Archive for Vision News
ETDRS Acuity Testing
Posted by:ETDRS acuity testing has become the worldwide standard for visual acuity testing, replacing the Snellen and Sloan acuity tests.
ETDRS stands for Early Treatment Diabetic Retinopathy Study. The ETDRS test is designed to eliminate inaccuracies in the Snellen and Sloan tests.
The ETDRS acuity test was developed to aid in evaluating the changes in vision following panretinal photocoagulation in patients with diabetic retinopathy.
Previous studies had somewhat confusing results due to inadequacies of the acuity tests used in those early studies. For example, the Snellen acuity test has a different number of letters per row, e.g. 10 letters on the 20/20 line, but only 3 letters on the 20/70 line.
Therefore, if the results of a study showed that the patients “gained three letters of acuity,” the results could indicate the gain of a full acuity line, as in the 20/70 line, or only a portion of an acuity line, as in the 20/20 line.
Also, the individual lines on the Snellen acuity test are not equally spaced. For example, the change from the 20/25 line to the 20/20 line is a 20% change, while the change from the 20/30 line to the 20/25 line is a 16% change.
Again, referring back to the diabetic studies, if a study demonstrated a two line increase in acuity, it could mean a 33% improvement from 20/30 to 20/20, or a 40% improvement from 20/50 to 20/30. These inadequacies of the Snellen acuity test made it impossible to properly evaluate the acuity data and to compare data from study to study.
The ETDRS test incorporates specific design criteria to make it more accurate than the Snellen or Sloan acuity tests. These include:
- Same number of letters per row (5)
- Equal spacing of the rows on a log scale
- Equal spacing of the letters on a log scale
- Individual rows balanced for letter difficulty
To prevent memorization, different versions of the ETDRS test chart are available. The three standard versions of the ETDRS chart are R, 1 and 2.
For eye care professionals now are available the outstanding LCD Chart systems: unique solutions for both monocular and binocular tests.
Snellen Chart Eye Test
Posted by:A Snellen chart is an eye chart used by eye care professionals and others to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart during 1862.
The person being tested stands 20 feet from the chart and reads as many of the symbols as possible, reading each line and proceeding downward from the top.
A score is assigned in the form of a ratio, comparing the subject’s performance to that of a statistically normal subject’s performance. For example, a person who can read at 20 feet what the average person can read at this distance has 20/20 vision, whereas a person who can read at 20 feet what the average person can read at 40 feet has 20/40 vision.
Only the ten Sloan letters C, D, E, F, L, N, O, P, T, Z are used in the traditional Snellen chart. The perception of five out of six letters (or similar ratio) is judged to be the Snellen fraction.
The evolution of letter charts from Snellen’s original chart to the ETDRS chart, which is considered today’s gold standard, push practitioners and researchers from all parts of the world turn to ETDRS charts and other high-quality vision testing tools. Now are available the LCD Chart systems: unique solutions for both monocular and binocular tests.
For many years contrast sensitivity testing has been recognized to be an useful strategy to assess visual function in many ophthalmological diseases as glaucoma, optic neuropathies, amblyopia as well as in neurological and, recently, even psychiatric conditions.
So far as we know, available contrast sensitivity tests are performed by means of paper-made screens or backlighted windows and do not employ a psychophysical procedure to assess the exact threshold value for every tested spatial frequency.
The new VistaVision Contrast Sensibility Test© (DMD Med Tech, Turin, Italy) is a computer-based psychophysical tool, using a particular staircase procedure to fit the psychometric function.
The exam evaluates spatial frequency ranging from 0.75 c/deg to 18 c/deg, widely covering the values processed by the magnocellular (under 1.3-2 c/deg, according to Legge,1978) and parvocellular ganglionar pathway.
Within this range, the VistaVision evaluates contrast sensitivity across six different spatial frequency values (0.75, 1.5, 3, 6, 12, 18 c/deg). Test distance is 3 meters. Subjects are presented sinewave gratings (mean luminance 120 cd/m2) in random order, each oriented along the vertical or tilted left/right side and are asked to report the orientation of the displayed grating by a remote control. For each spatial frequency value, threshold level is obtained by a 4-2 staircase procedure.
The difference between VV function and a 3-forced choice paradigm (3AFC) relies on the further possibility to answer “null” by clicking an appropriate button. X normal subjects aged x year (±y) were recruited. Inclusion criteria were BVCA: 60/60, ametropy <±3 diopters, absence of ophthalmological and systemic diseases.
Exclusion criteria were intraocular pressure higher than 17 mm Hg (G) or inheritance for glaucoma, strabismus, amblyopia, diabetes, systemic therapies able to induce visual field defects, cognitive disability and bad collaboration. The exam was performed monocularly.
Every patient showed foveal fixation as tested by Cuppers’ visuscope.
An high correspondence both in the shape and in the relative threshold values is found between the obtained spatial contrast sensitivity function and the reference one. To account for any age effect, a correlation analysis has been performed by Pearson test. A negative significant correlation is found between age and contrast sensitivity above 12 c/deg.
The question arises if this correlation may be accounted simply for the mild age-dependent reduction of the media transparencies. To investigate this point, the correlation of the two higher spatial frequencies tested has been compared. Indeed, since ocular media light absorption is proportional to the age and mainly the higher frequencies are affected, then an higher correlation with the 18 c/deg as compared to the 12 c/deg is expected to occur.
Actually, it was not the case and the age-spatial frequency correlation resulted to be stronger for 12 c/deg than for 18 c/deg. This suggests that media changes due to ageing account for the CS decrease mainly at high spatial frequencies whereas other factors, namely the retinal tissue involution, would affect contrast sensitivity at lower spatial frequencies. In any case an ageing effect seems to worsen contrast sensitivity for spatial frequencies above 6c/deg.
In conclusion, VistaVision contrast sensitivity test is a fast, precise and reliable device to assess this function in ophthalmological and neurophthalmological field. Mean examination duration resulted to be less than 2 minutes per eye, and test-retest variability was negligible. The obtained psychometric curve fits well in shape and values with data reported in literature and has the advantage to examine a wider range of frequencies compared to the other current instruments. Consistently with previous studies, contrast sensitivity decreases as a function of age at the higher tested frequencies.
Carlo Aleci, MD, PhD
Ophthalmology Department, The Gradenigo Hospital, Turin, Italy
carlo.aleci@gradenigo.it
We suggest to personalize the medical examination to the patient for the child, for the adult and for the elderly people, in order to carry out the examination to the patient as quick as possible.
Open the SETUP window and enter in the VISIT EXAMINATION window: in this window, it is possible to personalize the left column, central column and right column list of tests according to the kind of examination.
Press the CHANGE key in order to choose the kind of child examination and it will appear the lists of tests entered until that moment for this kind of examination: the adult examination with its tests, the elderly person examination even it with its linked tests.
After having personalized the medical examination to the patient according to your preferences, press the menu key in order to start the examination according to the patient to test.
The kind of visit appears on the top side of the page, near the selected test.
In order to carry out the medical examination to the patient, you can move the selection and press the CHANGE key to start the test. Press the TEST key to return to the previous window or to use the three linked yellow keys:
to the left column the yellow key one, to the central column the yellow key two, to the right column the yellow key three.
Vista Vision Chart Panel – Video Highlights
Posted by:VistaVision Software Highlights
Posted by:Eye Chart Test Use – Video
Posted by:During an eye test, eye doctors use eye charts to measure how well you see in the distance.
The classic example of an eye chart is the Snellen eye chart, developed by Dutch eye doctor Hermann Snellen in the 1860s.
In the TEST window, press the TEST key in order to access: the eye-chart tests are situated on the left column, which corresponds to the group test 1 yellow key.
Select a test and press CHANGE in order to start it. The test comprehends three eye-chart lines with increasing visual acuity value. In the right edge and in the bottom are showed the data related to the displayed table.
In order to display or hidden these data, press the DATA key. All eye-chart tests have the same functions:
• the UP and DOWN keys permit to increase or decrease the visual acuity value;
• the CHANGE key allows to choose in a pseudo-random way other stimuli to display;
• the left arrow and right arrow keys permit to modify the contrast of the table displayed, according to the logarithmic scale of the sensitivity to the contrast.
In order to change the display of the table, you can use the CHAR, LIN and DIM keys:
the CHAR key allows to display a single type,
the LIN key allows to display either a single or more lines,
the DIM key allows to display lines with equal or increasing visual acuity.
There are two other possible displays by pressing the RED e GREEN key; the table will be divided with a green background on the right and a red one on the left.
The BLACK and WHITE key, on the contrary, allows to invert the background colour with the eye-chart one.
Obviously, whichever is your display, it is possible to change the displayed stimuli by pressing the CHANGE key.
The test works according to a scale chosen in the Scale SETUP menu, as displayed in this window.
With the single type display, by pressing the CHAR key, it is possible to insert the Crowding effect by pressing the RED and GREEN key on the remote control.
VistaVision has just released the lastest version of software for all models. A great effort from the DMD MedTech Company to mantain the products at the top with the best price available worldwide.
DMD Medtech is the european leader company for 22″, Anti-glare, Positive polarization, LCD Chart system: a unique solution for both monocular and binocular tests.
The new software improvements availbale for free are:
New CROSS test (with or without fixation point) added to test phoria;
- ETDRS test: the three ETDRS tables are now with a white background with the brightness of 200 cd/m2 (however you can switch to the brightness of 85.5 cd/m2 as required by U.S. Standards by pressing B/W)
- New Optotypes Display Mode: decreasing VA lines with vertical alignment (default view), equal VA lines (press DIM once), decreasing AV lines with same crowding (press DIM twice)
- New Optotypes Masking: single character view (press CHAR), horizontal line view (press LINE), vertical line view (press LINE twice); you can move masking selection by pressing the arrow keys
- New bigger Fixation Point – Screen saver movie: in case of idle personal movie can run in infinite loop mode.
- New tests (Positive Polarized Tests): Osterberg (Stereo Test, Minute Stereo Test), Polarized Red/Green tests, Polarized Letters and Numbers, Horizontal and Vertical Phoria (w/ or w/o fix point), Horizontal Coincidence, Polarized Cross (w/ or w/o fix point).
Digital refraction support:
-The connection software for the integration with the Digital Refraction System has been implemented.
The support is granted for the Digital Refraction System provided by Huvitz and Potec in substitution of their chart projector (the Huvitz Digital CCP-3100 and the Potec Digital PACP-6100)
- The BlueKit allow you to connect the POLA VistaVision (or the VistaVision) to your digital phoropter without any cables.
With his superb 5 years warranty plan, DMD Medtech satisfy customers and distributors from all countries.
Vista Vision is a completely silent (fan-less) superb chart panel including all tests: charts, ETDRS, Contrast Sensitivity Test, Ishihara Tables (25 brightness calibrated tables), Stereo Test (15 tables) to use with red-green glasses (included)
DMD Med Tech designs and manufactures Visual Acuity Chart System which is specified and branded by another firm for sale, as ODM (Original Design Manufacturer).
All the firms who would like to buy the ODM product can personalize many features, and especially:
- to brand the products with their own name
- to customize settings preferences and graphical user interface
- to insert new or improved vision tests
- to insert an advertising movie for screensaver (ex: a movie to show your products)
- to personalize external look
- to personalize all connected documents (user manual, brochure, etc.)
- to enjoy a download area on your website, providing software updates dedicated to your customers
Indo and Carl Zeiss chosen DMD Medtech for VistaVision products: the right choice.
High technology, continuously clinic and scientific improvement, high reliability, 5 years warranty, at a really lower price than our competitors is the key of DMD Medtech success story.
And now DMD Medtech is looking for exclusive distributors worldwide. A unique occasion to sell a superlative product with high profit margins.
The only commitment DMD demands to an exclusive right distributor is just a minimum annual withdrawn amount, in order to maintain the exclusive right in the country.
For inquiries please contact:
DMD Med Tech s.r.l.
via Monviso 14 10090 Villarbasse (TO) ITALY
Phone#: +39.011.952.8282 Fax#: +39.011.952.840
www.visualacuitytesteyechart.com
Press any key in the remote control in order to turn on the Vista Vision. After it’s been turned on the page with the system language choice will be displayed. By using the cursor keys, select the desired language and press the ENTER key: the welcome page. will appear on the screen.
Now, it is possible to proceed in two ways. For a complete configuration, we suggest to follow the guided personalization, where a series of windows in which it will be possible to change the different parameters of the Vista Vision will be displayed in a sequence.
For a quick configuration we suggest to press the SETUP key on the remote control, enter in the Setup Preferences Window by pressing the CHANGE key and modify the distance between the patient and the Vista Vision.
Press again the CHANGE key, then the cursor UP and DOWN keys in order to change the value, until to reach the desired value. Press the ENTER key to confirm.
In order to return to the main menu, press the SETUP key. We furthermore suggest to deactivate the welcome window: by using the cursor keys, select the user icon and press the ENTER or CHANGE key to enter.
Press 3 times the right cursor key and then the central CHANGE key, in that way the welcome window will do not appear anymore at the next turning on. The Vista Vision is now personalized and ready to be used.
For a complete personalization, we suggest to enter the single windows present in SETUP and to modify the parameters according to your needs.
1) I would like to buy, but how can I be sure about the high quality of your products?
An excellent result has been obtained: the percentage of products come back for repair is lower than 0,5%. The costs of expedition for repair are so zeroized and the profit of our distributors/resellers is intact, as the whole high satisfaction of the final customer.
The feedbacks from our main customers confirm us that VistaVision quality is very high:
* “Our evaluation is good. The relation price / features is good, so I think that we can expect good sales in our country. – Yes we have received them and displayed them at the trade show. There was a lot of interest. We will be placing an order for more units.”
* “We are very excited about your product and plan to sell many.”
Your money for demonstration units (25% off) is without risk: read ‘refund policy’ in distribution agreement proposal.
Have you tried VistaVision? Please send us your feedback!
2) What is the Distribution Proposal (DP), and what does it contain?
Our Distribution Proposal is an exclusive sale agreement between DMD Med Tech and the distributor who wants the exclusive marketing for the VistaVision, on a specified country.
Inside the DP you will find the prices and the discount depending on the annual purchased amount. Please, note the possibility to buy one evaluation unit at 25% off, to let you begin easily your commercial work.
The only commitment we demand to an exclusive right distributor is just a minimum annual withdrawn amount, in order to maintain the exclusive right.
3) We would like to distribute this product under our own trademark, could it be possible?
We consider the possibility (usually arranged to prestigious distributors, who are able to realize high amounts each year) to distribute VistaVision not as a DMD Med Tech product, but under their trademark/brand.
In this case, the distributor could personalize the product name, the logo, the serigraphy, the labels, all the informations inside the software, the user manual, etc., as it would be a product developed by the distributor himself.
If you are interested in a product markable with your brand, please visit the ODM Chart System page and send us an email with the following informations:
- estimated quantity/year
- required territory limits
we’ll send you a proposal agreement.
4) I signed the distribution agreement. What information do you give to whom you are contacted by?
Each commercial contact coming from your exclusive right territory, will be immediately send to the right area distributor. We commit to insert your company name and contact information on our distributors page, as you shall commit to show on your website the products purchased from DMD Med Tech (pictures and features).
From our download area you can obtained high quality images of all the products (in order to insert on your catalogue), as other informations to fit in the product webpage on your website.
5) My customers want to maintain up-to-date the product they buy: how can I do?
Our automatic updating system “VUP” is available.
A VUP is a USB flash disk ready to use. It is provided by DMD Med Tech to the users, to update automatically VistaVision to the last software release, in just 3 minutes.
Buy a VUP for each VistaVision and the final customer will benefit of a valuable service: free updating forever! Click here.
Is VUP an ordinary USB flash disk? Not at all! VUP is a programmed with an ad-hoc Linux operation system called openmamba, supplied by mambaSoft.
6) Is it possible to pay the evaluation unit once tested the high quality?
Sorry, we understand your needs, but it’s not possible to test the evaluation unit before purchasing it.
In any case, remember that DMD Med Tech will refund the purchase money for evaluation unit if you’ll send it back (read refund policy in distribution/reseller agreement)! Note that until now, this situation never happened.
Remember that evaluation base unit is 25% off.
7) What is the purchasing procedure?
Send an order (by email or fax or web), in accordance with the distribution/reseller agreement, please indicating:
# your PO number
# products codes (see ‘Item list’ on product page)
# amount
# your courier code (es: TNT 12345678) or ask for our shipping service
# delivery address
Within 3 days maximum, (usually you will be answered in 1 day), you will be sent a P-invoice, with the ETD (Estimated Delivery Date) as a PO confirmation.
The customers with “T/T in advance” payment terms, should send the wire transfer receipt no later than the ETD.
The goods will be picked up within the ETD; if you prefer our DMD Med Tech courier, you will be provided of the AWB code (tracking number) immediatly after courier pickup.
How to reduce shipping cost?
Products delivery is EXW, in accordance with the distribution/reseller agreement.
DMD Med Tech designed an ad hoc pallet, with the right dimensions to minimize shipping costs (depending on the whole expedition volume). We suggest you to buy parcel of VistaVisions of 3, 6, or 12 units, to obtain maximum efficiency.
Further, DMD MedTech stipulated an agreement with TNT to get very low shipping costs, probably lower than you could get (as we make high amount of expeditions each month). So a way to save your money is to order the goods with shipping included. Contact “Sales” to know shipping cost and shipping time.
9) Why is necessary to login? How to get an account?
Our products are continuously improved to satisfy customers needs. To preserve our efforts and to ensure this benefit for our customers we have been forced to introduced a restricted download area. The updates are free, available for all our customers through a login on the reserved area “Support-Downloads”. (No account yet? Register). Obtaining an account is easy: insert the S/N impressed on the box or on the label on the back of the instrument.
10) Right of Withdrawal
In case of direct sales to end user (i.e. not for resellers or distributors), the customer has the right to revoke his / her contractual statement without stating reasons within 2 weeks by either sending a receipt of the goods in writing (e.g. Letter, e-mail, fax) or by returning the goods. This period begins at the earliest on the day after payment has been received along with a copy of these instructions in written form. The prompt return of said merchandise or order satisfies a preservation of the revocation period.
Cancellations can be send to:
DMD Med Tech s.r.l.
Via Monviso, 14
10090 Villarbasse (TO) , Italy
Cancellation Consequences:
In the event of an effective cancellation the mutually provided goods and services shall be returned and, if applicable, any benefits enjoyed (e. g. interest) surrendered. In case the customer cannot return the received goods and services in total or in part or only in deteriorated condition, the customer has to, if applicable, provide compensation insofar. This does not apply for the delivery of goods, if the deterioration of the goods were due exclusively to their inspection – as would have been possible for you in a retail shop for example. Incidentally the customer can avoid the obligation for compensation by not using the goods, as if they were his/hers property, and by refraining from doing anything, that could impair their value. Items that are capable of being shipped are to be returned. The customer is responsible for the cost of said return. Goods that can be dispatched as parcels have to be returned at customer risk and expense. Obligations for refunding of payments will be fulfilled within 30 days after dispatch of the customer’s declaration of cancellation and the return of said merchandise.