Bachelor of Optometry and Vision Science

Purpose: This study investigated correlation between the duration of lens wear and epithelial and stromal thickness in low to moderate and high myope orthokeratology lens wearers.
Materials and methods: Twenty-six high myope (mean refractive error -7.64±1.54D) orthokeratology lens wearers and 30 low to moderate myopes (mean refractive error -3.08±1.06D) orthokeratology lens wearers were recruited cross-sectionally from the participating practices. These subjects were Chinese schoolchildren aged 9-18 years. The recruited orthokeratology lens wearers had worn lenses for 6-65 months. Epithelial and stromal thickness of the central and midperipheral cornea was measured with the Sonogage Cornea-gage Plus Ultrasound Pachometer (Sonogage, Cleveland, OH). In each group, epithelial and stromal thickness was analyzed with Spearman correlation test to assess correlation with the duration of orthokeratology lens wear.
Results: Minimal and almost absent correlation was found in epithelial measurements at all points in both low to moderate and high myopic groups. Correlation was also almost absent in the midperipheral stromal thickness when tested against the duration of lens wear. However, a weak correlation was found between stromal thickness and duration of wear in the central stroma measurements of the low to moderate myopes (r=0.207) and high myopes (r=-0.254).
Conclusions: The central stroma of the low to moderate myope orthokeratology wearer was found to become thicker with time and the central stroma of the high myope orthokeratology wearer was found to become thinner with time when tested for correlation with the duration of wear. These results suggest a possible longitudinal change in the corneal stromal thickness with orthokeratology lens wear.

Background: To determine the extent of scleral lens fitting worldwide and to characterise the associated patient demographics. Methods: Survey forms were sent to contact lens fitters around the world, every year for 20 consecutive years (2000 to 2019). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey. Data were analysed for those countries reporting ≥ 1,000 contact lens fits during this period. Results: A total of 369,209 contact lens fits were recorded from 40 eligible countries, comprising 2,309 scleral lens fits and 366,900 other (non-scleral) lens fits. Overall scleral lenses represented 0.76 per cent of all contact lens fits with significant differences between countries (p < 0.0001), ranging from no fits in six countries: Hungary, Indonesia, Iran, Korea, Malaysia and Singapore, to 5.9 per cent in Switzerland. There has been an increase in scleral lens fitting over the survey period (p < 0.0001), with the rate of fits increasing from negligible (< 0.50 per cent) before 2006 and then increasing from 2011 onward (p < 0.0001). Scleral lenses were fit to older patients (38.5 AE 15.0 years) compared to other lenses (31.4 AE 13.7 years) (p < 0.0001), this age disparity increasing over the survey period (p < 0.0001) and were more likely to be males (scleral lens fits 53 per cent, non-scleral lenses 33 per cent, p < 0.0001). The increase in scleral lens fits is commensurate with the increase in related publications in the peer-reviewed literature over the same period (p < 0.05, r 2 = 0.82). Conclusion: Scleral lens use has increased since 2011 with these specialised lenses more likely to be fitted to males and older patients than non-scleral lenses.