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. 2023 Oct 18;16(3):461-466.
doi: 10.4103/ojo.ojo_171_22. eCollection 2023 Sep-Dec.

The effect of sustained eye rotation upon eye length in healthy myopic adults

Saleh A Alkhaldi  1 , Lyle S Gray  2
Affiliations

The effect of sustained eye rotation upon eye length in healthy myopic adults

Saleh A Alkhaldi et al. Oman J Ophthalmol. .

Abstract

Aim: The aim of the study was to determine whether ocular movement can affect the shape of the globe and lead to measurable change in axial and peripheral eye length.

Methods: Ten subjects aged 18-30 years (6 M/4 F) participated with informed consent. The mean spherical equivalent refractive error was ≤-1.00 DS with cylindrical refraction <-1.25 DC. One drop of tropicamide hydrochloride 1% was instilled 20 min before measurement to induce mydriasis and mild cycloplegia. Using IOLMaster, eye length was measured centrally and temporally (25° off-axis) in four different positions. Subjects then rotated their eyes 25° in the temporal direction to fixate on a target for 10 min. After that, the same measurements were repeated.

Results: Before rotation, the group mean peripheral eye length was significantly shorter than the central eye length (P < 0.05). There was no significant variation in central or peripheral eye length due to off-axis fixation, either after the initial eye rotation or after fixation for 10 min at the off-axis point. The difference between central and peripheral eye lengths was maintained after 10 min of temporal fixation (P < 0.05).

Conclusion: Peripheral eye length was shorter than central eye length showing the prolate shape associated with myopia. The action of the extraocular muscles on the globe has no significant effect upon the retinal shape assessed by off-axis eye length measurement in myopic subjects.

Keywords: Central eye length; IOLMaster; eye rotation; eye shape; myopia; peripheral eye length.

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Conflict of interest statement

The authors disclosed no conflict of interest.

Figures

Figure 1
Figure 1
The infrared beam entering the right eye at 0˚ to measure the central AL (a), how both the eye and the instrument were rotated 25˚ temporally to measure the central AL again (b), eye rotation 25˚ temporally with the infrared beam entering the right eye at 0˚ to measure the PL (c), and how the instrument was rotated 25˚ nasally in order to measure the PL again (d), It can be seen that both beams entered the eye through the central curvature of the cornea and passed close to the nodal point
Figure 2
Figure 2
The relationship between central and peripheral eye lengths with no eye rotation and no temporal fixation at the beginning of the experiment. AL: Axial length, PL: Peripheral length
Figure 3
Figure 3
The significant relationship between refractive error (mean spherical equivalent) and central axial length. AL: Axial length, MSE: Mean spherical equivalent
Figure 4
Figure 4
The relationship between central and peripheral eye lengths after temporal fixation with the eye in the straight-ahead position. AL: Axial length, PL: Peripheral length
Figure 5
Figure 5
The difference between rotated and nonrotated measurements of central axial length (AL) before and after 10 min of off-axis fixation against the baseline measurement of AL. AL: Axial length
Figure 6
Figure 6
The difference between rotated and nonrotated measurements of peripheral length (PL) before and after 10 min of off-axis fixation against the baseline measurement of PL. PL: Peripheral length
See this image and copyright information in PMC

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