Official ESCRS | European Society of Cataract & Refractive Surgeons


Predictability of intraocular lens power calculation after Ahmed valve implantation

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Session Details

Session Title: Presented Poster Session: Glaucoma I

Venue: Poster Village: Pod 3

First Author: : D.Belov RUSSIA

Co Author(s): :    V. Nikolaenko                       

Abstract Details


To assess refractive changes after Ahmed valve implantation and it is impact on IOL power calculation following phacoemulsification.


Russian Federation, Saint-Petersburg, Multifield Hospital № 2


In total, 52 eyes of 52 glaucoma patient (28 male and 24 female) undergoing Ahmed valve implantation; Observation time: from April 2017 to October 2018; Every patient underwent routine ophthalmological examination; Refractometry, keratometry,  Axial length (AL) measurement, IOP  (Topcon KR – 8800, IOL-Master 500 Carl Zeiss, iCare) was performed for each patient before tube implantation, in the 1st postsurgical day, in 1 month and in 6 months after surgery.


There was observed mild hyperopic shift after and Ahmed valve (+0,13 D) implantation. We found mild AL decrease after tube surgery (from 23,65 ± 0,98 mm to 23,57 ± 1,02 mm, ∆ = -0,08 mm). There was expressed correlation between AL shortening and IOP lowering after Ahmed valve implantation (p < 0,00001). We found out insignificant decrease of corneal power (from 44,08 ± 1,06 to 43,94 ± 1,21 D, ∆ = -0,14 D). However, these changes were statistically significant (p < 0,05).   .


Thus, Ahmed valve implantation could correlate with small myopic IOL power calculation error (-0,33 D), due to axial length shortening (from 23,65 ± 0,98 mm to 23,57 ± 1,02 mm, ∆ = -0,08 mm) and corneal curvature flattening (from 44,08 ± 1,06 to 43,94 ± 1,21 D, ∆ = -0,14 D). Nevertheless, this myopic shift is quite insignificant and smaller than value of division (0,5 D) of modern IOL models.

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