Repeatability and Reproducibility of Corneal Biometric Measurements Using the Visante Omni and a Rabbit Experimental Model of Post-Surgical Corneal Ectasia.
OBJECTIVE
To investigate the repeatability and reproducibility of the Visante Omni topography in obtaining topography measurements of rabbit corneas and to develop a post-surgical model of corneal ectasia.


METHODS
Eight rabbits were used to study the repeatability and reproducibility by assessing the intra- and interobserver bias and limits of agreement. Another nine rabbits underwent different diopters (D) of laser in situ keratosmileusis (LASIK) were used for the development of ectasia model. All eyes were examined with the Visante Omni, and corneal ultrastructure were evaluated with transmission electron microscopy (TEM).


RESULTS
There was no significant intra- or interobserver difference for mean steep and flat keratometry (K) values of simulated K, anterior, and posterior elevation measurements. Eyes underwent -5 D LASIK had a significant increase in mean amplitude of astigmatism and posterior surface elevation with time (Pfor trend < 0.05). At 2 and 3 months, the -5 D LASIK group had significant greater mean amplitude of astigmatism (P= 0.036;P= 0.027) and posterior surface elevation (bothP< 0.005) compared with control group. On TEM, the mean collagen fibril diameter and interfibril distance in the -5 D LASIK eyes were significantly greater than in controls at 3 months (P= 0.018;P< 0.001).


CONCLUSIONS
The Visante Omni provided imaging of the rabbit cornea with good repeatability and reproducibility. Application of -5 D LASIK treatment produced a rabbit model of corneal ectasia that was gradual in development and simulated the human condition.


CONCLUSIONS
The results provide the foundations for the future evaluation of novel treatment modalities for post-surgical ectasia and keratoconus.
Singapore Eye Research Institute, Singapore ; Singapore National Eye Centre, Singapore.
Yu-Chi
YC
Liu
Singapore Eye Research Institute, Singapore ; Singapore National Eye Centre, Singapore.
Aris
A
Konstantopoulos
Singapore Eye Research Institute, Singapore.
Andri K
AK
Riau
Singapore Eye Research Institute, Singapore ; The Pennine Acute Hospitals NHS Trust, Crumpsall, United Kingdom.
Raj
R
Bhayani
Singapore Eye Research Institute, Singapore.
Nyein C
NC
Lwin
Singapore Eye Research Institute, Singapore.
Ericia Pei Wen
EP
Teo
Singapore Eye Research Institute, Singapore.
Gary Hin Fai
GH
Yam
Singapore Eye Research Institute, Singapore ; Singapore National Eye Centre, Singapore ; Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore ; School of Material Science & Engineering and School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
Jodhbir S
JS
Mehta
Visante omni topography; animal model; corneal ectasia