[Visual field loss in eyes undergoing minimally invasive glaucoma surgery in Iceland].

Introduction: Glaucoma is a degenerative disease of the optic nerve and is marked by visual field defects (VFD). The only approved treatment is IOP lowering, either with eye drops, laser or surgery. Minimally invasive glaucoma surgery (MIGS) has become an appealing treatment modality, offering IOP lowering effect without the complication rates of trabeculectomy or the patient adherence required for pharmacologic therapy. In this study we aim to describe the severity of VFD in patients undergoing their first MIGS surgery.

Methods: Retrospective study reviewing the medical records of all patients that underwent MIGS surgery at the University Hospital of Iceland from January 2019 to June 2020. Eyes with previous glaucoma surgeries and secondary glaucomas were excluded. The results were divided into two groups, MIGS with phacoemulsification and standalone MIGS.

Results: 112 eyes included in the study. Mean age 74.5 ± 10.6 years. The mean defect (MD) score was 8.8 ± 6.4 and the number of glaucoma medications 1.8 ± 1.0 for the group as a whole. Significant difference (p<0.01) was between the age, MD score and the number of glaucoma medications between the two groups. Looking at the eyes that did not undergo phacoemulsification a significant difference (p<0.05) was between the MD score of primary open angle glaucoma eyes, 11.2 ± 6.5 dB and pseudoexfoliation glaucoma, 6.0 ± 3.3 dB.

Conclusion: Visual field defect and the number of glaucoma medications at referral to surgery was markedly less compared to a trabeculectomy study done in Iceland 3 years prior. Few comparable studies include MD score in their results, most focus on changes in intraocular pressure. Comparing the MD score to three studies from Germany and Austria the MD score seems to be similar. In our study a lower MD score for pseudoexfoliation glaucoma implies that Icelandic ophthalmologists send pseudoexfoliation eyes earlier for an operation.