Comparing axial length measurements among optical, immersion, and applanation biometry: A cross-sectional study

• Author Details:   
• Rishabh Sathya Shah
• Varsha Nitin Kulkarni ^*
• Sanjiv Agrawal
• Shivali Madhusudan Gadewar
• Kalyani Ravindra Lohokare
• Jaishnavi Devi Kommineni

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Background: For optimal visual outcomes after cataract surgery, accurate preoperative intraocular lens (IOL) power calculation is crucial, with axial length being the most important biometric parameter. We aimed to compare axial length (AL) measurements obtained via optical, immersion, and applanation biometry methods. Additionally, we compared anterior chamber depth (ACD), lens thickness (LT), and IOL power calculations across these techniques.

Materials and Methods: This cross-sectional observational study included 70 eyes from patients aged 20 years and older with nuclear sclerosis grade II or less. AL, ACD, and LT measurements were obtained using optical biometry, immersion biometry, and applanation biometry. IOL power was calculated using the SRK/T formula. The results were compared to assess differences among the three biometry techniques.

Results: Optical biometry provided significantly higher AL values compared to immersion (mean difference: 0.128 mm, p < 0>

Conclusion: Optical biometry remains the gold standard for AL measurements but may not be feasible in cases of dense cataracts. In such situations, immersion and applanation biometry offer reliable alternatives without compromising the accuracy of IOL power calculations. Although optical biometry provided higher measurements for AL, ACD, and LT, the limited impact on IOL power underscores the viability of ultrasound-based methods when optical biometry is unavailable.

Keywords: Axial length, IOL power calculation, Optical biometry, Immersion biometry, Applanation biometry, A-Scan.