Porównanie kontaktowej metody pomiaru długości gałki ocznej z metodą immersyjną
Comparision of Contact and Immersion Techniques for Axial Length Measurement
Marcin Jezierski, Marek Prost, Jarosław Kuliński, Karol Stasiak, Michał Szot
Klinika Okulistyczna Wojskowego Instytutu Medycyny Lotniczej w Warszawie Kierownik: prof. dr hab. n. med. Marek E. Prost
Summary: Purpose: To calculate IOL power usually A-scan ultrasound technique is used. The aim of the study was to evaluate the results of axial length measurements obtained with contact and immersion technique and to assess the accuracy of these methods. Material and Methods: One hundred and forty five eyes were measured by both methods using ultrasound device Ocu Scan Rxp ALCON, done by one investigator. We measured the correction for the best corrected visual acuity two months after surgery. The differences between this correction and expected correction determined before surgery were defined as the mean refractive error. The magnitude of this error was used to evaluate the accuracy of the both methods. Results: The mean axial length was found to be 23.05 mm with the contact technique and 23.28 mm with the immersion technique. The mean anterior chamber depth measured by contact method was 3.15 mm and by immersion technique was 3.28 mm. The mean thickness of the lens was also different; with the contact technique was 4.61 mm, with immersion method was 4.68 mm. The mean standard deviation between repeated measurements of the same eye was smaller with the immersion technique (0.071) than with the contact technique (0.087). The mean refractive error was found to be 0.76 Dsph using the contact method. The mean refractive error was 0.53 Dsph when the immersion technique was used. Conclusions: The axial length was smaller with the contact technique. Shorter measurements produced stronger intraocular lens power by using the contact technique. Smaller mean refractive error and smaller mean standard deviation between repeated measurements of the same eye suggest, that the immersion method is more accurate than the contact method.