Table 1.
Summary of the key similarities and differences in both pathophysiology and symptomatic physiology between those suffering from seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), vernal keratoconjunctivitis (VKC), or atopic keratoconjunctivitis (AKC) [18,19].
| SAC | PAC | VKC | AKC | |
|---|---|---|---|---|
| Presentation | Intermittent | Persistent | Intermittent and persistent phases | Chronic |
| Allergic mechanism | IgE-mediated | IgE-mediated | IgE and non-IgE mediated | IgE and non-IgE mediated |
| Cell types involved | Mast cells | Mast cells | Mast cells, eosinophils, lymphocytes, basophils, plasma cells, and macrophages | Mast cells, eosinophils, and lymphocytes |
| Background | Atopic | Atopic | Childhood and/or atopic | Atopic |
| Eyelids | Oedema | Oedema | Oedema, pseudoptosis (saggy eyelid) | Eczema, meibomitis (tear gland inflammation), blepharitis (oil gland inflammation) |
| Conjunctiva | Follicles and/or papillae | Follicles and/or papillae | Giant papillae | Papillae and/or fibrosis |
| Limbus | No effect | No effect | Thickening, Trantas dots | Thickening, Trantas dots |
| Cornea | No effect | No effect | Ulcer, vernal plaques | Ulcer, vernal plaque, opacities, neovascularization |
| Discharge | Clear mucoid | Clear mucoid | Stringy mucoid | Stringy mucoid |
| Symptoms | Watery eyes, itchy eyes, inflammation, discomfort, conjunctivitis, swollen eyelids, blurred vision | Watery eyes, itchy eyes, inflammation, discomfort, conjunctivitis, swollen eyelids, blurred vision | Itchy eyes, irritation, discomfort, conjunctivitis, photosensitivity, papillae | Itchy eyes, irritation, discomfort, conjunctivitis, swollen eyelids, papillae, photosensitivity |