Pizzirani S, Davidson M G, Gilger B C
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA.
Vet Ophthalmol. 2003 Sep;6(3):227-35. doi: 10.1046/j.1463-5224.2003.00299.x.
To evaluate the ophthalmoscopic, fluorescein angiographic and light microscopic effects of diode laser retinopexy application in the tapetal and nontapetal fundus in the dog, and to ascertain appropriate laser power settings for production of photocoagulative lesions in these two regions.
Three adult female Beagle dogs.
Laser burns were applied to selected areas in the fundus with an indirect headset delivery system using settings varying from 100 to 200 milliWatts (mW) and from 100 to 600 milliSeconds (mS) with total delivered energy ranging between 15 and 100 milliJoules (mJ). The dogs were then monitored by ophthalmoscopic examination and fluorescein angiography at regular intervals for 7-28 days. Histopathologic studies were performed at 7, 14 and 28 days after laser application.
The diode laser produced ophthalmoscopically visible lesions in the nontapetal fundus with all laser settings used, and the appearance of these lesions corresponded to the energy levels used, and degree of pigment in the lased region. Gray-white colored lesions with minimal subsensory retinal edema were seen with settings as low as 100 mWatts/150 mSeconds. In the tapetal fundus, laser burns were more difficult to produce, less repeatable, and required higher energy levels. Laser burns appeared as bronze, dark green or black discolorations of the tapetum with varying degrees of subsensory retinal edema. Lesions were more reproducible and were achieved with lower settings in the tapetal area of the tapetal/nontapetal junction. Ophthalmoscopically, depigmentation and repigmentation of the RPE (nontapetal fundus) and degenerative changes in the overlying retina (tapetal fundus) developed in the laser burns over the 28-day study period. Fluorescein angiographic studies showed disruption of the blood-retinal barrier at the level of the RPE and fluorescein leakage into the subsensory retinal space was seen in most lesions at 24 h, was minimal at 3 days, and had resolved by 7 days. Histologically, grayish-white lesions in the nontapetal fundus, and bronze to small black lesions in the tapetal fundus were typically characterized by outer retinal necrosis and RPE migration. Gliosis was considered minimal, was confined to the retina, and no inflammatory cells were seen. Peripheral intense white lesions (nontapetum) and lesions with a black center (tapetal fundus) were characterized by more extensive panretinal and choroidal necrosis. Most of the nontapetal lesions and a few in the tapetal fundus showed the formation of a central retinal detachment.
The diode laser effectively produces lesions suitable for retinopexy in both the nontapetal, pigmented fundus and the tapetal fundus, although variably so in the latter region. Initial laser settings of 100-150 mW/200 mS for the pigmented fundus, and 150 mW/200-300 mS for the peripheral tapetal fundus are recommended, and the clinician should gradually increase time interval settings to achieve a grayish-white lesion in the nontapetum, and a bronze to slightly black lesion in the tapetal fundus. If possible, retinopexy should be applied to the peripheral tapetal area or tapetal/nontapetal junction.
评估二极管激光视网膜光凝术应用于犬的绒毡层和非绒毡层眼底的检眼镜、荧光素血管造影及光学显微镜下的效果，并确定在这两个区域产生光凝性病变的合适激光功率设置。
三只成年雌性比格犬。
使用间接头戴式传输系统，对眼底选定区域进行激光烧灼，设置范围为100至200毫瓦（mW）、100至600毫秒（mS），总传输能量在15至100毫焦（mJ）之间。然后定期通过检眼镜检查和荧光素血管造影对犬进行7至28天的监测。在激光照射后7天、14天和28天进行组织病理学研究。
使用所有激光设置时，二极管激光在非绒毡层眼底产生了检眼镜可见的病变，这些病变的外观与所用能量水平及激光照射区域的色素程度相对应。低至100毫瓦/150毫秒的设置可产生灰白色病变，视网膜下感觉层水肿轻微。在绒毡层眼底，激光烧灼更难产生，重复性较差，且需要更高的能量水平。激光烧灼表现为绒毡层的青铜色、深绿色或黑色变色，伴有不同程度的视网膜下感觉层水肿。在绒毡层/非绒毡层交界处的绒毡层区域，病变更具可重复性，且在较低设置下即可实现。在28天的研究期间，检眼镜检查显示激光烧灼处视网膜色素上皮（非绒毡层眼底）出现色素脱失和再色素沉着，以及上方视网膜（绒毡层眼底）发生退行性改变。荧光素血管造影研究显示，在视网膜色素上皮水平血视网膜屏障被破坏，24小时时大多数病变可见荧光素渗漏至视网膜下感觉层间隙，3天时渗漏最少，7天时渗漏消失。组织学上，非绒毡层眼底的灰白色病变以及绒毡层眼底的青铜色至小黑褐色病变的典型特征为外层视网膜坏死和视网膜色素上皮迁移。胶质增生被认为轻微，局限于视网膜，未见炎性细胞。周边强烈的白色病变（非绒毡层）和中心为黑色的病变（绒毡层眼底）的特征为更广泛的全视网膜和脉络膜坏死。大多数非绒毡层病变以及绒毡层眼底的少数病变显示形成中心性视网膜脱离。
二极管激光可有效在非绒毡层、色素性眼底和绒毡层眼底产生适合视网膜光凝的病变，尽管在后者区域效果有所不同。对于色素性眼底，建议初始激光设置为100 - 150毫瓦/200毫秒，对于周边绒毡层眼底为150毫瓦/200 - 300毫秒，临床医生应逐渐增加时间间隔设置，以在非绒毡层产生灰白色病变，在绒毡层眼底产生青铜色至微黑色病变。如有可能，视网膜光凝应应用于周边绒毡层区域或绒毡层/非绒毡层交界处。
