Abstract
Purpose :
An ideal scleral lens fit will result a comfortable wear and minimize ocular complications. A successful scleral lens design starts with understanding the ocular topography of the wearer.
Methods :
997 (517 right eyes and 480 left eyes) EyeFit data from EyePrint Pro was analyzed. Ocular topography information was collected using impression-based technology. Scleral elevation data was exported every 10 degrees radially, starting 0.5mm outside of limbus up to 8mm (0.5mm step), which is roughly 30mm in diameter. Data was analyzed via elevation change measured perpendicular to the average limbal plane. Scleral steepness change was then calculated to evaluate the meridional symmetricity and the distribution of this population data is examined. In addition, the potential for successful interpolation and extrapolation of missing data is also assessed.
Results :
On average, the eye is steeper at Superior and Temporal, flatter at Inferior and Nasal quadrants (Figure 1). Where Nasal is the flattest quadrant and Temple is the steepest. That means the nasal and temporal sag height differences increases as the chord length increases. As the distance from limbus increases, the range of the population distribution also widens (Table 1, AVG+/- SD). If the slope at adjacent chord length is similar, then a linear extrapolation is possible, but the zone for linear extrapolation is minimal for most eyes. If the slope at adjacent meridian is similar, an interpolation is possible without resulting in localized ridges; however, not all areas can be applied.
Conclusions :
Ocular surface is not spherical; the shape becomes more aspheric and asymmetrical as it goes out from the limbus. The ocular shape also deviates from person to person making generalization difficult. A sclera landing zone accounting for the asymmetrical shape of individual eye will have the best outcomes and success.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.