Tập trung hình 11 fluorescein tại trang web bông thủy tinh tiếp giáp với võng mạc sau một liều tiêm mL 15 hoặc 100 lân cận võng mạc trên trục đối xứng của thủy tinh thể. Khối lượng fluorescein tiêm trong mỗi trường hợp là giống nhau, dẫn đến nồng độ đỉnh cao hơn liền kề với võng mạc sau 15 trường hợp tiêm mL và, do đó, một cao hơn ban đầu mất fluorescein trên võng mạc. | Drug Distribution in Vitreous Humor 203 Figure 11 Concentration of fluorescein at the vitreous site adjacent to the retina following a 15 or 100 mL injection adjacent the retina on symmetry axis of vitreous. The mass of fluorescein injected in each case was identical resulting in higher peak concentrations adjacent to the retina following the 15 mL injection case and therefore a higher initial loss of fluorescein across the retina. mainly across the hyaloid membrane the 15 mL injections placed closer to the hyaloid membrane hyaloid-displaced and lens-displaced resulted in lower mean concentrations at 24 hours than the 100 mL injections at the same locations due to a higher initial rate of elimination across the hyaloid membrane. Figure 12 shows the concentration adjacent to the hyaloid membrane for the 15 and 100 mL hyaloid-displaced injections of fluorescein glucuronide. Similar to fluorescein when the injection of fluorescein glucuronide was not placed next to its elimination surface central and retina-displaced higher elimination is produced by the 100 mL injection. 3. Clinical Implications of Changes in Injection Conditions From a clinical perspective the results of changes in injection conditions are very significant. Retinal damage from excessive drug concentrations is observed periodically following an intravitreal injection. The results of this Copyright 2003 Marcel Dekker Inc. Drug Distribution in Vitreous Humor 205 the injection positions that were examined in this study are extremes within the anatomy of the eye a variation of only 5-8 mm from a central injection will produce these extremes. Slight changes in the injection conditions can easily produce these variations. Knowledge of concentration variations that are present at different sites within the vitreous will facilitate the optimization of administration techniques for diseases that affect the posterior segment of the eye. C. Effects of Aphakia and Changes in Retinal Permeability and Vitreous .
