A 66-year-old woman with type 2 diabetes of 13 years has a dense cataract in her right eye (vision 6/60) and severe non-proliferative diabetic retinopathy behind it. The retinal view is hazy but no new vessels are certain. She asks whether cataract surgery will fix her vision and whether it is safe with her retinopathy.
Examination Findings
Right eye: dense nuclear cataract, vision 6/60, hazy fundus view showing severe NPDR changes — haemorrhages in multiple quadrants — but the periphery cannot be fully assessed. Left eye: moderate NPDR, clear view, vision 6/12 with early cataract. B-scan of the right eye shows a flat retina.
Investigations
B-scan confirms an attached retina with no tractional membranes. OCT through the cataract is degraded but suggests a flat macula. Blood sugar control and blood pressure are optimised before any surgery is planned.
Questions to Think About
- In what order should the cataract and the retinopathy be managed?
- How does cataract surgery affect diabetic retinopathy, and how do you counsel this patient?
Diagnosis
Dense cataract with severe non-proliferative diabetic retinopathy (incompletely visualised) — staged management required.
Reasoning
The retinopathy should be assessed and stabilised as far as possible before cataract surgery: complete PRP if PDR or very severe NPDR is found, and treat any macular oedema, because cataract surgery can accelerate retinopathy and macular oedema postoperatively. When the view is too poor to grade, B-scan excludes tractional detachment, and surgery proceeds with a plan — often with intraoperative or early postoperative retinal assessment and laser once the view clears. Typical management: optimise systemic control, treat sight-threatening retinopathy first where visible, then perform cataract surgery with postoperative OCT surveillance for macular oedema; counsel honestly that final vision depends on the macula and that diabetic patients face higher risks of postoperative oedema and retinopathy progression. Diagnosis: dense cataract with severe NPDR behind it — sequence retinopathy assessment/treatment before or around cataract surgery.
Differential Diagnosis
- Severe NPDR hidden behind cataract — most likely: visible haemorrhages in multiple quadrants with an incomplete peripheral view.
- Undetected PDR behind the cataract — cannot be excluded until the view improves; this drives the sequencing decision.
- Cataract as the main cause of vision loss — likely contributory given 6/60, but retinopathy may limit the final result.
Management
Grade and treat the retinopathy as far as the view allows before cataract surgery: PRP for PDR/very severe NPDR, macular OCT and treatment for oedema. If the cataract blocks grading, use B-scan to exclude tractional detachment, then proceed to surgery with a plan for prompt postoperative retinal examination and laser. Monitor closely after surgery with OCT for macular oedema and dilated reviews for retinopathy progression. Counsel that cataract surgery may worsen retinopathy and that visual outcome depends on the macula.
Key Learning Points
- Retinopathy first, cataract second (where the view allows): stabilise PDR and macular oedema before cataract surgery, because surgery can accelerate both.
- A cataract that hides the retina is a B-scan indication: exclude tractional detachment before operating, and plan postoperative retinal surveillance with OCT.
Red Flags
- Tractional detachment on B-scan behind a dense cataract — needs vitreoretinal planning, not routine cataract surgery alone.
- Active PDR with rubeosis — complete PRP before elective cataract surgery where possible.
- Postoperative vision worse than expected with a quiet eye — OCT the macula for oedema rather than assuming refractive surprise.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.
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