Microscan Visum

microscan_visum

New-generation excimer ophthalmic system

MicroScan Visum was manufactured by Optosystems – Russia’s leading manufacturer of medical, scientific and technological laser systems. MicroScan Visum was developed in collaboration with the Physics Instrumentation Center (Prokhorov General Physics Institute) and the Fyodorov Eye Microsurgery Complex. It facilitates correction of all kinds of regular and irregular refractive errors based on keratometer and aberrometer readings.

We bring to the industry many years of expertise and we have our own production facilities. This has enabled us to be able to create a system with high level of safety, accuracy, reliability and efficiency.

Using the innovative flying spot technology, MicroScan Visum can create a corneal surface of any desired shape. This makes the system suitable for a wide range of therapeutic and fiber-reconstructive surgeries: Lasik, PRK, PTK, Epi-Lasik.

Microscan Visum – optimal performance and top-quality results

  • Flying Spot technology
  • Spot diameter: 0.9 mm
  • Pulse repetition frequency: 500 Hz
  • High-speed tracking system
  • Built-in aspiration system
  • Continuous laser energy computer control
  • The functional optical zone matches exactly with the given ablation zone
  • Creation of a smooth corneal surface with a smooth transition zone
  • No central islands
  • Processes data obtained from corneal topography machine and aberrometer
  • A full range of maintenance services

Types of operations performed with Microscan Visum

Algorithm for preservation of natural corneal shape in correction of primary ametropia (standard operation)

Preservation of aspheric form in “aspherical surface – minus – aspherical surface” surgery, and thus preservation of spherical aberration, is a factor of its aberration neutrality with an accuracy of small correction of 0.01 per diopter. The corneal profile formed from surgery is much closer to the natural profile than standard ablation. It ensures recovery of spatial contrast sensitivity, visual acuity in illumination, glare and low light conditions.

Tissue-saving ablation algorithm – multifocal correction technology (tissue-saving operation)

“Justified” corneal shape deformation is possible in certain situations where the doctor and the patient in advance agree to
reduce sight quality to get rid of glasses in presbyopic age or in insufficient cornea thickness and where there is unwillingness or inability to perform intraocular surgery.

Multifocal ablation profile is a single aspheric surface with a flattened central area for farsightedness and myopic periphery for nearsightedness. Multifocal correction enables patients to avoid spectacle correction of near-sightedness, while simultaneously maintaining satisfactory visual acuity at a distance.

The tissue-saving ablation algorithms developed save about 20% of tissue in myopia treatment. Visual acuity in mesopic conditions in patients with tissue-saving scanning algorithm is slightly lower than in standard ablation, but higher than before surgery with usual spectacle correction.

Restoration of natural corneal shape in correction of induced refractive disorders (aspheric surgery)

Depending on the severity of corneal irregularities and on whether there is surface haze or not, topography-guided ablation can be superficial (topo-PRK) or subvalvular (topo-LASIK). Topo-guided ablation is the most effective way of performing refractive surgery in severe corneal irregularities. This became possible after development of KeraScan –software for topography-guided customized correction.

Q-factor customized aspheric correction algorithm (Q-factor customized aspheric surgery)

Correction of twilight and night vision in patients with large pupils can be addressed via Q-factor customized aspheric ablation profile. The recommended Q-factor change value in such operations is from -0.3 to -0.4. Negative Q-factor produces negative spherical aberrations, which should compensate positive spherical aberrations in the optical zone periphery. Such pre-compensation of spherical aberrations optimizes the corneal wavefront and substantially expands the flattening of the wavefront at the optical zone periphery. With an increase in the negative Q-factor, the effective optical zone increases to 6.5 mm, which allows for reducing the mortgaged OZ from 6.0 mm to 5.5 mm. In this case, the size of the effective optical zone size remains close to 6.0 mm, while the ablation depth is reduced to 13 microns (from 16 microns) per diopter.

Optimized algorithm for wavefront-guided customized surgery (customized surgery)

Platoscan – software for optimized wavefront-guided customized surgery – is used to maintain natural aberration balance, minimize deformation of the original corneal shape and correct unwanted aberrations resulting from correction of refractive disorders. The software generates ready operational files for excimer laser.

Wavefront-guided operations (for myopia and myopic astigmatism) on the Microscan Visum platform using PlatoScan achieve high refractive outcome and excellent visual acuity.

This is the result of optimized ablation profile, large optical zone, upgraded tracking system, accurate centering and high ablation stability.

Proprietary excimer laser

Microscan Visum uses excimer laser manufactured by Optosystems. The excimer laser is made based on metal-ceramic technology. The stability of the average energy capacity in the laser is high and the gas mixture has a long service life. Computer control maintains the required energy level in generation pulses, automatically replaces gas mixture and performs the necessary calibrations.

The excimer laser of the Microscan Visum system uses a four-component gas mixture (Ne, Ar, He, F2). The gas mixture is excited with high-current electrical discharge, which leads to formation of ArF molecules. Transition to main state is accompanied by collapse of excimer molecules and release of energy in the form of UV radiation (with a 193 nm wavelength), which is formed by the laser cavity in the powerful directed pulse beam of the laser.

When working with the excimer laser, the gas mixture should be replaced after a certain number of pulses because it is degraded as reactive fluorine reacts with laser design materials.

Generation of laser radiation is triggered through the control program of the system. Laser pulses are initiated using a remote foot pedal. At the end of the surgery, the control computer automatically shuts off laser radiation.

Specifications

Name of system Microscan Visum
Surgery types PRK, LASIK, Epi-LASIK, Femto-LASIK
Refractive error correction range Sphere:                 LASIK: from -14D to +7D

PRK: up to -17D

Cylinder:  up to -10D

Ablation profile standard, aspheric,  tissue-saving
Nomograms for standard and tissue-saving surgery integrated
Customized ablation aberrometry-guided and topography-guided
Optical zone extension technology bigger than pupil size
Phototherapeutic operations in different zones flat PTK and complex  PTK with controlled ablation depth by the center and periphery
Increase in the optical power of

all aberrations during surgery

simultaneous
Tracking a limb or pupil yes
Switching of tracking between limb or pupil during surgery possible
Pupil shift compensation  when pupil diameter changes yes
Identification of visual axis automatic
Preoperative compensation of the torsion rotation of the eye when the patient’s position changes from the sitting position, with aberrometry, to the supine position, during surgery  automatic
Dynamic tracking of torsion rotations of the eye during the operation automatic
Resumption of interrupted surgery possible
Video recording of surgery on a color camera possible
Recording of surgery process

in a nonvolatile memory

in real time
Observation system microscope (5 zoom levels)
Control system built-in personal computer
Software Windows 8.1 Industry Pro
Monitor

23″ touchscreen monitor spinning around two axes

Connection of demonstration monitor possible
Compatible with Femto Visum possible
Visum ophthalmic complex possible

Innovative technologies

Excimer system MicroScan Visum is designed to correct various refractive errors and aberrations of the eye under computer control – using modern refractive surgery technologies, such as:

  • LASIK using Femto laser
  • Modern PRK categories
  • Customized wavefront-guided LASIK and topography-guided PRK; phototherapeutic keratectomy and transepithelial PRK
Laser pulse repetition frequency 500 Hz

A 500 Hz pulse frequency together with high efficiency of the chosen ablation method reduces surgery duration significantly.

Spherical myopia (Sph -10.0 diopters) with 6.0 mm optical zone is corrected within 23.0 seconds, i.e. 2.3 seconds per diopter.

Efficient ablation algorithm – ensures high optical precision of the ablation profile at a high correction speed

The complex solution to selecting energy density, size, spot shape, and ablation algorithm allows to obtain the smoothest ablation zone surface and high optical precision of ablation profile, which provides maximum visual acuity exceeding the standard norm – 100%. Low energy density during the entire operation reduces the thermal load on the cornea.

 
Super-Gaussian spot

Fig4a

The high ablation efficiency of a flattened super-Gaussian spot (0.9 mm in diameter) allows to reduce the laser pulse energy without reducing the volume of the ablated tissue. This reduces the thermal load on the cornea.

Peak ablation depth per pulse is reduced simultaneously, reducing ablation roughness.

  

 

Minimizing thermal load on the cornea

Random pulse distribution on the corneal surface, as well as special thermal control, particularly in the maximum ablation depth zones, can reduce thermal load on the cornea considerably.

Multidimensional active tracking system 750 Hz

The tracking system (pupil- and limbus-based) tracks the eye position 750 times per second. The total latency time is 3 ms. Tracking does not depend on the size and shape of the pupil. It detects the following:

  • Slow longitudinal eye displacements (1st and 2nd axis)
  • Fast vertical and horizontal eye turns (3rd and 4th axis)
  • Fast torsion rotations of the eye during the operation (5th axis)
  • Torsion rotation of the eye when the patient’s position changes from the sitting position, with aberrometry, to the prone position, during surgery
  • Simultaneous capture of the limbus, pupil and coaxial corneal reflex tracking system
  • Selection of the visual axis after aiming
  • Shift of a narrow pupil in the surgical area relative to a wide pupil with aberrometryLimb_Aberr
Ultra-high ablation stability

Modern optical scheme Microscan Visum stabilizes laser spot size on the cornea. Ablation stability depends on laser energy stabilization and energy density stability on the cornea. Microscan Visum has two types of energy measuring sensors to ensure proper control:

  • The first sensor is located at the output aperture of the system. It is used to measure the energy of each pulse, and is included in the laser energy stabilization circuit. Energy measurement at the exit of the optical system allows to compensate for absorption in the optical path of the laser due to random appearance of absorbing vapors of flying absorbing substances in the operating room
  • The second energy sensor is used to calibrate the first energy sensor and is placed exactly at the corneal plane

Mandatory preoperative calibration is the first thing done on the day of surgery. It is carried out again after handling 3-4 patients depending on atmospheric purity in the operating room.

Transepithelial surgeries

During transepithelial PRK, the epithelium is removed using an excimer laser beam in PTK mode with a variable profile that takes into account the uneven epithelial thickness. For tissue-saving purposes, surgery is interrupted when stroma cells appear and is resumed in PRK mode.

Standard flat PTK is used when treating various pathologies, such as dystrophies, degenerations, opacity, and recurrent corneal erosions.

Corneal collagen crosslinking systems

Microscan Visum can be used in conjunction with a corneal crosslinking system, which, in combination with the Kerascan program, allows for topo-guided PRK + crosslinking surgeries for the treatment of keratoconus.

 

Efficient aspiration system

аспиратор

The aspiration system removes ablation products (generated from the impact of laser radiation on the cornea), smell and vapors from the surgery area without drying the cornea. It adjusts the laminar flow height over the eye from 3 cm to 5 cm.

 

 

Slit Illumination Unit

Illumination from two slits converging on the top of the cornea allows to:

щелевая подсветка

  • Diagnose the postoperative state of the corneal flap,
  • Carry out 3D corneal focusing and eye tilt control

Comparative characteristics

Name of system Microscan Visum Microscan PIC (the previous generation)
Radiation source Optosystems CLS5000 Optosystems CL5000
Laser pulse repetition frequency 500 Hz 300 Hz
Pulse energy deviation from average value during surgery less than 2% less than 4%
Cross laser beam energy distribution profile Super-Gaussian Super-Gaussian
Diameter of treated corneal zone (ablation zone) 4-12 mm 4-12 mm
Tracking system frequency 750 Hz 100 Hz
Limbus-based tracking during surgery [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Automatic detection of corneal vertex [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Second color camera for observation and broadcasts [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Recording unfinished surgery, including emergency termination of surgery without data lose [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Built-in position sensor in the scanner [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Central controller [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Modern program interface, touchscreen [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
Included in Visum ophthalmic complex [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
European Conformity (CE marking) [icon name=”check” class=”” unprefixed_class=””] [icon name=”times” class=”” unprefixed_class=””]
China Registration Certificate (CFDA certified) [icon name=”times” class=”” unprefixed_class=””] [icon name=”check” class=”” unprefixed_class=””]

Service support

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We have independently developed and deployed a full production cycle, which enables us to quickly respond to customer needs for product change and provide service support. We also provide all the necessary supplies and accessories.

 

 

Visum – ophthalmic complex

Femto Visum and MicroScan Visum are combined into single ophthalmic complex Visum. The two systems are programmatically integrated using an in-built local server for rapid information exchange. This solution enhances the comfort of using the complex and allows for a systematic approach to taking records of performed and scheduled surgeries.

The surgeon will be able to use a single rotary operating table, thus reducing room size requirements significantly.

 

Key publications

V. V. Atezhev, B. V. Barchunov, S. K. Vartapetov, A. S. Zav’yalov, K. E. Lapshin, V. G. Movshev, I. A. Shcherbakov (Laser Physics 2016, №26)

Laser technologies in ophthalmic surgery

Г.Ф. Качалина, Ю.И. Кишкин, Н.В. Майчук, Н.Х. Тахчиди (Вестник ОГУ 2012, №12)

Оптимизированный подход к эксимерлазерной коррекции миопии

С.Б. Измайлова, А.В. Дога, Е.С. Бранчевская (Вестник ОГУ 2013, №4)

Опыт коррекции остаточной аметропии после кросслинкинга на “Микроскан Визум”

А.В. Дога, А.Д. Семенов, И.А. Мушкова, Ю.И. Кишкин, Н.В. Майчук, А.Н. Каримова, А.М. Демчинский (Вестник ТГУ 2015, №3)

Анализ результатов и перспективы развития технологии при коррекции “сверхвысокой миопии”

Г.Ф. Качалина, Н.В. Майнчук, Н.Х. Тахчиди (Кубанский медицинский вестник 2013, №2)

Сравнительный анализ аберраций после Фемтолазик на Микроскан Визуме по конической константе

Н.В. Майнчук, А.В. Дога, Н.Х. Тахчиди  (Практическая медицина 2012, №4)

Новый подход к повышению качества зрения у пациентов с кераторефракционными нарушениями

Brochure

Miсrosсan Visum Broсhure