ESCRS - P086 - THEORETICAL CORRECTION OF AXIAL LENGTH MEASUREMENT IN PERFLUOROCARBON LIQUID-FILLED EYES

THEORETICAL CORRECTION OF AXIAL LENGTH MEASUREMENT IN PERFLUOROCARBON LIQUID-FILLED EYES

Published 2023 - 27th ESCRS Winter Meeting

Reference: P086 | Type: Free Paper Submission | DOI: 10.82333/gw0w-g602

Authors: David Cordeiro Sousa* 1 , Jack Kane 2 , David Fabinyi 3

1Ophthalmology,Royal Victorian Eye and Ear Hospital,East Melbourne,Australia;Vision Sciences Study Center,Universidade de Lisboa,Lisboa,Portugal, 2Ophthalmology,Alfred Health,Melbourne,Australia, 3Ophthalmology,Royal Victorian Eye and Ear Hospital,East Melbourne,Australia

Purpose

Increasingly, perfluorocarbon liquids (PFCL) are used as a short-term tamponade in vitreoretinal surgery. There is no available formula to accurately calculate the axial length (AL) and therefore intraocular lens (IOL) power if cataract surgery needs to be performed at the time of the PFCL removal. This study aims to present the necessary adjustments in AL measurement for a reliable IOL choice.

Setting

Vitreoretinal Unit - Royal Victorian Eye and Ear Hospital, Melbourne, Australia.

Methods

A manually derived formula to adjust the measured AL of optical biometry (IOLMaster 700, Carl Zeiss Pty Ltd, NSW, Australia) is presented and discussed, in the context of 3 patients who underwent combined cataract surgery along with PFCL removal from the vitreous cavity. 

Results

The measured AL (using ‘vitreous body’ setting) for PFCL (n=1.262) should be corrected by multiplying it by 1.059 and subtracting 0.059*anterior segment depth. This allows for a much more accurate AL estimation, compared to the use of the unadjusted AL value. From this, a general equation has been developed to correct the measured axial length for any vitreous replacement by simply knowing the refractive index of the substance.

Conclusion

Generally, intraocular biometry with PFCL in situ should be avoided, however in some circumstances it will be unavoidable. In these cases, we recommend using the standard “vitreous body” setting on the biometry device, and manually correcting the axial length value using the equation described above.