Abstract
Methods This audit was conducted in a UK ophthalmology department and included 48 eyes of 42 patients. Surgery was performed during 2019 in patients with 2.50 diopters (D) or more corneal astigmatism. Anterior keratometry readings were used to determine the toric IOL power. Vector analysis using the Alpins method was used to assess changes in astigmatism pre to postoperatively. Results There were 18 right and 26 left eyes included. In terms of gender, 61% of patients were female and 39% were male. The mean (±standard deviation (SD)) age was 70 (±11) years. The mean (±SD) axial length, K1, K2, and delta K was 23.55 (±1.4) mm, 42.71 (±1.39) D, 45.78 (±1.60) D, and 3.01 (±0.89) D, respectively. Postoperatively, the median spherical, cylinder, and spherical equivalent refraction was 0.00 D, −1.00 D, and 0.00 D, respectively. Postoperatively, 41% of the eyes had ≤0.50 D of spectacle astigmatism and 80% had ≤1.00 D. No patient required a secondary procedure to reposition the IOL from rotation. In vector analysis with the use of polar diagrams, there was a tendency for overcorrection of with-the-rule astigmatism and undercorrection of against-the-rule astigmatism. Conclusions Significant reductions in astigmatism can be achieved with the use of toric IOLs in patients undergoing cataract surgery. Further improvements may be possible with surgeon-specific determination of their surgically induced astigmatism and flattening effect from the main corneal incision. Furthermore, the use of an optical biometer that directly measures the posterior corneal curvature and permits automatic toric IOL power determination with modern formulas avoiding the need for manual data entry may reduce the risk of human error and improve visual and refractive outcomes.
Highlights
Cataract surgery is one of the most commonly performed operations in the NHS [1]
Phacoemulsification is almost universally the technique employed to remove the cataract, and following this, an intraocular lens (IOL) is implanted into the remaining capsular bag [2]. e power of this lens is accurately determined with the use of ocular biometry, a device which measures the axial length of the eye and curvature of the cornea [3]. ese parameters, as well as other parameters can use via various formulas to determine the optimal IOL power for an individual eye for the desired refractive outcome [4]
Four eyes were excluded from the analysis due to 2 eyes received a different toric IOL manufacturer and 2 eyes had missing pre or postoperative data. e Barrett toric formula was used to calculate the required IOL power using the anterior K-readings [13]
Summary
E power of this lens is accurately determined with the use of ocular biometry, a device which measures the axial length of the eye and curvature of the cornea [3]. In patients with astigmatism, where the refractive power of the eye is most in one direction and least 90 degrees away, a standard monofocal IOL is unable to correct both powers. In such situations, the residual astigmatism causes reduced uncorrected visual acuity [5]. Incisional techniques may be used at the time of cataract surgery to induce changes in the curvature of the cornea in an attempt to reduce corneal astigmatism. Incisional techniques may be used at the time of cataract surgery to induce changes in the curvature of the cornea in an attempt to reduce corneal astigmatism. is is based on the coupling effect, a term to describe the ratio of the flattening of the principal (steeper) meridian to the steepening of the flatter meridian with corneal incisions [6]
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