Purpose
To compare the accuracy of SRK/T and Haigis formulae used for intraocular lens (IOL) power calculation by a partial coherence interferometer in patients undergoing phacoemulsification surgery.
Patients and methods
A prospective interventional clinical study included 70 eyes of 60 patients, who underwent uncomplicated phacoemulsification with IOL implantation from October 2015 to December 2017. Preoperative axial length (AL), corneal curvature (keratometry), and preoperative anterior chamber depth (preoperative ACD) were measured using Nidek AL-scan optical biometer and the IOL power was determined using both SRK/T and Haigis formulae. The difference between the predicted value and the postoperative spherical equivalent was calculated for both the formulae by the end of the follow-up (3 months postoperatively).
Results
The mean errors of the two formulae were SRK/T: −0.225±0.61 D and Haigis: 0.171±0.68 D; the mean absolute errors of the two formulae were 0.534±0.36 and 0.533±0.44 D, respectively. There was no statistically significant difference between the mean error of the two formulas used in the overall performance, but was significant in eyes with an AL of more than 25 mm. The proportion of patients having a prediction error within ±0.50 D of SRK/T formula (54.29%) was comparable to those of Haigis (55.71%) and the prediction errors within ±1.0 D were 87.14 and 85.71%, respectively. There is a weak correlation between the mean AL, keratometry and the Haigis–SRK/T prediction differences (r
2=0.273).
Conclusion
The calculation of IOL power using SRK/T and Haigis formulae resulted in an accurate postoperative refraction. In long AL subcategory, the mean absolute error of Haigis was less compared with the SRK/T formula.
To evaluate the accuracy of SRK/T formula used for IOL power calculation by partial coherence interferometer in patients undergoing phacoemulsification surgery. Patients and methods: A prospective interventional clinical study included 40 eyes of 34 patients who underwent uncomplicated phacoemulsification with IOL implantation from March 2015 to March 2017. Biometries were measured using ultrasound or AL-scan and intraocular lens power was calculated using the SRK-T formula. Patients were divided into 2 groups based on device used for IOL power calculation: ALscan or ultrasound ; Axial length: >=25 mm or < 25mm; or lens opacity: Cataractous or clear lens. The mean error (ME) was calculated from the difference between the formula predicted refractive error and the actual post operative refractive error by the end of the followup (3 months postoperative). Results: Mean axial length measured preoperatively was 27.47 ± 316mm (21.55-34.05) mm. 60 percent of the patients were within 0.5 D of the predicted refractive error and 90 percent were within 1.0 D. There was no statistically significant difference in the overall performance of the SRK/T formula between the mean error when dividing the patients into 2 groups according to: device used for IOL power calculation (P= 0.274); Axial length (P= 0.46); or lens opacity (P= 0.18) in precision of predicting postoperative refraction. Conclusions : SRK/T formula helps in improvement of the accuracy of IOL power calculation and decreasing the postoperative refractive error. By using SRK/T formula, there was no statistically significant difference between the AL-scan or applanation ultrasound used in biometry.
Hallermann-Streiff syndrome (HSS) is a rare genetic disorder that is primarily characterized by distinctive malformations of the skull and facial (craniofacial) region; sparse hair (hypotrichosis); eye abnormalities; dental defects; degenerative skin changes (atrophy), particularly in the scalp and nasal regions; and proportionate short stature. Here we describe a case with HSS.
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