- Accommodation
- Adenovirus
- Allergic conjunctivitis
- Amblyopia
- AMD (age-related macular degeneration)
- Anisometropia
- Anterior chamber
- Anterior chamber depth
- Anterior chamber anesthesia
- Anterior segment OCT
- Aqueous humor
- Artisan Phakic Intraocular lens
- Artiflex
- Astigmatism
- Autorefractometer
- Avellino corneal dystrophy
- Avellino test
- Binocular vision
- Cataract
- Certifying physician
- Ciliary body
- Clinical trial
- Clean room
- Cornea
- Congenital cataract
- Corneal Cross-Linking
- Corneal degeneration
- Corneal diameter
- Corneal endothelium
- Corneal ectatic disorders
- Corneal neovascularization
- Corneal thickness
- Corneal topographer
- Corrected vision
- Conjunctiva
- Conjunctivitis
- Collamer
- Contact lens
- Contrast sensitivity testing
- Chalazion
- CE mark
- Color blindness (color vision deficiency)
- D(diopter)
- Diabetic retinopathy
- Dry eye