Contact Lens and Anterior Segment Procedures
Soft and rigid lens fitting
Before fitting, assess the ocular surface: fluorescein staining, tear break-up time, lid margins and meibomian glands, corneal topography and keratometry, and previous lens history. For soft lenses, select base curve, diameter and material from measured curvature and refraction, then judge the fit by centration, complete corneal coverage and 0.2 to 0.4 mm of post-blink movement. For rigid lenses, interpret the fluorescein pattern - apical clearance or touch, mid-peripheral bearing, edge lift - and refine the base curve in small steps guided by the pattern rather than the numbers alone.
Toric and presbyopic designs
Toric soft lenses require stabilisation: check for rotation and use LARS (left add, right subtract) to adjust the cylinder axis, over-refracting over the settled lens. Multifocal designs are judged on vision at the patient's real working distances, not distance acuity alone.
Anterior segment procedures
These include fluorescein and lissamine green staining, tear film assessment, eyelid eversion for subtarsal foreign bodies, superficial foreign body removal under appropriate magnification and anaesthesia, Seidel testing, punctal plug insertion and correct instillation technique. Each carries its own consent and documentation requirements.
Traps
Failing to evert the upper lid; using a cotton bud on the central cornea; missing a positive Seidel test in a walking-wounded patient; not removing lenses before staining; blaming red eye on lens overwear when the true problem is microbial keratitis; and ignoring limbal neovascularisation or a lens with no movement.
Rule of thumb
If a lens shows less than about 0.1 mm of movement after a blink, or a push-up test fails to release it, the fit is too tight - stop and refit rather than letting the patient "settle in".