Since its inception in the late 1990s, corneal cross-linking has grown from an interesting concept to a primary treatment for corneal ectatic disease worldwide. Using a combination of ultraviolet-A light and a chromophore (vitamin B2, riboflavin), the cornea can be stiffened, usually with a single application, and progressive thinning diseases such as keratoconus arrested. Despite being in clinical use for many years, some of the underlying processes, such as the role of oxygen and the optimal treatment times, are still being worked out. More than a treatment technique, corneal cross-links represent a physiological principle of connective tissue, which may explain the enormous versatility of the method. We highlight the history of corneal cross-linking, the scientific underpinnings of current techniques, evolving clinical treatment parameters, and the use of cross-linking in combination with refractive surgery and for the treatment of infectious keratitis.

Purpose Multifocal intraocular lenses (IOLs) offer the possibility of spectacle-free vision following cataract surgery compared to standard IOLs. Existing systematic reviews have generally concluded that multifocal IOLs result in better uncorrected near vision and greater spectacle independence, but more unwanted visual phenomena such as glare and halos, compared to monofocal IOLs. However, the certainty of evidence has been low for most outcomes, and pooled analyses have grouped together technologically obsolete lenses with newer lenses, potentially obscuring differences in performance across different lens types. Methods We performed a systematic review searching for RCTs of a multifocal IOL to a standard IOL or monovision that reported spectacle independence, visual acuity, or quality of life. Databases were searched from 1/1/2006-4/30/2017. Existing reviews were used to identify older studies. Title/abstract screening and data extraction were done in duplicate. Where possible, random effects metaanalysis was performed to synthesize results. In addition to comparing multifocal IOLs as a group to monofocal IOLs, we also compared newer diffractive lenses to obsolete or refractive lenses. Results Twenty-five eligible studies were identified. There was no difference in pooled estimates of corrected or uncorrected distance vision between multifocal and standard IOLs. Compared to monofocal IOLs, multifocal IOLs had statistically significantly better pooled results for the outcome of near vision (10 studies, 1025 patients, mean difference in logMAR of-0.26 (95% CI-0.37,-0.15)); spectacle dependence (12 studies, 1237 patients, relative risk of 0.27 (95% CI 0.20, 0.38)) and borderline significantly better quality of vision (6 studies, 596 patients, standardized mean difference of-0.54, (95% CI-1.12, 0.04)). Compared to monofocal IOLs, multifocal IOLs had statistically significantly worse pooled results for the outcomes of glare (9 studies, 847 patients, risk ratio of 1.36 (95% CI 1.15, 1.61) and halos (7 studies, 754 patients, risk ratio of 3.14 (95% CI 1.63, 6.08). Newer multifocal lenses had statistically significantly better outcomes than older diffractive lenses or refractive lenses, when compared to monofocal IOLs, in near vision, quality of vision, and risk of halos. Conclusions Multifocal IOLs compared to standard IOLs or monovision result in better uncorrected near vision and a higher proportion of patients who achieve spectacle independence, but greater risk of unwanted visual phenomena. Newer diffractive lenses may be better than refractive lenses in near vision and quality of vision outcomes, with less risk of halos than older diffractive lenses and refractive lenses.

Purpose: To compare the relative 12-month corneal crosslinking (CXL) functional outcomes using standard protocol and accelerated protocols in patients with progressive keratoconus. Methods: CXL was performed using 3 epithelium-off protocols: standard [3 mW/cm2 for 30 minutes, 5.4 J/cm2 (S3/30-CXL)], accelerated with equivalent total irradiance [9 mW/cm2 for 10 minutes, 5.4 J/cm2 (A9/10-CXL)], and accelerated with increased total irradiance [30 mW/cm2 for 4 minutes, 7.2 J/cm2 (A30/4-CXL)]. Efficacy measurements were evaluated 12 months after treatment with Scheimpflug imaging (Pentacam HR) and included change in maximum keratometry (K Max), corrected distance visual acuity (CDVA), other keratometric variables, pachymetry, keratoconus indices, astigmatism, asphericity, manifest refraction, and higher order aberrations. Results: Ninety-three eyes (67 patients) were evaluated: 35 eyes (26 patients) with S3/30-CXL, 29 eyes (19 patients) with A9/10-CXL, and 29 eyes (22 patients) with A30/4-CXL. Mean ∆K Max was −1.53 ± 2.1 diopter (D) for S3/30-CXL, −0.71 ± 1.3 D for A9/10-CXL, and −0.70 ± 2.3 D for A30/4-CXL (P = 0.37). Mean ∆CDVA(logMAR) was −0.18 ± 0.2 for S3/30-CXL, −0.13 ± 0.2 for A9/10-CXL, and −0.18 ± 0.2 for A30/4-CXL (P = 0.79). ∆K Mean (r = −0.29 to −0.46), anterior asphericity (r = −0.34 to −0.40), and central keratoconus index (r = −0.18 to −0.38) best correlated with ∆CDVA. S3/30-CXL had greater changes in index of surface variance, index of vertical asymmetry, keratoconus index, and regularization index compared to A9/10-CXL and A30/4-CXL. There were no other differences between protocols. Conclusions: All 3 protocols showed improvements in K Max, CDVA, and other variables, with similar functional outcomes for each despite greater change in keratoconus indices after S3/30-CXL. Correlations between change in measured variables and CDVA were poor overall; however, K Mean, central keratoconus index, and anterior asphericity were better correlated with CDVA than K Max.

Drs. Koch, Weikert, and Wang received research support from Ziemer USA, Inc. No other author has a financial or proprietary interest in any material or method mentioned.