A 52-year-old woman with a 6-month history of chronic bilateral conjunctival injection and mucoid discharge presents with complaints of grittiness and mild photophobia. She reports worsening symptoms in the evening and relief with cool compresses. Examination reveals mild papillary hypertrophy of the upper tarsal conjunctiva, no follicles, and a stringy, ropy discharge. Schirmer test is normal. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Atopic Keratoconjunctivitis (AKC) **Key Point:** AKC is a chronic, bilateral allergic inflammation of the conjunctiva and cornea, typically affecting older adults (40–60 years) with a personal or family history of atopy (eczema, asthma, allergic rhinitis). ### Differential Diagnosis of Chronic Allergic Conjunctivitis | Feature | AKC | VKC | SAC | Chronic Bacterial | |---------|-----|-----|-----|-------------------| | **Age** | 40–60 years | 5–25 years | Any age | Any age | | **Seasonality** | Perennial, worse in winter | Seasonal (spring/summer) | Seasonal | Non-seasonal | | **Discharge** | Ropy, stringy, mucoid | Thick, ropy | Watery | Purulent | | **Papillae location** | Upper tarsal (mild) | Giant papillae (>1 mm) | Small papillae | Absent | | **Follicles** | Absent | Absent | Absent | Present | | **Lid involvement** | Lichenification, dermatitis | Absent | Absent | Absent | | **Photophobia** | Mild to moderate | Severe | Mild | Absent | | **Schirmer test** | Normal or ↓ | Normal | Normal | Normal | | **Corneal involvement** | Shield ulcer, scarring | Giant papillae, shield ulcer | Rare | Absent | **High-Yield:** The combination of **chronic (6 months) bilateral presentation, perennial symptoms, normal Schirmer test, ropy discharge, and papillary (not follicular) response** in a middle-aged woman is diagnostic of AKC. ### Pathophysiology of AKC 1. **Type I and Type IV hypersensitivity** — both IgE-mediated and T-cell-mediated responses 2. **Mast cell and eosinophil infiltration** of conjunctiva and lid margin 3. **Chronic inflammation** → fibrosis, lid margin scarring, and trichiasis 4. **Corneal involvement** → shield ulcers, scarring, and potential vision loss **Clinical Pearl:** AKC is distinguished from VKC by age (AKC: older adults; VKC: children/young adults) and lid involvement (AKC: lichenification and dermatitis; VKC: absent). SAC is seasonal and milder; AKC is perennial and more severe. ### Clinical Features of AKC - **Lid signs:** Lichenification, dermatitis, madarosis (eyelash loss), trichiasis - **Conjunctival signs:** Papillary hypertrophy (mild, <1 mm), ropy discharge, chemosis - **Corneal signs:** Shield ulcers (superior cornea), scarring, neovascularization - **Systemic associations:** Atopic dermatitis, asthma, allergic rhinitis **Warning:** Do NOT confuse AKC with VKC — VKC is seasonal, affects children, and presents with giant papillae and severe photophobia. AKC is perennial, affects older adults, and is associated with atopic dermatitis. ### Management Algorithm ```mermaid flowchart TD A[Atopic Keratoconjunctivitis diagnosis]:::outcome --> B[Mild disease?]:::decision B -->|Yes| C[Topical antihistamines<br/>Mast cell stabilizers<br/>Cool compresses]:::action B -->|No| D[Topical corticosteroids<br/>Tacrolimus ointment<br/>Cyclosporine drops]:::action D --> E{Corneal involvement?}:::decision E -->|Shield ulcer| F[Aggressive topical steroids<br/>Lubricants<br/>Consider bandage CL]:::action E -->|Scarring/vision threat| G[Systemic immunosuppression<br/>Cyclosporine/azathioprine]:::action C --> H[Follow-up in 2-4 weeks]:::action F --> H G --> H ``` **High-Yield:** Topical **tacrolimus 0.03% ointment** and **cyclosporine 0.05% ophthalmic emulsion** are steroid-sparing agents increasingly used in AKC to avoid long-term topical steroid side effects (glaucoma, cataract).