This study evaluated the predictive accuracy of the SRK-2 formula for calculating intraocular lens (IOL) power in 274 eyes undergoing phacoemulsification cataract surgery in Sri Lanka. The mean age was 65.3 years and axial length ranged from 22-26mm. The SRK-2 formula predicted post-operative refractive errors with a mean error of -0.300±0.145D. The actual achieved refractive error was -0.220±0.732D, showing a slight hyperopic shift. 79% of patients had 6/6 vision 7 days post-op. The study concluded that the SRK-2 formula provides a good option for predicting refractive outcomes in eyes with medium axial

1. Does Sanders-Retzlaff-Kraff (SRK-2) formula suit a Sri Lankan
population in phacoemulsification cataract surgery
of medium axial length?
MS MS Amaratunge , J De Silva1, IM Wasthuhewaarachchi , SH Uyangoda , MAJI Mallawaarachchi , R
1 2 1 1
Premarathna3, AAN Nishad4
Vijaya Kumaratunge Memorial Hospital, Seeduwa Teaching Hospital, Vavuniya
1 2
3
Faculty of Medicine, University of Kelaniya 4Post Graduate Institute of Medicine, University of Colombo
Results
274 patients, mean (S.D.) age was 65.3(10) years.
56% were females.
Introduction 90(32.8%) had diabetes mellitus and 107(39%) had
Intraocular lens (IOL) power calculation formulas hypertension.
have evolved over the past 25 years. The most The right eye was operated in 142 (51.8%) patients and the
recent formulas (third and fourth generation) are the left eye in 132 (48.2%).
most useful and precise Table 1. Visual acuity 7 days post operatively
Prediction accuracy depends on three factors: Visual acuity Percentage
#accuracy of the biometric data (axial length and 6/6 79%
keratometry readings),
#accuracy of manufactured IOL power quality > 6/9 93%
control #accuracy of the IOL power formulas > 6/12 to 6/36 97%
Introduction of phacoemulsification with small Mean (S.D.) IOL power used was 21.50D (1.90D), (range; 10.0D to
incision techniques, minimizing cylindrical error, and 25.5D).
continuous curvilinear capsulorhexis technique, that The mean predicted refractive error with SRK-2 was -0.300 ± 0.145 D
allows better IOL capsular fixation and more (range, -0.05D to -0.7D).
predictable ELP The mean achieved refractive error was -0.220 ± 0.732 D (range,
+1.00 to -1.5 D).
The difference between predicted and achieved refractive error
The correct IOL power became a crucial step for
presented a slight hyperopic shift (mean ± SD: 0.054 ± 0.397 D),
good refractive outcome in the preoperative
examination of cataract surgery. 
ranging from -1.31 D to + 1.19 D.
Graph 1. Correlation between Targeted refraction and
Refraction Targeted with SRK 2 (Pearson Correlation=0.126
(p=0.038)
Objectives
To evaluate the predictive accuracy of post operative
refraction using SRK-2 formula in phacoemulsification in
eyes with 22-26mm axial length.
Methods
Senile cataract patients who underwent
phacoemulsification and IOL between January to
December 2010 in Gampaha district by a single Conclusion
surgeon. SRK-2 formula as a good option to predict the refractive error
Eyes with 22-26mm axial length. after cataract extraction by phacoemulsification in eyes with
Single examiner measured simulated manual medium axial length.
keratometry preoperatively and seven days
postoperatively; uncorrected visual acuity, slit lamp Unique in reporting eyes implanted in the capsular bag by the
examination of the anterior segment and best same surgeon, with preoperative measurements obtained from
spectacle-corrected visual acuity (BSCVA) were taken. the same instrumentation by the same method and same
The implanted IOL power was used to calculate technician, using SRK-2 formula for IOL power calculation in eyes
predicted postoperative refractive error by SRK-2 with medium axial length that underwent phacoemulsification
formula. with foldable IOL implantation.
Sri Lanka Medical Association , 125th Anniversary International Medical Congress, Colombo, Sri Lanka