Posters

Biomechanical and tomographic corneal evaluation in high myopia after correction with iris-fixated phakic intraocular lens implantation

Poster Details

First Author: I.Almeida PORTUGAL

Co Author(s):    P. Neves   L. Dias   A. da Silva   J. Gonzalez-Meijome   J. Salgado Borges  

Abstract Details

Purpose:

Knowledge of corneal biomechanics is essential to understand the behavior of the cornea in certain corneal diseases, surgical procedures, and intraocular pressure (IOP) measurements. The authors pretend to analyze the changes in anterior chamber dimensions and biomechanical corneal properties after implantation of an iris fixated phakic intra-ocular lens (PIOL) for high myopia.

Setting:

Department of Ophthalmology - Hospital de S. Sebastião - CHEDV, Sta. Maria da Feira, Portugal

Methods:

A retrospective cohort of 34 eyes with high myopia undergone uneventful iris fixated PIOL implantation to correct high myopia (Veriflex, AMO, Santa Ana, CA). All patients were evaluated with Pentacam® and Corvis® ST (Oculus, Wetzlar, Germany) in random order in the same session, between 1 and 3 months after surgery. Biomechanical corneal properties were evaluated after PIOL implantation and compared against a control population of healthy young eyes. Central corneal thickness and thinnest point as well as several parameters of the anterior chamber dimensions were measured prior and after PIOL implantation with Pentacam® in 22 of these operated patients. Considering the normal distribution of data, comparisons were performed using independent sample T-test for statistical analysis.

Results:

Mean patient age was 38.6 ±7.3 years and the power of the mean power of the implanted PIOL was 11.02±3.2 diopters. Corvis® ST IOP measurements were not significantly different between the PIOL group (IOP: 16,00±1,47 mm Hg) and the control group (IOP:15,49±1,44 mm Hg) (p>0,05); comparison of biomechanical characteristics between the 2 groups showed a small, but statistically significant reduction in three applanation features, A1 length, A1 velocity and A2 time, and in the highest concavity reached and the distance between the 2 non-deformed peaks (p<0.05). Tomographic Pentacam® evaluation documented a preoperative anterior chamber volume of 220.19±39.05 mm3 and an anterior chamber depth of 3.34±0.37 mm; both significantly decrease to 205.67±31.80 mm3 and to 3.34±0.35 mm, respectively after surgery (p<0,05). Central corneal thickness and thinnest point did not change after surgery (p>0.05).

Conclusions:

This pilot study shows corneal biomechanical features modification after iris fixated PIOL implantation besides relatively minor changes in tomographic parameters. The biomechanical changes suggest a delay in the applanation times and applanation length that should be further investigated in larger cohorts and for longer periods of time. FINANCIAL INTEREST: NONE