is needed to determine the power of the intraocular lens needed. Plus, it can even accurately take measurements from eyes affected with dense cataract conditions.
• Long Battery Life: This handheld device runs on battery that can take and record A-scan measurements of multiple patients.
• Generate and Store Patient Reports: Make your office paperless with PalmScan A-Scan. Store patient’s reports right on the device and analyze them right there. It generates PDF reports that are easy for printing and are compatible with other devices.
• E-Z Tip Probe: This revolutionary new addition to the PalmScan has made it an even better solution for conducting A-Scans.
• Corneal Compression Detection: This device will warn the user if there is any corneal
compression in the patient’s eye. Therefore, it has an in-built mechanism to help the doctor avoid taking any inaccurate measurements.
• IOL Calculator: It comes with an IOL calculator that automatically does all the calculations for the doctor. There is also an added feature of a customizable lens library.

EZ-Tips vs. Traditional Immersion Biometry
Traditional methods of Immersion Biometry are highly intrusive. It requires insertion of a foreign object in the eye so that ultrasonic waves can be used to measure its axial length. PalmScan’s new E-Z Tip Immersion Shell keeps contact to a minimum. The procedure becomes so non-intrusive that a patient doesn’t even have to be reclined to take a reading. The type of the immersion shell is so soft that the patient barely feels anything and within second a reading has been taken on the PalmScan A-Scan.
Traditional immersion biometry is extremely uncomfortable for the patient and the patient has to be reclined to introduce fluid in the eye. It is also difficult to perform in patients with dense cataract. EZ Tips comes with disposable soft shells. Just 2 drops of BSS solution is enough to take a reading from the eye. It easily takes accurate penetration from dense cataract penetrated eyes without causing the patient any discomfort.

Ray of Hope Across the Globe – Humanitarian Efforts using MMD devices

A Farsighted Cause

Micro Medical Devices, Inc. (MMD) was founded with a mission to promote health and well-being around the globe. While the company focuses on technological innovations in the development of handheld medical devices, MMD also offers support to humanitarian groups serving beyond their borders.
Under the Mission Outreach program, MMD provides its PalmScan devices to such humanitarian organization that are providing eye care to remote locations around the globe. Since, MMD’s devices are battery operated and portable, they perfectly complement the objectives of Mission Outreach Programs.

Statistical Insight

MMD’s Mission Outreach is an extraordinary effort to save the vision of people living in remote areas with no access to proper medical care. According to a currently published report, around 90% of blind people live in under developed countries. This is primarily due to unavailability of proper living conditions and medical facilities.
A more shocking study revealed that 70% of blindness and visual impairment can be prevented or treated with proper and timely medical help. This is the reason why a good number of humanitarian groups in developed countries including the US have started their campaign to save the vision of people living in underprivileged areas across the globe.

The disease identified as the major cause of blindness worldwide is Cataracts. This disease affects the vision of more than 30 million people around the world. Again, the risk is higher in developing countries. This is the reason MMD’s PalmScan A2000 A-Scan biometer is the most requested device for mission work. PalmScan A2000 A-Scan is an ultrasonic biometer that can accurately measure the structures of the human eye and based on those measurements recommend the proper lens power that will be implanted during Cataract lens replacement surgery. By implanting the proper lens during Cataract surgery, ophthalmologists can give their patients as close to perfect vision as possible. This will relieve patients from the need for prescription glasses which may be hard to find in some of these remote villages.

Sights & Stories

MMD’s Mission Outreach has helped numerous groups and organizations in their missions outside the US. The following are the highlights from some of the countries that have benefited from this program.

Guatemala – Since 2007, MMD has joined forces with three different organizations working in Guatemala. PalmScan A2000 was highly praised for its ease of use as two of the team members with no ophthalmic knowledge learned its usage through basic probe technique training.

Sierra Leone – MMD has helped Southern Eye Institute and Vision Outreach International in their philanthropic efforts in the region.

Dominican Republic – Sanford Clinic has trusted MMD for two of its missions in Dominican Republic since 2009. Achieve Eye & Laser Specialists also plan to use MMD’s scanner again for their second mission in the region.

Haiti – PalmScan A2000 has been a constant partner of Baptist Eye Surgeons on their continuous crusade against blindness and vision impairment due to cataract and other related diseases in Haiti.

Philippines –The portable scanner was a real relief while Kaiser Permanente traveled to remote areas of the Philippines despite strict weight restrictions. The accuracy of MMD devices helped them receive aimed results.

El Salvador – North Idaho Cataract and Laser Center launched their El Salvador mission in 2007. During their mission, the organization faced a terrible case where a baby had a serious eye injury. Despite the complications, PalmScan helped them acquire accurate readings and positive results.

Visit our Humanitarian Efforts Page to read letters and view pictures of the good work done.

http://micromedinc.com/humanitarian-efforts.html

Micro Medical Devices, saving vision from a box.

Palm-sized Pachymeters and A-Scans Offer Unprecedented Versatility in a Small Package

Space saving handheld pachymeters and A-Scans not only simplify your lane layout, but they can facilitate the examination of children, the elderly, and wheelchair-bound patients. Additionally, these devices help free-up room for other diagnostic equipment that occupies more space such as visual field analyzers and digital retinal imaging systems. With each iteration of new handheld technologies, greater levels of accuracy and functionality become available. Handheld ultrasound biometers now are capable of being precise pachymeters and A-Scans.

When purchasing a new handheld pachymeter or A-Scan there are several considerations of importance: the accuracy of the device, whether it can be readily upgraded with the latest IOL calculation software algorithms, whether the data collected can be easily migrated into your electronic medical records system, and of course, associated cost.

The fact is, many handheld ultrasound biometers are just as accurate as their stationary cousins. Accuracy is dependant upon several factors. Probe frequency is typically 10-20MHz for these devices. In the case of the PalmScan Systems by Micro Medical Devices Inc. (MMD) the sampling rate is 264 MHz. This makes the PalmScan Pachymeter the fastest digital Pachymeter in the market today. This sampling speed equates to a device accuracy of ±3.1 microns.

PalmScan’s optional LRI Nomogram Software and 50MHz probe facilitates the planning of LRIs (limbal relaxing incisions) to remedy the residual astigmatism in postoperative cataract patients. The LRI option allows fast and accurate peripheral corneal measurement and the software needed to calculate the size, location and the depth of LRI/AK incisions based on the NAPA (Nichamin Age & Pach-Adjusted) Nomogram. The results are displayed on the hi-res color touch-screen display in the form of a graphical and textual “surgical plan” that can be printed, stored electronically and archived.

Another unique feature of this family of pachymeters is that they also display corneal waveforms on the device itself. Several new software innovations provide users the additional ability to display, store and recall, corneal waveforms on a per patient basis. You can also confirm the calibration of your femtosecond laser microkeratome by measuring the depth of flap and bed prior to lifting the flap. This ensures accurate direct flap measurements without the need for subtraction pachymetry. In A-Scan mode, the PalmScan actually slows its sampling rate by half. This equates to an accuracy of ±5.75 microns. This degree of accuracy and reproducibility gives you results that will allow you to more confidently prescribe the right IOL. PalmScan’s immersion capability along with its ultrasonic alignment detection software ensures accurate results.

A typical pitfall in purchasing any new technology is that two months after you purchase it, the release of the next version renders it obsolete. Nowhere is this more evident than in home electronics, as you are personally aware. To avoid these issues, medical device manufacturers like MMD are designing instruments that can be “field-upgradeable” to the latest software. This means that new releases of the system software can be loaded to systems that are already in clinical use. This ensures that users have access to the latest software releases available. Hardware upgrades are another problem, which MMD has a good solution. The PalmScan A2000 (A-Scan) and PalmScan P2000 (Pachymeter) are upgradeable to the PalmScan AP2000 (A-Scan/Pachymeter combination device).

Sparked by a presidential mandate stating that all Americans will have an electronic medical record by 2014, many device manufacturers and software companies have endeavored to become pioneers in this field. The ability to easily transfer captured data from a medical device to a network PC has a myriad of benefits: facilitating patient care, office administration and billing, enabling clinical research, and easing the reimbursement process. The PalmScan devices utilize widely available wireless networking technology (Bluetooth, 802.11b,g,n, etc.) in order to bring connectivity and efficiency to the ophthalmology practice.

Portability brings convenience and efficiency. In today’s competitive medical environment, most physicians are discovering that their practice requires multiple lanes, multiple office locations or even visiting patients outside of the office setting. The PalmScan product line provides a solution to reduce costs associated with purchasing equipment for these multiple settings, while increasing the convenience and overall efficiency of any practice. The secret is mobility.

Innovation has brought about handheld versions of many of the mainstay technologies in ophthalmology. The price-points of these new handheld devices, and their stationary cousins are quite comparable. You then have a choice as to how you want to arrange your practice; one handheld pachymeter/A-Scan that can be used in all of your exam lanes, or a station for each system that would potentially create a patient back-up and scheduling hassle. Having a mobile system is simply faster and more efficient. This is one of the many ways handheld devices can help generate revenue and save time. Collectively, medical device companies have brought to market an impressive quiver of diagnostic devices that give today’s healthcare providers a better means to detect disease and treat patients. While conveniently packaged in small forms, these innovative handheld medical devices can actually improve therapies and reduce costs, while enhancing the quality of the healthcare delivery.

Thin Flap Measurment with the PalmScan P2000 Surgical Pachymeter

Corneal waveform Pachymetry is essential when measuring the ultra-thin, created corneal flap

Traditional ultrasonic pachymeters work by providing the user with a number which represents the thickness of the human cornea.  Until recently, physicians had no way to confirm the accuracy of that number. As a result, physicians found pachymeters to have poor reproducibility.  Recently, with advent of newer surgical techniques, such as DSEAK, it has become more important to be able to accurately measure ultra-thin corneal thickness flaps

In this paper, the author, director of the International sight restoration, and board certified ophthalmologist explains the techniques and advantages of the corneal waveform pachymetry when measuring the posterior ultra thin corneal flap.

The technique uses the PalmScan P2000 Pachymeter with DSEAK mode manufactured by Micro Medical Devices, Inc. PalmScan is the first and only Pachymeter designed to capture the actual ultrasonic corneal echogram. The Corneal Waveform is the ultra-high precision echogram of the cornea, using sampling speed of 264 MHz to digitally reconstruct the analog corneal echogram. By capturing the echogram of the cornea, the user is assured of the validity of their measurements. Additionally, the corneal waveform has the benefit of providing details about the corneal stroma.

Normal human corneal waveform fig.1 measuring 575 micron

A valid corneal wave form has anterior and posterior corneal spikes that are perpendicular, without any other stromal echoes.  See fig. 1.  Abnormal corneal waveforms may have additional spikes due to corneal scars, contact lens, or any other conditions that cause reflection of sound wave within the cornea stroma see fig 2. In addition when using the PalmScan Pachymeter the physician can manually recalculate the corneal thickness by placing the cursers on the peek of the anterior and posterior corneal spikes.

PalmScan P2000 in DSEAK mode with the high frequency probe can capture flaps down to 50 micron thickness; the corneal spikes could be visualized in the C-wave mode.(see fig3 this is from Erics database)  To increase accuracy, peak to peak measurements of the corneal echogram are preferred when measuring under DSEAK mode. If any of the peaks are saturated, a warning massage will inform the user to adjust the gain so no clipping occurs.

This figure shows the cornea waveform after the femtosecond laser flap cut, this is used to directly measure the flap thickness (FT) of 99 micron and bed thickness (BT) of 475 micron and total corneal thickness (CT) of 574 micron.

Conclusion

This study demonstrates PalmScan P2000 pachymeter’s superior accuracy in measuring ultra thin corneal flaps as compared to conventional pachymeters, which lack corneal waveform technology.

Rafi Israel MD is a board certified ophthalmologist and the director of Beverly Hills Eye Institute located at 9025 Wilshire Blvd #209 Beverly Hills, CA 90211, phone 310-276-3450, Fax 310-276-3548. He is an associated clinical professor of ophthalmology at Cedar Sinai Medical Center in Los Angeles, CA.

Comparison of AScan results obtained with EZ-immersion Tip vs. Prager immersion shell.

Abstract:

This paper studies the accuracy of the EZ tip immersion vs. Prager immersion shell while using the PalmScan A2000 immersion ultrasound with a 132MHz sampling rate. This study shows that there are no statistical differences in accuracy between the two methods. However, the EZ tip immersion is less messy and less technically complicated, making it more convenient then the Prager shell. At the same time, providing the added benefit of being disposable. Using a PalmScan A2000 A-Scan with E-Z Tip Immersion eliminates the risk of cross contamination between patients.

Background:

The refractive success of cataract surgery depends on accurate preoperative measurements of the eye’s biometric values, such as keratomery, axial length and anterior chamber depth measurements. According to “Vision 20/20” around 150 Million eyes worldwide with cataract issues will need to undergo cataract extraction each year. This emphasizes the need for simple, fast, accurate and accessible biometry in order to effectively treat these patients.

Historically, ultrasonic A-scan pulse-echo technology has successfully been used to measure the ocular axial length, and anterior chamber depth. Originally these AScan ultrasound machines would measure the patient’s eye biometry using the contact method, which involved touching the cornea with the ultrasound transducer. Because of the contact nature of this method, some amount of corneal indentation was inevitable. This compression caused a variability in measurements, which were operator and device dependent. As cataract surgery evolved into the realm of refractive surgery, so did the need for more accurate methods of biometric measurement. Immersion methods were designed using an immersion shell, now the eye’s biometry can be measured through water without the need for contacting the cornea directly. This method eliminates any compression of the cornea by the ultrasound transducer. This proved immersion method has less variability in measurements, which are caused by the operator. Using the PalmScan A2000′s immersion technique will provide a more accurate method of measuring the biometry, compared to using the contact method. However, it was more cumbersome and messy then the contact method.

Recently the non-contact laser interferometric method has gained much popularity. However, this method is not without its short falls. First, patients with a denser cataract may not be good candidates for this technique; second, these units are expensive, bulky and stationary and require that the patients sit in front of the device for accurate measurements. In addition, laser interferometers are non-gated systems that utilize the average velocity of light through the eye and therefore they provide a less accurate anterior chamber depth and lens thickness measurements. Also, it is a known fact the IOL master was originally calibrated using an immersion ultrasound device with a sampling rate of 40MHz. For these reasons, immersion ultrasound biometry remains as the gold standard for measuring ocular axial length.

In 2008, an independent comparison of PalmScan A2000 A-Scan in immersion mode vs. IOL Master was made for the measurement of axial lengths of 72 eyes by Ray Oyakawa, MD (ASCRS publication 2008). In this study Dr. Oyakawa showed that the mean difference in measurement of axial length between IOL master and PalmScan using the Prager shell was .022 mm with correlation coefficient R=0.998.

Although the accuracy of immersion biometry is rarely questioned, based on my personal experience, many physicians and technicians are apprehensive of this method, mainly, calling it messy, cumbersome and time consuming. This is understandable since up to now this method consisted of placing a large shell on the patient’s eye, and then filling this shell with coupling fluid such as BSS. The disadvantages of this method are that patients need to be reclined and the shell held on the sclera in such a way to create a seal that allows for it to hold the water bath. The shell is made of hard material and it needs to be disinfected and cleaned between patients. Also, when the exam is done about 1.5 cc to 2.0 cc of fluid comes running down the patient’s face which contributes to the messy reputation of immersion biometry.

Picture 1. ( a typical set up for immersion biometry using Prager Shell)

In contrast to the immersion shells on the market, the new PalmScan E-Z immersion tip is made of very soft medical grade material, it uses only 2 to 3 drops of fluid (BSS) to fill, and only a fraction of that fluid is release to the patient’s eye during the exam. E-Z immersion tip is clean and disposable; hence it alleviates patient cross contamination. The E-Z Tip is designed to hold a small convexity of water meniscus at any angle, hence the patient could be in upright or a reclined position for measurements. In addition the software built in the PalmScan A2000 is design to capture valid Ascan echogram of the eye while using this meniscus of water and uses internal gates to eliminate compression of the cornea. The actual technique is as easy as the contact method, with the added advantage of immersion quality accuracy.

Pic. 2 (EZ immersion tip filled with BSS, notice the water meniscus at the tip)

Discussion, results and conclusion:

This paper studies the accuracy of the EZ immersion tip vs. Prager immersion shell while using the PalmScan A2000 immersion ultrasound. In this study, 20 consecutive eyes undergo cataract surgery and IOL implantation; first the eyes were measured using the Prager immersion shell, and then the same eye was scanned using the E-Z immersion tip. The results were tabulated and differences (delta) between the two techniques were measured.

Proper statistical test were perform to reject or accept the null hypothesis that there are no statistical differences between the EZ immersion tip and Prager shell immersion of Ascan biometry.

The average difference between the two methods was calculated to be .0195 mm; with the standard deviation of 0.061 mm. the figure below shows the trend line that best fits this curve with coefficient correlation R= 0.998.

References
Haigis W, Lege B, Miller N, Schneider B. Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation according to Haigis. Graefes Arch Clin Exp Ophthalmol 2000; 238:765-773