Luis Fernández-Vega Cueto

Inferior Intrastromal Corneal Ring Segments in Paracentral Keratoconus With No Coincident Topographic and Coma Axis

PURPOSEnTo assess the visual and refractive outcomes of implantation of intrastromal corneal ring segments (ICRS) in keratoconic eyes with no coincident topographic and comatic axes.nnnMETHODSnForty-one keratoconic eyes of 39 patients with no coincident topographic and comatic axes were implanted inferiorly with a Ferrara-type ICRS (Keraring SI6; Mediphacos Inc., Belo Horizonte, Brazil) of 150° of arc with a thickness of 150, 200, and 250 μm. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal coma-like root mean square, and residual refractive errors analyzed using vector analysis were recorded before and 6 months after the ICRS implantation.nnnRESULTSnMean UDVA was 0.76 ± 0.41 logMAR before and 0.53 ± 0.46 logMAR after surgery (P = .0006). CDVA was 0.13 ± 0.14 logMAR before and 0.07 ± 0.09 logMAR after surgery (P = .0007). Two eyes (4.9%) lost two lines or more of CDVA, 3 eyes (7.32%) lost one line, 16 eyes (39.02%) had no change in CDVA, 9 eyes (21.95%) gained one line, and 11 eyes (26.83%) gained two lines or more of CDVA. The safety index was 1.10. Spherical equivalent was significantly reduced after ICRS implantation (P < .001). Corneal coma-like root mean square changed from 0.80 ± 0.53 μm before surgery to 0.61 ± 0.59 μm after surgery (P = .02) for 4.5 mm of pupil size.nnnCONCLUSIONSnOne Ferrara-type ICRS of 150° of arc with a thickness of 150, 200, or 250 μm implanted inferiorly may reduce both astigmatism and corneal coma-like aberrations in keratoconic eyes with no coincident topographic and comatic axes, providing an improvement of UDVA and CDVA values.

Intrastromal Corneal Ring Segment Implantation in 409 Paracentral Keratoconic Eyes.

Purpose: To assess the efficacy outcomes of implanting intrastromal corneal ring segments (ICRS) to correct paracentral keratoconus. Methods: Four hundred nine eyes with paracentral keratoconus, in which the differences between the axes of refractive cylinder and the corneal flattest meridian and the comatic aberration map were less than 30 degrees, were evaluated before and after the implantation of Ferrara-type ICRS. Snellen uncorrected and best-corrected distance visual acuity, residual refractive errors analyzed with vector analysis, and the root mean square for corneal coma-like aberration for a pupil size of 4.5 mm were recorded before and 6 months after ICRS implantation. Results: The mean uncorrected distance visual acuity (Snellen decimal scale) rose from 0.19 ± 0.19 before ICRS implantation to 0.42 ± 0.30 after implantation (P < 0.0001). The mean preoperative best-corrected distance visual acuity was 0.69 ± 0.24 and the postoperative value was 0.77 ± 0.23 (P < 0.0001). The safety index was 1.13. The spherical equivalent declined steeply after ICRS implantation (P < 0.0001). Cylinder power decreased by more than 50% in 71% of the eyes. The root mean square for corneal coma-like aberration for a 4.5-mm pupil changed from 1.32 ± 1.01 &mgr;m before surgery to 1.06 ± 0.85 &mgr;m after surgery (P ⩽ 0.001). Conclusions: The Ferrara-type ICRS implantation is a safe and effective procedure for treating patients with keratoconus that meets the morphological characteristics of the sample under study.

Differential Expression of Proteoglycans by Corneal Stromal Cells in Keratoconus.

PURPOSEnKeratoconus is a heterogeneous disease associated with a range of pathologies, including disorders that involve proteoglycans (PGs). Some PG alterations, mainly in keratan sulfate (KS), occur in keratoconus. In this article, we studied the differential expression of the genes encoding PGs in cells isolated from keratoconus patients and healthy controls, as well as in corneal sections.nnnMETHODSnHuman central corneal tissue was obtained from cadaver donors and patients undergoing penetrating keratoplasty surgery. A transcriptomic approach was used, employing quantitative PCR, to analyze both the expression of the enzymes involved in glycosaminoglycan (GAG) biosynthesis and the PG core proteins. The expressions of the differentially expressed core proteins and of the GAG chains were also analyzed by immunocytochemistry in the cultured cells, as well as by immunohistochemistry in corneal sections.nnnRESULTSnThe mRNA levels of most major matrix PG mRNAs in the cultured keratoconic stromal cells decreased except collagen XVIII, which increased. At keratocyte surfaces, some heparan sulfate PGs were down-regulated. With respect to GAGs, there were changes in gene expression for the polymerization of the GAG chains, mainly KS and chondroitin sulfate, and in the modification of the saccharidic chains, pointing to an alteration of the sulfation patterns of all GAG species.nnnCONCLUSIONSnMost of the PG core proteins underwent significant changes in cultured keratoconic cells and corneas. With regard to GAG chains, the polymerization of the chains and their chemical modification was modified in way that depended on the specific type of GAG involved.

Silk Fibroin Films for Corneal Endothelial Regeneration: Transplant in a Rabbit Descemet Membrane Endothelial Keratoplasty

PurposenDevelop a silk fibroin (SF)-based artificial endothelial graft for its use in a rabbit Descemet membrane endothelial keratoplasty (DMEK).nnnMethodsnHuman and rabbit artificial corneal endothelial grafts were developed through the culture of human and rabbit corneal endothelial cells (CECs) on SF films. Rabbit artificial SF endothelial grafts were transplanted in a DMEK surgery into a rabbit in vivo model.nnnResultsnSF artificial endothelial grafts showed the characteristic endothelial markers: zonula occludens (ZO-1) and Na+/K+ ATPase. In a rabbit model of DMEK surgery, SF artificial endothelial graft restored the corneal transparency and thickness at 6 week of follow-up. Anterior segment optical coherence tomography revealed the SF graft as a fully integrated component in the corneal tissue, displaying a similar corneal thickness and endothelial cell count when compared with its healthy contralateral cornea. Histologic analysis showed that the SF artificial endothelial graft was attached and integrated on the surface of the corneal stroma without a significant inflammatory reaction, and rabbit CECs consisted in a monolayer that showed their characteristic markers ZO-1 and Na+/K+ ATPase, suggesting proper intercellular junctions and cellular pump function.nnnConclusionsnWe have developed SF films with biological properties that supported the growth of rabbit and human CECs, which showed normal morphology and characteristic markers; and with mechanical properties that allowed its use in a DMEK surgery, proving its in vivo functionality in a rabbit model of endothelial dysfunction.

Treatment of patients with neurotrophic keratitis stages 2 and 3 with plasma rich in growth factors (PRGF-Endoret) eye-drops

PurposeTo provide preliminary data about efficacy and safety of plasma rich in growth factors (PRGF) eye-drops in neurotrophic keratitis (NK) and to analyze the possible influence of certain variables on treatment outcomes.MethodsThis retrospective study included patients with stages 2–3 of NK treated with PRGF eye-drops. Primary endpoint was the resolution time of corneal ulcer defect. Outcome measures including percentage of ulcer closure at 4xa0weeks, Ocular Surface Disease Index (OSDI), Best-Corrected Visual Acuity (BCVA) and Visual Analogue Scale (VAS) were also evaluated before and after treatment with PRGF. The influence of some patients’ clinical variables on results was assessed. Safety assessment was also performed reporting all adverse events.ResultsThirty-eight treated eyes in a total of thirty-one patients were evaluated, of which five cases had no prior response to autologous serum treatment. Most cases (97.4%) achieved the complete resolution of corneal defect/ulcer. Mean resolution time was 11.4xa0weeks (SDxa0=xa013.7). A statistical significant (pxa0<xa00.05) reduction in OSDI (60.9%), VAS frequency (59.9%), VAS severity (57.0%) and improvement in BCVA (52.8%) was observed. The results were stratified according to the pathology stage and to the identified potential effect modifiers variables. Only one adverse event was reported in one patient (2.6%).ConclusionsPRGF eye-drops could be a safe and effective therapeutic option for patients with stages 2–3 of NK, showing high rates of corneal defect/ulcer resolution in short times, either in reducing signs and symptoms of NK, and therefore preventing the progression of NK to greater ocular complications.

Visual function after implantation of a diffractive aspheric trifocal intraocular lens.

Purpose To evaluate distance, intermediate, and near vision after bilateral implantation of a diffractive aspheric trifocal intraocular lens (IOL). Methods This study enrolled 204 eyes of 102 patients who had bilateral implantation of the AT LISA tri 839MP IOL. Monocular and binocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) (4 meters), monocular and binocular uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA) (30, 40 centimeters), binocular uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA) (50, 60, 70 centimeters), the defocus curve, and binocular photopic and mesopic contrast sensitivity with and without glare were evaluated over 6 months. Results No statistically significant differences in visual acuity outcomes between follow-up visits were found at any distance evaluated (p>0.05). Six months postoperatively, the mean monocular UDVA and UNVA were comparable to preoperative CDVA and DCNVA, respectively. All patients achieved a binocular CDVA of 20/25 or better. The mean binocular DCIVA ranged from 0.11 ± 0.11 (70 cm) to 0.07 ± 0.11 logMAR (50 cm). The mean binocular DCNVA was 20/25 or better in nearly 87% of patients. The defocus curve showed a wide range of useful vision, with no statistically significant differences in visual acuity at intermediate distances (p = 0.151). Mesopic contrast sensitivity was lower than under photopic conditions, particularly at medium and high spatial frequencies (p<0.001). Conclusions Bilateral implantation of this trifocal IOL provides good visual outcomes at far, intermediate, and near distances, being an effective solution to reduce spectacle dependence after lensectomy.

Long-Term Follow-Up of Intrastromal Corneal Ring Segments in Paracentral Keratoconus with Coincident Corneal Keratometric, Comatic, and Refractive Axes: Stability of the Procedure

Purpose To assess the long-term outcomes of implanting intrastromal corneal ring segments (ICRS) in paracentral keratoconic eyes. Methods 58 eyes with paracentral keratoconus with coincident refractive, keratometric, and comatic axes were evaluated. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and refractive errors were recorded before and at all follow-up visits. The postoperative follow-up was 5 years. Patients were divided into two groups: group I (30 years old or younger) and group II (more than 30 years old). Results The mean UDVA (logMAR) rose from a preoperative 0.83u2009±u20090.31 to a five-year postoperative 0.42u2009±u20090.33 (P < 0.0001). The mean CDVA varied from 0.16u2009±u20090.17 to 0.11u2009±u20090.18 (P = 0.0003). Both the UDVA and CDVA were stable over the postoperative period in both groups (P > 0.05). The spherical equivalent and the refractive cylinder declined steeply after ICRS implantation in both groups (P < 0.001), and were stable over the postoperative period (P > 0.05). The keratometric values were also stable over the postoperative follow-up. Conclusion Ferrara-type ICRS implantation in keratoconus that meets the characteristics of the sample under study reduces the refractive error at the same time as it improves postoperative UDVA and CDVA six months after surgery and that these results remain stable over five years of follow-up.

Quantitative distribution of Zn, Fe and Cu in the human lens and study of the Zn–metallothionein redox system in cultured lens epithelial cells by elemental MS

The human lens is constantly subjected to exogenous and endogenous stressors, leading to oxidative cellular damage and, with time, to cataract formation. Metallothioneins (MTs) are a group of important enzymes that use metals (i.e., Zn and Cu) to protect tissues from the deleterious effects of free radicals associated with oxidative stress. This work combines elemental mass spectrometry with bio-analytical methodologies to determine (i) the total amount, the quantitative speciation and the cellular distribution of trace elements (i.e., Zn, Fe, and Cu) in human lenses and their corresponding capsules; and (ii) the effects of “exogenous” metal (i.e., 68ZnSO4, isotopically enriched in 68Zn) and stressor (i.e., IL-1α) on the zinc–MT redox system in cultured human lens epithelial cells (HLEsv) in vitro. Of all the elements analyzed, Zn was the most abundant, and it was equally present in both the capsule (9.7 ± 2.5 μg g−1 tissue) and the lens (9.5 ± 1.2 μg g−1 tissue). In contrast, Fe was found to be more than 6-fold more abundant in the capsule (1.6 ± 0.4 μg g−1) than in the lens (0.2 ± 0.1 μg g−1). Zinc in the lens is mainly associated with high molecular mass proteins, whereas in the capsule it is mostly bound to low and medium molecular mass proteins. The localization of Zn, Cu and MTs in the lens showed their preferential co-distribution in the lens epithelial cell layer, underneath the anterior capsule. Exogenous Zn is capable of inducing a stoichiometric change in MT proteins from Zn3–MT to Zn7–MT within lens epithelial cells in vitro, which may be related to their antioxidant capacity.

Intraocular Pressure After Implantation of a Phakic Collamer Intraocular Lens With a Central Hole.

PURPOSEnTo investigate the middle-term intraocular pressure (IOP) results after implantation of a posterior chamber collagen copolymer phakic intraocular lens (IOL) (V4c Visian; STAAR Surgical Co., Nidau, Switzerland) with a central hole in patients with myopia.nnnMETHODSnThis retrospective study enrolled patients who had implantation of a phakic IOL with a central hole. IOP, central vault, and adverse events were evaluated 1, 3, 6, 12, and 24 months postoperatively.nnnRESULTSnThe study enrolled 763 eyes (384 patients, 128 men and 256 women). Mean follow-up was 7.0 ± 7.2 months (range: 1 to 24 months). The mean IOP was 13.2 ± 2.1 mm Hg preoperatively. Postoperatively, the mean IOP was 12.4 ± 1.7 mm Hg at 1 month, 12.5 ± 1.8 mm Hg at 3 months, 12.6 ± 1.3 mm Hg at 6 months, 12.6 ± 1.4 mm Hg at 12 months, and 12.7 ± 1.1 mm Hg at 24 months. Only one case (0.13%) presented an increased IOP (> 21 mm Hg) during the observation period. No pupillary block or acute angle closure was recorded. IOP at the final follow-up visit was 12.8 ± 1.3 mm Hg.nnnCONCLUSIONSnImplantation of central hole phakic IOL in myopic patients provided good and safe IOP outcomes throughout the 24-month observation period. [J Refract Surg. 2017;33(4):244-249.].

Refractive Correction Treatment in Ectatic Corneal Disorders

Corneal ectasia is a progressive disorder in which microstructural changes within the cornea cause an alteration of its normal gradient curvature and of its biomechanical behaviour. Over the last few years, different treatments have proved to be safe and effective in halting or slowing the corneal ectasia progression and/or in remodelling of the cornea (such as corneal collagen cross-linking and/or intrastromal corneal ring segments). In this special issue, the latest research about the surgical and parasurgical treatments of corneal ectasia for therapeutic and refractive perspective is discussed, in terms of halting the ectatic process in keratoconus patients, improving the corneal shape, and minimizing the residual refractive error. An overview is presented of the last 20 years of outcomes and complications for the conservative management of keratoconus (glasses and contact lenses). Cross-linking can halt the disease progression, and intrastromal corneal ring segments can improve the corneal shape and hence the visual quality and reduce the refractive error. Combined treatment of intrastromal corneal ring segments and corneal cross-linking may be a successful option to halt progressive keratoconus and improve visual acuity. It must be noted that, in particular corneal morphology, such as in central keratoconus with high corneal asphericity and in paracentral keratoconic eyes, a Ferraratype intrastromal corneal ring segments implantation reported an improvement of postoperative visual acuity and stability over long-term follow-up [1, 2]. Sequential treatment, such as intrastromal corneal ring segments and an extended range of vision intraocular lens implantation, for patients with keratoconus and cataract seems to be an effective option in terms of visual acuity.