Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus
AIM: To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants (ICRS) in order to determine the corneal response to ICRS surgery in keratoconus (KC). Thereafter, to present the concept and early results of a newly derived topography...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Press of International Journal of Ophthalmology (IJO PRESS)
2017-01-01
|
| Series: | International Journal of Ophthalmology |
| Subjects: | |
| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5360767/ |
| _version_ | 1819028097686568960 |
|---|---|
| author | Elias F. Jarade Elise Slim Carole Cherfan Hala El Rami Toufic Hassan Elias Chelala |
| author_facet | Elias F. Jarade Elise Slim Carole Cherfan Hala El Rami Toufic Hassan Elias Chelala |
| author_sort | Elias F. Jarade |
| collection | DOAJ |
| description | AIM: To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants (ICRS) in order to determine the corneal response to ICRS surgery in keratoconus (KC). Thereafter, to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia.
METHODS: The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of: the ring size, position (steep vs flat), location (distance from the geometric centre of the cornea), and the discrepancy between the ring’s curvature and the tunnel’s curvature. Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction.
RESULTS: The conic section had a more prolate shape in the steep area of the cornea than in the flat area, depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) than the conventional nomogram.
CONCLUSION: The newly derived nomogram can produce better results than the conventional nomogram. Moreover, based on this concept, a new nomogram can be integrated into the femtosecond laser software to create topography-guided, customized, elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea. |
| first_indexed | 2024-12-21T05:52:57Z |
| format | Article |
| id | doaj.art-6d3cfb3d9aab44eab41cb5a017fac967 |
| institution | Directory Open Access Journal |
| issn | 2222-3959 2227-4898 |
| language | English |
| last_indexed | 2024-12-21T05:52:57Z |
| publishDate | 2017-01-01 |
| publisher | Press of International Journal of Ophthalmology (IJO PRESS) |
| record_format | Article |
| series | International Journal of Ophthalmology |
| spelling | doaj.art-6d3cfb3d9aab44eab41cb5a017fac9672022-12-21T19:13:56ZengPress of International Journal of Ophthalmology (IJO PRESS)International Journal of Ophthalmology2222-39592227-48982017-01-0110334835410.18240/ijo.2017.03.04Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconusElias F. Jarade0Elise Slim1Carole Cherfan2Hala El Rami3Toufic Hassan4Elias Chelala5Beirut Eye Specialist Hospital, Beirut P.O box 116-5311, Lebanon; Mediclinic, Dubai Mall, Dubai P.O box 282890, United Arab EmiratesBeirut Eye Specialist Hospital, Beirut P.O box 116-5311, Lebanon; Saint-Joseph University, Faculty of Medicine, Beirut P.O Box 11-5076, LebanonBeirut Eye Specialist Hospital, Beirut P.O box 116-5311, LebanonSaint-Joseph University, Faculty of Medicine, Beirut P.O Box 11-5076, LebanonSaint-Joseph University, Faculty of Medicine, Beirut P.O Box 11-5076, LebanonSaint-Joseph University, Faculty of Medicine, Beirut P.O Box 11-5076, LebanonAIM: To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants (ICRS) in order to determine the corneal response to ICRS surgery in keratoconus (KC). Thereafter, to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS: The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of: the ring size, position (steep vs flat), location (distance from the geometric centre of the cornea), and the discrepancy between the ring’s curvature and the tunnel’s curvature. Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction. RESULTS: The conic section had a more prolate shape in the steep area of the cornea than in the flat area, depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) than the conventional nomogram. CONCLUSION: The newly derived nomogram can produce better results than the conventional nomogram. Moreover, based on this concept, a new nomogram can be integrated into the femtosecond laser software to create topography-guided, customized, elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5360767/keratoconusintracorneal ringmathematical modelcorneatopography guidednomogram.nomogram. |
| spellingShingle | Elias F. Jarade Elise Slim Carole Cherfan Hala El Rami Toufic Hassan Elias Chelala Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus International Journal of Ophthalmology keratoconus intracorneal ring mathematical model cornea topography guided nomogram. nomogram. |
| title | Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| title_full | Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| title_fullStr | Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| title_full_unstemmed | Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| title_short | Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| title_sort | mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus |
| topic | keratoconus intracorneal ring mathematical model cornea topography guided nomogram. nomogram. |
| url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5360767/ |
| work_keys_str_mv | AT eliasfjarade mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus AT eliseslim mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus AT carolecherfan mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus AT halaelrami mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus AT toufichassan mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus AT eliaschelala mathematicalanalysisofcornealremodellingafterintracornealringsurgeryinkeratoconus |