Prediction error and accuracy of intraocular lens power calculation in pediatric patient comparing SRK II and Pediatric IOL Calculator

<p>Abstract</p> <p>Background</p> <p>Despite growing number of intraocular lens power calculation formulas, there is no evidence that these formulas have good predictive accuracy in pediatric, whose eyes are still undergoing rapid growth and refractive changes. This study is intended to compare the prediction error and the accuracy of predictability of intraocular lens power calculation in pediatric patients at 3 month post cataract surgery with primary implantation of an intraocular lens using SRK II versus Pediatric IOL Calculator for pediatric intraocular lens calculation. Pediatric IOL Calculator is a modification of SRK II using Holladay algorithm. This program attempts to predict the refraction of a pseudophakic child as he grows, using a Holladay algorithm model. This model is based on refraction measurements of pediatric aphakic eyes. Pediatric IOL Calculator uses computer software for intraocular lens calculation.</p> <p>Methods</p> <p>This comparative study consists of 31 eyes (24 patients) that successfully underwent cataract surgery and intraocular lens implantations. All patients were 12 years old and below (range: 4 months to 12 years old). Patients were randomized into 2 groups; SRK II group and Pediatric IOL Calculator group using envelope technique sampling procedure. Intraocular lens power calculations were made using either SRK II or Pediatric IOL Calculator for pediatric intraocular lens calculation based on the printed technique selected for every patient. Thirteen patients were assigned for SRK II group and another 11 patients for Pediatric IOL Calculator group. For SRK II group, the predicted postoperative refraction is based on the patient's axial length and is aimed for emmetropic at the time of surgery. However for Pediatric IOL Calculator group, the predicted postoperative refraction is aimed for emmetropic spherical equivalent at age 2 years old. The postoperative refractive outcome was taken as the spherical equivalent of the refraction at 3 month postoperative follow-up. The data were analysed to compare the mean prediction error and the accuracy of predictability of intraocular lens power calculation between SRK II and Pediatric IOL Calculator.</p> <p>Results</p> <p>There were 16 eyes in SRK II group and 15 eyes in Pediatric IOL Calculator group. The mean prediction error in the SRK II group was 1.03 D (SD, 0.69 D) while in Pediatric IOL Calculator group was 1.14 D (SD, 1.19 D). The SRK II group showed lower prediction error of 0.11 D compared to Pediatric IOL Calculator group, but this was not statistically significant (p = 0.74). There were 3 eyes (18.75%) in SRK II group achieved acccurate predictability where the refraction postoperatively was within ± 0.5 D from predicted refraction compared to 7 eyes (46.67%) in the Pediatric IOL Calculator group. However the difference of the accuracy of predictability of postoperative refraction between the two formulas was also not statistically significant (p = 0.097).</p> <p>Conclusions</p> <p>The prediction error and the accuracy of predictability of postoperative refraction in pediatric cataract surgery are comparable between SRK II and Pediatric IOL Calculator. The existence of the Pediatric IOL Calculator provides an alternative to the ophthalmologist for intraocular lens calculation in pediatric patients. Relatively small sample size and unequal distribution of patients especially the younger children (less than 3 years) with a short time follow-up (3 months), considering spherical equivalent only.</p

The Early Treatment for Retinopathy Of Prematurity Study: structural findings at age 2 years

OBJECTIVE: To determine whether earlier treatment of high‐risk, prethreshold retinopathy of prematurity (ROP) improves retinal structural outcome at 2 years of age. METHODS: Infants with bilateral high‐risk prethreshold ROP had one eye randomly assigned to treatment with peripheral retinal ablation. The fellow eye was managed conventionally, and either treated at threshold ROP or observed if threshold was never reached. In patients with asymmetrical disease, the high‐risk, prethreshold eye was randomised to earlier treatment or to conventional management. At 2 years of age, children were examined comprehensively by certified ophthalmologists to determine structural outcomes for their eyes. For the purposes of this study, an unfavourable structural outcome was defined as (1) a posterior retinal fold involving the macula, (2) a retinal detachment involving the macula or (3) retrolental tissue or “mass” obscuring the view of the posterior pole. Results of the 2‐year examination were compared with those from the 9 months examination. RESULTS: Data were available on 339 of 374 (90.6%) surviving children. Unfavourable structural outcomes were reduced from 15.4% in conventionally managed eyes to 9.1% in earlier‐treated eyes (p = 0.002) at 2 years of age. Ophthalmic side effects (excluding retinal structure) from the ROP or its treatment were similar in the earlier‐treated eyes and the conventionally managed eyes. CONCLUSION: The benefit of earlier treatment of high‐risk prethreshold ROP on retinal structure endures to 2 years of age, and is not counterbalanced by any known side effect caused by earlier intervention. Earlier treatment improves the chance for long‐term favourable retinal structural outcome in eyes with high‐risk prethreshold ROP. Long‐term follow‐up is planned to determine structural and functional outcomes at 6 years of age