Wavefront-Guided Scleral Lens Correction in Keratoconus

Abstract

Purpose To examine the performance of state-of-the-art wavefront-guided scleral contact lenses (wfgSCLs) on a sample of keratoconic eyes, with emphasis on performance quantified with visual quality metrics; and to provide a detailed discussion of the process used to design, manufacture and evaluate wfgSCLs. Methods Fourteen eyes of 7 subjects with keratoconus were enrolled and a wfgSCL was designed for each eye. High-contrast visual acuity and visual quality metrics were used to assess the on-eye performance of the lenses. Results The wfgSCL provided statistically lower levels of both lower-order RMS (p < 0.001) and higher-order RMS (p < 0.02) than an intermediate spherical equivalent scleral contact lens. The wfgSCL provided lower levels of lower-order RMS than a normal group of well-corrected observers (p < < 0.001). However, the wfgSCL does not provide less higher-order RMS than the normal group (p = 0.41). Of the 14 eyes studied, 10 successfully reached the exit criteria, achieving residual higher-order root mean square wavefront error (HORMS) less than or within 1 SD of the levels experienced by normal, age-matched subjects. In addition, measures of visual image quality (logVSX, logNS and logLIB) for the 10 eyes were well distributed within the range of values seen in normal eyes. However, visual performance as measured by high contrast acuity did not reach normal, age-matched levels, which is in agreement with prior results associated with the acute application of wavefront correction to KC eyes. Conclusions Wavefront-guided scleral contact lenses are capable of optically compensating for the deleterious effects of higher-order aberration concomitant with the disease, and can provide visual image quality equivalent to that seen in normal eyes. Longer duration studies are needed to assess whether the visual system of the highly aberrated eye wearing a wfgSCL is capable of producing visual performance levels typical of the normal population.

Response to Re: Contact lens management of keratoconus

“…In particular, we outline the literature that has demonstrated the limitations associated with aberration-controlled soft contact lens designs and the need for further work to validate the clinical feasibility of such modalities for the management of keratoconus. Although still currently limited to the research domain and not yet directly applicable to managing patients in clinical practice, we agree with the sentiment that customised aberration-controlled scleral lenses 2,3 show promise as a potential future vision-correction platform for keratoconus. In a small population of seven individuals with keratoconus, Marsack and colleagues 2 have shown that wave-front guided scleral contact lenses can optically compensate for higher-order aberrations; however, as these authors note, 2 a range of factors will need to be surmounted in order for the custom correction of highly aberrated eyes to achieve clinical translation.…”

“…Although still currently limited to the research domain and not yet directly applicable to managing patients in clinical practice, we agree with the sentiment that customised aberration-controlled scleral lenses 2,3 show promise as a potential future vision-correction platform for keratoconus. In a small population of seven individuals with keratoconus, Marsack and colleagues 2 have shown that wave-front guided scleral contact lenses can optically compensate for higher-order aberrations; however, as these authors note, 2 a range of factors will need to be surmounted in order for the custom correction of highly aberrated eyes to achieve clinical translation. Such factors include the complexity of fitting (and the need for highly repeatable centration), the current cost of the devices (to patient and practitioner) and longer-duration studies to assess real-world effects on visual performance.…”

A Comparison of Three Methods to Increase Scleral Contact Lens On-Eye Stability

“…10,11 However this level of performance requires that the wavefront-guided correction remain aligned with the underlying WFE of the eye. Here three separate stabilization designs (DTLD, DTSC and DTBSC) were evaluated and compared to the traditional spherical lens with no stabilizing methods (SLD).…”

“…10,11 However, unlike a typical scleral contact lens intended to correct defocus, a wavefront-guided contact lens must remain well-aligned to the underlying optical components of the eye. 12-15 Failure to align a wavefront-guided correction (which incorporates higher order aberration compensation in addition to the sphero-cylindrical correction) leads to the induction of complex, unintended wavefront errors that, depending on their magnitude, can be optically devastating.…”

History of the Shack Hartmann wavefront sensor and its impact in ophthalmic optics

“…18 Furthermore, large scleral lenses with excellent positional stability on the eye are being used to correct ocular aberrations. 19 Intraocular lenses (IOLs) are routinely used to replace the natural crystalline lens following cataract surgery. These lenses may also benefit from wavefront correction.…”