An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses

Visual and physiological outcomes of scleral lens wear

“…Recent literature includes single-center, retrospective case series which generally describe a single lens design and unified fitting philosophy [2][3][4][5][6][7]. Studies on observed or potential impact of scleral lenses on ocular surface structures have also been published within the past 5 years [8,9], as has research on the structure and contour of conjunctival, episcleral, and scleral tissue [10][11][12][13]. Phenomena related to scleral lens fitting characteristics have also been described [14][15][16].…”

Anterior eye surface changes following miniscleral contact lens wear

“…Our findings are in line with theirs, since the partial recovery in this study amounts to 77% of the total flattening. Scleral toricity [19,24,25] may result in an uneven distribution of the load for a lens with a spherical landing zone, like the ones used on this experiment, which might contribute to uneven compression across sectors. The orientation of extraocular rectus muscle insertions, eyelid forces and lid position have been designated as potential factors influencing scleral shape [24].…”

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

“…The angle of the corneoscleral junction varies with the ocular meridian, being sharpest (a less obtuse angle) nasally and flattest (closest to a tangent) superiorly (Figure ) . The greatest asymmetry in the corneoscleral junction angle is typically observed along the horizontal meridian, which may contribute to excessive limbal clearance or lens stand‐off temporally, and reduced limbal clearance nasally . The corneoscleral junction angle also steepens slightly with age and varies with ethnicity (a more pronounced angle in Caucasians compared to Asians) .…”

“…The black line (180°) represents a tangential extension of the peripheral cornea to the sclera. A: Adapted from Hall et al (measured at a chord length equal to the corneal diameter for each subject), and B: Ritzmann et al (measured at a set 12.8 mm chord).…”

“…Meridional differences in the scleral angle increase with increasing distance from the limbus, most notably a nasal‐temporal asymmetry, particularly for chord lengths greater than 15 mm (for example, an increase in the maximum meridional difference of about 2° at 15 mm up to 7° at 20 mm) . Therefore, rotationally symmetric lens designs with a proximal landing zone edge of about 15 mm or less should provide an adequate fit for most eyes; however, a toric or quadrant‐specific haptic zone may be required for larger diameter lenses to achieve a comfortable, stable fit with appropriate landing zone alignment.…”