Refractive and topographic effects of single-segment intrastromal corneal ring segments in eyes with moderate to severe keratoconus and inferior cones.

PURPOSE: To evaluate the efficacy and safety of a single intrastromal corneal ring segment (ICRS) (450 µm Intacs SK) in moderate to severe keratoconic eyes with an inferiorly located cone and a noninvolved center. SETTING: Ophthalmology Department, American University of Beirut Medical Center, Beirut, Lebanon. DESIGN: Retrospective case series. METHODS: The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, central and inferior maximum topographic keratometry (K) values, manifest cylinder, and spherical equivalent (SE) were recorded preoperatively and 1 week and 1, 3, and 6 months postoperatively. RESULTS: Thirty eyes were studied. The mean age was 29.6 years ± 8.0 (SD). The mean preoperative UDVA and CDVA were 20/86 and 20/42, respectively. The mean center K was 49.14 ± 4.39 diopters (D); the mean maximum K, 56.78 ± 6.02 D; and the mean center K - maximum K, -7.45 ± 5.61 D. The mean SE and cylinder were -2.24 ± 2.32 D and -4.33 ± 1.43 D, respectively, with sphere ranging from +2.00 to -18.00 D. At 6 months, the UDVA improved to 20/32. The mean SE was -1.02 ± 2.04 D (P = .0330); the mean cylinder, -1.67 ± 1.00 D (P < .00); and the mean center K - maximum K, -4.92 ± 4.36 D (P < .05). The CDVA improved more than 2 lines; no eye lost any lines. Topographic indices improved in all eyes. CONCLUSIONS: Single ICRS implantation in eyes with moderate to severe keratoconus and inferiorly located cones was safe and effective. The development of a nomogram relying more on topographic data is suggested. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Static cyclotorsion measurements using the Schwind Amaris laser.

PURPOSE: To assess the reliability and reproducibility of static cyclotorsion correction (SCC) measurements made using the Schwind Amaris Excimer laser in patients undergoing LASIK or PRK, and compare the outcomes of treating astigmatism with and without SCC. METHODS: Eighty eyes of 40 patients were included in this study. All eyes underwent 2 or 3 sets of five measurements: before and after speculum placement, and after flap-lift (in LASIK cases). We assessed the reproducibility, accuracy, and the percentage of "no catch" measurements. The astigmatism was calculated pre-and 3-months-postoperatively by vector analysis. RESULTS: The mean age of the patients was 23.67 ・} 4.19 years. Preoperative spherical equivalent and astigmatism were -2.56 ・} 2.86 D and +1.36 ・} 0.98 D, respectively. The mean measurement time was 15.1 seconds per measurement. The percentages of "no catch" were: 63.8%, 14.9%, and 26.9%; pre-speculum, post-speculum, and post flap-lift, respectively. Cyclotorsion of ≥}2° was seen in 41.25% and 66% of the cases before and after the flap-lift, respectively. Significant cyclotorsion (≥}5°) was seen in 12.50% and 18% of the eyes pre and post flap-lift. The mean astigmatism dropped from +1.53 D@1° to +0.34D@3° when SCC was used and from +1.86D@1° to +0.23D@7° when SCC was not used. No statistical difference was noticed between the groups (p>0.05) in the postoperative residual astigmatism. A postoperative astigmatism of ≥ D was seen in 10% and 20% of eyes with and without SCC, respectively (p<0.01). CONCLUSION: Although not always feasible, the SCC measurement is a simple and useful tool. Postoperative astigmatism showed less variability when SCC was used.

Delineation of LASIK flaps with prednisolone acetate eyedrops.

We describe the use and safety of prednisolone acetate eyedrops at the end of laser in situ keratomileusis (LASIK) to aid proper positioning of the corneal flap. The LASIK flap is created using the preferred technique. Following laser ablation and flap repositioning, one drop of prednisolone acetate is instilled on the eye. This delineates the flap "gutters" and allows perfect flap positioning and centration. We used this technique in 425 eyes undergoing LASIK for correction of spherocylindrical refractive errors. Flap margins were adequately delineated intraoperatively. The only complication related to the use of the steroid suspension was crystal deposition under the flap in one case which resolved completely in 48 hours.

Static cyclotorsion measurements using the Schwind Amaris laser / Medições da ciclotorção estática usando o laser Schwind Amaris

Purpose: To assess the reliability and reproducibility of static cyclotorsion correction (SCC) measurements made using the Schwind Amaris Excimer laser in patients undergoing LASIK or PRK, and compare the outcomes of treating astigmatism with and without SCC. Methods: Eighty eyes of 40 patients were included in this study. All eyes underwent 2 or 3 sets of five measurements: before and after speculum placement, and after flap-lift (in LASIK cases). We assessed the reproducibility, accuracy, and the percentage of "no catch" measurements. The astigmatism was calculated pre-and 3-months-postoperatively by vector analysis. Results: The mean age of the patients was 23.67 ± 4.19 years. Preoperative spherical equivalent and astigmatism were -2.56 ± 2.86 D and +1.36 ± 0.98 D, respectively. The mean measurement time was 15.1 seconds per measurement. The percentages of "no catch" were: 63.8%, 14.9%, and 26.9%; pre-speculum, post-speculum, and post flap-lift, respectively. Cyclotorsion of ≥±2º was seen in 41.25% and 66% of the cases before and after the flap-lift, respectively. Significant cyclotorsion (≥±5º) was seen in 12.50% and 18% of the eyes pre and post flap-lift. The mean astigmatism dropped from +1.53 D@1º to +0.34D@3º when SCC was used and from +1.86D@1º to +0.23D@7º when SCC was not used. No statistical difference was noticed between the groups (p>0.05) in the postoperative residual astigmatism. A postoperative astigmatism of ≥1 D was seen in 10% and 20% of eyes with and without SCC, respectively (p<0.01). Conclusion: Although not always feasible, the SCC measurement is a simple and useful tool. Postoperative astigmatism showed less variability when SCC was used. .

Objetivo: Avaliar a confiabilidade e reprodutibilidade da correção da medida de ciclotorção estática (SCC), realizada com o excimer laser Schwind Amaris em pacientes submetidos a LASIK ou PRK, e comparar os resultados do tratamento de astigmatismo com e sem SCC. Método: Oitenta olhos (40 pacientes). Todos os olhos foram submetidos a 2 ou 3 séries de 5 medições: antes e após a colocação do espéculo, e depois do levantamento do flap (nos casos de LASIK). Foram avaliadas a reprodutibilidade, a precisão e a porcentagem de medições "não obtidas". O astigmatismo foi avaliado no pré-operatório e aos 3 meses de pós-operatório, por meio de análise vetorial. Resultados: A idade foi 23,67 ± 4,19 anos. O equivalente esférico e o astigmatismo pré-operatórios foram -2,56 ± 2,86 D, e 1,36 ± 0,98 D, respectivamente. O tempo de medição médio foi 15,1 segundos por medição; as porcentagens de medidas "não obtidas" foram: 63,8%, 14,9% e 26,9%; pré, pós-espéculo, e pós-levantamento do flap, respectivamente. Ciclotorção ≥±2º foi observada em 41,25% e 66 % dos casos pré e pós-levantamento do flap. Ciclotorção significativa (≥±5º) foi observada em 12,50% e 18% pré e pós-levantamento do flap. A média do astigmatismo diminuiu de 1,53D @ 1º para 0,34D @ 3º quando SCC foi usado e de 1,86D @ 1º a 0,23D @7º quando SCC não foi usado. O astigmatismo residual pós-operatório não foi estatisticamente diferente entre os grupos (p>0,05). O astigmatismo pós-operatório ≥1D foi observado em 10% e 20 % dos olhos com e sem SCC, respectivamente (p<0,01). Conclusão: A medição do SCC é fácil e útil, apesar de nem sempre ...

Intrastromal corneal ring segment SK for moderate to severe keratoconus: a case series.

PURPOSE: To report clinical results and safety profiles of symmetrical intrastromal corneal ring segment (ICRS; Intacs SK, Addition Technology Inc) implantation in eyes with moderate to severe keratoconus. METHODS: Interventional case series of 24 eyes from 22 patients implanted with Intacs SK using the femtosecond laser. Evaluation included uncorrected (UDVA) and corrected distance visual acuity (CDVA), manifest refraction, and Placido-based Scheimpflug imaging. Postoperative follow-up was 1 day, 1 week, and 1, 3, and 6 months. RESULTS: Mean patient age was 28±7 years (range: 16 to 41 years). All eyes had keratoconus. Twenty-one of 24 eyes had 2, 450-µm symmetrical segments inserted. Mean UDVA and CDVA were significantly better at 1, 3, and 6 months postoperatively (UDVA: 20/340 preoperatively vs 20/70 at 6 months [P<.001]; CDVA: 20/70 preoperatively vs 20/40 at 6 months [P<.001]; UDVA analysis of variance [ANOVA]: F=6.46, P=.0057; CDVA ANOVA: F=5.24, P=.0138). Pre- and 6-months postoperative clinical results were: mean spherical equivalent refractive error -9.60±4.86 diopters (D) and -3.05±2.05 D (P<.001), respectively; mean refractive cylinder, -3.20±1.50 D and -1.55±1.10 D, respectively (P<.001); and mean average total corneal power 52.03±4.49 D and 46.95±4.61 D, respectively (P<.001). No complications occurred, and no patients were lost to follow-up. Eyes with steeper preoperative corneal keratometry readings had the greatest flattening in corneal curvature and thus the greatest decrease in myopic refraction (r=-0.4, P<.001). No correlation was found between preoperative thinnest corneal pachymetry and postoperative curvature flattening. CONCLUSIONS: Implantation of Intacs SK for moderate to severe keratoconus is safe and effective, leading to significant decrease in myopia and appreciable decrease in astigmatism with improvement in CDVA.

MT1-MMP modulates bFGF-induced VEGF-A expression in corneal fibroblasts.

The cornea is physiologically avascular. Following a corneal injury, wound healing often proceeds without neovascularization (NV); however, corneal NV may be induced during wound healing in certain inflammatory, infectious, degenerative, and traumatic states. Such states disrupt the physiologic balance between pro-angiogenic and antiangiogenic mediators, favoring angiogenesis. Contributors to such states are matrix metalloproteinases (MMPs), which are key factors in both extracellular matrix remodeling and angiogenesis. Similarly, vascular endothelial growth factor A (VEGF-A) and basic fibroblast growth factor (bFGF) exert pro-angiogenic effects. Here, we elaborate on the facilitative role of MMPs-specifically Membrane Type 1 MMP (MT1-MMP, MMP14)-in corneal NV. Additionally, we provide new insight into the signaling relating to MT1-MMP, Ras, and ERK in the bFGF-induced VEGF-A expression pathways within the corneal fibroblasts.