Decades of Night-Shift Work Induce Diurnal Disruption and Corneal Adaptations: Evidence from Pentacam Analysis

Abstract

We aimed to determine the effects of night-shift work on corneal parameters in thirty-five healthy individuals (24-59 years) in a retrospective cohort study. Among them, 12 hospital nurses regularly worked two shifts, spending a third of their nights awake, whereas 23 age-matched controls never worked shifts and slept regularly. Measurements were performed at least five times within 12 h. We analyzed the keratometric parameters of the corneal front (F) and back (B) surfaces, including the refractive power in the flattest and steepest axes (K1, K2), astigmatism (Astig); and corneal pachymetry (Pachy) at the thinnest corneal point and pupil center, volume relative to the 10 mm corneal diagonal (Vol D10); and surface variance index (ISV). A multilevel mixed-effects linear regression adjusted for age was applied to 905 measurements. All parameters exhibited significant periodic fluctuations (p ≤ 0.005). The two groups also showed significantly different periodic fluctuations (p ≤ 0.008), except in K1B and AstigB. K1/K2 (F and B), AstigF, Pachy, and ISV differed significantly (p < 0.0001). Surprisingly, prolonged night shift work did not increase the ISV, and no evidence of age-related corneal thinning was observed. Long-term night-shift exposures change various corneal parameters, reflecting both concomitant and adaptive effects. This study highlights the impact of consistent sleep deprivation on corneal properties, warranting further research into understanding the long-term effects of night-shift work.

Keywords: Scheimpflug parameters; anterior segment of the eye; cornea; diurnal changes; keratometry; night shift; pachymetry; sleep deprivation.

Figure 1

Periodic fluctuations of the flat (K1)—and steep-keratometry (K2) on the front (F) and the back (B) surface of the cornea in the control group (not nurses) and the nurses. Significant periodic fluctuations can be observed in all parameters (p ≤ 0.005), and significant heterogeneity is present between the groups in all parameters (p ≤ 0.001), except K1B (p = 0.6797). The higher front corneal surface keratometry values (more convex) in the nurses’ group are compensated for with the lower (more concave) values on the back surface.

Figure 2

Periodic fluctuations in astigmatism (Astig) on the front (F) and the back (B) surface of the cornea in the control group (not nurses) and the nurses. Significant periodic fluctuations can be observed on both surfaces (p ≤ 0.0004). Significant heterogeneity is present between the groups in the case of the front surface (p = 0.0084), but not in the back surface (p = 0.0547).

Figure 3

Periodic fluctuations in the corneal thickness at the thinnest point of the cornea (Pachy Min) and the volume of the cornea in a diameter of 10 mm centered on the anterior corneal apex (Vol D 10 mm) in the control group (not nurses) and the nurses (age-adjusted data). Significant periodic fluctuations can be observed (both p ≤ 0.0001), and significant heterogeneity is present between the groups (p = 0.0002 and p < 0.0001, respectively).

Figure 4

Periodic fluctuations in the index of surface variance (ISV) in the control group (not nurses) and the nurses. Significant variation can be observed (p = 0.0002), and significant heterogeneity is present between the groups (p = 0.0063).