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Differences in keratocyte apoptosis following transepithelial and laser-scrape photorefractive keratectomy in rabbits
1Eye Institute, Cleveland Clinic Foundation, OH, USA.
Background:
Anterior stromal keratocyte cells undergo programmed cell death (apoptosis) in response to corneal epithelial injury. Keratocyte apoptosis may be an initiator of the corneal wound healing response that includes keratocyte proliferation and activation, as well as changes to the overlying epithelium, occurring following refractive surgical procedures such as photorefractive keratectomy (PRK). This study compared the effect of laser-scrape and transepithelial PRK on keratocyte apoptosis.
Methods:
Photorefractive keratectomy was performed in both eyes of 10 New Zealand white rabbits using the Summit Apex excimer laser. Surgery was performed using transepithelial PRK in one eye and laser-scrape PRK in the other. The central cornea was analyzed at 4 hours after surgery using a quantitative TUNEL assay that detects fragmented DNA characteristic of apoptosis. Hepatocyte growth factor (HGF) production by keratocytes was detected by immunocytochemistry.
Results:
Average apoptotic cells per 400X microscopic field determined by 2 independent masked observers were 0.9 +/- 0.5 (scanning electron microscopy) and 0.2 +/- 0.2 in the transepithelial PRK group compared with 5.1 +/- 2.9 and 4.1 +/- 3.2 in the laser-scrape group. The difference between the two groups was statistically significant for both observers (P < .05, ANOVA). HGF was detected within keratocytes throughout the corneal stroma. Less HGF was detected in the anterior stroma in the laser-scrape group at 4 hours after surgery, consistent with more anterior keratocyte apoptosis in this group.
Conclusions:
Transepithelial PRK induced less anterior keratocyte apoptosis in rabbits than laser-scrape PRK. This suggests that transepithelial PRK could be useful in preventing or minimizing refractive regression and subepithelial scarring.
Insights
Transepithelial photorefractive keratectomy (PRK) causes less corneal cell death than laser-scrape PRK. This finding suggests transepithelial PRK may reduce scarring and refractive errors after eye surgery.
Area of Science:
- Ophthalmology
- Corneal Surgery
- Cell Biology
Background:
- Anterior stromal keratocytes undergo apoptosis after corneal injury, initiating wound healing.
- This process is relevant to refractive surgery outcomes like photorefractive keratectomy (PRK).
- Comparing PRK methods is crucial for understanding their impact on corneal healing.
Purpose of the Study:
- To compare the effects of laser-scrape PRK and transepithelial PRK on keratocyte apoptosis.
- To investigate the role of hepatocyte growth factor (HGF) in the context of different PRK methods.
Main Methods:
- Excimer laser PRK (transepithelial vs. laser-scrape) was performed on rabbit eyes.
- Corneal apoptosis was quantified using TUNEL assay at 4 hours post-surgery.
- HGF production in keratocytes was assessed via immunocytochemistry.
Main Results:
- Transepithelial PRK resulted in significantly lower anterior keratocyte apoptosis compared to laser-scrape PRK.
- HGF was detected in corneal stromal keratocytes.
- Reduced HGF in the anterior stroma correlated with increased apoptosis in the laser-scrape group.
Conclusions:
- Transepithelial PRK induces less anterior keratocyte apoptosis than laser-scrape PRK in rabbits.
- This suggests transepithelial PRK may minimize refractive regression and subepithelial scarring.
- The findings support transepithelial PRK as a potentially beneficial approach in refractive surgery.