Original article
Accuracy of Intraocular Lens Power Calculation Formulae in Children Less Than Two Years

https://doi.org/10.1016/j.ajo.2011.11.031Get rights and content

Purpose

To assess the accuracy of IOL power calculation formulae in children less than 2 years of age.

Design

Retrospective, comparative study, comprising of 128 eyes of 84 children.

Methods

We analyzed records of children less than 2 years with congenital cataract who underwent primary IOL implantation. Data were analyzed for prediction error using the 4 commonly used IOL power calculation formulae. We calculated the absolute prediction error with each of the formulae and the formula that gave least variability was determined. The formula that gave the best prediction error was determined.

Results

Mean age at surgery was 11.7 ± 6.2 months. Absolute prediction error was found to be 2.27 ± 1.69 diopters (D) with SRK II, 3.23 ± 2.24 D with SRK T, 3.62 ± 2.42 D with Holladay, and 4.61 ± 3.12 D with Hoffer Q. The number of eyes with absolute prediction error within 0.5 D was 27 (21.1%) with SRK II, 8 (6.3%) with SRK T, 12 (9.4%) with Holladay, and 5 (3.9%) with Hoffer Q. Comparison between different formulae showed that the absolute prediction error with SRK II formula was significantly better than with other formulae (P < .001). Prediction error with SRK II formula was not affected by any factor such as age (P = .31), keratometry (P = .32), and axial length (P = .27) of the patient. Axial length influenced the absolute prediction error with Holladay (P = .05) and Hoffer Q formulae (P = .002). Mean keratometry influenced prediction error (P = .03) with SRK T formula.

Conclusion

Although absolute prediction error tends to remain high with all present IOL power calculation formulae, SRK II was the most predictable formula in our series.

Section snippets

Materials and Methods

We retrospectively analyzed the records of all children less than 2 years of age who had undergone cataract surgery with primary IOL implantation at our institute between January 1, 2006 and December 2007. We included the patients with a minimum follow-up of 4 weeks. We excluded cases with history of ocular trauma, sulcus fixated IOLs, and evidence of any ocular or systemic abnormality.

Preoperatively, a detailed history and complete ocular examination was done for all children.

Results

During this period, 135 eyes of 88 children with congenital/developmental cataract underwent surgery with primary IOL implantation (phaco-aspiration/lens aspiration with primary posterior capsulotomy with posterior chamber IOL). Of these, we included 128 eyes of 84 children aged below 2 years (4–98 weeks) with a minimum of 6 weeks follow-up. Seven eyes were excluded as a result of insufficient follow-up.

There were 43 girls and 41 boys. The mean (± SD) age at surgery was 11.7 months (range:

Discussion

Modern-day cataract surgery aims at minimizing the postoperative refractive error. In adults, it is generally accepted that less than 5% of the patients have a refractive surprise following an IOL implantation.17, 18 Newer studies have proposed the accuracy to be 99.9% within ±2.00 D of predicted refraction.19, 20 However, the prediction error in pediatric eyes remains much larger.

In adults, regression formulae such as SRK and SRK II have been shown to be less predictable than the theoretical

Ramesh Kekunnaya, MD, FRCS, is an Associate Professor at Jasti V Ramanamma Children's Eye care Centre at LV Prasad Eye Institute, KAR campus, Hyderabad, India. He completed a fellowship training at L V Prasad Eye Institute followed by a Pediatric Ophthalmology and Strabismus Fellowship (AAPOS accredited) at Jules Stein Eye Institute, University of California, Los Angeles, USA. Dr Kekunnaya is a member of the American Academy for Pediatric Ophthalmology and Strabismus (AAPOS) and AAO. His areas

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    Ramesh Kekunnaya, MD, FRCS, is an Associate Professor at Jasti V Ramanamma Children's Eye care Centre at LV Prasad Eye Institute, KAR campus, Hyderabad, India. He completed a fellowship training at L V Prasad Eye Institute followed by a Pediatric Ophthalmology and Strabismus Fellowship (AAPOS accredited) at Jules Stein Eye Institute, University of California, Los Angeles, USA. Dr Kekunnaya is a member of the American Academy for Pediatric Ophthalmology and Strabismus (AAPOS) and AAO. His areas of keen interest are pediatric cataract, complex strabismus, vision development and neuro-opthalmogical disorders. He has authored publications in various peer-reviewed journals, book chapters and is a reviewer for many indexed journals.

    Amit Gupta, MS, DNB, is currently a consultant at Jasti V Ramanamma Children's Eye care Centre, LV Prasad Eye Institute, KAR campus, Hyderabad, India. He completed a fellowship in Pediatric Ophthalmology at L V Prasad Eye Institute. His areas of keen interest are amblyopia, paediatric cataract, complex strabismus, retinopathy of premarurity, paediatric lid disorders and neuro-opthalmogical disorders. Dr Gupta has authored publications in various peer-reviewed journals and is a reviewer for British Journal of Ophthalmology, JPOS, and JAAPOS.

    See Accompanying Editorial on page 1.

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