Change in Axial Length Pre and Post Cataract Surgery Measured with IOL Master

Objective: Cataract surgery with intraocular lens (IOL) implantation tries to get a refractive result nearby to the optic emmetropia. So an accurate IOL power calculation is mandatory, and axial length (AL) measurement is one of the most influential parameter in this calculation. IOL Master is one of the most popular devices to measure AL, which uses the same group refractive index of the lens for all patients, independently of the cataract grade. But lens refractive index is higher as cataract grade increases. Nowadays cataract tends to be operated earlier, so moderate cataracts are the most extracted in clinical practice. Therefore, it is important to study the influence of moderate lens opacity in AL measurements. The objective of this study was to compare the AL value measures with IOL Master, before and after uncomplicated cataract surgery in patients with moderate cataracts. Material and methods: This study included 153 eyes of 105 patients (67.51 ± 13.56 years old) undergoing uncomplicated cataract surgery. Lens opacity was determined with the LOCSIII scale and AL was measured using optical biometry (IOL Master; Carl Zeiss Meditec) before and one month after intervention. Intraoperative measurements (ultrasound time and fluid volume) were also registered. Results: Mean preoperative AL of 25.10 ± 3.19 mm (range 20.54 to 36.06; IC95% 24.59 to 25.60 mm) and postoperative of 24.88 ± 3.16 mm (IC 95% 24.37 to 25.39; range 20.43 to 35.79 mm). The mean AL difference before and after surgery was 0.19 ± 0.05 mm (p=0.549 ANOVA) with agreement limits from 0.09 to 0.29 mm. It was observed more difference in eyes with larger AL (r2=0.14 p<0.01). The average cataract grade in each category was: nuclear opacity 2.25 ± 1.00 (range 1 to 5) (p=0.564 ANCOVA), cortical opacity 2.04 ± 0.73 (range 0 to 4) (p=0.543 ANCOVA), posterior subcapsular opacity 0.44 ± 0.90 (range 0 to 4) (p=0.563 ANCOVA), and nuclear color 2.40 ± 1.05 (range 0 to 5) (p=0.558 ANCOVA), without statistical significant effect in the AL difference pre and after cataract surgery. The ultrasound time used during the surgery was 43 ± 29 seconds (p=0.525 ANCOVA) and the fluid volume was 4.73 ± 1.31 (p=0.560 ANCOVA) cubic centimeters without statistically significant relationship between these parameters and the difference in the AL measurement. Conclusions: The difference in AL measurement with IOL Master before and after cataract surgery in eyes with low grade of cataract should be related with IOL Master reproducibility especially in extreme-long eyes. Moderate cataract showed non-statistically effect on AL measurement with IOL Master biometry.