The authors present the findings of a retrospective study to examine the cause of treatment failures in type 1 retinopathy of prematurity (ROP). They reviewed the medical charts of all infants with persistent disease post laser treatment at Uppsala University Hospital, Sweden over 10 years (2009-2019). Documenting the retinal images before and after retreatment was done through RetCam photography and angiography. They recruited a cohort of 10 infants with 18 eyes suffering from persistent type 1 ROP despite previous laser treatment. The mean gestational age of the infants was 24 weeks and their mean birth weight was 618g. All infants in this study were extremely premature (<27 weeks) and the majority had ROP in zone I or posterior zone II. Seven of the 18 eyes were diagnosed at stage 3+, eight eyes as stage 4A and three eyes as stage 4B. In eight of the infants (14 eyes), inadequate laser coagulation was suspected to be causing the persistence of type 1 disease. To treat the persistence of type 1 ROP, five infants (seven eyes) had vitrectomies, two infants (three eyes) with laser photocoagulation and anti-VEGF, two further infants (four eyes) were treated with anti-VEGF alone and the last two infants (four eyes) were treated with laser photocoagulation alone. The outcomes were good in 14/18 eyes and poor in 4/18 eyes. Eight of the 10 infants were considered to have had inadequate laser coagulation demonstrated as overtreatment of physiologic retina, incomplete treatment of ischaemic retina and / or presence of skip lesions. The authors conclude that the causes of treatment failure of laser in ROP disease may be laser treatment in zone I and inadequate laser coagulation. They also recommend centralisation of the treatment to fewer hospitals and fewer surgeons. The limitations of this study include its retrospective nature and the small number of patients in this study may not be representative for the quality of laser coagulation on a national level. This study can be expanded to a larger cohort that may assist with the identification of issues on a national level.