Laser Applications in Oncology and Ophthalmology PDF

```markdown ## B.2.2 Laser applications ### a) Oncology * Photodynamic therapy (PDT) (photochemical) * injection of photosensitizer (e.g. HpD: hematoporphyrin derivate) * clearance (quasi-accumulation in tumor (48h)) * laser irradiation $\rightarrow$ chemical reactions...

```markdown ## B.2.2 Laser applications ### a) Oncology * Photodynamic therapy (PDT) (photochemical) * injection of photosensitizer (e.g. HpD: hematoporphyrin derivate) * clearance (quasi-accumulation in tumor (48h)) * laser irradiation $\rightarrow$ chemical reactions $\rightarrow$ excited $O_2$ states oxidation $\rightarrow$ cell damage * laser-induced fluorescence diagnostics (photodynamic diagnostics) * Tumor diagnostics use fluorescent dyes * natural * external * e.g. by injection of 5-ALA * increased formation of protoporphyrin IX * thermal interaction: LITT * laser-induced thermotherapy * T ~ 60°C in tumor, minimally invasive * $\lambda \sim 1\mu m$ (Nd: YAG) * MRI to control temperature * Surgery * CW-CO₂-laser (thermal) $\lambda \sim 10\mu m (IR)$ * strong absorption of water $\rightarrow$ vaporisation * Cervix: tissue ablation of early tumor stages by vaporisation * lung: less bleeding than with regular knife ### b) Ophthalmology * diagnostic, by optical coherence tomography (OCT) * e.g. -retinal detachment * glaucoma (Grüner Star): over pressure * treatment of glaucoma * create a channel through sclera without damage to the conjuctiva * treatment of retinal detachment * thermal sealing with choroidea (coagulation) * lens: cataract: clouding of lens (Grauer Star) * removal of lens * then: opaque membranes * photodisruption for ablation Nd:YAG, 30us * refractive corneal surgery * Laser: photorefractive keratectomy ArF- lase 193 nm, photo aslation, rauge $\sim \mu m$ * better: infrastromal ablation NdYAG, gas diffuses into tissue $\rightarrow$ cavity collapses keeps the membranes intact * LASIK: laser-in-situ - keratomileusis * cutting of a flap * modelling of the stroma (ArF) * replace flap * before: detailed analysis of corneal surface ```