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K. Mireskandari, A.L. Mead, S.J. Tuft, I.K. Anderson, P.T. Khaw; A model of cataract surgery, digital imaging and software analysis to investigate posterior capsular opacification in the rabbit . Invest. Ophthalmol. Vis. Sci. 2004;45(13):357.
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Purpose:Posterior Capsular Opacification (PCO) is the commonest complication ofcataract surgery affecting 10–50% of patients over five years. Animal models of PCO investigation rely on clinical or histological grading which are subjective and far removed from the sophisticated methods used in clinical human investigations. This makes it difficult for animal studies to quickly bridge the gap to clinical applicability. Our aim is to demonstrate a system of high quality in–vivo imaging and quantification of PCO in an experimental model of cataract surgery in the rabbit. Methods:Small incision phacoemulsification cataract surgery with intra–ocular lens implantation closely resembling the technique used in humans was performed in New Zealand White rabbits. Surgery was performed under general anaesthesia. Digital co–axial retro–illumination images of the capsule were captured using the NikonCoolpix 995 digital camera attached to the Leica M841EBS operating microscope. High resolution digital images in raw format were obtained in eight rabbits. Imaging at weekly intervals was performed on anaesthetised rabbits to document the development of PCO. The images were analysed using the POCOMAN software (DJ Spalton, St. Thomas’s Hospital, London) to quantify both the percentage area and severity (0–3 scale, 0=no PCO, 3=maximal Severity) of PCO. Results:We demonstrate an initial proliferation of lens epithelial cells (LEC) in the first two weeks after surgery followed by near complete regression over the ensuing two weeks. After five weeks a new wave of LEC growth from the periphery begins to cover the posterior capsule completely by eight to ten weeks. Mean percentage area and severity of PCO were 23% and 0.48 respectively at two weeks, reducing to 12% and 0.29 at four weeks before rising to 99% and 2.93 by ten weeks. Also a large Sommering’s cataract had formed in the periphery of the capsular bag. High resolution imaging has allowed us to record the development of PCO in great detail including the fate of individual LECs as they regress in the initial period. Conclusions:Adapting the co–axial retro–illumination imaging to the rabbit model of cataract surgery has effectively provided us with high resolution images to visualisecellular fate. Furthermore, when assessing various treatment modalities to prevent PCO in an animal model , this technique allows imaging and analyses in a manner similar to that utilised in human clinical studies.
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