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New applanation tonometer for myopic patients after laser refractive surgery

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First Author: M.Iglesias SPAIN

Co Author(s):    M. Iglesias   B. Kudsieh   F. Yebra   A. Laiseca   R. Barraquer        

Abstract Details

Purpose:

This study aims to assess the agreement of intraocular pressure (IOP) measurements between the Goldmann applanation tonometer (GAT), and a new experimental applanation tonometer – with a convexly shaped apex (CT) – after laser myopic refractive surgery.

Setting:

The study was carried out on myopic subjects that were going in for laser refractive surgery: laser assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) at the Barraquer Ophthalmology Center in Barcelona.

Methods:

Two different CT radii (CT1 and CT2) were designed with a finite element analyser, and a prospective double masked study on 102 eyes from 102 patients was carried out. A Bland-Altman plot and intra-class correlation coefficient (ICC) were calculated to assess the agreement between GAT measurements and the measurements of both CT1 and CT2 before and after myopic laser assisted in situ keratomileusis (LASIK; n=73) and photorefractive keratectomy (PRK; n=29). We evaluated a subset of two subgroups (n=36 each) for intra and inter-observer (IA/IE) error.

Results:

From the whole cohort, the best IOP agreement was observed between GATpre and CT1post surgery: 16.09 ± 2.92 vs 16.42 ± 2.87 (p<0.001); ICC = 0.675 (95% CI: 0.554 - 0.768). In the analysis of LASIK vs PRK, GATpre and CT1post showed the highest agreement, although LASIK measurements were more accurate than PRK, as the ICC = 0.718 (95% CI: 0.594 - 0.812) and ICC = 0.578 (95% CI: 0.182 - 0.795) respectively. Excellent agreement was observed for IA/IE, and there was an ICC>0.8 (95% CI) in all cases. CT1 proved more accurate in the LASIK subgroup.

Conclusions:

In conclusion, our new version of GAT could be used with post-surgery LASIK patients as a more accurate measurement device compared to the current reference tonometer.

Financial Disclosure:

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