What is the most common predisposing factor for primary rhegmatogenous retinal detachment in developed countries?

Explanation

## Pathogenesis of Rhegmatogenous Retinal Detachment **Key Point:** Posterior vitreous detachment (PVD) with formation of a retinal break is the most common predisposing factor for primary RRD in developed countries. This accounts for >90% of cases. ### The RRD Triad Three elements must coexist for rhegmatogenous RD to occur: 1. **Retinal break** (hole or tear) 2. **Vitreous traction** (pulling force) 3. **Liquefied vitreous** (fluid to seep through break) ### Posterior Vitreous Detachment (PVD) Mechanism **High-Yield:** PVD is an age-related process where the vitreous gel separates from the retina. During this process: - Vitreous traction on the retina can create a tear - Liquefied vitreous fluid enters the subretinal space through the break - Gravity and eye movements propagate the detachment ### Risk Factors for PVD and RRD | Risk Factor | Mechanism | | --- | --- | | High myopia | Elongated globe, thin retina, lattice degeneration | | Aphakia / Pseudophakia | Loss of lens support, vitreous instability | | Family history of RD | Genetic predisposition to vitreous degeneration | | Previous RD in fellow eye | Bilateral risk | | Vitreous hemorrhage | Indicates vitreous traction | | Lattice degeneration | Thin retinal areas prone to breaks | ### Why Other Options Are Wrong **Diabetic retinopathy** causes tractional RD (not rhegmatogenous) through neovascular scar tissue, not through PVD with breaks. **Ocular trauma** can cause RD but is less common than PVD-related breaks in developed countries; trauma is a secondary cause. **Sickle cell retinopathy** causes peripheral retinal ischemia and neovascularization but is geographically and ethnically restricted; not the most common factor overall. **Clinical Pearl:** Patients with acute PVD symptoms (floaters, photopsia, shadow in visual field) require urgent dilated fundoscopy to rule out retinal breaks before RD develops. **Mnemonic — RHEGMATOGENOUS RD RISK FACTORS:** **MY FLAUNT** - **M**yopia (high) - **Y**oung age at PVD onset - **F**amily history - **L**attice degeneration - **A**phakia - **U**veal coloboma - **N**ecrotic retinitis (acute retinal necrosis) - **T**rauma (prior) [cite:Parson's Diseases of the Eye 22e Ch 9; Boyd & Malone's Ophthalmology 5e Ch 8]