Biometry of the silicone oil-filled eye: II

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optics

Background:

• Phacoemulsification with intraocular lens (IOL) implantation can be combined with silicone oil removal in phakic eyes.
• Accurate axial length (AL) measurement is crucial for effective IOL power calculation.
• Silicone oil (1300 centistokes) increases the apparent AL, necessitating a conversion factor for accurate biometry.

Purpose of the Study:

• To evaluate the clinical efficacy of a 0.71 conversion factor for estimating true axial length (AL) in silicone oil-filled eyes.
• To assess the accuracy of intraocular lens (IOL) power calculation using this conversion factor in conjunction with the SRK/T formula.
• To compare refractive outcomes based on IOL placement (capsular bag vs. ciliary sulcus).

Main Methods:

• Eleven patients undergoing combined silicone oil removal and phacoemulsification with IOL implantation were studied.
• Patients were divided into two groups: capsular bag IOL placement (Group 1) and ciliary sulcus IOL placement (Group 2).
• Measured AL (MAL) in silicone oil-filled eyes was converted to calculated AL (CAL) using the 0.71 factor; IOL power was calculated using SRK/T, and postoperative refractive error was compared to predicted error.

Main Results:

• The mean refractive prediction error was 0.74 D (SD 0.75 D) for capsular bag IOL placement (Group 1).
• The mean refractive prediction error was 1.31 D (SD 1.4 D) for ciliary sulcus IOL placement (Group 2).
• The 0.71 conversion factor demonstrated effectiveness in correcting for silicone oil's effect on AL.

Conclusions:

• The 0.71 conversion factor accurately corrects for the increased AL caused by 1300 centistokes silicone oil.
• Accurate IOL power prediction is achievable in eyes undergoing combined cataract surgery and silicone oil removal.
• Capsular bag IOL implantation provides more predictable refractive results compared to ciliary sulcus placement.