Transepithelial PRK (TransPRK / SmartPulse): Single-Step No-Touch Laser Surface Ablation Biophysics

In standard PRK, exposing the eye to $20\%$ ethanol for 20 seconds chemically kills epithelial cells, but diffuses into anterior stroma, triggering keratocyte necrosis, high IL-1 $\alpha$ release, and severe corneal myofibroblast activation (the root cause of corneal subepithelial haze). Furthermore, mechanical scraping tears ragged borders, delaying epithelial healing to 5–7 days.

TransPRK utilizes an inverted ablation algorithm. Because epithelial tissue ablates faster than dense stromal collagen, the excimer laser applies a population-calibrated epithelial profile ($55\ \mu\text{m}$ centrally, $65\ \mu\text{m}$ peripherally) directly before executing refractive correction:

$$t_{\text{total}}(r) = t_{\text{epithelium}}(r) + t_{\text{refractive}}(r) \implies \text{Executed in Under 40 Seconds Touch-Free}$$

Epithelial margins are cut with laser-sharp, pristine vertical edges, accelerating healing (re-epithelialization complete in $48\text{ to } 72\ \text{hours}$) and reducing post-operative pain scores by over $50\%$.

Pioneered by the Schwind Amaris platform, SmartPulse technology arranges laser pulses according to a 3D fullerene (buckyball) geometric lattice. This eliminates microscopic step ridges between pulses, producing a stromal surface that is $3\times\text{ smoother}$ on atomic force microscopy, accelerating initial visual recovery.