The effect of transient increase in intraocular pressure on subfoveal choroidal thickness.

Significance: Myopia prevalence has increased over the last few decades. Studies have documented that the choroid is considered an important biomarker in myopia development. As myopia and choroidal thinning are associated with increased glaucoma risk, understanding the role of the choroid in myopia and glaucoma is imperative.

Purpose: This study investigates the effect of transiently elevated intraocular pressure on axial length, subfoveal choroidal thickness, and central retinal thickness in emmetropes, low myopes, and high myopes.

Methods: This study involved 29 young adults (23 ± 1 years), including 10 emmetropes (-0.50 D < SE < +0.50 D), 10 low myopes (-6.00 D < SE ≤ -0.50 D), and 9 high myopes (SE ≤ -6.00 D). Participants were fitted with modified swimming goggles for 5 minutes to transiently change intraocular pressure. Noncontact tonometry, optical biometry, and optical coherence tomography were used to measure intraocular pressure, axial length, central retinal thickness, and subfoveal choroidal thickness, respectively. Measurements were taken at before, during goggle wear, immediately after, and 3 minutes after goggles removal. Repeated-measures analysis of variance with Bonferroni adjustment was used to assess the effect of transiently changed intraocular pressure and to elucidate any differences between refractive groups in response to the intraocular pressure change.

Results: Intraocular pressure increased by 1.7 ± 2.1 mmHg (p=0.002) from baseline, accompanied by axial elongation of 14 ± 21 μm (p = 0.012) and subfoveal choroidal thinning of 13 ± 15 μm (p=0.01). However, central retinal thickness did not change significantly (p>0.05). Most of the changes in the axial length were due to changes in the choroidal thickness. Observed changes returned to baseline immediately following goggles removal. There was no significant difference between refractive error groups' changes associated with the transient increase in intraocular pressure (p>0.05).

Conclusions: Transiently increased intraocular pressure caused temporary axial elongation and subfoveal choroidal thinning, with no significant differences between refractive groups. Further studies are required to assess the impact of long-term increased intraocular pressure on ocular components.