Other related posts:. » optimal User Manual PDF - Zeiss Atlas 993 - Ron Kaiser. ATLAS Carl Zeiss Meditec The Humphrey Atlas Corneal Topography System is available in two models, the 993 and the 995. The Atlas 993 is for primary care, computerized contact lens fitting and pathology detection. Topographers are the ATLAS 995 and 9000 (Carl Zeiss Meditec). Microns) or pooling (blue/negative microns).4,5 This information will guide you in.
DescriptionThe Zeiss Atlas 995 offers ultra-low illumination and increased peripheral coverage ideal for high volume corneal and contact lens specialists who require comprehensive and detailed peripheral corneal and pupil assessments.The greatest advantage of corneal topography is its ability to detect irregular conditions of your cornea invisible to most conventional testing. Because the Zeiss Atlas 995 can save your exam information, a practice can monitor any changes to the patient’s cornea and their corneal stability over time.The Zeiss Atlas 995 corneal topographer consists of a computer linked to a lighted bowl that contains a pattern of rings. During a diagnostic test, a patient sits in front of the bowl with their head pressed against a bar while a series of data points are generated. The Zeiss Atlas 995’s computer software digitizes these data points to produce a printout of the corneal shape, using different colors to identify different elevations, much like a topographic map of the earth displays changes in the land surface.
Above image: Axial curvature map from the Zeiss Atlas 9000 topographer displaying the ring values. For prior RK, the 1 mm, 2 mm, 3 mm and 4 mm ring values are used to estimate the central corneal power.The key concept here is that we are looking to discoverthe corneal power at its center. Instruments such as manual keratometers,autokeratometers, or simulated keratometry using a standard topographerwill typically over-estimate the central corneal power, resulting ina post-operative hyperopic surprise.Of course, correctly estimating the central corneal power following RK isonly half of the exercise. The calculated IOL power must also be adjusted toprevent the artifact of a very flat central corneal power from having the formulaunderestimate IOL power. Follow this link: for a summary of why this is so and how thisis carried out.Transient hyperopia following cataract surgery andprior radial keratotomyPatients with previous 8-incision radial keratotomy will commonly show variableamounts of transient hyperopia in the immediate post-operative period followingcataract surgery. This is felt to be due to stromal edema around the radialincisions, producing a temporary enhancement of central corneal flattening.While this central corneal flattening is usually transient, it can be as muchas +4.00 D, and is further accentuated by greater than eight incisions, anoptical zone of less than 2.0 mm, or incisions that extend all the way to thelimbus.If a patient exhibits any of the above, significant unanticipated hyperopiamay be seen in the immediate post-operative period, which should graduallyresolve after eight to twelve weeks.
Sometimes, due to a lack of corneal stability,the post-operative refraction can continue to slowly shift myopic over a severalmonth period. We have seen several patients with myopic shifts as large a -5.00D over a 12-week period.If the final post-operative refractive objective remains elusive, plans foran IOL exchange, or a piggyback IOL, should not be made until at least twomonths have passed and two consecutive refractions, two weeks apart (at thesame time of the day), are stable (the 'rule of twos.'
).Also, ifmore than six months passes before cataract surgery is required for the felloweye, the corneal measurements should be repeated due to the fact that additionalcorneal flattening frequently occurs over time following radial keratotomy.For this reason, IOL power calculations are usually targeted for between -0.75D and -1.00 D and are designed to make the operative eye more myopic than usual,so that five to ten years from surgery, the post-cataract surgery refractiveerror does not drift into hyperopia. This also helps to avoid hyperopic refractiveresults, which are quite common, in spite of every precaution being taken.Of all the various forms of keratorefractive surgery, we have had the bestoverall accuracy following radial keratotomy using the above technique. East Valley Ophthalmology5620 East Broadway RoadMesa, Arizona 85206Tel: +1-480-981-6111FAX: +1-480-985-2426Arizona's Top Eye Doctors - East Valley Ophthalmology provides this onlineinformation for educational and communication purposes only andit should not be construed as personal medical advice. Informationpublished on this website is not intended to replace,supplant, or augment a consultation with an eye care professionalregarding the viewer/user's own medical care. East Valley Ophthalmology'sdisclaims any and all liability for injury or other damages thatcould result from use of the information obtained from this site.
Zeiss Atlas 995 Manual Pdf
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