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Novel altered stromal molecular pathways associated with post SMILE ectasia

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Session Details

Session Title: Primary and Secondary Ectasia

Session Date/Time: Sunday 23/09/2018 | 08:00-10:00

Paper Time: 08:06

Venue: Room A4

First Author: : P.Khamar INDIA

Co Author(s): :    R. Shetty   A. Ghosh   A. Roy   S. Sethu   A. Nair   M. Francis     

Abstract Details


Despite appropriate clinical patient selection criteria being followed, undesirable surgical outcomes like ectasia may occur post SMILE (small incision lenticule extraction) surgery. Thus, we analysed extracellular matrix regulators and inflammatory factors in pre-stored lenticules from a patient who developed post-SMILE ectasia.




Corneal lenticules were collected intra-operatively from patients undergoing SMILE surgery and stored at -80°C after approval of Institutional Ethics Committee and written informed consent.1 subject, out of the 572 subjects, had developed bilaterally asymmetric ectasia, post-SMILE surgery. Pre-operative MRSE was -9.25D and -10D, BAD-D values were 0.76 and 0.94 in OD and OS, respectively. Lenticules from both eyes of the ectasia subject and 6 control (age, sex and duration of follow up matched) eyes were used for gene expression analysis of Lysyl Oxidase (LOX), MMP9, Collagens (COL IA1, COL IVA1), TGFβ, BMP7, IL-6, CD68, and TIMP1 by quantitative PCR.


The ectatic eye had reduced fold change expression of LOX (0.57), COL IA1 (0.063), COL IVA1 (0.5) compared to controls without ectasia. Increased mRNA fold change expression of TGFβ (1.5), BMP7 (1.4), IL6 (1.5), CTSK (1.37), Integrin β1 (1.4) was noted in severely ectatic eye when compared to controls. However, MMP9 and TIMP1 levels were not altered in the ectatic eye compared to controls. LOX overexpression in HCF induced significantly more collagen gel contraction (25%) indicating its role in strengthening the corneal stroma. LOX expression was also reduced to 0.5 fold upon inflammatory stimulus.


Reduced pre-existing LOX and collagen levels may predispose clinically healthy eyes undergoing refractive surgery to ectasia, possibly via weakened stroma due to lack of cross-linked collagen. Thus, diagnostic testing for molecular factors can reveal susceptibility in absence of topographical evidence.

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