McCance 1989.

Study characteristics
Methods	Study design: retrospective cohort longitudinal Location: UK Time period: diagnosed between January 1968 and December 1986 Outcome: PDR Outcome measurement: incidence and median difference
Participants	Number of participants: 271 Diabetes type: T1D Inclusion criteria: classic insulin‐dependent diabetes diagnosed between January 1968 and December 1986; 25 years or younger at diagnosis Exclusion criteria: unable to be contacted; failed to attend; received diabetic care abroad; in prison, refused to participate, temporarily abroad or died; congenital nystagmus; medial opacities preventing retinal photography
Notes	Link to data extraction table, risk of bias assessment, and results: osf.io/t2bzq/?view_only=ad9a16f7610a4e7385e115d13dedc3dc
Item	Authors' judgement	Support for judgement
Study participation	Unclear	See ‘Notes’ above for link to risk of bias assessment
Study attrition	No	See ‘Notes’ above for link to risk of bias assessment
Prognostic factor measurement	Unclear	See ‘Notes’ above for link to risk of bias assessment
Outcome measurement	Yes	See ‘Notes’ above for link to risk of bias assessment
Adjustment for other prognostic factors	No	See ‘Notes’ above for link to risk of bias assessment
Statistical analysis and reporting	Unclear	See ‘Notes’ above for link to risk of bias assessment