Ophthalmology is full of acronyms. For the uninitiated it can be quite a minefield of confusing terminology. Here is a guide to help you with the basic terms used.
1. Therapeutic Corneal Laser Procedure Types.
The type of procedure is dependant on whether the epithelium is included or not with laser ablation.
- PTK – PhotoTherapeutic Keratectomy
The epithelium is manually removed, sometimes with the help of alcohol or a brush. The laser is then applied to the exposed stromal bed.
The refractive equivalent of this procedure is a PRK, PhotoRefractive Keratectomy.
- TransPTK – Transepithelial PhotoTherapeutic Keratectomy
With this procedure the laser is applied straight to the epithelium and then stroma without pause. The epithelium acts as a masking agent.
The refractive equivalent of this procedure is a TransPRK, Transepithelial PhotoRefractive Keratectomy.
Fluid is used as masking agent to smooth the stromal bed. Usually done after one of the other therapeutic profiles, or after removal of the epithelium alone.
- SCTK – Sequential Custom Thereapeutic Keratectomy
This is a combination of multiple Wavefront/Topography guided profiles. First, a TransPTK/PTK is done. Then a WetPTK to smooth the stromal bed. The eye is remeasured immediately. A new custom PTK profile is planned, and steps one and two are repeated. The process can be repeated a few times, usually 3 or 4 times, but even up to 5 times or more is possible, all in one setting.
2. Special Profiles
The profile is the shape of the laser application, ie the shape of the tissue that will be removed with the Excimer Laser.
The corneal shape can be described mathematically in a wavefront using Zernike polynomials. The same maths can then be applied to create a custom profile to address the individual corneal global irregularity.
The corneal shape can be plotted using Placido disc rings. The rings are equivalent to the valleys and peaks on a geographical contour map, but to a very precise scale. This shape can then be applied to create a custom ablation profile for the individual.
3. Laser Platforms and Company Terminology
Amaris – current Excimer laser platform
Atos – current Femtosecond laser platform (can perform SMILE)
SmartSurface – technology that creates a very smooth stromal bed with the TransPRK type procedure. The only company with this technology.
PresbyMax – presbyopic excimer laser module on the Amaris
Mel 90/80 – current Excimer laser platform
VisuMax – current Femtosecond laser platform (can perform SMILE)
Presbyond – presbyopic excimer laser module on the Mel 90/80
Laser Blended Vision – name given to the presbyopic excimer laser profile created by the Zeiss software
WaveLight – refractive platform
WaveLight EX500 – current Excimer laser platform
Wavelight FS200 – current Femtosecond laser platform (cannot perform SMILE)
LenSx – Femtosecond laser platform designed to assist surgeons with cataract surgery
Contoura – Alcon’s name for Topography guided LASIK ablation profiles
StreamLight – Alcon’s name for a TransPRK