COMPARISON OF MEAN AGE AND DENSITOMETRY IN THE CATARACT ONSET IN PATIENTS WITH PREVIOUS REFRACTIVE LASER REFRACTIVE SURGERY (LASIK).

To compare the mean age and refractive outcomes in the cataract onset between patients with previous laser in situ keratomileusis (LASIK). 

UVEG Cátedra Alcon- University of Valencia. FISABIO Medical Ophthalmology. 

This prospective comparative study enroled patients from FISABIO Medical Ophthalmology (FOM). Each patient went through an exhaustive ophthalmologic and optometric evaluation. The sample comprised 211 subjects with senile cataracts, with LOCSIII grades from N2 to N4. The control group comprised 180 eyes, and the experimental group with previous LASIK had 31 eyes. Abnormal axial lengths, anterior chamber depths above 4mm and previous ocular and systemic pathological condition were excluded from the study. The data collected were endothelial cell density and corneal thickness (CT) using Nidek CEM-530 (Nidek CO., LTD; Japan). Horizontal and vertical densitometry (D_180º, D_90º) were determined using Pentacam® (Oculus Optikgeräte GmbH, Germany). Axial length and anterior chamber depth (AXL_IOL, ACD_IOL) were measured with IOL Master 700 biometer (Carl Zeiss Meditec AG, Germany). Subjective refraction and best corrected visual acuity (BCVA) were also measured before and 1 month after surgery. Refraction was conversed from spherocylindrical to vectorial components (M, J₀, J₄₅)¹. This study included eyes of patients scheduled to have manual phacoemulsification technique to develop the cataract surgery. 

The variables compared in the analysis were the age, endothelial cell parameters, CT, D_180º, D_90º, AXL_IOL, ACD_IOL, D_180º and D_90º before phacoemulsification. M, J₀, J₄₅ and BCVA were compared also after surgery. The Kolmogorov-Smirnov normality test revealed that the samples followed a non-parametric distribution (p<0,05). U Mann-Whitney’s test for independent samples revealed significant differences between both groups before phacoemulsification in the age (z=4,677, p<0.001) and D_90º (z=2.639, p=0.008). The post-surgery analysis revealed significant differences in M (z=2.074, p=0.038) and J₄₅ (z=2.118, p=0.034). Spearman’s Rho correlation confirms that D_180º and D_90º is related to age (r=0.260, p<0.001; r=0.282, p<0.001; respectively) and J₀(r=-0.236, p<0.001 and r=-0.190, p<0.006).

Experimental group had shown an early development of cataracts that some authors attribute to high AXLs.^(1–3) However, AXL and ACD were limited and yet the results show a lower mean age on the cataract onset in the experimental group. Corneal ablation during LASIK have a direct impact in the UV absorption capacity yielding to an early cataract onset.^(4–6) On the other hand, transparency was different between both groups, showing lower values for the experimental group due to the age discrepancy between the samples⁽⁵⁾, although this was only significant for the vertical meridian. Finally, refractive outcomes are more negative in the experimental group which can be explained by the miscalculation of the IOL and the changes in the refractive index after LASIK.^(1,7)