Miniscleral lens wear influences corneal curvature and optics

Abstract

Miniscleral contact lenses that vault the cornea induce significant changes in anterior corneal surface topography and higher order aberrations following 8 h of lens wear. The region of greatest corneal flattening was observed in the superior-nasal mid-periphery, more so in East Asian participants. Practitioners should be aware that corneal measurements obtained following miniscleral lens removal may mask underlying corneal steepening.

Anterior eye surface changes following miniscleral contact lens wear

“…Corneal flattening due to miniscleral contact lens wear was on average −3 ± 17 μm, which was less than the statistically significant value of −30 ± 20 μm reported after three hours of lens wear by Vincent et al [13]. In another work by the same team, corneal curvature changes following 8 h of miniscleral lens wear was significant respect to baseline [14] but not substantially greater than that observed following 3 h of lens wear [13]. They analysed corneal flattening by means of corneal axial curvature using Scheimpflug imaging, while in this work the height elevation maps using profilometry were examined.…”

“…However, information on how ocular surface topography is affected by scleral contact lens wear is scarce. This has traditionally been evaluated with Scheimpflug cameras [12,13,14,15], but the main limitation of this technique is that their range of measurement is essentially restricted to the cornea. Anterior Segment Optical Coherence Tomography (AS−OCT) allows expanding the imaging range to the corneo-scleral transition and sclera, but in this case the analysis is limited to selected meridians [16].…”

Recommendations for analysis of repeated‐measures designs: testing and correcting for sphericity and use of manova and mixed model analysis

“…The Huynh and Feld adjustment is similar but is regarded as more liberal than Greenhouse and Geisser. When search terms were used to specifically identify those articles which tested and corrected for sphericity, 14/66 (21%) used Mauchly's test, 24 47/66 (71%) the Greenhouse-Geisser correction, [25][26][27] and 5/66 (8%) the Huynh and Feld correction, 28 62% of which were published in the period 2012 to the present. A problem with these procedures, however, is that they may not protect against multiple testing using post-hoc tests after RM-ANOVA especially if an overall error term is used.…”

Optical coherence tomography and scleral contact lenses: clinical and research applications

“…Low corneal clearance may also result in adverse ocular changes during scleral lens wear such as unintentional corneal touch following lens settling, or excessive suction in a sealed scleral system (so called ‘thin film adhesion’). Tear film, suction, and landing zone forces have also been hypothesised to induce changes in corneal astigmatism and higher order aberrations that persist following lens removal …”