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Purpose: The purpose of this study is to investigate and compare the effects of cyclopentolate and tropicamide drops on anterior segment parameters in healthy individuals. Methods: Two hundred and fifty-eight eyes of 129 healthy volunteers were included in this randomized clinical study. Cyclopentolate 1% drop was applied to 75 (58%) participants (group 1) and tropicamide 0.5% drop was applied to 54 (42%) participants (group 2). Flat keratometry (K1), steep keratometry (K2), axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), white-to-white (WTW) distance, pupil diameter, total pupil offset and intraocular lens (IOL) power were measured before and after drops, using Lenstar 900 optical biometry. Results: The increase in CCT, ACD, pupil diameter, and pupil offset was significant in group 1 after the drop (P < 0.05), while the increase in ACD, pupil diameter, and pupil offset was significant in group 2 (P < 0.05). When the two groups were compared, there was no significant difference in K1, K2, CCT, ACD, WTW, pupil diameter, pupil offset, and IOL power (using Sanders–Retzlaff–Kraff T formula) changes after drops (P > 0.05), whereas the change in AL was significant (P = 0.01). Conclusion: The effects of cyclopentolate and tropicamide drops on anterior segment parameters were similar; they did not make significant changes in K1, K2, AL, WTW, and third-generation IOL power calculation. However, ACD values significantly changed after these drops; thus, measuring anterior segment parameters before mydriatic agents should be taken into account particularly for fourth-generation IOL formulas and phakic IOL implantation. The change in pupil offset, which can be important in excimer laser and multifocal IOL applications, was not clinically significant.

To compare the clinical and topographical findings of the keratoconus patients according to the prescribed contact lens type and to investigate the effects of corneal collagen cross-linking (CXL) and cone location on lens selection.The records of 301 eyes of 195 keratoconus patients who were prescribed contact lenses were analyzed retrospectively. The eyes were grouped according to the lens type: Soft toric contact lens (STCL), rigid gas-permeable contact lens (RGPCL), hybrid contact lens (HCL) and mini-scleral contact lens (MSCL). The history of having CXL, ophthalmological examination findings, and the topographical findings were compared between the groups. Brown-Forsythe, Chi-square, and post-hoc tests were used to compare the groups. Mann-Whitney U test was used for subgroup analysis. Comparison of the lens-corrected visual acuity (LCVA) and spectacle-corrected visual acuity (SCVA) levels was made with Wilcoxon signed-ranks test.There was no significant difference between the groups regarding topographical cone location, CXL history, spherical refraction, and LCVA. The difference between spectacle-corrected visual acuity and LCVA was higher in RGPCL and MSCL groups than STCL group (p=0.01). Keratometry of RGPCL and MSCL groups were higher than STCL and HCL groups (p=0.01, p0.001). In RGPCL group, eyes with central cones had a higher increase in visual acuity with contact lenses compared to eyes with paracentral cones (p=0.043). STCL and MSCL were mostly prescribed in mild and severe keratoconic eyes, respectively. In RGPCL group, the increase in visual acuity with contact lens was higher in eyes treated with CXL (p=0.01).While STCL and HCL were mostly prescribed in mild keratoconus, RGPCL and MSCL were selected for moderate or advanced disease. If appropriately chosen, all types of contact lenses could result in a good visual acuity level. CXL history did not affect the prescribed lens type. Having central cone location and CXL history in RGPCL group improved visual acuity more efficiently.