Posters

Evaluation of white-to-white distance and anterior chamber depth measurements using IOLMaster, Sl-OCT and digital photographs in phakic eyes

Poster Details

First Author: M.Wilczynski POLAND

Co Author(s):    A. Pospiech-Zabierek              

Abstract Details

Purpose:

The purpose was to evaluate prospectively white-to-white (WTW) distance using IOL Master and compare these values with internal anterior chamber diameter using Sl-OCT and WTW distance measured using digital photography in healthy phakic eyes, as well as to compare anterior chamber depth (ACD) measurements done using IOL Master with measurements done using Sl-OCT.

Setting:

Department of Ophthalmology, Medical University of Lodz, Poland.

Methods:

The analyzed data were gathered prospectively from a non-randomized consecutive series of phakic patients. The examined group consisted of 46 eyes of 39 patients, mean age 74.6 years. All measurements were done in the 3 o'clock and 9 o'clock meridian. WTW diameter was measured using IOL Master device (Zeiss), internal anterior chamber diameter measurements were performed between two iridocorneal angles, with the slit-lamp adapted OCT of the anterior segment of the eye (Sl-OCT) with standard software which enables performing accurate measurements on scans using digital calipers. WTW diameter was also measured on a digital photograph of the anterior segment of the eye taken using a slit lamp with a digital camera. Anterior chamber depth (ACD) was measured using IOL Master with automatic mode, as well as with SL-OCT. Statistical analysis was performed using parametric tests. A Bland-Altman plot was drawn to show the level of agreement between the evaluated methods.

Results:

Values of white-to-white diameter measured by IOL Master were compared with values obtained by Sl-OCT examination and the slit lamp digital photography. Mean WTW diameter measured using IOL Master was 11.8 ±0.40 mm, mean internal AC diameter measured using Sl-OCT was 11.34 ±0.54 mm and mean WTW diameter measured using digital photographs was 11.29 ±0.58 mm A significant difference in mean WTW measurements done with IOL Master and Sl-OCT was found (p<0.01), as well as between measurements done with IOL Master and digital photograph (p<0.01). There was no difference of measurements between Sl-OCT and digital photograph (p>0.05). Values obtained with these methods were significantly correlated (Spearman p<0.001). Values of anterior chamber depth measured by IOL Master was compared with values obtained with Sl-OCT examination. Mean ACD measured by IOL Master was 2.99 ±0.50 mm and mean ACD measured using Sl-OCT was 2.56 ±0.46 mm. The difference was statistically significant (p<0.001). These values were significantly correlated (Spearman p<0.001).

Conclusions:

It is critical to know the internal diameter and the depth of the anterior chamber for implantation of anterior chamber intraocular lenses, including phakic lenses. Automatic measurements of IOL Master yield constantly higher values than measurements based on direct visualization of the eye, i.e. Sl-OCT and digital photographs. In order to obtain precise measurements of internal AC diameter and AC depth, a method of direct visualization of the intraocular structures should be preferred. FINANCIAL INTEREST: NONE