Purpose: To obtain an expression of the adjusted IOL power (P_IOLadj) in keratoconus eyes associated with minimal errors in IOL power calculation. Materials and methods: This retrospective study included a total of 25 eyes of 25 patients with ages ranging from 20 years to 76 years. The following IOLs were implanted: Acrysof IQ Toric, Acrysof SA60AT in 9 eyes, Sensar in 3 eyes, Tecnis 1 in 4 eyes, and Tecnis Toric in 2 eyes. The P_IOLadj is based on Gauss equations, using adjusted keratometric index (n_kadj) specific to keratoconus eyes. From this n_kadj, an adjusted keratometric corneal power is calculated (P_kadj). The P_IOLadj calculation was performed after estimating the effective lens position (ELP) using a mathematical expression obtained by multiple regression analysis (named ELP_adj). Comparison between the P_IOLadj and the real intraocular power implanted in each patient (P_IOLreal) was carried out. Results: No significant differences between P_IOLreal and P_IOLadj were found. However, differences could be clinically relevant up to of 2.54 D as P_IOLreal increases. But, in the range of P_IOLreal between 0 and 20 D, differences were lower than 1.5 D, being most of them below 1 D. Conclusion: A new formula of IOL power calculation (P_IOLadj) based on the use of an adjusted keratometric power (P_kadj) that considers a variable keratometric index due to the influence of the posterior corneal surface (n_kadj) and adjusted effective lens position (ELP_adj) is useful for estimating IOL power in low-to-moderate keratoconus, with more limitation in the most advanced keratoconus.

Purpose: To compare the efficacy of rigid gas-permeable (RGP) lens and soft hydrogel lens in patients with keratoconus and to assess their impact on quality of life (QoL). Setting: Tertiary care referral center. Materials and methods: A randomized, comparative, clinical interventional trial was conducted in patients with keratoconus. From July 2014 to June 2017, patients were enrolled for this study and were fitted with RGP contact lens (CL) (RoseK© Menicon Limited) or silicone hydrogel lens (Kerasoft© International Limited). The two groups were compared in terms of best spectacle corrected visual acuity (BSCVA), best CL corrected visual acuity (BCLCVA), corneal topography, Schirmer's test, and contrast sensitivity. Quality of life was assessed by asking the patients to fill a self-reported questionnaire. Results: Forty eyes were enrolled and randomized to the Rose-K and Kerasoft groups. The two groups were comparable with respect to the mean patient age, sex, and mean K values. A statistically significant improvement was observed in BCLCVA in both groups at 6 months (p < 0.01). The Kerasoft group had a better comfort score at 6 months’ follow-up compared to Rose K (p < 0.05). In terms of contrast sensitivity, Rose K group fared better than Kerasoft group (p = 0.001). Conclusion: Both Kerasoft and Rose K groups showed improvement in visual acuity. Kerasoft lens users had better comfort and also required less number of trials before final fit. Rose K lens provided a better contrast sensitivity. We conclude that Kerasoft lens can be considered as a good alternative for optical correction of corneal astigmatism in patients with keratoconus, not tolerating RGP lenses.

Purpose: Keratoconus is a degenerative, ectatic corneal disorder. Recently, corneal crosslinking (CXL) as a stabilizing procedure has been combined with other procedures to improve visual and refractive outcomes as in Athens and Cretan protocols. The aim of the study is to present the efficacy and safety of a modified Athens protocol over 1-year follow-up. Materials and methods: The study is a retrospective descriptive one with a total of 43 eyes (36 patients) with progressive keratoconus who underwent combined transepithelial phototherapeutic keratectomy (PTK), partial wavefront-optimized photorefractive keratectomy, and corneal collagen CXL. Visual, refractive, pachymetric and keratometric preoperative and postoperative follow-up data at 1 month, 3 months, 6 months, and 1 year were taken from patients’ medical records. Results: The mean uncorrected distance visual acuity (UDVA) improved from (0.33 ± 0.19) preoperatively to (0.64 ± 0.27) at 1 year postoperatively and the mean corrected distance visual acuity (CDVA) from (0.62 ± 0.21) to (0.80 ± 0.20). At 1-year postoperative visit, the mean spherical and cylindrical values changed significantly from (−2.10 ± 2.45) to (−0.34 ± 2.26) and from (−3.50 ± 1.85) to (−1.23 ± 1.02), respectively. The mean steep and flat K readings significantly decreased from (50.97 ± 4.46) to (47.58 ± 5.61) and from (47.08 ± 4.02) to (44.84 ± 4.47), respectively. The mean K_max also decreased from (56.27 ± 6.40) preoperatively to (51.22 ± 7.94) postoperatively. The thinnest corneal thickness mean was (462.49 ± 36.17 μm) preoperatively and (388.21 ± 56.64 μm) postoperatively. Conclusion: Our modified Athens protocol has shown to be safe and efficacious in the management of progressive keratoconus. Impressive improvements in visual, refractive, and keratometric values were noted. This approach offers a more tissue saving protocol than the original Athens protocol with less alteration to the surface of the cornea, which may offer more predictability and less refractive surprises.

Aim: Corneal collagen cross-linking (CCL) is a procedure that exposes the cornea to ultraviolet light and/or riboflavin to halt the progression of corneal ectatic disease. Currently, most investigations using Fourier-transform infrared spectroscopy (FTIR) of corneal changes following CCL focus on corneal ultrastructure, and not on changes at the molecular level. The aim of this study was to investigate the temporal and spatial separation of corneal collagen linkages that underlie the success of CCL. Materials and methods: Controlled experimental trial. Pairs of donor globes from five patients (n = 10) were divided into interventional and control groups. Interventional group corneas (n = 5) were exposed to riboflavin 0.1% and ultraviolet-A (UVA) light according to the modified Dresden protocol, harvested, cryo-microtomed, and placed on glass slides. Control group corneas (n = 5) underwent cryo-microtoming without CCL. Molecular changes were imaged using the synchrotron mid-infrared beamline at the Canadian Light Source. Results: Fourier-transform infrared spectroscopy imaging of total protein, integrated area under the amide I band from 1,700 to 1,600 cm⁻¹, FTIR imaging of collagen triple helix structures, second-derivative intensity as 1,666 cm⁻¹, and FTIR imaging of aggregated proteins, second-derivative intensity as 1,625 cm⁻¹ detected no difference in intramolecular cross-links between the interventional and control corneas. The secondary structure of collagen was neither significantly altered nor was its evidence of aggregation or denaturation within the cornea. Conclusion: Our data suggest that intramolecular cross-linking does not play a major role in CCL and that it is more likely to increase in intermolecular linkages that accounts for increased corneal strength. Clinical significance: An increase in intermolecular linkages likely accounts for the increased corneal strength observed following CCL. We hope that these results will guide future work to optimize techniques for CCL.

Aim: We present a case series involving five eyes in four young patients with advanced keratoconus who were implanted with Ferrara intrastromal corneal ring segments (ICRS) followed by phakic intraocular lens (PIOLs). Background: ICRS have been used for the management of keratoconus in order to prevent further keratoconus progression and improve visual performance. Nonetheless, many patients may still suffer from moderate to high myopia after ICRS, requiring refractive error correction, which may not be achieved with glasses, contact lenses, or laser refractive surgery. For such cases, PIOLs have emerged as an alternative to correct residual refractive errors. Case description: Patients were aged between 13 years and 32 years at ICRS implantation. Around 6 months after ICRS implantation, patients were submitted to a second procedure for the implantation of an implantable collamer lens (ICL), Artisan or Artiflex PIOL to correct residual myopia. After the combined Ferrara ICRS and PIOL implantation, all treated eyes demonstrated a significant improvement in topographic findings and visual acuity, with reduced refraction and keratometric astigmatism. Conclusion: The combined procedure was successful in reshaping the cornea and improving visual acuity of patients. Clinical significance: The association of ICRS and PIOL can be an important alternative that should be considered to provide young patients with improved visual acuity in a moment of their lives when they are at their most productive phase.

We report the long-term follow-up of two cases of untreated corneal ectasia presenting a crab claw-like sagittal and tangential topographic pattern at baseline, but without peripheral thinning. Currently, according to clinical examination, these two cases are diagnosed as pellucid-like keratoconus (PLK). The first case was a 58-year-old male who developed a true pellucid marginal degeneration (PMD) in one eye and with a nonprogressive PLK in the other eye. The second case presented was a 19-year-old male without clinical signs of ectasia at baseline that progressed to PLK with evident changes in topographic and pachymetric maps but maintaining the point of minimum corneal thickness (MCT) in the central area. The presence of two different conditions in the same patient (case 1) and the progression from inferosuperior asymmetry to the development of a crab claw-pattern (case 2) suggest that PMD, PLK, and keratoconus may be different phenotypic presentations of the same pathophysiological condition.