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Treatment parameters for selective occlusion of experimental corneal neovascularization by photodynamic therapy using
1Department of Ophthalmology, Osaka City University Medical School, Abenoku, Osaka, Japan.
Abstract:
Time dependent change of an accumulation of an amphiphilic photosensitizer, ATX-S10(Na) on rabbit corneal neovascularization (CoNV) was evaluated by angiography using ATX-S10(Na) as a fluorescent dye on three rabbits. The angiography showed that the dye accumulated on CoNV 3-5 hr after dye injection when the dye in the iris was minimum. The results suggested 3-5 hr after might be the optimal time to start photodynamic therapy (PDT) to occlude CoNV selectively without damage to the surrounding normal tissue such as the iris. Then the optimal treatment parameters in PDT using ATX-S10(Na) for selective occlusion of the CoNV were investigated on rabbit eyes. PDT was performed with two different time intervals between dye injection and laser irradiation of a diode laser (670 nm), different laser doses and three different dye doses on 21 animals. PDT performed immediately after dye injection selectively occluded CoNV with laser irradiations from 30.6 to 38.2 J cm(-2)and a 2 mg kg(-1)dose of ATX-S10(Na), as well as with 15.3 J cm(-2)and a 6 mg kg(-1)dose. PDT performed 4 hr after dye injection with 107.0-152.8 J cm(-2)and a 6 mg kg(-1)dose, as well as with 38.2-53.5 J cm(-2)and a 12 mg kg(-1)dose was also effective. Although PDT performed either immediately or 4 hr after ATX-S10(Na) injection selectively occluded CoNV, the width of the optimal range of radiant exposures seemed wider in PDT performed 4 hr after dye injection. It is supposed that this result is associated with the difference of dye accumulation between in CoNV and in normal tissue as shown by the present angiographical findings.
Insights
Photodynamic therapy (PDT) using ATX-S10(Na) is effective for corneal neovascularization (CoNV). Optimal timing for PDT is 4 hours post-injection, offering a wider treatment window for selective CoNV occlusion with minimal iris damage.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Photochemistry
Background:
- Corneal neovascularization (CoNV) poses a risk to vision.
- Photodynamic therapy (PDT) offers a potential treatment for CoNV.
- ATX-S10(Na) is an amphiphilic photosensitizer investigated for PDT.
Purpose of the Study:
- To evaluate the time-dependent accumulation of ATX-S10(Na) on rabbit CoNV.
- To determine optimal PDT parameters for selective CoNV occlusion.
- To assess the safety of PDT concerning surrounding ocular tissues.
Main Methods:
- Angiography was used to track ATX-S10(Na) accumulation in rabbit CoNV.
- PDT was performed at different time intervals (immediately and 4 hours post-injection) after ATX-S10(Na) administration.
- Varied laser doses, dye doses, and irradiation parameters were tested on rabbit eyes.
Main Results:
- ATX-S10(Na) showed maximum accumulation on CoNV 3-5 hours post-injection, coinciding with minimum iris accumulation.
- Both immediate and 4-hour post-injection PDT effectively occluded CoNV.
- PDT performed 4 hours post-injection demonstrated a wider optimal range of radiant exposures for selective CoNV occlusion.
Conclusions:
- A 3-5 hour interval post-ATX-S10(Na) injection may be optimal for initiating PDT.
- PDT parameters, including timing and laser/dye doses, are crucial for selective CoNV treatment.
- The timing of PDT influences the therapeutic window, suggesting strategic application for improved outcomes in CoNV treatment.