The effect of cataract surgery on the refractive index of the cornea estimated by optical pachymetry

Session Details

Session Title: Presented Poster Session: Imaging

Venue: Poster Village: Pod 3

First Author: : L.Tutchenko UKRAINE

Co Author(s): :    S. Patel   O. Horak   V. Sanin   S. Kosuba              

Abstract Details

Purpose:

To evaluate the refractive index of the central cornea (RI) along the antero-posterior direction before and after routine phacoemulsification using a modification of traditional optical pachymetry.

Setting:

Department of Ophthalmology, Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine; Kyiv City Clinical Ophthalmological Hospital “Eye Microsurgery Center”, Ukraine

Methods:

Using two optical setups for a standard optical pachymeter the ratio of observed optical section widths (OSW) is a function of RI. Corneal RI could be estimated following calibration equating OSW ratios with known refractive index values. OSW was measured by two independent observers on cases (n=31) before and after routine uncomplicated phacoemulsification.

Results:

Mean(±sd) corneal RI values for observer 1 and 2 were respectively I) preop, 1.426±0.004 & 1.424±0.004 II) postop, 1.427±0.004 & 1.426±0.003. Inter-observer differences were not significant (p>0.05). Differences between these pre- and postop values were significant only according to observer 2 significant (p=0.026). A significant association was revealed between the change in estimated RI (ΔRI) and pre-op estimated RI (x). The equation of the least squares regression line linking ΔRI with the RI were of the form: For Observer 1, ΔRI = 0.844x-1.203 (r=0.694, n=31, p=<0.001). For Observer 2, ΔRI = 0.755x-1.108 (r=0.681, n=31, p=<0.001).

Conclusions:

The refractive index of the human cornea along the antero-posterior axis estimated non-invasively using a modified application of traditional optical pachymetry yielded results higher compared with contemporaneous values. There is no real change in the average RI following surgery. However, for individual cases the change in RI depended on the RI prior to surgery.

Financial Disclosure:

None