Evaluation of biometric methods for measuring the anterior chamber depth in the non-contact mode.
OBJECTIVE
High-resolution biometry of the anterior ocular segment is now becoming more and more important against a background of refractive surgery and the evaluation of potentially accommodative lens replacement materials. The aim of this study was a systematic investigation of the currently available non-contact methods for measuring the anterior chamber depth (ACD).


METHODS
The ACDs of 50 phakic eyes of 27 patients aged between 19 and 59 years were measured with the IOL-Master (Zeiss), the AC-Master (Zeiss), the Pentacam (Oculus) and slit-lamp pachymetry by Jaeger (Haag-Streit).


RESULTS
The median anterior chamber depth in the investigated eyes was 3.63 mm for the IOL-Master (minimum 2.88 mm, maximum 4.22 mm), 3.802 mm for the AC-Master (2.816 mm-4.373 mm), 3.915 mm for the Pentacam (minimum 2.994 mm, maximum 4.614 mm) and 3.75 mm for Jaeger (2.887 mm-4.29 mm). With a probability of error of alpha=0.05 there were no significant differences concerning the ACD between the methods of Jaeger and AC-Master, Jaeger and IOL-Master, or Pentacam and AC-Master (Wilcoxon and Wilcox). The intra-individual variability was +/-5.4 microm for AC-Master, +/-12.7 microm for Pentacam, +/-24.5 microm for IOL-Master and +/-41.2 microm for Jaeger. The maximum method-dependent difference in ACD determination was 285 microm.


CONCLUSIONS
All the methods allow non-contact biometry, but the results might differ due to measuring principles inherent to the system, experience of the examiner and compliance of the patient. Partial coherence interferometry with the AC-Master offers the advantage of measurement exactly along the optical axis with the highest reproducibility and patient compliance.
Meinhardt
B
B
Eye Clinic of the University of Rostock, Rostock, Germany.
Stachs
O
O
Stave
J
J
Beck
R
R
Guthoff
R
R
D000328:Adult; D000867:Anterior Chamber / Q000033:anatomy & histology*; D001699:Biometry / Q000379:methods*; D001837:Body Weights and Measures; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007908:Lens, Crystalline / Q000502:physiology; D008875:Middle Aged; D011446:Prospective Studies