Posters

Analysis of corneal stromal and corneal nerve changes following LASIK using in vivo confocal microscopy (IVCM)

Poster Details

First Author: I.Agarwalla INDIA

Co Author(s):    K. Bhattacharjee   M. Garg   P. Shukla              

Abstract Details

Purpose:

Aim: To analyse the corneal stromal and corneal nerve changes after Lasik with In Vivo Confocal Microscopy. Primary objective: To analyse structural corneal nerve and stromal changes in the ultra-structure of cornea following Lasik using IVCM in terms of keratocyte density in anterior and posterior stromal layers, flap thickness
and keratocyte activation. Secondary objective: To see the amount of healing that has occurred following Lasik in terms of corneal nerve changes pre and post Lasik and their regeneration. 


Setting:

Materials and methods :- Study area: The study was conducted at Sri Sankaradeva Nethralaya, a tertiary eye care institute in Guwahati, Assam. Study design:- Hospital based prospective longitudinal study Study Period:- 2 year (15.7.2017 – 15.6.2019)

Methods:

Consecutive eyes undergoing Myopic Lasik surgery who have had stable refractive power for 1 year sample size was calculated based on prevalence of similar nature in past. After the patients were enrolled in the study, their general information were noted down. All patients underwent standard eye examination, including Manifest and Cycloplegic Refraction, best-corrected visual acuity, slit-lamp biomicroscopy and ophthalmoscopy. Lasik investigations such as Topography and Pentacam were done along with In Vivo Confocal Microscopy scanning of the cornea.
 Examinations were performed before surgery, within 1 week, 1 month and 3 months after surgery.


Results:

Demography: Mean age for patients 26.93 ± 4.68 (18-35) years. Out of these 29 were male and 43 were female patients. Right eye got operated in 75 patients and left eye in 69 patients. Spherical Equivalent : The mean spherical equivalent pre-operatively ranged from -0.50 DS upto -13.75 DS (Mean S.E. -4.72 ± 2.48) .. Only patients having myopia and myopic astigmatism were included in the study.
 Mean Ablation depth and Keratocyte density: Mean keratocyte density pre-operatively was 20660.82 cells/mm3 and in the post operative 1 week period the density was reduced to 19927.94 cells/mm3. However the keratocyte density increased in the 3rd post operative month. [( p < 0.05), significant)

The mean ablation depth was the difference between keratocyte density pre operatively and post operatively. The ablation depth noted has a direct correlation with speroequivalent of the patient, i.e. higher the spheroequivant refractive value, higher the ablation depth. Keratocyte Activation: Keratocyte activation was noted in 79.2% of the patients, indicating the regenerative changes and healing changes occurring in stroma after the insult.



Conclusions:

Endothelial cell count: The mean endothelial cell count showed no significant reduction in the post- operative period. However an increase in the endothelial cell count was noted post operatively from 2888 cells/mm3 to 2919 cells/mm3. (p>0.05) was not statistically significant.

 Nerve Plexus Orientation: The number of nerve fiber bundles per per eye per visit were noted in the sub-epithelial and sub-basal regions mainly, but could be located anywhere along the full-thickness stroma which included the stromal flap and the stromal bed. Only a qualitative analysis for this parameter was done. 
 Following Lasik, the normal anatomical and physiological corneas healed well by the fibroblast activity as seen in the keratocytes. The flap creation and stromal ablation caused insult to the corneal stromal keratocytes, which then induced apoptosis and stimulated fibroblasts to form newer activated keratocytes and thus healing occurred. The nerve plexus that were disrupted during the process were also seen to regenerate following the surgery.

Financial Disclosure:

None