Impact of hypoxic and mesopic environments on visual acuity, contrast sensitivity and accommodation in subjects with LASIK surgery and aircrew candidate

Hsin-Ting Lin; Hui-Ju Chan; Cheng-Wen Ho; Ming-Cheng Tai; Jiann-Torng Chen; Chang-Min Liang

doi:10.1016/j.jcma.2018.04.009

Impact of hypoxic and mesopic environments on visual acuity, contrast sensitivity and accommodation in subjects with LASIK surgery and aircrew candidate

J Chin Med Assoc. 2018 Nov;81(11):998-1007. doi: 10.1016/j.jcma.2018.04.009. Epub 2018 Sep 15.

Authors

Hsin-Ting Lin¹, Hui-Ju Chan², Cheng-Wen Ho², Ming-Cheng Tai¹, Jiann-Torng Chen¹, Chang-Min Liang³

Affiliations

¹ Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
² Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan, ROC.
³ Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan, ROC. Electronic address: doc30875@yahoo.com.tw.

PMID: 30228078
DOI: 10.1016/j.jcma.2018.04.009

Abstract

Background: The safety of Laser-assisted in situ keratomileusis (LASIK) in aircrew was unclear, in addition, LASIK was not yet approved for aircrew of Taiwan Air Force. This study was aimed to evaluate visual performance in LASIK eyes in hypoxic and twilight environment.

Methods: 48 myopic eyes of 24 subjects enrolled in this study were divided into LASIK group and control group. Subjects were exposed in hypoxic (15% O₂) and mesopic (3 cd/m²) environment. Visual performance was evaluated using the Early Treatment of Diabetic Retinopathy Study (ETDRS) visual chart, and Functional Acuity Contrast Test (FACT) before and after the expirement. Physiological parameters of all subjects were measured and recorded throughout the experiment.

Results: There was no significant difference of the two groups regarding their age, height, weight, and BMI. There is significant difference of preoperative spherical refractive error between the two groups. The results of physiological parameters were similar between two groups. Under normoxic conditions, there were no significant difference regarding distant vision in photopic and mesopic environments, so as for near vision. As a whole, the contrast sensitivity of the LASIK group were lowered than that of the control group about 35%, under whether normoxic or hypoxic conditions; photopic or mesopic circumstances. Under normoxic conditions, the measured accommodation of the LASIK group were 21% lowered than that of the control group and 31% lowered under hypoxic circumstances.

Conclusion: There was no significant difference of visual acuity between the two groups regarding hypoxic and mesopic environment, but reduced contrast sensitivity was significant in LASIK group as compared to those of the control group. Accommodation was significantly lowered in LASIK group, compared with control group, in hypoxic environment. Whether postoperative visual performance after LASIK in aircrew during flying duty is safe might need further investigation.

Keywords: Accommodation; Aircrew safety; Contrast sensitivity; Hypoxic; LASIK surgery; Mesopic environment; Visual acuity.

MeSH terms

Accommodation, Ocular*
Adult
Aviation
Contrast Sensitivity*
Female
Humans
Hypoxia
Keratomileusis, Laser In Situ*
Male
Prospective Studies
Visual Acuity*