Some specific symptoms and their hypothesised pathogenesis
| Symptom | Proposed (hypothesised) cause(s) |
|---|---|
| Dry eyes | |
| Gritty and sandy | Air exposed nerve endings in the microvilli layer of epithelium, where the mucin layer has been ruptured, exposing patches of bare microvilli and nerve endings152 |
| Fuzzy vision | Meibomitis58 |
| Allergic conjunctivitis66,139 | |
| The mucin layer is intact, but the water layer over the mucin layer breaks up into small islands that distort the transfer of light152 | |
| Irritation | |
| Stinging, burning, pain | Break up of PTF, possibly followed by chemical stimulation, including increased osmolarity due to evaporation. This may stimulate nociceptors, which are sensitive to chemical and mechanical stimuli123 |
| Burning, irritation, tearing, dryness | Upgaze, glare, small font, flicker118 |
| Ache and strain | Near work, lens flipper, mixed astigmatism conditions (accommodative and vengeance stress) |