Differences

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--- calculating_contact_lens_power_aphakia [2026/07/22 13:11] – Scott Larson
+++ calculating_contact_lens_power_aphakia [2026/08/08 18:17] (current) – [References] Scott Larson
@@ Line 1: / Line 1: @@
 ====== Calculating Contact Lens Power In Aphakia ======
   * Primarily used with [[silsoft_contact_lenses|Silsoft Contact lenses]]
 ====Methods====
 ===Trivedi-Wilson (TW) Regression Formula===
- Contact Lens power = 84.4 -(3.2 x Axial Eye Length mm)
+$P = 84.4 - (3.2 \times AL)$
+  * P= Contact Lens Power
+  * AL = Axial Length in millimeters
+Go to the [[https://eyefixer.org/aphakic-contact-lens-power-calculator/|Calculator]]
 <WRAP round info 60%>
 The TW formula was derived from 50 eyes of infants who underwent cataract surgery before 1 year of age (mean age 2.4 months) using SilSoft silicone elastomer lenses. The R² was 0.82
 </WRAP>
-[[https://www.aao.org/education/editors-choice/guidelines-selecting-contact-lens-power-in-aphakic]]
-===SRK/T formula===
+===Aphakic Contact Lens (aCL) Formula===
+$P = \frac{1334}{Al} - 0.6685 \cdot K - 15.25 + Tr$
+  * P = contact lens power
+  * Al = axial eye length (mm)
+  * K = mean keratometry (D)
+  * Tr = desired target refraction (D)
+Go to the [[https://eyefixer.org/aphakic-contact-lens-power-calculator/|Calculator]]
+<WRAP round info 60%>
+Christoph Lwowski et. al. developed the **aCL formula**, and showed **median absolute prediction error of only 0.53 D**, comparable to retinoscopy (0.69 D) and substantially outperforming the TW formula (median AE 3.25 D) and the default +32 D lens (median AE 2.63 D). [3]
+</WRAP>
+===SRK/T formula ===
 [[srk|SRK/T formula]]
 Input the following:
@@ Line 16: / Line 34: @@
   * Keratometry readings
   * Axial Eye Length
-[[http://www.eyecalcs.com/WEBCALCS/IOLcalc3/IOL3.html|SRK/T at eyecalcs.com]]\\
+==SRK/T Calculators==
-[[https://eyecalc.org/srk-t/|SRK/T at EyeCalc.org]]
+  * [[http://www.eyecalcs.com/WEBCALCS/IOLcalc3/IOL3.html|SRK/T at eyecalcs.com]]
+  * [[https://eyecalc.org/srk-t/|SRK/T at EyeCalc.org]]
 <WRAP round info 60%>
 In the IATS cohort, using the SRK/T formula yielded a mean prediction error of −2.0 D and mean absolute PE of 2.9 D.
 </WRAP>
-===Aphakic Contact Lens (aCL) Formula===
-Contact lens power = (1334/Axial Length mm) - 0.6685 Mean Keratometry D -15.25 + Desired Target Refraction
-<WRAP round info 60%>
-Christoph Lwowski et al developed the **aCL formula**, and showed **median absolute prediction error of only 0.53 D**, comparable to retinoscopy (0.69 D) and substantially outperforming the TW formula (median AE 3.25 D) and the default +32 D lens (median AE 2.63 D). [3]
-</WRAP>
 ====References====
@@ Line 34: / Line 46: @@
   - [[https://pubmed.ncbi.nlm.nih.gov/23706701/|Selection of an Initial Contact Lens Power for Infantile Cataract Surgery Without Primary Intraocular Lens Implantation. Trivedi RH, Wilson ME. Ophthalmology. 2013;120(10):1973-6]]
   - [[https://pubmed.ncbi.nlm.nih.gov/24924278/|The Role of Preoperative Biometry in Selecting Initial Contact Lens Power in the Infant Aphakia Treatment Study. Trivedi RH, Lambert SR, Lynn MJ, Wilson ME. Journal of AAPOS : The Official Publication of the American Association for Pediatric Ophthalmology and Strabismus. 2014;18(3):251-4]]
-  - [[https://docs.eyefixer.org/Cataract/Silsoft%20Contact%20Lenses/Correction%20of%20aphakia%20using%20biometry%20based%20contact%20lens%20calculation.pdf|Correction of Aphakia Using Biometry-Based Contact Lens Calculation in Pediatric Cataract Extraction: Introducing the Aphakic Contact Lens Formula. Lwowski C, Kaiser KP, Wenner Y, et al. Graefe's Archive for Clinical and Experimental Ophthalmology = Albrecht Von Graefes Archiv Fur Klinische Und Experimentelle Ophthalmologie. 2026;:10.1007/s00417-026-07370-6]]
+  - [[https://docs.eyefixer.org/vault/Silsoft%20Contact%20Lenses/Correction%20of%20aphakia%20using%20biometry%20based%20contact%20lens%20calculation.pdf|Correction of Aphakia Using Biometry-Based Contact Lens Calculation in Pediatric Cataract Extraction: Introducing the Aphakic Contact Lens Formula. Lwowski C, Kaiser KP, Wenner Y, et al. Graefe's Archive for Clinical and Experimental Ophthalmology = Albrecht Von Graefes Archiv Fur Klinische Und Experimentelle Ophthalmologie. 2026;:10.1007/s00417-026-07370-6]]
   - [[https://pubmed.ncbi.nlm.nih.gov/31517738/|Rigid Gas-Permeable Contact Lenses Fitting Philosophy for Unilateral Aphakic Infants. Zhang X, Zeng J, Zhai Z, Li C, Yang X. Eye & Contact Lens. 2020;46(6):381-384]]
   - [[https://pubmed.ncbi.nlm.nih.gov/24011524/|Predictability of Intraocular Lens Power Calculation Formulae in Infantile Eyes With Unilateral Congenital Cataract: Results From the Infant Aphakia Treatment Study. Vanderveen DK, Trivedi RH, Nizam A, Lynn MJ, Lambert SR. American Journal of Ophthalmology. 2013;156(6):1252-1260.e2]]
   - [[https://pubmed.ncbi.nlm.nih.gov/34901049/|Accuracy of Intraocular Lens Power Calculation Formulas in Pediatric Cataract Patients: A Systematic Review and Meta-Analysis. Zhong Y, Yu Y, Li J, et al. Frontiers in Medicine. 2021;8:710492]]
   - [[https://pubmed.ncbi.nlm.nih.gov/29423513/|Association of Contact Lens Adherence With Visual Outcome in the Infant Aphakia Treatment Study. Cromelin CH, Drews-Botsch C, Russell B, Lambert SR, Infant Aphakia Treatment Study Group. JAMA Ophthalmology. 2018;136(3):279-285]]
+  - [[https://www.aao.org/education/editors-choice/guidelines-selecting-contact-lens-power-in-aphakic|AAO 2014 Guidelines for Selecting Contact Lens Power in Aphakic Infants]]