Alexandra E. Karavitaki

Simultaneous topography-guided PRK followed by corneal collagen cross-linking for keratoconus.

PURPOSE To present the results after simultaneous photorefractive keratectomy (PRK) followed by corneal collagen cross-linking (CXL) for progressive keratoconus. METHODS Twelve patients (14 eyes) with progressive keratoconus were prospectively treated with customized topography-guided PRK with the Pulzar Z1 (wavelength 213 nm, CustomVis) immediately followed by corneal collagen CXL with the use of riboflavin and ultraviolet A irradiation. RESULTS Mean follow-up was 10.69+/-5.95 months (range: 3 to 16 months). Mean preoperative spherical equivalent refraction (SE) was -3.03+/-3.23 diopters (D) and defocus was 4.67+/-3.29 D; at last follow-up SE and defocus were statistically significantly reduced to -1.29+/-2.05 D and 3.04+/-2.53 D, respectively (P<.01). Preoperative mean (logMAR) uncorrected visual acuity was 0.99+/-0.81 and best spectacle-corrected visual acuity was 0.21+/-0.19, which improved postoperatively to 0.16+/-0.15 and 0.11+/-0.15, respectively. The mean steepest keratometry was reduced from 48.20+/-3.40 D preoperatively to 45.13+/-1.80 D at last follow-up. CONCLUSIONS Simultaneous PRK followed by CXL seems to be a promising treatment capable of offering functional vision in patients with keratoconus.

Intraoperative Pachymetric Measurements during Corneal Collagen Cross-Linking with Riboflavin and Ultraviolet A Irradiation

OBJECTIVE To study central corneal pachymetric variations during corneal collagen cross-linking (CXL) treatment with the use of riboflavin and ultraviolet A irradiation (UVA). DESIGN Prospective, noncomparative, interventional clinical study. PARTICIPANTS Fifteen keratoconic patients (19 eyes) were enrolled. METHODS All patients underwent riboflavin-UVA-induced corneal CXL. Intraoperative central corneal thickness (CCT) measurements using ultrasound pachymetry were performed during the procedure. Measurements were obtained after epithelial removal, after riboflavin drop instillation, and every 5 minutes (6 interval times) during UVA irradiation (30 minutes). MAIN OUTCOME MEASURES Central corneal thickness measurements. RESULTS Mean patient age was 26.9+/-6.5 years (range, 17-40 years). Ten were male and 5 were female. Mean preoperative CCT was 458.5+/-21.5 microm (range, 427-494 microm; 95% confidence interval [CI], 448-467 microm) and 415.7+/-20.6 microm (range, 400-468 microm; 95% CI, 406-426 microm) before and after epithelial removal, respectively. There was a statistically significant decrease (mean, 75 microm) of CCT between the epithelial removal interval (415.7+/-20.6 microm; range, 400-468 microm) and at the end of riboflavin solution instillation (340.7+/-22.9 microm; range, 292-386 microm; P<0.001). There was no statistically significant change in CCT during irradiation (P>0.05). There was no statistically significant difference between preoperative and 1-month postoperative endothelial cell count (preoperative, 2780+/-197 to 1-month postoperative, 2713+/-116; P = 0.14). No intraoperative, early postoperative, or late postoperative complications were observed in this patient series. CONCLUSIONS During corneal CXL with the use of riboflavin and UVA irradiation, a statistically significant decrease of CCT was demonstrated.

Management of post laser in situ keratomileusis ectasia with simultaneous topography guided photorefractive keratectomy and collagen cross-linking.

A thirty-nine year old man was referred to our institute due to progressive decreased visual acuity five years after bilateral Laser in situ Keratomileusis (LASIK). Topography revealed signs of post – LASIK ectasia. Patients’ left eye was treated with simultaneous Topography Guided Photorefractive Keratectomy (PRK) followed by Corneal Collagen Cross Linking (CXL). Twelve months after the combined procedure both uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) showed significant improvement while topographic findings revealed an improvement of the astigmatic pattern. All higher order aberrations showed a significant decrease twelve months postoperatively. Combined topography guided PRK and corneal cross linking could represent an alternative treatment for post – LASIK ectasia.We consider a set of nine polycyclic conjugated hydrocarbons, which includes at one extreme benzene, the prototype of aromatic compounds, and at the other extreme cyclooctatetraene, a well-known nonaromatic compound, while the remaining seven compounds illustrate molecules of decreasing degree of aromaticity. Using the model of conjugated circuits for calculations of ring currents, we report on variations in the -electron ring currents in these molecules with the decrease of their degree of aromaticity. This contribution is a hybrid of original scientific paper and a review, and if viewed as provocative, it is so by design.

Photorefractive keratectomy followed by same-day corneal collagen crosslinking after intrastromal corneal ring segment implantation for pellucid marginal degeneration

A 28-year-old man with progressive pellucid marginal degeneration (PMD) had photorefractive keratectomy (PRK) followed by same-day corneal collagen crosslinking (CXL) for progressive PMD 12 months after intrastromal corneal ring segment implantation (Intacs). No intraoperative or early postoperative complications occurred. Nine months postoperatively, the uncorrected distance visual acuity improved from finger counting to 20/63 and the corrected distance visual acuity improved from 20/40 to 20/25. Corneal topography revealed a significant improvement in keratometry (from 46.73/38.67 to 44.92/39.01), which remained stable during the 9-month follow-up period. Despite the encouraging results, longer follow-up is necessary to evaluate the outcomes of this approach.

Safety of high-intensity corneal collagen crosslinking

Purpose To evaluate the safety of a new high‐intensity corneal collagen crosslinking (CXL) treatment protocol for keratoconus. Setting Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design Prospective interventional case series. Methods Patients with progressive keratoconus had CXL using a new treatment protocol with 9 mW/cm2 irradiance for duration of 10 minutes. The rate of reepithelialization, endothelial cell density (ECD), corrected distance visual acuity (CDVA), and steep and flat keratometry (K) values were evaluated preoperatively and 3 months postoperatively. Results Nine patients (10 eyes) were enrolled. No intraoperative or early postoperative complications were observed in any patient. The ECD did not change significantly 3 months postoperatively (P=.169). The CDVA improved from 0.19 logMAR ± 0.20 (SD) preoperatively to 0.10 ± 0.16 logMAR 3 months postoperatively; however, the improvement did not attain significance (P=.141). No eye lost lines of CDVA. The mean steep K readings decreased significantly from 48.04 ± 2.57 diopters (D) preoperatively to 46.51 ± 2.81 D 3 months postoperatively (P=.047); the mean flat K readings did not change significantly postoperatively (P=.285). Conclusions Corneal collagen crosslinking at 9 mW/cm2 irradiance for 10 minutes did not cause significant changes in ECD or intraoperative or early postoperative complications. None patient lost a line of CDVA 3 months after the procedure. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Transepithelial Phototherapeutic Keratectomy Using a 213-nm Solid-State Laser System Followed by Corneal Collagen Cross-Linking with Riboflavin and UVA Irradiation.

Purpose. To present a case of a keratoconic patient who underwent epithelial removal with transepithelial phototherapeutic keratectomy (t-PTK) using a 213-nm solid-state laser system followed by corneal collagen cross-linking (CXL) with riboflavin and ultraviolet-A (UVA) irradiation. Methods. Case report. Results. A twenty-four-year-old male with keratoconus underwent CXL treatment after epithelial removal with t-PTK using a solid-state laser system. No intra- or early postoperative complications were found. One month postoperatively, uncorrected visual acuity (UCVA) improved from 20/63 to 20/32 while best spectacle- corrected visual acuity (BSCVA) improved from 20/40 to 20/25. Corneal topography revealed a significant improvement which remained stable during the six-month followup period. Conclusions. Epithelial removal with t-PTK before CXL could improve patients visual outcome.

Combined corneal collagen cross-linking and posterior chamber toric implantable collamer lens implantation for keratoconus.

A 29-year-old woman with keratoconus underwent posterior chamber toric implantable Collamer lens (Visian ICL; STAAR Surgical, Monrovia, CA) implantation 12 months after corneal collagen cross-linking with riboflavin and ultraviolet radiation-A. No intraoperative or postoperative complications were observed. Three months postoperatively, uncorrected distance visual acuity improved from counting fingers to 20/40 and corrected distance visual acuity improved from 20/100 to 20/30. Combined cross-linking treatment and posterior chamber toric phakic Collamer lens implantation in a two-step procedure seems to be an effective method for correcting keratoconus in patients with high myopia and astigmatism. Despite the encouraging results, longer follow-up is necessary to evaluate the outcomes of this approach.

LASIK flap buttonhole treated immediately by PRK with mitomycin C

PURPOSE To describe the visual outcomes of three patients who had LASIK flap buttonhole and were treated immediately with photorefractive keratectomy (PRK) and topical mitomycin C (MMC) 0.02%. METHODS Three patients underwent bilateral LASIK with the SCHWIND Carriazo-Pendula 90 microm head microkeratome. In all three cases, a buttonhole flap occurred in the left eye. The flap was repositioned and phototherapeutic keratectomy for 50 microm was used for epithelial removal while immediate PRK with MMC was performed to treat the buttonhole flap. RESULTS Three months after the procedure, uncorrected distance visual acuity and corrected distance visual acuity were 20/20 with regular topographic findings. CONCLUSIONS Using PRK with MCC immediately after the occurrence of the LASIK flap buttonhole may be an effective treatment.

Descemet stripping automated endothelial keratoplasty in a child after failed penetrating keratoplasty

Use of Descemet stripping automated endothelial keratoplasty (DSAEK) has been reported in children for the treatment of postoperative endothelial decompensation and Descemet membrane break after forceps delivery. Rapid visual recovery and minimally induced postoperative astigmatism make DSAEK preferable to penetrating keratoplasty for the management of isolated endothelial disorders in this age group. We present a case of DSAEK in a 4-year-old boy for the management of irreversible endothelial rejection after penetrating keratoplasty. Three months after the procedure, the cornea remained clear with the donor button in place.

INTACS followed by KeraRing intrastromal corneal ring segment implantation for keratoconus.

PURPOSE To describe the visual and refractive outcomes in three eyes (two keratoconic patients) with previous intrastromal corneal ring segments (INTACS, Addition Technology Inc) that underwent adjuvant single KeraRing (Mediphacos) intrastromal corneal ring segment implantation. METHODS Two keratoconic patients (three eyes) with implanted INTACS segments underwent an additional (without explanting previous INTACS) single KeraRing segment implantation. RESULTS No intraoperative complications occurred. Six months postoperatively, uncorrected distance visual acuity improved from 20/100 and 20/200 to 20/32 and 20/40 in the right and left eyes, respectively, of patient 1, and from 20/400 to 20/50 in the treated right eye of patient 2. Corrected distance visual acuity improved from 20/50 and 20/100 to 20/30 and 20/32 in the right and left eyes, respectively, of patient 1 and from 20/200 to 20/40 in patient 2. Keratometric measurements improved from 51.00/45.70 to 47.00/44.60 diopters (D) and from 50.80/48.80 to 42.70/40.30 D in the right and left eyes, respectively, of patient 1, and from 49.30/45.70 to 45.60/44.10 D in patient 2. CONCLUSIONS In keratoconic patients with INTACS in place, adjuvant single intrastromal corneal ring segment (KeraRing) implantation could improve visual and refractive outcome.