Comparison of the influence of corneo-scleral and scleral lenses on ocular surface and tear film metrics in a presbyopic population

Abstract

C-ScL lead to a lesser reduction in the TMA and a lower induced hypoxic stress than the ScL. Osmolarity levels remained within normal values across the day with no clinical difference between lenses. Both designs can represent a good optical platform for correcting presbyopia as well as protecting the ocular surface by vaulting the cornea.

The time course and nature of corneal oedema during sealed miniscleral contact lens wear

“…The mean peak total corneal oedema observed in our subjects after 90 min of sealed miniscleral lens wear (1.18 ± 0.20%) is consistent with a number of previous studies also using high resolution imaging techniques to quantify corneal thickness changes following 3-8 h of high Dk scleral lens wear in young participants (typically between 1 and 2% swelling) [5][6][7][8]. Lafosse et al [25], however, recently reported corneal oedema of 5.1% after 8 h of 18 mm diameter high Dk (100) scleral contact lens wear. This significantly greater level of oedema compared to previous studies [5][6][7][8] is most likely due to the older patient cohort (mean age 54 years) with a presumably slightly reduced endothelial cell count (∼6% reduction has been reported between 30 and 50 years of age [26]), and is possibly also a consequence of the baseline corneal thickness measures being captured without the scleral lens on eye compared to subsequent thickness measures obtained through the lens on eye (i.e.…”

“…a potential magnification effect), or the lower axial resolution of the OCT used (18 μm) [27]. Interestingly, Lafosse et al [25] observed a significant increase in oedema between 20 min and 8 h of lens wear (∼3.8%), whereas in our study, corneal oedema had returned to 0.49% after 8 h (originally 0.47% oedema after 15 min). This implies an impaired endothelial pump mechanism in their older cohort of unadapted lens wearers compared to the younger participants included in previous studies (mean ages ranging from 22 to 34 years) [5][6][7][8].…”

The influence of centre thickness on miniscleral lens flexure

“…While several clinical studies have demonstrated that minimal corneal oedema occurs during short-term high Dk sealed miniscleral lens wear in young healthy eyes (typically 1-2%) [8][9][10], reducing the centre thickness of a scleral lens will increase the transmission of oxygen to the cornea, even for highly permeable materials [11]. This may be of particular benefit for eyes with reduced endothelial cell counts [12,13]. However, scleral lenses with a reduced central thickness may flex on-eye resulting in unwanted residual astigmatism and higher order aberrations or permanent lens warpage due to routine handling.…”

Preliminary Clinical Exploration of Scleral Lens Performance on Normal Eyes

“…Lafosse et al compared the effect of scleral and corneo-scleral lenses on tear film parameters and central corneal thickness in healthy, presbyopic subjects at baseline, 20 minutes postinsertion and after 8 hours of continuous lens wear. 19 No clinical difference was observed between lenses, including tear osmolarity, throughout a full day of continuous wear.…”

“…18 This principle is particularly applicable to patients with high astigmatism, as rigid gas permeable contact lenses are preferred to soft toric contact lenses to improve visual outcomes. 19 Scleral lenses also reduce higher order aberrations (HOAs) via enhanced lens parameter customization and improved centration e16 compared to soft and gas permeable contact lenses. The optic zone diameter of scleral lenses can often be larger than other types of modalities, including corneal gas permeable, soft spherical, soft toric and hybrid contact lenses.…”