Post-penetrating keratoplasty astigmatism measured by Scheimpflug imaging, autorefractometer and subjective refraction

Poster Details

First Author: Z.Yalniz-Akkaya TURKEY

Co Author(s):    A. Burcu   E. Dogan   F. Ornek        

Abstract Details

Purpose:

The purpose of this study was to evaluate the astigmatism and flat axis measured by rotating Scheimpflug camera, auto refractometer and subjective refraction.

Setting:

Ankara Training and Research Hospital

Methods:

Sixty four penetrating keratoplasty eyes were included in the study. Rotating Scheimpflug imaging (Pentacam, PC), autorefractometry (Huvitz, AR) measurements were undertaken and subjective refraction (SR) was performed. The agreement characteristics were analyzed by MedCalc statistical software and descriptive statistics and other analyses were performed by SPSS software. Correlation which can be misleading was not used. Astigmatism and flat axis were the main outcome measures.

Results:

The median age was 36.0 years (min-max: 15-81). The mean SR, PC and AR astigmatisms were 3.5±1.7 D, 6.2±3.2 D and 5.2±2.3 D, respectively. The mean deference of astigmatism was 2.6±3.5 D (limits of agreement: - 9.4 D (95% CI, 7.9 -10.9 D) to 4.3 (95% CI, 2.8 to 5.8 D) for SR minus PC. The mean deference of astigmatism was 1.7±1.8 D [limits of agreement: - 5.4 D (95%, 4.5-6.1 D) to 1.9 (95%, CI, 2.9-10.0)] for SR minus AR. Thirteen (20.3%) patients had 1.00 D or less difference in astigmatism between SR and PC, 24 patients (37.5%) had 1.00 D or less difference in astigmatism between SR and AR (p=0.93). The mean SR, PC and AR axis were 87.0±49.5ŗ, 88.5±46.9ŗ and 88.5±49.3ŗ, respectively. SR minus PC was 21.1ŗ±20.3 and SR minus AR was 8.6ŗ±14.5. Twenty five (39.1%) patients had 10ŗ or less difference of astigmatism axis between SR and PC, 45 (70.3%) patients had 10ŗ or less difference of astigmatism axis between SR and AR. The difference between SR and AR was significantly lower than the difference between the SR and PC (p<0.001). In 25 patients the astigmatism axis determined by SR and AR were equal.

Conclusions:

Although 93% of the astigmatism measurements lie between the limits of agreement, the wide range of limitis for SR minus PC (-9.4 to 4.3 D) and for SR minus AR (-5.4 to 1.9 D) indicate poor agreement between PC and SR, and between AR and SR. Autorefractometer measurements of astigmatism axis were closer to the axis determined by the SR than the PC. According to this results it can be concluded that autorefractometer measurements can be a better starting point for subjective refraction. FINANCIAL DISCLOSURE?: No