- Sarcoidosis
- Sarcoma
- Schizophrenia
- Scurvy
- Severe Acute Respiratory Syndrome (SARS)
- Swine Flu
- Syphilis
- Superior Limbic Keratoconjunctivitis
- Stroke
- Scrub Typhus
- Sexually transmitted infections (STIs)
- Shaken Baby Syndrome
- Seasonal Allergic Conjunctivitis
- Spheroidal Degeneration
- Salzmann's Nodular Degeneration
- Substance abuse
- Scabies
- Solar Retinopathy
- Steatoblepharon
- Silicosis
- Sub-conjunctival Haemorrhage