Laser treatment effective in glaucoma

Glaucoma, one of the most common causes of permanent vision loss, involves damage to the optic nerve usually caused by increased eye pressure.
– In the studies in the thesis, we were able to show that TCP produced a long-term pressure-lowering effect, but that the risk of pressure peaks during the first day of treatment was great. The effect of LTP was strongly dependent on the eye pressure level before the treatment, and patients with a higher pressure benefited the most from the therapy, says Erika Rasmuson, doctor at the eye clinic, Norrland University Hospital.

Erika Rasmuson

ImagePrivat, Johan Rasmuson

Long-term effect

TCP (transscleral cyclophotocoagulation) is a pressure-lowering treatment in which the structures in the eye that produce aqueous humor are partially destroyed using laser energy. This leads to a reduction in newly formed aqueous humor and thus a lower eye pressure. The treatment is usually used when the eye has already been damaged by the glaucoma disease, as the treatment is restrictive for fear of complications in healthier eyes.
– To increase the understanding of the effects of TCP, we wanted to study how effective and safe the treatment is both in the short and long term. In our two-year studies, we saw that TCP had a good long-term pressure-lowering effect, while there were few complications, says Erika Rasmuson.

Valuable knowledge

The impact of TCP was also studied in the short term, and about 40% of treated eyes experienced a potentially dangerous pressure peak during the first day after treatment. This suggests a need for preventive antihypertensive treatment and possible extra monitoring in connection with TCP. Interestingly, patients with exfoliation glaucoma, a common type of glaucoma in northern Sweden, responded well to the treatment but were found to be extra vulnerable to pressure peaks after TCP. This type of glaucoma has previously been limited in studies of TCP, and the results in the thesis therefore contribute valuable knowledge especially for patients with this type of glaucoma.

Gentler method

LTP (laser trabeculoplasty) involves increased outflow of chamber fluid via the eye's drainage system using laser treatment. This method is considerably more gentle than TCP and is therefore used to a greater extent in mild glaucoma or in the case of elevated eye pressure without signs of glaucomatous damage, so-called ocular hypertension.
– In our studies, eyes that had already been treated with several pressure-lowering eye drops were examined to see how much additional effect LTP could give. We saw that the pressure-lowering effect after LTP was clearly related to the eye pressure level before the treatment, says Erika Rasmuson.

Easier medical assessment

A dividing line was found to be at an IOP value of 15 mmHg, where patients with pressure below that level had very limited benefit from LTP treatment. If, on the other hand, the eye pressure was 15 mmHg or higher, LTP could provide a good and lasting effect, even though the patients already had eye drop treatment. The results can provide guidance in clinical everyday life and facilitate doctors' assessment of when LTP can best benefit each individual patient.

Method: When studying the long-term effects of TCP, these were done on a retrospective medical record review of 300 glaucoma patients living in northern Sweden who received treatment at the eye clinic in Umeå. Data collected and analyzed included eye pressure, visual acuity, need for other pressure-lowering treatment and any complications during two years after treatment. To study the short-term effects of TCP, 58 patients with glaucoma were included in a prospective study. IOP was measured before TCP and at several times during the first postoperative day.

In the studies of the effects of LTP, 122 patients were studied who in Umeå or Malmö participated in the forward-looking GITS study (Glaucoma Intensive Treatment Study) and in it were randomized to multiple intensive treatment instead of traditional step-by-step treatment for newly discovered glaucoma. The treatment for the studied patients included LTP performed one week after starting medical treatment with drops. The patients were followed over a five-year period with regular eye pressure measurements.

Erika Rasmuson was born and raised in Umeå, where she then studied biomedicine and the medical program at the university. Since 2014, in parallel with the research, she has worked as a doctor at the eye clinic, with a special focus on glaucoma.