Late-onset refractive shift after small-aperture corneal inlay implantation.

We present a series of 5 consecutive cases in which a small-aperture corneal inlay (Kamra ACI7000PDT) was uneventfully implanted in a corneal pocket created at a depth between 200 µm and 250 µm. Three months after surgery, all patients had good visual results, normal corneal surfaces, and adequate stromal healing. Between 6 months and 19 months after surgery, visually significant refractive changes appeared in the form of a hyperopic shift in 4 cases and a myopic shift in 1 case. Topical steroids were ineffective. In 2 cases, the inlay was explanted. Among the adverse events reported in the 2015 approval of the small-aperture corneal inlay was a low incidence of late refractive changes. Recently, we have encountered a relatively higher frequency of these adverse events. Thus, we evaluated the hypothesis that a relationship between these late refractive changes and the decreased diffusivity of nutritional fluid to the anterior stroma accentuated by a lower depth of implantation is the cause.

Refractive Changes Induced by Spherical Aberration in Laser Correction Procedures: An Adaptive Optics Study.

PURPOSE: To study the effect on vision of induced negative and positive spherical aberration within the range of laser vision correction procedures. METHODS: In 10 eyes (mean age: 35.8 years) under cyclopegic conditions, spherical aberration values from -0.75 to +0.75 µm in 0.25-µm steps were induced by an adaptive optics system. Astigmatism and spherical refraction were corrected, whereas the other natural aberrations remained untouched. Visual acuity, depth of focus defined as the interval of vision for which the target was still perceived acceptable, contrast sensitivity, and change in spherical refraction associated with the variation in pupil diameter from 6 to 2.5 mm were measured. RESULTS: A refractive change of 1.60 D/µm of induced spherical aberration was obtained. Emmetropic eyes became myopic when positive spherical aberration was induced and hyperopic when negative spherical aberration was induced (R2 = 81%). There were weak correlations between spherical aberration and visual acuity or depth of focus (R2 = 2% and 3%, respectively). Contrast sensitivity worsened with the increment of spherical aberration (R2 = 59%). When pupil size decreased, emmetropic eyes became hyperopic when preexisting spherical aberration was positive and myopic when spherical aberration was negative, with an average refractive change of 0.60 D/µm of spherical aberration (R2 = 54%). CONCLUSIONS: An inverse linear correlation exists between the refractive state of the eye and spherical aberration induced within the range of laser vision correction. Small values of spherical aberration do not worsen visual acuity or depth of focus, but positive spherical aberration may induce night myopia. In addition, the changes in spherical refraction when the pupil constricts may worsen near vision when positive spherical aberration is induced or improve it when spherical aberration is negative. [J Refract Surg. 2017;33(7):470-474.].