Zeffren B S, Applegate R A, Bradley A, van Heuven W A
Department of Ophthalmology, University of Texas Health Science Center, San Antonio 78284-7779.
Invest Ophthalmol Vis Sci. 1990 Oct;31(10):2099-105.
The site of normal fixation is often assumed to be centered in the foveal avascular zone (FAZ). This assumed anatomic relationship is used during photocoagulation therapy as an objective guide to avoid damaging critical retinal structures on or near fixation. With laser therapy being directed closer and closer to the center of the FAZ, the accuracy with which the center of the FAZ locates the retinal point of fixation becomes an important therapeutic issue. Using an optimized technique for visualizing the retinal vasculature entoptically, the authors determined the location of the retinal point of fixation with respect to the foveal area vasculature in 26 eyes of 14 healthy subjects. In 23 eyes (12 subjects), a traditional FAZ was observed, the other three eyes (two subjects) had capillaries near or crossing the center of fixation. Of the 23 eyes with a traditional FAZ, 20 had centers of fixation located eccentric to the center but in the FAZ, (average deviation from the center of the FAZ, 66.5 +/- 49.5 microns) with the direction of deviation from the FAZ center appearing random. Consequently, when following protocols that advocate photocoagulation treatment with spot centers closer to the FAZ center than 300 microns, the center of the FAZ is a poor locator of a subject's retinal point of fixation. When using the FAZ as a reference, the resulting uncertainty in the location of the subject's retinal point of fixation increases the probability of significant damage to the actual point of fixation by up to 20%.
正常注视点的位置通常被认为是以黄斑无血管区（FAZ）为中心。在光凝治疗过程中，这种假定的解剖关系被用作客观指导，以避免损伤注视点上或其附近的关键视网膜结构。随着激光治疗越来越靠近FAZ中心，FAZ中心定位视网膜注视点的准确性成为一个重要的治疗问题。作者采用一种优化的内视法来观察视网膜血管系统，确定了14名健康受试者26只眼中视网膜注视点相对于黄斑区血管系统的位置。在23只眼（12名受试者）中观察到传统的FAZ，另外三只眼（两名受试者）在注视点中心附近或有毛细血管穿过。在有传统FAZ的23只眼中，20只眼的注视点中心位于FAZ中心的偏心位置，但仍在FAZ内（与FAZ中心的平均偏差为66.5±49.5微米），且偏离FAZ中心的方向似乎是随机的。因此，当遵循将光斑中心比FAZ中心更靠近300微米的光凝治疗方案时，FAZ中心作为受试者视网膜注视点的定位效果不佳。当以FAZ为参考时，受试者视网膜注视点位置的不确定性会使实际注视点受到严重损伤的概率增加高达20%。
