Erratum

This article refers to:

In Volume 30, Issue 11 of Current Eye Research, a Letter to the Editor by Ronald A. Schachar, M.D., Ph.D., appeared without the response by Martin J. Lizak, Ph.D. Both letters are shown below.

The publisher wishes to express its sincere regrets for any inconvenience this may have caused the authors and Current Eye Research readers.

Dear Editor,

Lizak et al.[[1]] demonstrate that above 1 atmosphere (760 mm Hg) the bovine lens responds syneretically in a linear fashion to incremental pressures of 0.2 atmospheres (152 mm Hg). Linearity of the syneretic response at pressures above one atmosphere does not necessarily infer that the linearity will hold at pressures below one atmosphere. Furthermore, even if it does occur below 1 atmosphere, the response may be too small to have an influence on accommodation.

Normal intraocular pressure (IOP) is approximately 20 mm Hg, which is 0.026 atmospheres. The change in intralenticular pressure during accommodation is approximately 0.013 atmospheres (10 mm Hg).[[2], [3]] The authors must demonstrate the presence of a syneretic response commencing at 0.026 atmospheres. Then they need to demonstrate that the size of the syneretic response during accommodation is sufficient to affect the mechanical response of the lens to zonular traction. Only after performing experiments in the physiologic pressure range will the authors have data that may directly apply to an understanding of the physiological mechanism of accommodation and the etiology of presbyopia.

Dear Editor,

In our paper “Syneretic response to incremental pressures in calf lenses”[[1]] we investigated the effect of varying pressure on the syneretic effect of water in the lens. The pressures used varied from 1 atmosphere to 3 atmosphere. In other work we have used pressures as low as 0.03 atmosphere[[2]]. Because the tissue-water system is not close to a phase transition, basic thermodynamics dictates that the syneretic effect can not be discontinuous. In the worst case, there is a smooth variation with pressure. There will be some effect, even if it is too small to observe with current instrumentation.

It should be noted that IOP is actually the differential pressure between the eye and the outside world. Therefore the intralenticular pressure during accommodation is 1 atmosphere with a small additional change up or down. This is well within the range of pressures we investigated. Due to the requirements of time and instrumentation, we could not investigate any finer pressure variations. Despite this, the data suggest that there is a syneretic change that accompanies the pressure variation due to accomodation.