Seasonal Variation in Diurnal Rhythms of the Human Eye: Implications for Continuing Ocular Growth in Adolescents and Young Adults

Abstract

Purpose To investigate the diurnal rhythms in the human eye in winter and summer in southeast Norway (latitude 60°N). Methods Eight measures (epochs) of intraocular pressure, ocular biometry, and optical coherence tomography were obtained from healthy participants (17–24 years of age) on a mid-winter's day ( n = 35; 6 hours of daylight at solstice) and on a day the following summer ( n = 24; 18 hours of daylight at solstice). Participants wore an activity monitor 7 days before measurements. The epochs were scheduled relative to the individual's habitual wake and sleep time: two in the day (morning and midday) and six in the evening (every hour until and 1 hour after sleep time). Saliva was collected for melatonin. A linear mixed-effects model was used to determine significant diurnal variations, and a sinusoid with a 24-hour period was fitted to the data with a nonlinear mixed-effects model to estimate rhythmic statistics. Results All parameters underwent significant diurnal variation in winter and summer ( P < 0.002). A 1-hour phase advance was observed for melatonin and ocular axial length in the summer ( P < 0.001). The degree of change in axial length was associated with axial length phase advance ( R 2 = 0.81, P < 0.001) and choroidal thickening ( R 2 = 0.54, P < 0.001) in summer. Conclusions Diurnal rhythms in ocular biometry appear to be synchronized with melatonin secretion in both winter and summer, revealing seasonal variation of diurnal rhythms in young adult eyes. The association between axial length and seasonal changes in the phase relationships between ocular parameters and melatonin suggests a between-individual variation in adaptation to seasonal changes in ocular diurnal rhythms.

Comparing ocular biometry and autorefraction measurements from the Myopia Master with the IOLMaster 700 and the Huvitz HRK‐8000A autorefractor

“…In a review of the repeatability of autorefraction, the mean estimated 95% LoA for repeatability of cycloplegic SER was ±0.41 D 28 . Although SER is an important clinical measurement, most autorefractors do not have comparable accuracy to that of ocular biometers, except perhaps the HRK‐8000A with a reported repeatability of ±0.056 D (95% CI 0.052, 0.061) 20 . Compared with the HRK‐8000A, the Myopia Master measured on average 0.19 D more minus SER, but no differences on average for J 0 and J 45 (Table 2, Figure 2).…”

“…The autorefraction values reported by the instrument are the mean of five measurements obtained with a minimum pupil diameter of 2.0 mm. The instrument has been reported to have high measurement repeatability 20 …”

“…[13][14][15][16] The Huvitz Auto Ref/ Keratometer (HRK-8000A, Huvitz Co. Ltd., huvitz.com) is widely used for autorefraction [17][18][19] with reportedly high repeatability. 20 The aim of this study was to assess the LoA between the Myopia Master and the IOLMaster 700 for measurements of CR and AL, and between the Myopia Master and the HRK-8000A for measurements of cycloplegic refractive errors. The 95% LoA between the Myopia Master and the IOLMaster 700 for AL and CR, and between the Myopia Master and the HRK-8000A for cycloplegic refractive error, were larger than deemed acceptable, implying that measurements obtained by the instruments are not directly interchangeable for these three parameters.…”

Non-cycloplegic refraction cannot replace cycloplegic refraction in primary school children.

“…The children viewed a large letter or another suitable non-accommodative object at a distance of at least 6 metres. Non-cycloplegic and cycloplegic autorefraction were performed utilising the Huvitz HRK-8000A Auto-REF Keratometer (Huvitz Co. Ltd., Gyeonggi-do, Korea), which has been shown to have high repeatability (Nilsen et al, 2022). Results from autorefraction were automatically calculated from five measurements.…”

“…A Norwegian study found significantly higher degrees of hyperopia (0.5 D) after cycloplegia (cyclopentolate 1%) in children aged 10-15 years (Thorud et al, 2021). Some studies have found good inter-and intra-repeatability of cycloplegic retinoscopy in children for experienced clinicians (Hirsch, 1956;McCullough et al, 2017), although cycloplegic autorefraction typically gives higher repeatability than cycloplegic retinoscopy (Fotouhi et al, 2012;Nilsen et al, 2022;Sankaridurg et al, 2017;Zadnik et al, 1992). Clinical studies show considerable between-individual variation when noncycloplegic and cycloplegic refraction methods are compared (L. B.…”