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Register a new userStudy of The Ultra Structure Changes of Pigment Epithelium and Photoreceptors of Eye Retina of Lacerta Laevis after Exposure To He-Ne Laser
دراسة التبدلات البنيوية الدقيقة للطبقة الظهارية الصباغية و المستقبلات الضوئية على شبكية عين العظاء laevis lacerta إثر تسليط الحزمة الليزرية (هليوم-نيون)
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بشير الزالق( باحث )
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تؤكد نتائجنا وجود ارتباط وظيفي فعال بين الطبقة الظهارية الصباغية (.E.P) و طبقـة المـستقبلات الضوئية (و هي من نمط مخروط في شبكية عين العظاء). تسبب الحزمة الليزرية (هليوم-نيون) المستمرة و المسلطة على العين تبدلات بنيوية خطرة (وفق معطيات المجهر الإلكتروني النافذ) تمثلت بتخريب واضح شمل أجزاء و عضيات الخلايا الظهارية الصباغية، و كذلك خلايا الاستقبال الضوئي من الـشبكية، و كانـت أولى النتائج الخطرة على حس الرؤية هو انفصال الطبقة الظهارية عن طبقة المستقبلات الضوئية (أي ما يسمى بانفصال الشبكية). و نتج عن هذا الانفصال فقدان حماية المستقبلات الضوئية من الشدات الضوئية العالية (التي كانت توفرها حبيبات الميلانين المنتشرة في الاستطالات الخلايا الظهارية و المحيطة بـالقطع الخارجية للمستقبلات). أصبحت القطع الخارجية للمستقبلات إذاً عرضة لشدات ضوئية عالية من أشـعة الليزر الأمر الذي ألحق بالغ الأثر من تخريب في بنية الأغشية البلاسـمية لأقـراص القطـع الخارجيـة و تخريب البنية الكيميائية لأصبغة الرؤية (الأصبغة المميزة للألوان في المخاريط) و يتوقـع نتيجـة لـذلك فقدان أقطاب الإحساس الضوئي وظيفتها في نقل الشارة الضوئية لإطلاق وظيفة الرؤية. ترافقت أذيـات أشعة الليزر في المخاريط بتبدلات خطرة أخرى تناولت التراجع الواضح في حجم النواة و تخريـب مـادة الكروماتين و تلاشي عضيات التركيب الحيوي للبروتينات الخلوية و تفكيك جزيئات الغليكـوجين (جزيئـات الطاقة)، و لكن الشيء الأشد خطورة في ذلك هو ماحدث من تخريب في بنية السويقات المشبكية للمخاريط (فقدان التشابك مع الخلايا العصبية ثنائية القطب، و الخيوط المشبكية ) و يتوقع بذلك فقدان قطـب النقـل العصبي وظيفته في النقل العصبي عبر طبقات المشابك العصبية للشبكية.
Our results assured the presence of functional association between the pigment epithelium (P.E) and photoreceptors of eye retina of lacerta laevis. The continuous effect of He-Ne laser on eye produce dangerous structure changes (according to studies by transmission electron microscope) led to damage of parts and organelles of pigment epithelium and photoreceptors of eye retina. The displacement of the epithelium from the photoreceptors layer was the first dangerous results on vision (Retinal detachment). This detachment conduced to no protection of photoreceptors from high intense light (which usually maintained by melanin pigments spread in epithelium cells surrounding the outer segments [O.S] of photoreceptors) so that the outer segments of photoreceptor became under the influence of intense light of He-Ne laser which conduced to damage of cytoplasmic membrane of outer segment disks and damage of chemical structure of visual pigments (pigment necessary for discrimination of color in cones) so the photo sensible pole lost its function in transferring the sign of light necessary for vision. The lesion happened by the influence of He-Ne laser in the cones, associated by dangerous changes in the retardation of nucleus size and damage of chromatin material and the absence of organelles responsible for biological synthesis of cellular protein, and deconstruction of glycogen molecules (energy mols.). The most dangerous thing is the resulted damage of synaptic pedicle of cones (lost of connection between bipolar nerve cells and synaptic ribbons) so the neurotransmission pole lost its function in neurotransmission across the layer of neurosynapsis of retina. The damaged photoreceptor cells (cones) (which were almost dead) became disables to do their function in vision.
References used
Roider, J., Brinkmann, R., Wirberlauer, C., Laqua, H., Birngruber, R. (2006). Subthreshold (retinal pigment epithelium) photocoagultion in macular diseaes : a Pilot study. Br J.Ophthalmol;84:40-47
Abraham, M. (2001). Laser safety considerations waac, Newsletter .Jan.vol.23 N .1
Tasman, W. (1999). Student suffers permanent eye damage from laser pointer: only second of exposure can cause retinal damage .School News, Top news mon,Feb. 01.1999
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