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Purpose: To study the alterations on the lenticules extracted after femtosecond (Femto) small incision lenticule extraction (SMILE) versus the corneal free cap removed using a microkeratome. Methods: The visuMax (500 kHz; laser energy: 180 nJ) was used for small-incision lenticule extraction. Free caps from human cadaveric corneas were excised by microkeratome. The collected lenticules were examined with the light and transmission electron microscope (TEM) for histological analysis, DNA fragmentation was assessed by agarose gel electrophoresis, DNA damage was evaluated using comet assay, and corneal proteins secondary structure was assessed by Fourier transform infrared spectroscopy (FTIR). Results: Light microscopic examination showed the presence of more edematous stroma under Femto SMILE than under free cap with a percentage change of 101.6%. In the Femto SMILE group, TEM examination showed pyknotic keratocytes, disruption, and cavitation of the collagen arrays stromal area under Femto SMILE. The DNA fragmentation for the Femto SMILE group revealed one undefined band with a size of 1.1 Kbp. The comet assay analysis indicated the presence of 3% and 8.0% tailed cells for the free cap and Femto SMILE groups, respectively. The tail lengths were 1.33 ± 0.16 and 1.67 ± 0.13 µm (P < 0.01), the percentage of tail DNA was 1.41 ± 0.18% (P < 0.01) and 1.72 ± 0.15%, and the tail moments were 1.88 ± 0.12 AU and 2.87 ± 0.14 AU (P < 0.001) for the free cap and Femto SMILE groups, respectively. FTIR spectroscopy of the Femto smile group revealed disorders in the secondary and tertiary structure of the proteins. Conclusion: Femto SMILE technique induced more structural changes, DNA fragmentation, DNA damage, and corneal proteins secondary structure alteration than those induced by a microkeratome cutting. These changes may be attributed to the deep penetration of high energy levels to the corneal layer. These findings may highlight the potential impact of the Femto SMILE on the cornea and the necessity for managing the laser parameters used.
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INTRODUCTION: Recurrent corneal erosion occurs when the wounded corneal epithelium failed to adhere to the underlying stroma. Therefore, this work aimed to assess the effect of treatment of corneal injury using Q- switched Nd:YAG laser. METHOD: Twenty one New Zealand male rabbits weighing 2-2.5 kg and 3 months old were classified into three main groups. The control group: did not received any treatment (n=3 rabbits). The rest of the animals (n= 18 rabbits), corneal epithelium was injured by syringe needle and blade 15 and divided into:(A) Normal healing group: which was divided into three subgroups (n=3 rabbits each), and the animals were left for normal healing for1 day, 1 week, and 4 weeks respectively, (B) Laser treated group: divided into three subgroups (n=3 rabbit seach) and subjected to anterior stromal puncture using Q-switched Nd: YAG laser on corneal sub-epithelium or superficial stroma, and the animals were left for 1 day, 1 week, and 4 weeksrespectively. After the demonstrated periods, the corneas were isolated for estimation of total protein content, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), total antioxidative capacity (TAC), total oxidative capacity (TOC) and oxidative stress index (OSI). RESULTS: The present results of corneal total protein showed increment in the percentage change in normal healed groups after 1 day, 1 week and 4 weeks by values of 93%, 68% and 39%. In Q-switched Nd: YAG laser treated group the results showed better improvement in corneal protein than normal healed group with percentage changes of 58%, 29%, and 7.5% respectively. In SDS- PAGE, a protein band at 110 KD appeared in the migrating epithelium for both normal healed group and Q-switched Nd:YAG laser treated group with changes in the peaks intensities at middle and low molecular weight regions. Moreover, after 4 weeks the peak at 110 KD disappeared in the wounded epithelium treated with Q-switched Nd:YAG. After four weeks, the OSI in laser treated corneas showed pronounced balance between antioxidative capacityand oxidative capacity. CONCLUSION: Anterior stromal puncture by Q-switched Nd:YAG laser is an effective, simple, safe and promising procedure to treat recurrent corneal erosion than normal healing.
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INTRODUCTION: 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). METHODS: 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 approximately1mm 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/cm2. 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. RESULTS: 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. CONCLUSION: PDT with Verteporfin can provide efficacious treatment of corneal neovascularization.
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INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
