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Updated: May 12, 2025
Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis
Published on: November 12, 2015
Comparative study of the corneal morphological characteristics of keratoconus evaluated using Pentacam, Sirius, and
Bingqing Sun1, Xiaojun Hu1, Xiaoliao Peng1
1Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai 200031, China; Key Laboratory of Myopia and Related Eye Diseases, NHC; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care, Shanghai, 200031, China.
Purpose:
To compare the corneal morphology measurements of keratoconus using Pentacam, Sirius, and CASIA2.
Methods:
Patients diagnosed with keratoconus at Fudan Eye and ENT Hospital (January to November, 2022) were included. Corneal refraction, astigmatism, thickness, and elevation parameters were measured using Pentacam, Sirius, and CASIA2. The measurement differences, agreement, and the sensitivity and specificity of each instrument for diagnosing keratoconus was evaluated. P < 0.05 was considered statistically significant.
Results:
A total of 61 keratoconus eyes and 48 healthy myopic eyes were included. The steepest and flattest keratometry measured using Sirius were the highest (all p < 0.05). Pentacam measured the highest thinnest corneal thickness values in maximun keratometry >48D keratoconus paticipants (all p < 0.05). When the best fit sphere was aligned, the anterior and posterior elevations at thinnest points measured using Sirius were the highest in keratoconus group and the lowest in control group (all p < 0.05). Corneal refractive power measurements significantly differed among three instruments (p < 0.0001). The intraclass correlation coefficient results demonstrated excellent agreement in total corneal refractive power (TCRP), mean keratometry of the corneal front and posterior surface (fKm and pKm) measurements among control, corneal crosslinking treated, and untreated keratoconus groups. In the control group, the agreement limits for TCRP, fKm, and pKm were narrower than those in keratoconus. In keratoconus group, Pentacam and CASIA2 showed the best consistency in the measurement of TCRP and fKm, whereas Pentacam and Sirius showed the best consistency in the measurement of pKm. Sensitivities for diagnosing keratoconus ranked from high to low: Pentacam, CASIA2, Sirius.
Conclusion:
Comprehensive evaluation of anterior and posterior corneal parameters is crucial for keratoconus screening. Pentacam, Sirius, and CASIA2 showed limited agreement in keratoconus refractive parameters and are not interchangeable in keratoconus management. Sirius yielded higher corneal anterior keratometry and posterior elevation values, while Pentacam demonstrated the highest diagnostic sensitivity for keratoconus.
