Impact of the COVID-19 pandemic on retinopathy of prematurity (ROP) screening outcomes in a multi-ethnic cohort from Kunming, China

Background Retinopathy of prematurity (ROP) is a leading cause of childhood blindness worldwide. While national-level data from China have reported an overall ROP incidence of 11.21% among at-risk preterm infants [1], there is a paucity of data from multi-ethnic regions. Yunnan Province, home to 25 ethnic minority groups, lacks systematic data on ROP distribution across ethnicities. Furthermore, it remains unclear how the COVID-19 pandemic affected ROP screening outcomes in resource-limited settings. This study aimed to describe the prevalence, treatment requirement, and temporal trends of ROP in a large multi-ethnic cohort from Kunming, China. Methods This real-world retrospective cohort study included 74,989 newborns who underwent ophthalmic screening at Kunming Maternal and Child Health Hospital between January 2018 and May 2026. Preterm infants (gestational age < 37 weeks) were identified. ROP was diagnosed and classified according to the International Classification of ROP [3]. Treatment-requiring ROP (TR-ROP) was defined as ROP requiring laser or anti-VEGF therapy. Treatment was indicated for Type 1 ROP, defined according to the Chinese expert consensus on ROP treatment and the ETROP criteria, as: zone I, any stage with plus disease; zone I, stage 3 without plus disease; zone II, stage 2 or 3 with plus disease; or aggressive posterior ROP (A-ROP). Infants were stratified into three phases based on COVID-19 control measures in Kunming: Phase 1 (Pre-outbreak baseline, January 2018 – February 2022), Phase 2 (strict lockdown, March – November 2022), and Phase 3 (post-lockdown, December 2022 – May 2026). ROP and TR-ROP rates were compared across phases and ethnic groups using chi-square tests. Multivariable logistic regression was used to assess whether ethnicity was independently associated with TR-ROP after adjusting for gestational age and birth weight. Results Among 7,129 preterm infants (9.5% of all screened newborns), ROP was diagnosed in 337 cases (4.7%), with 118 (35.0%) requiring treatment. The overall screening coverage was 95.0% (74,989/78,973) and remained stable across the three phases: 94.8% (34,256/36,135) in Phase 1, 95.0% (5,971/6,285) in Phase 2, and 95.1% (34,762/36,553) in Phase 3. Among NICU preterm infants (< 37 weeks), 4,518 of 6,453 were screened, yielding a coverage of 70.0% (70.1%, 69.5%, and 69.9% in Phase 1, 2, and 3, respectively).ROP detection rates remained stable across the three COVID-19 phases: 4.73% in Phase 1 (172/3,636), 4.87%, in Phase 2 (33/677), and 4.69% in Phase 3 (132/2,816) ( p = 0.961). The TR-ROP proportion was 33.1% (57/172), 36.4% (12/33), and 37.1% (49/132), respectively, showing no significant difference ( p = 0.806). In multivariable analysis adjusted for gestational age and birth weight, ethnicity was not independently associated with TR-ROP (OR = 1.056, 95% CI: 0.613–1.819, p = 0.845). Gestational age (OR = 0.624, 95% CI: 0.542–0.718, p < 0.0001) and birth weight (OR = 0.998, 95% CI: 0.997–0.999, p < 0.0001) were significant independent predictors. Conclusions ROP screening in Kunming demonstrated resilience during the pandemic, with stable detection rates and coverage across all phases. The high TR-ROP proportion (35%) warrants optimization of treatment strategies. Although crude TR-ROP rates differed across ethnic groups, ethnicity was not independently associated with TR-ROP after adjusting for gestational age and birth weight, suggesting that these differences were largely explained by baseline characteristics.These findings provide a baseline for ROP surveillance in multi-ethnic Chinese populations.