Comparative Evaluation Of Corneal Biomechanics With Corvis-St In Normal And Post-Deep Anterior Lamellar Keratoplasty Corneas.
Published 2023 - 41st Congress of the ESCRS
Reference: PO0237 | Type: Free paper | DOI: 10.82333/9g2w-3t17
Authors: Tapashree Ghosh* 1 , Murugesan Vanathi 1 , Radhika Tandon 1 , Noopur Gupta 1 , MA Khan 2
1Dr. R. P. Centre for Ophthalmic Sciences, ALL INDIA INSTITUTE OF MEDICAL SCIENCES,New Delhi,India, 2Department of Biostatistics, ALL INDIA INSTITUTE OF MEDICAL SCIENCES,New Delhi,India
Purpose
Deep anterior lamellar keratoplasty (DALK) surgery for advanced corneal ectasia helps in visual rehabilitation and restoration of the tectonic integrity of these thin corneas. Study of corneal biomechanics of corneas that have undergone DALK will help to enhance our understanding of the extent by which the corneal biomechanics improves after the surgery in comparison to that of normal corneas. The current study aims to compare the corneal biomechanics in healthy normal corneas and post-DALK corneas using dynamic corneal visualization [CORVIS-ST] imaging.
Setting
Dr. R. P. Centre for Ophthalmic Sciences, ALL INDIA INSTITUTE OF MEDICAL SCIENCES, New Delhi, India.
Methods
Retrospective cross-sectional observational study of 40 normal & 40 post-DALK corneas was done. Demographic details, postoperative period, VA, Pentacam & CORVIS ST imaging was seen. Comparative evaluation of 17 CORVIS-ST parameters: bIOP, 1st Applanation time(AT1), Highest concavity time(HCT), 2nd Applanation time(AT2), 1st Applanation length(AL1), Deformation amplitude (DA), Wing distance(WD), Highest concavity radius(HCR), Velocity in(VEL in), Velocity out (VEL out), Deformation amplitude ratio(DA ratio), Integrated radius(IR), Inverse concave radius (IVR), Stress strain index(SSI), Stiffness parameter(SP-A1), Ambrosio relational thickness horizontal(ARTh) Corneal biomechanical index (CBI), Tomographic biomechanical index was done.
Results
The mean age of normal and post DALK corneas (mean postoperative period 2.96+2.33 years) were 22.5+5.1 & 23.7+10.08 years respectively and median CBI was 0.19 & 0.93(0.001)respectively. Median value of 14 CORVIS parameters of normal & post-DALK corneas respectively, was found to be significantly decreased in DALK group for bIOP[16.4 & 14 (0.001)], AT1[7.48 & 7.23 (0.001)], HCR[7.69 & 6.07 (0.001)], SPA1[99.65 & 63 (0.001)], SSI[1.11 & 0.85 (0.001)], ARTh[557.05 & 148.7 (0.001)] & increased for DA[1.01 & 1.22 (0.001)], AT2[21.43 & 21.98 (0.001)], Vel in[0.14 & 0.17 (0.001)], Vel out[0.26 & 0.32 (0.001)], DA ratio[4.15 & 4.4 (0.003)], IVR[0.16 & 0.17 (0.001)], IR [7.15 & 9.6 (0.001)]. There was no statistical difference in WD, AL1 & HCT.
Conclusions
Comparative analysis of CORVIS-ST parameters in normal & post-DALK corneas noted a decreased corneal biomechanical strength in post-DALK corneas as compared to normal corneas. Hence cornea seems to regain tensile strength only partially following DALK surgery.