Unit 7: Gradual Loss of Vision

Local anaesthesia
Local anaesthesia
- The most common form is subtenons local anaesthetic, in which a small opening is made in the conjunctiva, and underlying tenons capsule, to access the subtenons space.
- Approximately 5-8 mls of local anaesthetic (eg, lignocaine) is injected into the subtenons space using a blunt tip canula.
- Some surgeons use anaesthetic eye drops instead.
- Others use a syringe and needle to inject a 'peribulbar' local anaesthetic, via the lower lid or inferior conjunctiva.
Self-sealing corneal incision into the anterior chamber
Circular opening of the anterior lens capsule (capsulorhexus)
Break up (phakoemulsification) and aspiration of lens material
Insertion of intraocular lens with chosen power to correct for any refractive error

>90% achieve visual acuity of 6/12 or better (driving vision)
May develop Posterior capsular opacification (PCO)

Posterior capsular opacification (PCO)

Slit lamp showing a membrane forming behind the intra ocular lens.

Source: EyeRounds.org. Contributor: Andrew Doan, MD, PhD, University of Iowa.

PCO interfering with the red reflex.

Source: EyeRounds.org. Contributor: Andrew Doan, MD, PhD, University of Iowa.

, where residual lens cells proliferate, causing lens capsule opacity
Laser can be used to treat PCO, by opening the thickened, opaque capsule (YAG laser capsulotomy)

1: Cataract