Accuracy of Intraocular Lens Calculation by SRK/T Formula in Pediatric Cataracts
Sukhumal Thanapaisal MD*, Phanthipha Wongwai MD, PhD*, Warachaya Phanphruk MD*, Sirinya Suwannaraj MD*
Affiliation : * KKU Eye Center, Department of Ophthalmology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
Objective : To examine the accuracy of the intraocular lens calculation by SRK/T formula in pediatric cataract patients, by
means of the prediction error after the cataract surgery.
Material and Method: A retrospective review of pediatric patients requiring cataract extraction with intraocular lens
implantation, between January 2006 and December 2013 was performed. Post-operative spherical equivalent was compared
with the predicted calculation value from pre-operative SRK/T measurement, defined as prediction error (PE).
Results : 139 eyes from 106 patients were studied. The median age of patients at surgery was 4.56 years (IQR, 14). The two
most common causes of cataract were idiopathic and traumatic; 85 eyes (61.2%) and 36 eyes (25.9%), respectively. Primary
intraocular lens (IOL) implantation was performed in 87 (62.6%) eyes. The mean PE was -1.32+1.89 D (-7.78, 2.24). At one
to three months after surgery, the mean PE of IOL in bag and sulcus were -0.87 D and -2.02 D, respectively. In non-traumatic
group, the mean PE of IOL in bag and sulcus were -1.1 D and 2.28 D, respectively, whilst the traumatic group was -0.33 D
and -1.16 D, respectively. Post-operative PE within +1 diopter was found in 30 eyes (37.97%) at one to three months of
follow-ups.
Conclusion : The majority of post-operative refraction was more myopic than the targeted refractive error, which was
calculated by SRK/T formula. Aiming for a more hyperopic target and IOL implantation in the bag would decrease the post-
operative prediction error in the use of the SRK/T formula in pediatric cataract patients.
Keywords : Intraocular lens calculation, SRK/T formula, Pediatric cataract
