Iolmaster 500

Ocular globe flattening can occur during spaceflight, leading to hyperopic shifts in refractive error (Lee et al., 2020 (link); Mader et al., 2011 (link)). Therefore, we investigated whether similar changes occur during 60 days of HDTBR. Optical biometry was performed using the IOLMaster 500 (Carl Zeiss Meditec AG) between BDC‐11 and BDC‐3 and between R+6 and R+9 in the seated posture to detect changes in axial length, anterior chamber depth, and corneal curvature. Cycloplegic refraction was performed on BDC‐12 and R+6 to determine whether a shift in refractive error had occurred.

Holladay 2 formula was applied to calculate the IOL power for all eyes (IOLMaster 500, Carl Zeiss Meditec AG). Optimized A-constants of the trifocal IOL and the bifocal IOL for the surgeon in this study were applied. To improve the intermediate visual acuity and avoid distant drift of the near focal point and hyperopia and presbyopia symptoms, a mild myopic target SE was expected for every group [22 (link)]. However, as IOL type had significant influence in the accuracy of IOL power calculation, personalized refractive targets were selected based on clinical experience (a target of -0.10 D for the trifocal IOL and 0.10 D for the bifocal IOL).

The distance VA was estimated using Early Treatment Diabetic Retinopathy Study Tumbling E charts (Precision Vision, La Salle, IL, USA). Ocular biometry was measured before pupil dilation with non-contact partial-coherence laser interferometry (IOLMaster 500; Carl Zeiss Meditec, Oberkochen, Germany) (13 (link)).
The non-cycloplegia autorefraction was measured first. Then, cycloplegia was induced with 2 drops of 1% cyclopentolate, administered 5 min apart, with a third drop administered 20 min later. The cycloplegia and pupil dilation were evaluated after an additional 15 min. Refraction was performed with a desktop autorefractor (KR8800; Topcon Corp., Tokyo, Japan) in participants with their pupils dilated to at least 6 mm, and when their pupillary light reflex was absent. The data on the spherical and cylindrical power and axis were extracted from the device.
The trained and certified examiners (three optometrists, two public health physicians, and one ophthalmologist) were from Peking University People's Hospital. The examinations were performed according to standard measurement procedures. All the participants with uncorrected visual acuity (VA >0.0 logMAR) received recommendations to be referred to eye care practitioners for further detailed ophthalmic examinations and evaluations.

The main ocular examinations included slit-lamp biomicroscopy for anterior segment, fundus imaging by Optos Daytona, and axial length by Zeiss IOL Master 500.
HIV infection was identified by self-reporting and a previous positive test. For patients with HIV infection, critical HIV-related parameters were collected, including the duration of infection, duration of ART, CD4/CD8, nadir CD4 counts, and blood HIV-RNA.