An estimate of the size and shape of the human lens fibre in vivo.

The size and shape of the lens fibres were estimated by specular reflex photography. The fibres were measured in three separate regions. Peripheral fibres have a mean width of 10.2 micron, the central fibres 11.9 micron, and the central fibres with suture 15.8 micron. Measurements were made of the taper (becoming narrower towards the suture) and flare (becoming wider towards the suture). The peripheral fibres have a mean taper of 0.3 micron per 100 micron. The central fibres have a mean flare of 0.6 micron per 100 micron, and the central fibres with suture have a mean flare of 2.4 micron per 100 micron. These differences are highly significant (p less than 10(-6]. From these measurements the overall shape of the average lens fibre was estimated. This fibre tapers as it passes forward from the equator to the peripheral extent of the lens sutures and then flares increasingly as the junction with the lens suture is approached. A mean increase in peripheral lens fibre width with age at 0.028 micron per year was demonstrated. This is significant (p = 0.042). No difference in fibre width was found in diabetics and non-diabetics.