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Artifacts on Sem Study of Eye Tissues
ARTIFACTS ON SEM STUDY OF EYE TISSUES To the Editor: Thank you for publishing our article "Scanning Electron Microscopic Study of Eye Tissues" (Am IntraOcular Implant Soc] 10:169-175, 1984). I would like to comment on plate IV, page 174, which shows peculiar extrusions of nuclei and large endothelial defects. We recently found that these are preparation artifacts, not strictly correlated with clinical phenomena. We are currently investigating this effect in more detail, as we were intrigued by the conspicuous nuclei extrusion. These artifacts serendipitously provided us with a new means for SEM investigation of endothelial post-mortem physical behavior of endothelial cells. Thank you for publishing this additional information on our paper.
In the last issue, the two photographs in the article "Forceps for Implantation of Posterior Chamber Loop Haptic Lenses" (page 366) were printed incorrectly. They should have appeared as follows:
J.G.F. Worst, M.D. Haren, The Netherlands
PERSPEX CQ GRADE FOR IOLs To the Editor: I would like to refute part of the findings published in a report circulated by Optical Radiation Corporation concerning the presence of ethyl acrylate in lathe-cut IOLs. In this report, it is alleged that lathe-cut IOLs, made by a number of well-known manufacturers in the United States, contain up to 8.8% of ethyl acrylate using one detection method or, indeed, up to 9.6% using another, confirmatory method. Whilst not wishing to enter into discussions as to the sUitability of the test methods used, I must challenge the accuracy of the results, since most of the lathe-cut lenses are made from Perspex CQ grade, which ICI Plastics Division has manufactured for more than 40 years. Both the methyl methacrylate monomer used (also made by ICI) and the CQ polymer itself have full FDA approval in America. The level of ethyl acrylate present in the monomer used to make CQ grade is less than 10 parts per million. The latest gas chromatography equipment (supplied by Hewlett Packard) is used to monitor the level of this and other impurities, which may be present at similar levels. Since no ethyl acrylate is added during the manufacture ofPerspex CQ grade, it follows that the maximum level of this material present in the final polymer is less than 10 parts per million. I hope these comments will reassure the various manufacturers of IOLs using CQ Perspex.
Fig. 2.
(Thornton) Forceps' hinge at base of the jaws.
G.R. Cheal
Darwen, England
474
AM INTRA-OCULAR IMPLANT SOC J-VOL 10, FALL 1984
In the last issue, the two photographs in the article "Forceps for Implantation of Posterior Chamber Loop Haptic Lenses" (page 366) were printed incorrectly. They should have appeared as follows:
J.G.F. Worst, M.D. Haren, The Netherlands
PERSPEX CQ GRADE FOR IOLs To the Editor: I would like to refute part of the findings published in a report circulated by Optical Radiation Corporation concerning the presence of ethyl acrylate in lathe-cut IOLs. In this report, it is alleged that lathe-cut IOLs, made by a number of well-known manufacturers in the United States, contain up to 8.8% of ethyl acrylate using one detection method or, indeed, up to 9.6% using another, confirmatory method. Whilst not wishing to enter into discussions as to the sUitability of the test methods used, I must challenge the accuracy of the results, since most of the lathe-cut lenses are made from Perspex CQ grade, which ICI Plastics Division has manufactured for more than 40 years. Both the methyl methacrylate monomer used (also made by ICI) and the CQ polymer itself have full FDA approval in America. The level of ethyl acrylate present in the monomer used to make CQ grade is less than 10 parts per million. The latest gas chromatography equipment (supplied by Hewlett Packard) is used to monitor the level of this and other impurities, which may be present at similar levels. Since no ethyl acrylate is added during the manufacture ofPerspex CQ grade, it follows that the maximum level of this material present in the final polymer is less than 10 parts per million. I hope these comments will reassure the various manufacturers of IOLs using CQ Perspex.
Fig. 2.
(Thornton) Forceps' hinge at base of the jaws.
G.R. Cheal
Darwen, England
474
AM INTRA-OCULAR IMPLANT SOC J-VOL 10, FALL 1984