Locating the Centre of Visual Axis when doing Laser Posterior Capsulotomy

Keith Ong^1,2

¹Royal North Shore Hospital, Sydney, Australia
²Department of Ophthalmology, Northern Clinical School, University of Sydney

Purpose: It can be difficult to estimate the centre of visual axis when doing YAG laser posterior capsulotomy with a dilated pupil. A 2.5 to 3 mm well centred laser posterior capsulotomy would be ideal. A 2 mm posterior capsulotomy which is well centred in the pupil region may be adequate. Laser posterior capsulotomies larger than 4.5 mm is usually not necessary and if not well centred may extend over the edge of optic of intraocular lens risking vitreous coming forward around the optic if anterior capsulorrhexis does not cover the edge of optic completely; or even risking posterior migration of intraocular lens with the plate haptic intraocular lens.

Method: The Zeiss IOL master can help with finding the centre of the visual axis. When in axial length measurement mode, there is a central dot with a ring around it. When the patient looks at the central light, that denotes the centre of visual axis. When the eye is illuminated during the measurement phase, one can then see the edge/shadow/outline of the capsulotomy. If it is not central or big enough, we can enlarge in the direction/position required. Fundus camera may also be used.

Results & Conclusions: With this method, it minimises the risk of eccentric or too large a capsulotomy. When we check the patient again with the pupil in the normal state; with this method most often we would find that the capsulotomy is adequate and central.