A 72-year-old woman from rural India undergoes phacoemulsification for a mature cataract in her left eye. Intraoperatively, during the aspiration phase, the posterior capsule ruptures. The surgeon completes the procedure by placing an IOL in the sulcus (not in the bag). Postoperatively, at 1 week, she reports good visual acuity (6/9) but complains of persistent monocular diplopia and glare, especially in bright sunlight. Slit-lamp examination shows the IOL is well-positioned in the sulcus with no decentration. What is the most likely cause of her symptoms?

Explanation

## Dysphotopsia and Sulcus IOL Placement ### Clinical Scenario A patient with IOL placed in the sulcus (due to posterior capsule rupture) presents with monocular diplopia and glare despite good visual acuity and proper IOL positioning. This is a classic presentation of **dysphotopsia**. ### Understanding Dysphotopsia **Dysphotopsia** = visual symptoms (glare, halos, shadows, diplopia) without objective refractive error or structural abnormality. | Type | Cause | Characteristics | Timing | | --- | --- | --- | --- | | **Negative dysphotopsia** | IOL edge shadows | Dark crescent in peripheral vision | Immediate/early | | **Positive dysphotopsia** | Light scattering from IOL optics | Glare, halos, streaks | Immediate/early | | **Edge-related dysphotopsia** | Sulcus IOL edge optics | Monocular diplopia, glare in bright light | Immediate/early | ### Key Point: **Sulcus IOL placement increases dysphotopsia risk** because: 1. IOL is positioned more anteriorly than bag placement 2. IOL edge is closer to the pupillary axis 3. Light rays hit the IOL edge at sharper angles, causing edge reflections and scattering 4. The optic edge becomes visible to the patient, especially in bright light ### High-Yield: **Dysphotopsia is NOT a refractive error** — it occurs despite: - Good visual acuity (6/9 in this case) - Proper IOL centration - Correct IOL power - Clear media ### Clinical Pearl: **Monocular diplopia + glare in sulcus IOL = edge optics phenomenon.** The patient sees a shadow or double image from the IOL edge reflecting light. This is more common with: - Older IOL designs with sharp edges - Sulcus placement (vs. bag placement) - Smaller optic diameters - Patients with larger pupils ### Mnemonic: **EDGE OPTICS** = Edge-related optical phenomena causing dysphotopsia in sulcus IOLs - **E**dge reflection from IOL optic - **D**ouble vision or shadow perception - **G**lare in bright light - **E**xacerbated by pupil dilation ### Management of Dysphotopsia ```mermaid flowchart TD A[Dysphotopsia after sulcus IOL]:::outcome --> B{Severity & impact on QOL?}:::decision B -->|Mild, tolerable| C[Observation & reassurance]:::action B -->|Moderate to severe| D[Consider interventions]:::action C --> E[Symptoms often improve in 3-6 months]:::outcome D --> F{IOL design issue?}:::decision F -->|Yes| G[IOL exchange to acrylic with rounded edges]:::action F -->|No| H[Optimize pupil size with miotics]:::action G --> I[Improved dysphotopsia]:::outcome H --> J[Reduces edge light entry]:::outcome ``` ### Tip: **Reassurance is key** — many dysphotopsia symptoms improve or resolve within 3–6 months as the brain adapts (neural adaptation). IOL exchange is reserved for severe, persistent symptoms that significantly impact quality of life. [cite:Garg & Garg Cataract Surgery Ch 9; American Academy of Ophthalmology Cataract & Anterior Segment Panel]