Viewing Study NCT02513134



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Study NCT ID: NCT02513134
Status: COMPLETED
Last Update Posted: 2015-07-31
First Post: 2014-06-02

Brief Title: Intraocular Lens Power Calculation Using Pre- and Intra-operative Measurements
Sponsor: Prim Prof Dr Oliver Findl MBA
Organization: Vienna Institute for Research in Ocular Surgery

Study Overview

Official Title: Intraocular Lens Power Calculation Using Pre- and Intra-operative
Status: COMPLETED
Status Verified Date: 2015-07
Last Known Status: None
Delayed Posting: No
If Stopped, Why?: Not Stopped
Has Expanded Access: False
If Expanded Access, NCT#: N/A
Has Expanded Access, NCT# Status: N/A
Acronym: None
Brief Summary: Recently a prototype of a combination of an anterior segment OCT VISANTE Carl Zeiss Meditec AG and an operating microscope OPMI 200 Carl Zeiss Meditec AG was introduced that allows measurements of the crystalline lens as well as the lens capsule itself after removing the crystalline lens of cataract patients intra-operatively This device uses OCT technology to create high resolution B-scans images of the anterior segment of the eye The OCT was shown to be highly reproducible for ACD measurements pre-operatively 12 and small changes of the IOLcrystalline lens can be detected 13

In a previous study EK-10-125-0710 that was recently published in the journal Investigative Ophthalmology Visual Science it was shown that intra-operative measurements of the anterior lens capsule improve the refractive outcome theoretically14 However in this previous study conventional eye models were used for IOL power calculation and only the intra-operative measurement replaced pre-operative ACD measurements

Aim of this study is to observe whether the postoperative refractive outcome could be improved theoretically by using both pre- and intra-operative measurements for retrospective IOL power calculation with new eye models
Detailed Description: Since the introduction of optical biometry 1 IOLMaster Carl Zeiss Meditec AG Jena Germany as a reliable non-contact measurement of the axial eye length the influence of the error of axial length measurement on the refractive error decreased from over 50 when measured with applanation ultrasound to 36 The mean error of corneal power measurement is approximately 22 2 These results show that the estimation of the post-operative intra-ocular lens IOL position and therefore the estimated anterior chamber depth ACD is nowadays the main source of error 35 3 to 42 2 in IOL power calculation and therefore for the refractive outcome of the patients after cataract surgery Early IOL power calculation formulae such as the Binkhorst I formula 4 used a fixed ACD value to predict the position of the IOL but the refractive results were not appropriate because the post-operative position of the IOL varied significantly between patients Later observations showed a correlation between the axial eye length and the post-operative ACD longermore myopic eyes showed a larger ACD post-operatively 5 These correlations were taken into account in later developed formulas such as the Binkhorst II formula Olsen et al 6 measured the post-operative ACD and substituted the predicted post-operative ACD with the true post-operative ACD in each case The result after correcting the IOL position was a highly accurate IOL power calculation where no fudge factors were needed Nowadays the pre-operatively measured ACD is taken into account for several IOL power calculation formulas such as the Haigis formula the Holladay II formula and the Olsen formula However this new generation of formulas use the pre-operative ACD without considering the thickness of the crystalline lens The ACD is measured as the distance between the anterior surface of the cornea anatomically correct would be the posterior surface of the cornea but in an optical context as in IOL power calculations the anterior surface is used and the anterior surface of the crystalline lens 2 Therefore the thickness of the crystalline lens has a significant impact on the predicted post-operative position of the IOL This parameter was first taken into account by Olsen 7 and later modified by Norrby 8 9 It should be mentioned that IOL power calculations developed from theoretical calculations based on Gaussian optics 10 to regression formulas such as the SRK formula 11 that uses retrospective data of a large number of patients All these findings suggest that proper measurements not only of the dimensions of the crystalline lens but also of the lens capsule after removing the crystalline lens are necessary to improve IOL power calculation

Recently a prototype of a combination of an anterior segment OCT VISANTE Carl Zeiss Meditec AG and an operating microscope OPMI 200 Carl Zeiss Meditec AG was introduced that allows measurements of the crystalline lens as well as the lens capsule itself after removing the crystalline lens of cataract patients intra-operatively This device uses OCT technology to create high resolution B-scans images of the anterior segment of the eye The OCT was shown to be highly reproducible for ACD measurements pre-operatively 12 and small changes of the IOLcrystalline lens can be detected 13

In a previous study EK-10-125-0710 that was recently published in the journal Investigative Ophthalmology Visual Science it was shown that intra-operative measurements of the anterior lens capsule improve the refractive outcome theoretically14 However in this previous study conventional eye models were used for IOL power calculation and only the intra-operative measurement replaced pre-operative ACD measurements

Aim of this study is to observe whether the postoperative refractive outcome could be improved theoretically by using both pre- and intra-operative measurements for retrospective IOL power calculation with new eye models

Study Oversight

Has Oversight DMC: None
Is a FDA Regulated Drug?: None
Is a FDA Regulated Device?: None
Is an Unapproved Device?: None
Is a PPSD?: None
Is a US Export?: None
Is an FDA AA801 Violation?: None
Secondary IDs
Secondary ID Type Domain Link
OC3 REGISTRY OC3 None