Histological evaluation of retina after photo disruption for vitreous humor by Q-switched neodymium-doped yttrium aluminium garnet [Nd: YAG] laser

Rabbits' eyes were exposed to vitreous humor liquefaction with Q - switched [sometimes called " giant pulses"] Neodymium-Doped Yttrium Aluminium Garnet [Nd: YAG] laser using two different energy protocols [5 mJ X 100 pulse and 10 mJ X 50 pulse] with and without vitamin C administration. The histological changes in the retina were investigated to evaluate the protective role of vitamin C. The rabbits were divided into four main groups [n= 12 each]. The first group was divided into three subgroups [n=4] and then treated with 5 mJ X 100 pulse [X means times] delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group. The third group was divided into three subgroups [n=4] and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed. The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina's tissues histology after laser. Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina's layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage.

Photothrombosis of corneal neovascularization by photodynamic therapy utilizing verteporfin and diode laser

The aim of the present study was to evaluate the effect of photodynamic therapy in the treatment of experimental corneal neovascularization [NV] with benzoporphyrin derivative [BPD]. One group was considered as control [n=6 eyes] then, corneal NV was induced in 30 New Zealand male rabbits [n=60 eyes] by placing 7.0 silk sutures at midstromal depth approximately 1mm from the limbus. Fifteen rabbits with corneal NV were left without any treatment, and 15 rabbits were subjected to photodynamic therapy [PDT] by intravenous injection with Verteporfin at a dose of 1.5 mg /Kg. Diode laser [660 nm] was applied after 15 minutes for 5 minutes with a power of 50 mW/cm[2]. All rabbits were successively followed up by slit lamp examination for periods of 1 day, 1, 2, 3 and 4 weeks. Three rabbits were selected and sacrificed weekly [n=6 eyes each] and the corneas were isolated for histopathological examination. The results of slit lamp examination indicated the gradual regression of the cornea neovascularization 4 weeks of PDT. Furthermore, regression of corneal neovascularization was documented clinically by decrease number and length of blood vessels and by histopathological examination. PDT with Verteporfin can provide efficacious treatment of corneal neovascularization