Abstract
Purpose: :
To investigate the impact of LASIK and PRK on central visual performance using Panoramic Night Vision Goggles (PNVG). The PNVG differs from other night vision goggles in its increased field of view. Regular night vision goggles provide a 40° field of view with two central tubes whereas the PNVGs provide a 100° field of view with two additional outboard tubes. This increased field of view of the goggles combined with a relatively large pupil size under low luminance conditions has the potential to impact central visual performance.
Methods: :
Subjects were 30 active duty military personnel (age 21 to 45, mean 30.0). Subjects were randomly divided into 15 cases of conventional PRK and 15 cases of WFG LASIK to correct ametropia. Mean preoperative manifest refraction was –2.1±1.7 D. Contrast acuity testing with the PNVG was done before and 1 and 3 months after surgery. Testing conditions included two contrast acuity levels (20% and 50%) under 2 chart illuminations (quarter moon and starlight) and 2 outboard channel luminance levels (high and off).
Results: :
Outboard tube illumination did not affect PNVG visual performance under any circumstances before and after surgery. Overall PNVG performance following PRK was significantly worse than WFG LASIK at 1–month postoperative (p<0.001), however no difference was found between the two surgical procedures 3 months after surgery. Furthermore, both conventional PRK and WFG–LASIK significantly enhanced PNVG visual performance at 3–months compared to preoperative measurement (p<0.001).
Conclusions: :
Central visual performance after conventional PRK or WFG–LASIK was not affected by outboard tube illumination. The only difference was found in the early postoperative stages of PRK, but ultimately both procedures improved central visual performance with the PNVG.
Keywords: refractive surgery • visual acuity • contrast sensitivity