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Evaluating biometric outcomes in cataract surgery using subjective refraction and aberrometric refraction

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First Author: E.Neves PORTUGAL

Co Author(s):    M. Raimundo   C. Saraiva   J. Simão   A. Rosa   C. Lobo   J. Murta     

Abstract Details

Purpose:

Subjective refraction is the natural refractive outcome evaluated in modern cataract surgery. However, it is, by definition, subjective and may be a source of noise that is difficult to remove and control for when evaluating biometric outcomes. Some raytracing wavefront devices can derive spherocylindrical refraction from whole-eye aberrometry and may be able to estimate post-operative refractive error in a less patient- and operator-dependent way. In this work we compare both techniques for post-operative refractive evaluation following cataract surgery.

Setting:

Tertiary public academic hospital.

Methods:

Prospective study including consecutive eyes submitted to uncomplicated cataract surgery with implantation of an Alcon AcrySof SN60AT intraocular lens. All patients underwent optical biometry (Allegro Biograph) and the post-operative spherical equivalent (SE) was estimated using the Barrett Universal II and Kane formulas. Post-operative subjective refraction (targeting red equal to green in duochrome test) was obtained from 6-12 weeks post-operatively. Same day aberrometric refraction (average of two measurements) was obtained in mesopic undilated conditions using the Tracey iTrace device. Prediction errors for both formulas were obtained by subtracting the pre-operative SE estimation from the post-operative SE using both techniques.

Results:

Twenty-four eyes were included. While postoperative sphere was similar using both techniques (0.03 ± 0.38D vs 0.09 ± 0.26D, p=0.440), measured cylinder was significantly lower in subjective refraction (-0.57 ± 0.31D vs -0.86 ± 0.44D, p=0.014). Post-operative subjective SE was slightly but significantly smaller than aberrometric SE (-0.21 ± 0.27D vs -0.38 ± 0.30D, p=0.029), which can be explained by the higher measured aberrometric cylinder Mean prediction errors for both formulas were higher using subjective refraction (Barrett: 0.410 ± 0.288D vs 0.230 ± 0.206D; Kane: 0.471 ± 0.313D vs 0.291 ± 0.285D; both p=0.029).

Conclusions:

In this exploratory study, we propose that aberrometric refraction could be used as an easy to obtain, operator and patient-independent supplementary outcome measure for evaluating biometric prediction errors and refractive outcomes following cataract surgery. Differences found between methods suggest that aberrometric refraction may better approximate preoperative predictions from modern formulas.

Financial Disclosure:

... gains financially from competing product or procedure, ... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... receives non-monetary benefits from a company producing, developing or supplying the product or procedure presented, ... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, ... is employed by a competing company, ... has significant investment interest in a company producing, developing or supplying product or procedure presented