Unexpected Refractive Results
Cataract surgery and IOL implantation can provide patients with desirable refractive outcomes. See Chapter 9 and BCSC Section 13, Refractive Surgery, for a discussion of cataract surgery as a refractive procedure.
Unintended postoperative refractive errors may be the result of a preoperative error in the measurement of axial length or in the keratometry readings. Choosing the correct IOL power is difficult in patients with high hyperopia, high myopia, or prior vitrectomy; patients undergoing simultaneous penetrating keratoplasty; patients with silicone oil in the vitreous cavity; and patients who have had prior refractive surgery (see Chapter 6). The surgeon’s failure to confirm the proper IOL at the time of surgery may result in implantation of an incorrect lens.
Unexpected postoperative refractive results may be due to inversion of an angulated IOL or placement of the lens in the sulcus when it was calculated for placement in the capsular bag, either of which results in anterior displacement and changes the effective power of the IOL. It is important to address other potential causes of an anterior or posterior shift in IOL position, such as posterior capsule rupture, capsular block, or malignant glaucoma. Mislabeling or manufacturing defects are the cause of these problems only in rare cases. If the visual acuity is less than expected early in the postoperative course and is confirmed by refraction, incorrect lens power may be suspected. Regardless of the source of the error, medical record documentation and full disclosure to the patient are necessary.
If the magnitude of the postoperative refractive error produces symptomatic ametropia, anisometropia, or patient dissatisfaction, the surgeon can consider several options:
refraction for glasses or contact lens wear
insertion of a piggyback IOL
secondary keratorefractive procedure
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.