Incision-induced astigmatic changes in eyes undergoing simultaneous phakic intraocular lens explantation and...

Area of Science:

• Ophthalmology
• Refractive Surgery
• Corneal Physiology

Background:

• Bilensectomy, involving simultaneous phakic intraocular lens (pIOL) explantation and cataract surgery, is a complex procedure.
• Understanding surgically-induced astigmatism (SIA) is crucial for refractive outcomes, especially when considering toric intraocular lens implantation.
• Corneal and scleral incision approaches may influence SIA differently.

Purpose of the Study:

• To compare SIA between corneal and scleral incision approaches during bilensectomy with pIOL explantation and femtosecond laser-assisted cataract surgery.
• To evaluate the variability of SIA using both anterior corneal curvature (SimK) and total corneal refractive power (TCRP) measurements.

Main Methods:

• Retrospective analysis of 41 eyes undergoing bilensectomy with pIOL explantation.
• Corneal explantation (C-Ex) via a 2.2-2.6 mm incision for soft pIOLs.
• Scleral explantation (S-Ex) via a 6-mm incision for rigid pIOLs.
• Scheimpflug-based tomography for SimK and TCRP assessment preoperatively and 3 months postoperatively.
• Vector analysis of SIA using difference vectors and confidence ellipses.

Main Results:

• Mean absolute SIA was 0.47±0.32 D (SimK) and 0.53±0.38 D (TCRP), with no significant difference between incision types (p=0.998).
• TCRP demonstrated greater SIA variability (CE 95%: 1.72 D²) compared to SimK (CE 95%: 1.22 D²).
• Astigmatic outcomes were comparable between C-Ex and S-Ex groups for soft pIOLs at 3 months.

Conclusions:

• SIA magnitudes are similar between corneal and scleral incision approaches in bilensectomy.
• TCRP measurements reveal higher SIA variability than SimK, necessitating careful consideration.
• Significant steep meridian shifts occur post-bilensectomy, impacting toric intraocular lens selection and placement.