Technical differences between various excimer lasers


Most excimer lasers-

Wavefront LASIK

Ex- 500 – Contoura™ LASIK with Occulyzer + Topolyser Vario

(only at Shroff Eye, Mumbai)

1) Synchronized eye trackers @ 500 Hz = 6 millisecs response time @1050 Hz

Laser falls on programmed target

Therefore feedback time which is a response time of 2 millisecs
2)                        – 3  times sturdier laser lead With Topolyzer Vario

→ Cyclotorsion for cylinder

≥  -1.5D

3) open to environment Sealed optics stable energy Auto neuro tracking and infrared camera in both topolyser and the laser. Also has a pupillometer for night vision issues. = Contura vision. Detects iris landmarks. Any from vertical to supine position means that eye rotates; therefore the compensation needs to be done. No human error as no punching of work. It is transferred software to software. The diagnostic and live image software overlaps to find differences and adjust those differences



Ex 500 Mel 90 Mel 80
1) 500 Hz 1) 250→500Hz 1) 250Hz
2) Wavefront optimized treatments. Does not induce higher order aberrations and maintains spherical profile 2) Becomes oblate and induces spherical aberrations




2) Becomes oblate and induces spherical aberrations



3) ASA + Corneal saving

FDA approved -12.00D

-14.00 D internal

CE approval.

Astigmatism ±5.00 D

±6.00 D internal


Optical zone 8.5 mm

True optical zone 6.5mm



AAA algorithim claims to do ASA + corneal save

Not FDA approved







ASA and tissue saving

Maintain natural aspherically


more corneal aberrations


though issue saving option

You will save tissue but not maintaining asphericity

6 D eye tracker

6 sigma multispectial eye tracker


3D tracker


3D tracker


With slit lamp

Online Pachymetry

No integrated slit lamp

No online Pachymetry



No integrated slit lamp

No online Pachymetry



Topography linked treatments were used earlier on cases who had some laser treatment done on their cornea. Not used as Primary treatment.

But now with Contoura, it is the only FDA approved Topography treatment to be used as a primary LASIK treatment.

Topography LASIK address the corneal irregularities as most aberrations are from cornea.



With contura one can expect gain in line of acuity in 30% cases.

At Shroff Eye we have the diagnostics which no centre has ie. the Occulyzer plus the Topolyser Vario. This is important to detect early Keraconus.

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