J Korean Ophthalmol Soc > Volume 55(1); 2014 > Article
Journal of the Korean Ophthalmological Society 2014;55(1):85-92.
DOI: https://doi.org/10.3341/jkos.2014.55.1.85    Published online January 15, 2014.
Theoretical and Clinical Comparison of the Hoffer Q and SRK/T Formulas.
Jin Ho Jeong, Sung Gon Kim, Hye Jin Lee, Sun Ho Lee, Dong Min Cha
Department of Ophthalmology, Jeju National University School of Medicine, Jeju, Korea. amario@naver.com
Hoffer Q와 SRK/T 인공수정체 도수 계산 공식의 이론적 임상적 비교
Department of Ophthalmology, Jeju National University School of Medicine, Jeju, Korea
To evaluate the biometric conditions causing increased disparity in the calculation of intraocular lens (IOL) power between the Hoffer Q and SRK/T formulas. METHODS: A prospective comparative study was conducted on 365 uneventful, cataract surgeries performed at a tertiary care center by one surgeon. The IOL power was calculated using both the Hoffer Q and SRK/T formulas with A-scan biometry. For a selected IOL power, the expected disparity between the 2 formulas (EDF) was measured and the EDF value was used to categorize the cases. The resultant error associated with each formula was determined at postoperative 6 weeks. KAL was defined as the product of mean corneal power (K) and axial length (AL). Postoperative errors of both formulas were calculated and their association with preoperative biometry measurements analyzed. RESULTS: In 17.8% of the cases, the EDF was larger than 0.4 D, possibly leading to different IOL diopter recommendations. The EDF value and the product of corneal curvature and axial length were significantly correlated (R2 = 0.855, p < 0.001). Multiple regression analysis of causative preoperative biometric factors on the postoperative formula errors showed that astigmatism, anterior chamber depth (ACD), and lens thickness (LT) were significantly associated with Hoffer Q error and SRK/T error. CONCLUSIONS: Overall, both formulas performed very well when recommending the correct IOL power. The cause of disparity between the predicted refraction for the 2 formulas was more associated with KAL than K or AL alone. Astigmatism, ACD, and LT were the causative factors for the postoperative errors in both formulas.
Key Words: Effective lens position;Hoffer Q formula;IOL formula comparison;SRK/T formula

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