Author: Claude (AI), from PubMed abstracts · Reviewed by: Dr Mina Abdelmseih · Reviewed: 2026-11-15 · Review due: 2027-11-15

Educational content only. Not personalised medical advice. Clinical decisions remain the responsibility of the treating clinician.

Proliferative Diabetic Retinopathy: Laser, Anti-VEGF and Vitrectomy

Proliferative diabetic retinopathy (PDR) is an advanced, sight-threatening stage of diabetic retinopathy in which abnormal new vessels grow on the retina, optic disc or anterior segment [S3], with a high risk of vitreous haemorrhage and tractional retinal detachment [S11]. Panretinal photocoagulation (PRP) remains the established treatment [S11] [S1]; anti-VEGF injections are an alternative or adjunct with similar long-term vision but a heavier visit burden and higher cost [S4] [S10].

Key points - PRP reduced the risk of severe visual loss by over 50% at 12 months compared with no or deferred treatment [S1]. - Ranibizumab was noninferior to PRP for vision at 2 years, and vision was similar (about 20/25) in both groups at 5 years [S2] [S4]. - Anti-VEGF caused less macular oedema and less visual field loss than PRP, but needed far more injections (mean 19.2 over 5 years) [S4]; its visual benefit over PRP is not clinically meaningful [S11] [S7]. - Most cost-effectiveness studies, largely from a US perspective, judged that anti-VEGF's extra cost outweighs its limited benefit over PRP [S10]. - Tractional detachment needs vitrectomy; earlier surgery with better preoperative vision gave better final vision [S6].

Evidence last checked: 2026-10-17 (PubMed abstracts).

Red flags

• Vitreous haemorrhage with vision loss in a person with diabetes: a complication of PDR [S7] [S5].
• Tractional retinal detachment, occurring in approximately 5% of people with PDR [S6]. Final vision after surgery is often poor (mean 0.94 logMAR, about 6/53), and worse when preoperative vision is worse [S6].
• Patient unlikely to attend frequent visits. Anti-VEGF alone needs repeated injections; anticipated visit compliance, cost and visit frequency should guide the choice of treatment [S4].
• High loss to follow-up. In Protocol S, only 66% of surviving participants completed the 5-year visit [S4].

Recognise it

• PDR shows new vessels in the retina, optic nerve head or anterior segment [S3], and may present with vitreous haemorrhage [S7].
• Trial participants were mostly middle-aged (mean age 52 to 57 years) [S2] [S5] [S7]; mean HbA1c in the Cochrane review trials was 8.25% to 8.45% [S7].
• More intensive blood pressure control reduced the 5-year incidence of diabetic retinopathy (risk ratio 0.82, moderate certainty), particularly in hypertensive type 2 diabetes, but did not clearly slow progression or prevent PDR [S8].

Confirm it

• Trials judged activity as active or regressed neovascularisation [S2] and measured regression of new vessels [S7].
• When the view is blocked by vitreous haemorrhage, the abstracts do not cover the investigation of the retina behind it; follow local practice.

Manage it

Before acting on this section, check the national and local guidelines, product information and regulatory approvals that apply where you practise. See the medical disclaimer.

Tier A (primary care / no specialist)

• Recognise sudden vision loss or floaters in diabetes as possible vitreous haemorrhage and refer (see Refer when) [S5].
• Support blood pressure control, especially in hypertensive type 2 diabetes, for its modest effect on preventing retinopathy [S8]. More intensive control increased hypotension (risk ratio 2.04) [S8].
• Stress that PDR treatment needs follow-up: loss to follow-up was high even in trials [S4].

Tier B (general eye clinic)

1. PRP is the mainstay. Laser reduced severe visual loss (risk ratio 0.46), progression of retinopathy (risk ratio 0.49) and vitreous haemorrhage (risk ratio 0.56) vs no or deferred treatment [S1]. In Protocol S, PRP was completed in 1 to 3 visits [S2].
2. Laser type and pattern. Evidence comparing alternative lasers or patterns with standard ETDRS argon PRP is limited and mostly low or very low certainty [S3]. Diode laser was more painful than argon (risk ratio 3.12, moderate certainty) [S3].
3. Pain relief. Analgesics or NSAIDs reduced pain during PRP compared with placebo in a meta-analysis of 13 RCTs; systemic analgesia was potentially better than eye drops [S9]. Specific doses are not covered; follow local formularies.
4. Watch for macular oedema after PRP. Diabetic macular oedema developed in 28% of PRP eyes vs 9% of ranibizumab eyes at 2 years [S2].

Tier C (specialist centre)

1. Anti-VEGF as alternative or adjunct. Ranibizumab 0.5 mg (as reported in [S2]) was noninferior to PRP at 2 years (+2.8 vs +0.2 letters), with less visual field loss, less vitrectomy (4% vs 15%) and less macular oedema [S2]. At 5 years, vision was similar (+3.1 vs +3.0 letters) [S4]. An individual participant data meta-analysis found a modest, not clinically meaningful, visual benefit at 1 year that declined over time, but fewer cases of macular oedema (relative risk 0.48) and retinal detachment (relative risk 0.41) [S11]. A Cochrane review found anti-VEGF with or without PRP probably reduced vitreous haemorrhage (risk ratio 0.72) and may reduce vitrectomy (risk ratio 0.67) [S7].
2. Vitreous haemorrhage. In Protocol AB, initial aflibercept (4 monthly injections) vs vitrectomy with PRP gave no significant difference in vision over 24 weeks; vision recovered faster with vitrectomy at 4 weeks and was similar (about 20/40) at 2 years [S5]. About a third of each group later crossed over [S5]. The trial may have been underpowered to show a benefit of early vitrectomy [S5].
3. Perioperative anti-VEGF. A network meta-analysis of 30 RCTs (2,646 eyes) found that anti-VEGF before or during vitrectomy improved postoperative vision and reduced intraoperative bleeding and recurrent haemorrhage, but evidence quality varied [S12].
4. Tractional detachment. Vitrectomy failed to reattach the retina after one operation in 5.9% of eyes across 38 studies; preoperative vision was the only factor linked to final vision [S6].

Refer when

Pitfalls

• Choosing anti-VEGF alone for a patient who cannot return regularly [S4].
• Expecting anti-VEGF to give clearly better vision than PRP: the difference is not clinically meaningful [S11] [S7].
• Forgetting macular oedema and field loss after PRP [S2] [S4].
• Delaying surgery for tractional detachment until vision has fallen [S6].

Evidence notes

• The landmark laser trials are old, mostly from the USA, with performance and attrition bias [S1]. Most anti-VEGF RCTs had unclear or high risk of bias [S7].
• Protocol S was run at US sites and Protocol AB at US and Canadian sites [S2] [S5]; cost-effectiveness evidence was mostly from a US perspective and its transfer to other settings is unclear [S10].
• Long-term effectiveness and safety of anti-VEGF for PDR are unclear, as further PRP and injections are needed over time [S11].
• 8 of 29 blood pressure trials were sponsored entirely by pharmaceutical companies [S8].
• Not covered by these sources: PRP settings and number of burns, B-scan ultrasound, neovascular glaucoma, PDR in pregnancy, and screening programme design.

Related articles

• Diabetic Macular Oedema
• Diabetic retinopathy screening programmes
• Fluorescein and indocyanine green angiography

References

See the numbered source list below. Each marker [S#] links to its PubMed and DOI record.