Characterization of abnormal epithelium after laser-assisted subepithelial keratectomy using in vivo confocal microscopy.

This study compared the abnormal corneal epithelium after laser-assisted subepithelial keratectomy (LASEK) with dystrophic cornea using in vivo using confocal microscopy (IVCM) and examined the effects of the abnormal epithelium on postoperative recovery of uncorrected distance visual acuity (UDVA) and sub-basal nerve plexus regeneration. The UDVA and wound healing were examined in 50 eyes of 25 patients undergoing LASEK at 1 week, 1 month, and 1 year postoperatively, including the visual acuity, slit lamp microscopy, and IVCM. After 1 week, the corneal epithelium was healed in all patients, but abnormal epithelial cells were detected in 33/50 patients using IVCM. Abnormal cells were limited to the surgical margin, and highly reflective granules were observed underneath. At 1 month and 1 year postoperatively, the abnormal epithelium was unchanged in size. At 1 year postoperatively, there were clear differences between the sub-basal nerve plexus in the normal and abnormal epithelium. At 1 month postoperatively, the UDVA was >1.0 in 88% of patients, which increased to 94% at 1 year, and there was no clear difference in the UDVA between abnormal (N = 33) and normal (N = 17) epithelium. After LASEK, abnormal epithelial cells may arise at the margin of the epithelial flap and persist 1 year postoperatively accompanied by poor regeneration of the sub-basal nerve plexus. However, this does not affect the UDVA postoperatively. The abnormal epithelium may be caused by residual necrotic basal cell debris on the epithelial basement membrane and abnormal neurotrophic metabolism between the corneal epithelium and nerve plexus.

Survey and analysis of visual acuity of Kazakhs in different lighting environments.

The effect of different lighting environments on the vision and refractive error were investigated in 427 Kazakhs (828 eyes) aged from 40 to 60 years old, of which 279 were pastoral (546 eyes) and 148 were urban (282 eyes). Pastoral Kazakhs use natural illumination, whereas city Kazakhs mainly use artificial illumination. Of all cases, 19.1% (54 cases) had a vision of 0.4 to 0.5, 20.9% (59 cases) had 0.6 to 0.8, and 17.7% (50 cases) had above 1.0. However, the visual acuity distribution of the pastoral Kazakhs had a more obvious characteristic, which was mainly concentrated above 0.6. The vision of 25.1% (137) of cases was 0.6 to 0.8, whereas 58.4% (319) of cases had vision above 1.0. There were more cases with vision above 1.0 in the pastoral Kazakhs compared to the city Kazakhs (P < 0.05). The diopter of the city Kazakhs was between 0 D and -4.0 D, whereas that of the pastoral Kazakhs was between +2.0 D and -2.0 D. Diopters between +2.0 D and 0 D or less than 3.0 D differed significantly between the two groups. Daylight lamps were the main illumination photosources of the city Kazakhs. Artificial light illuminated 70.9% (105 cases) of the city Kazakhs for more than 6 h. By contrast, natural light illuminated 75.3% (210 cases) of the pastoral Kazakhs for an outdoor activity time of more than 9 h. These results suggest that poor lighting environment is a very important factor contributing to refractive error.