Increased intraocular pressure (glaucoma) is one of the main causes of blindness worldwide. Every year, approximately 6.7 million people lose their eyesight due to this disease, as increased intraocular pressure leads to irreversible damage to the optic nerve. As a standard procedure, the first step is to try to treat glaucoma with medication, but the effect is limited by the side effects, the irregular application by the patient and also the limited effect in the case of excessive glaucoma.
Selective laser trabeculoplasty (SLT) is an alternative method of treatment for reducing high intraocular pressure in open-angle glaucoma. The laser treatment is based on the principle of selective photothermolysis, in which specifically pigmented tissue in the trabecular meshwork (the chamber angle) is loosened by microbubble formation in order to increase the outflow of the aqueous humor, which is formed in the ciliary body, into Schlemm's canal. A Q-switched, frequency-doubled Nd:YAG laser with a wavelength of 532 nm and a pulse duration of 3 ns is used for this purpose.
One problem of this laser treatment is the dosage of energy, as the laser effects generated are invisible to the ophthalmologist. The doctor therefore increases the pulse energy during irradiation until macroscopically large visible bubbles appear (champagne like bubbles), and then reduces the irradiation energy again by a percentage based on experience. In order to facilitate this time-consuming and undefined titration and to prevent damage caused by the large bubbles, we are working on an automatic dosage for each individual laser spot. For this purpose, different approaches are pursued to detect the microbubbles living only µs, which hypothetically should already be sufficient to loosen the trabecular meshwork, via light reflection or via acoustic signals and thus to control the laser itself in a feedback manner
Own publications, peer reviewed to SLT:
