Correlation of Nidek OPD-Scan objective refraction with subjective refraction.
OBJECTIVE
The aim of this study was to quantify how closely the Nidek OPD-Scan objective refraction correlated with subjective refraction.


METHODS
A retrospective audit of the preoperative refraction of 80 myopic and myopic astigmatic eyes before laser in situ keratomileusis (LASIK) or laser supepithelial keratomileusis (LASEK) was performed. Objective refraction in the 5-mm zone was performed using a Nidek OPD-Scan. Subjective refraction was performed by a senior optometrist. Statistical analysis of sphere, cylinder, and spherical equivalent refraction measurements was then performed.


RESULTS
Spherical measurements correlated well with a linear regression equation, with a correlation coefficient of 0.97. Cylinder measurements correlated less well, with a correlation coefficient of 0.85. Spherical equivalent refraction measurements correlated well, with a correlation coefficient of 0.97. Analyzing the numerical difference between each objective refraction and its corresponding subjective refraction, the majority of values were only 0.50 D apart for sphere, cylinder, and spherical equivalent refraction.


CONCLUSIONS
There was good correlation between objective OPD-Scan and subjective refraction, especially for sphere and spherical equivalent refraction measurements, with regression gradients and correlation coefficients close to 1.
Yeung
Ian Y L
IY
Midland Eye Institute, West Midlands, UK.
Mantry
Sanjay
S
Cunliffe
Ian A
IA
Benson
Mark T
MT
Shah
Sunil
S
D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted / Q000379:methods*; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies