Nearwork-induced transient myopia and accommodation function before and after laser-assisted in situ keratomileusis surgery

Effects of virtual distant viewing technology on preventing nearwork-induced ocular parameter changes

Purpose

This study investigates whether virtual distant viewing technology can prevent nearwork-induced ocular parameter changes.

Methods

Twenty-six volunteers read a textbook on one day and the same content on a virtual distant viewing display on another day based on a randomization sequence, with both reading sessions at 33 cm for 4 hours. Visual acuity, diopter, ocular biology, visual fatigue, and accommodative function before and after the nearwork, as well as the number of pages read, were recorded.

Results

After 4 hours of nearwork in the textbook group, the spherical equivalent refraction decreased from -3.13 ± 2.65 D to -3.32 ± 2.70 D (P < 0.001), corneal thickness decreased from 531.6 ± 33.5 μm to 528.9 ± 33.0 μm (P = 0.015), anterior chamber depth decreased from 3.65 ± 0.35 mm to 3.60 ± 0.30 mm (P = 0.002), accommodative facility increased from 15.1 ± 3.5 to 16.4 ± 3.9 (P = 0.018), and subjective visual fatigue increased from 14.0 ± 9.2 to 19.3 ± 7.6 (P = 0.002); no significant changes were seen in the other parameters. In the virtual distant viewing group, the spherical equivalent refraction (from -3.17 ± 2.60 D to -3.11 ± 2.73 D, P = 0.427), corneal thickness (from 531.9 ± 32.8 μm to 529.7 ± 33.2 μm, P = 0.054), and anterior chamber depth (from 3.67 ± 0.35 mm to 3.69 ± 0.32 mm, P = 0.331) did not show significant changes, whereas accommodative facility increased from 14.7 ± 5.8 to 15.9 ± 5.5 (P = 0.042) and subjective visual fatigue increased from 13.5 ± 8.4 to 18.9 ± 8.6 (P = 0.002). In addition, choroidal thickness (from 217.7 ± 76.0 μm to 243.0 ± 85.0 μm, P = 0.043), positive relative accommodation (from -2.32 ± 1.07 D to -2.85 ± 0.89 D, P = 0.007), and amplitude of accommodation (from 7.26 ± 1.41 D to 7.89 ± 1.69 D, P = 0.022) also significantly increased in the virtual distant viewing group. The textbook group and the virtual distant viewing group read 176.0 ± 133.1 pages and 188.0 ± 102.0 pages, respectively, and there was no significant difference between the two groups (P = 0.708).

Conclusion

Virtual distant viewing technology can prevent the increase in myopia degree due to nearwork and improve accommodation function without increasing visual fatigue.

The changes and causes of asthenopia after ICL implantation

OBJECTIVE

To detect the presence of asthenopia after implantation of Implantable Collamer Lens (ICL).

METHOD

Design: prospective observational case series. Patients with myopia and/or astigmatism who underwent ICL surgeries and completed 3-month follow-up were enrolled. Asthenopia scores, amplitude of accommodation (AA), positive/negative relative accommodation (PRA/NRA), accommodative facility (AF), the ratio of accommodative convergence and accommodation (AC/A), Schirmer test, noninvasive breakup time (NBUT), and HOA were examined before surgeries and at 1 week, 1 month and 3 months postoperatively then statistically analyzed.

RESULTS

Symptoms of asthenopia were significantly decreased at 1 week after ICL surgeries than those before surgeries, but increased gradually as time went by, eventually recovered at 3 months postoperatively. AA, AF, AC/A decreased 1 week postoperatively, returned to the baseline at 1 month and were improved at 3 months after surgeries. NBUT at 1 week, 1 month and 3 months after surgeries were significantly decreased and was the lowest at 1 week postoperatively. PRA, NRA, Schiermer values and HOA had no significant change. Correlation analysis showed that the lower AF and NBUT after ICL surgeries, the more severe the asthenopia symptoms.

CONCLUSION

The symptoms of asthenopia aggravated transiently after ICL implantation surgeries, but improved gradually with time. AF and NBUT were important factors affecting the changes of asthenopia.