Participants and Protocol

This study was approved by the ethics committee of Mugla University and conducted according to the Declaration of Helsinki. Each participant was informed of the purpose of the study and signed a written consent form. A sample of 38 eyes of 20 men and 18 women, with a mean age of 30.1 ± 6.8 years (range 24–39 years), and 42 eyes of 19 men and 23 women, with a mean age of 56.6 ± 7.3 years (range 47–64 years) participated in this cross-sectional study. The exclusion criteria were spherical equivalent refractive error > ±1.0 diopter (D), previous ocular surgery, corneal opacities, severe dry eye, history of contact lens wear, retinal disease (eg, cystoid macular edema), elevated scars, glaucoma, a narrow iridocorneal angle, cataract, an inability to open eyelids widely, ocular inflammatory disease, and poor ocular fixation.

All measurements were taken between 9 AM and 11 AM to eliminate the effect of diurnal variation on measurements. All the noncycloplegic and cycloplegic measurements were performed within 1 hour on the same day by the same experienced examiner according to the manufacturer’s recommendations. Three measurements were acquired using swept-source optical biometry before and after cycloplegia, and the average of the each parameter was used for analysis. The quality control criteria were used in accordance with the manufacturer recommendations; on the IOLMaster 700, the operator can see the whole scan image and visually check the eye geometry and axis of the measurements; also the foveal scan checks the correct fixation. Standard deviation (SD) values of the ACD and LT measurements are calculated, and the device warns the operator of low-quality results, such as the SD for ACD > 0.021 mm, for LT > 0.038 mm, and AL > 0.027 mm.

Participants were asked to blink just before measurements were taken to create an optically smooth tear film over the cornea. All measurements were taken in room light condition. Cycloplegia was achieved using 3 drops of an eye solution containing cyclopentolate 1% every 5 minutes. After cycloplegia, the pupillary light reflex was checked, and about 45 minutes later, the measurements were performed.

We recorded pupil diameter (PD), radius of corneal curvature values (R ₁ , R ₂ , and R _m ), central corneal thickness (CCT), WtW, ACD, LT, and AL both before and after cycloplegia. We completed IOL power calculations with the SRK/T, Holladay 2, and Haigis formulas using a target refraction of −0.50 D. IOLMaster 700 included the User Group for Laser Interference Biometry–optimized IOL constants for each IOL power formula within the device software. A 1-piece AcrySof SA60AT (Alcon Laboratories, Inc., Fort Worth, TX) was used to calculate IOL power with a 118.8 (A) constant for the SRK/T, +5.426 (ACD) constant for Holladay 2, and −0.111, +0.249, and +0.179 (a0, a1, and a2) constants for the Haigis. We evaluated changes in IOL power calculations according to changes in IOL power after cycloplegia, and to pinpoint the effect of cycloplegia, we recorded refractive predictions according to predilation IOL power both before and after cycloplegia.

Statistical Analysis

We used SPSS software for statistical analysis (version 18.0; SPSS Inc., Chicago, IL), as well as the Kolmogorov–Smirnov test to gauge normality in particular. We evaluated changes before and after dilation with a paired samples t test and compared parameters between groups with an unpaired samples t test. P < .05 was considered statistically significant.

Based on the previous studies with IOLMaster, setting the level of α = 0.05 and β = 80%, a sample size calculation indicates that a minimum of 36 subjects for each group would be required to give an 80% power at 5% 2-sided significance level for the statistical test to detect the difference.