Predilection of the Macular Region to High Incidence of Choroidal NeovascularizationAfter Intense Laser Photocoagulation in the Monkey

Abstract

To determine the key factors for creating a high incidence model of choroidal neovascularization (CNV) in the monkey. Methods: Intense laser photocoagulation was performed in 8 eyes of 4 monkeys using krypton red and green-yellow and Alcon frequency-doubled diode ophthalmic lasers. Eight to 13 lesions were delivered to an area between the temporal vascular arcades in each eye. Development of CNV was monitored by fluorescein angiography at 2 and 4 weeks after laser treatment, and the results were correlated with histological analysis. Results: A much higher incidence of CNV occurred in the macular region, which refers to an anatomic area equivalent to a mean ± SD 2.5 ± 0.4 times the horizontal diameter of the optic disc in the fundus. Regardless of the type of ophthalmic laser used, 72% of lesions developed fluorescein leakage within the macula, compared with 12% outside the macula (PϽ.001). By histological analysis, 89% of lesions developed microscopic CNV within the macula vs 22% outside the macula (PϽ.001). Conclusion: The macular region is predisposed to creation of laser-induced CNV in the monkey. Clinical Relevance: The predilection of the macular region to a high incidence of laser-induced CNV may account for the high recurrence rate of subfoveal CNV after laser treatment in humans.

Reduction of Laser-Induced Choroidal Neovascularization by Intravitreal Vasohibin-1 in Monkey Eyes

“…Fluorescein leakage from the laser spots close to the macula was greater than that of the other laser spots. These results are compatible with the results of Shen et al, 28 who also found that the laser spot was larger and the leakage was greater for lesions closer to the macula. We also found that fluorescein leakage was different among monkeys, even though we applied the same amount of vasohibin-1.…”

Reduction of Laser-Induced Choroidal Neovascularization by Intravitreal Vasohibin-1 in Monkey Eyes

“…Fluorescein leakage from the laser spots close to the macula was greater than that of the other laser spots. These results are compatible with the results of Shen et al, 28 who also found that the laser spot was larger and the leakage was greater for lesions closer to the macula. We also found that fluorescein leakage was different among monkeys, even though we applied the same amount of vasohibin-1.…”

Assessment of laser induction of Bruch's membrane disruption in monkey by spectral-domain optical coherence tomography

“…In fact, in the macular area CNV could only be induced at lesions with detectable disruption in the BM by OCT. Other lesions in the same area, where no BM disruption was detected by OCT, did not show any leakage of fluorescein although bubbles were also observed. In addition, Shen et al also showed that the haemorrhage at the time of photocoagulation was not necessary for CNV induction 12. Our results agreed with that as none of the leaking lesions were found with visible haemorrhage.…”

“…It was also suggested that the observed haemorrhage probably originated from the choroidal capillaries, which was indicative but not indispensible for the disruption of BM. Besides, the laser powers required for BM disruption seemed to be lower than those previously reported which were typically around 500 to 1000 mW 6 7 12. However, the findings were quite different in the posterior fundus, where we found that although equal or higher powers were used and bubbles could be produced at most lesions (33/36) except three created with the lowest power of 100 mW, the damages varied considerably with only around 45% of the lesions detected with BM disruption.…”

Early subfoveal choroidal neovascularization secondary to an accidental stage laser injury

“…The wavelength of the stage laser light in this case was 532 nm and the power was more than 20 mW. A study in monkeys showed that CNV lesions within the macular region mainly developed classic CNV, while the lesions outside it predominantly formed occult CNV [9]. Similarly, classic CNV developed in the subfovea of our patient.…”

Reduction of Laser-Induced Choroidal Neovascularization by Intravitreal Vasohibin-1 in Monkey Eyes

“…Fluorescein leakage from the laser spots close to the macula was greater than that of the other laser spots. These results are compatible with the results of Shen et al, 28 who also found that the laser spot was larger and the leakage was greater for lesions closer to the macula. We also found that fluorescein leakage was different among monkeys, even though we applied the same amount of vasohibin-1.…”

Assessment of laser induction of Bruch's membrane disruption in monkey by spectral-domain optical coherence tomography

“…In fact, in the macular area CNV could only be induced at lesions with detectable disruption in the BM by OCT. Other lesions in the same area, where no BM disruption was detected by OCT, did not show any leakage of fluorescein although bubbles were also observed. In addition, Shen et al also showed that the haemorrhage at the time of photocoagulation was not necessary for CNV induction 12. Our results agreed with that as none of the leaking lesions were found with visible haemorrhage.…”

“…It was also suggested that the observed haemorrhage probably originated from the choroidal capillaries, which was indicative but not indispensible for the disruption of BM. Besides, the laser powers required for BM disruption seemed to be lower than those previously reported which were typically around 500 to 1000 mW 6 7 12. However, the findings were quite different in the posterior fundus, where we found that although equal or higher powers were used and bubbles could be produced at most lesions (33/36) except three created with the lowest power of 100 mW, the damages varied considerably with only around 45% of the lesions detected with BM disruption.…”

Early subfoveal choroidal neovascularization secondary to an accidental stage laser injury

“…The wavelength of the stage laser light in this case was 532 nm and the power was more than 20 mW. A study in monkeys showed that CNV lesions within the macular region mainly developed classic CNV, while the lesions outside it predominantly formed occult CNV [9]. Similarly, classic CNV developed in the subfovea of our patient.…”

Reduction of Laser-Induced Choroidal Neovascularization by Intravitreal Vasohibin-1 in Monkey Eyes

“…Fluorescein leakage from the laser spots close to the macula was greater than that of the other laser spots. These results are compatible with the results of Shen et al, 28 who also found that the laser spot was larger and the leakage was greater for lesions closer to the macula. We also found that fluorescein leakage was different among monkeys, even though we applied the same amount of vasohibin-1.…”

Assessment of laser induction of Bruch's membrane disruption in monkey by spectral-domain optical coherence tomography

“…In fact, in the macular area CNV could only be induced at lesions with detectable disruption in the BM by OCT. Other lesions in the same area, where no BM disruption was detected by OCT, did not show any leakage of fluorescein although bubbles were also observed. In addition, Shen et al also showed that the haemorrhage at the time of photocoagulation was not necessary for CNV induction 12. Our results agreed with that as none of the leaking lesions were found with visible haemorrhage.…”

“…It was also suggested that the observed haemorrhage probably originated from the choroidal capillaries, which was indicative but not indispensible for the disruption of BM. Besides, the laser powers required for BM disruption seemed to be lower than those previously reported which were typically around 500 to 1000 mW 6 7 12. However, the findings were quite different in the posterior fundus, where we found that although equal or higher powers were used and bubbles could be produced at most lesions (33/36) except three created with the lowest power of 100 mW, the damages varied considerably with only around 45% of the lesions detected with BM disruption.…”

Early subfoveal choroidal neovascularization secondary to an accidental stage laser injury

“…The wavelength of the stage laser light in this case was 532 nm and the power was more than 20 mW. A study in monkeys showed that CNV lesions within the macular region mainly developed classic CNV, while the lesions outside it predominantly formed occult CNV [9]. Similarly, classic CNV developed in the subfovea of our patient.…”