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Analysis of the effectiveness of intrastromal corneal ring segments implantation with the use of the own method for calculating their parameters in pellucid marginal corneal degeneration

Poster Details

First Author: I.Vasilyeva RUSSIA

Co Author(s): V. Egorov   A. Vasilyev                 

Abstract Details


To analyze the anatomical and functional results of intrastromal corneal ring segments (ICRS) implantation in the pellucid marginal corneal degeneration (PMCD) using the own method of calculating their parameters. We analyzed the results of treatment of 9 patients (15 eyes) with PMCD, who underwent ICRS implantation, Patients age varied from 32 to 64 (on average 46±6) years. There were 5 men and 4 women in the study.


State Institution Eye Microsurgery Complex named after academician S.N. Fyodorov, Khabarovsk, Russia


The number and parameters of the implantable ICRS were determined using the own calculation method, based on the data of the corneal topogram. A feature of the calculation method of the ICRS parameters is the orientation on the size and position of sectors with weak corneal refraction, determined by the corneal topogram. In the studied eyes, the angular size of the sector with weak refraction in the upper zone of the cornea was from 115° to 135° (average 124.2±3.5°), in the lower zone – from 83° to 94° (average 87.3±2.1°).


Corresponding to this data, the ICRS with 120° was implanted in the upper corneal zone, and the ICRS with 90° – in the lower corneal zone. The height of the segments was calculated individually, based on the cylindrical component of the cornea (the refraction difference of the main meridians of the cornea on the corneal topogram).Already on the 1st day after operation, the mean of uncorrected visual acuity (UCVA) was improved from 0.11±0.08 to 0.39±0.24 due to expressed decrease in the astigmatic component. The mean of best-corrected visual acuity (BCVA) improved from 0.38±0.22 to 0.45±0.19.


Three months after operation, UCVA and cylindrical refractive component remained stable, in addition, there was an increase in BCVA by 20% compared to its value on the 1st day after the operation. Re-profiling of the cornea made it possible to reduce the magnitude of corneal astigmatism by an average of 4 times (from 7.85±3.12 D to 1.76±0.63 D)Expressed decrease in cylindrical refractive component allowed to obtain high visual acuity without correction or with an admissible ophthalmic correction in patients already on the 1st day after operation. Refractive and functional results remained stable in 3 months after operation.

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