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The influence of implant design on accuracy of postoperative refraction
S P B Percival1, A V Vyas, S S Setty
1Department of Ophthalmology, Scarborough District Hospital, Scarborough YO12 6QL, UK. spbpercival@yahoo.co.uk
Purpose:
To assess the degree of accuracy of postoperative refraction that may be achieved with modern techniques and a new lens of modern design.
Methods:
Five hundred eyes underwent refraction at one week and one month following phacoemulsification and implantation of the Centerflex lens (Rayner Intraocular Lenses Ltd style 570H). Results were compared with the target that had been computerised at the time of surgery, using the Hoffer Q formula for axial lengths less than 22.0 mm, the SRK-T for lengths greater than 24.5 mm and a mean of the two formulae for lengths between 22.0 and 24.5 mm. Statistical analysis used Fisher's exact and one way ANOVA tests.
Results:
At one month 97% of refractions were within 1.0 D spherical equivalent (SE) of target and 81% within 0.5 SE. The mean absolute error was 0.37 +/- 0.39 SD. 75.8% of all eyes achieved 6/12 unaided and 88.6% achieved 6/9 with correction. In only 1.2% the refraction between one week and one month had altered by 0.5 D or more.
Conclusions:
The Centerflex when combined with modern methods of power calculation, can be associated with a high degree of accuracy in postoperative refraction.