A 72-year-old woman from Mumbai undergoes phacoemulsification for a mature cataract in her right eye. Intraoperative biometry shows axial length 22.8 mm and keratometry 43.5 D. The surgeon selects an IOL power of +22.0 D targeting emmetropia. On postoperative day 1, the patient has uncorrected visual acuity of 6/9 and manifest refraction shows +1.50 D sphere with 6/6 vision. The posterior capsule is intact and the IOL is well-centered. What is the most likely explanation for this refractive outcome, and what is the recommended management?