Comparação entre os resultados do implante de um segmento de arco longo versus dois segmentos de arco tradicional no tratamento de pacientes com ceratocone / Comparison between the results of implanting a long-arch segment versus two standard arch segments for treatment of keratoconus patients

RESUMO Objetivo: Analisar retrospectivamente as alterações na ceratometria e no astigmatismo corneano obtidas após cirurgia de implante de anel intraestromal, comparando o uso de um segmento de arco longo versus o implante de dois segmentos de comprimento de arco tradicional. Métodos: A partir de um estudo transversal, obtivemos os dados de 94 olhos de pacientes diagnosticados com ceratocone, que foram submetidos ao implante de anel corneano. Eles foram divididos em dois grupos, dependendo do tipo de implante recebido: Grupo A, um segmento de arco longo; Grupo B, dois segmentos tradicionais. Todos os segmentos implantados possuíam 250µ de espessura. Os dados do pré-operatório dos dois grupos foram comparados, para garantir que as amostras eram similares (as diferenças encontradas entre os dois grupos não eram estatisticamente significativas). As variáveis analisadas no pré e no pós-operatório foram acuidade visual com correção, ceratometria, astigmatismo corneano e refração. Resultados: A amostra que recebeu apenas um segmento de arco longo (Grupo A) obteve redução da ceratometria média de 4,42D (8,7%) e do astigmatismo corneano de 2,43D (40,4%). Já na amostra dos olhos que receberam dois segmentos de arco tradicional (Grupo B), houve redução média de 2,66D (5,1%) em relação à ceratometria média e redução média de 2,11D (34,8%) em relação ao astigmatismo corneano. A redução obtida na ceratometria média no Grupo A foi maior que a obtida no Grupo B (diferença estatisticamente significativa). A redução obtida no astigmatismo do Grupo A não foi estatisticamente significante, se comparada com o resultado obtido no Grupo B (considerando p≤0,05). Conclusão: Foi demonstrado que o uso de um segmento de arco longo possui maior capacidade de aplanação corneana, se comparado com o uso de dois segmentos com comprimento de arco tradicional. Em relação à redução do astigmatismo, os dois grupos mostraram resultados equivalentes.

ABSTRACT Purpose: To retrospectively analyze the changes in corneal keratometry and astigmatism after intrastromal ring surgery, comparing the use of one long arch segment versus two traditional arc length segments. Methods: A cross-sectional study obtained data from 94 eyes of patients diagnosed with keratoconus that underwent surgical treatment with corneal ring implant. They were divided into two groups according to the type of implant received: one long-arch segment (Group A) or two traditional segments (Group B), both 250 microns thick. Preoperative data from the two groups were compared to ensure that the samples were similar (the differences between the two groups were not statistically significant). The variables (pre and post-operatively) analyzed were: best corrected visual acuity, keratometry, corneal astigmatism and refraction. Results: Group A, which received one long arch segment, showed a Km decrease of 4.42D (8.7%) and a corneal astigmatism reduction of 2.43D (40.4%). Group B, where the eyes acquired two traditional arch segments, showed an average Km decrease of 2.66D (5.1%) and corneal astigmatism reduction of 2.11D (34.8%). The mean keratometry (Km) reduction obtained was statistically significant (p≤0.05) when comparing both groups (A and B). The mean corneal astigmatism reduction was not statistically significant (p≤0.05) when comparing both groups (A and B). Conclusions: One long-arch segment has been demonstrated to have a greater capacity to reduce corneal curvature when compared to the use of two traditional-sized arch segments. No significant differences were found regarding the reduction of corneal astigmatism after comparing the results obtained in both groups.

Comparison of Visual, Tomographic, and Biomechanical Outcomes of 360 Degrees Intracorneal Ring Implantation With and Without Corneal Crosslinking for Progressive Keratoconus: A 5-Year Follow-up.

PURPOSE: To evaluate the long-term (5 years) results of 360 degrees intracorneal ring (ICR) implantation with and without corneal crosslinking (CXL) in patients with progressive keratoconus (KCN). METHOD: This historical cohort study was performed on 35 eyes with progressive KCN, which was randomly divided into 2 groups. Fourteen patients were implanted only with ICR, and 21 patients with KCN were treated with ICR plus CXL simultaneously. Uncorrected distance visual acuity (UCDVA), corrected distance visual acuity (CDVA), and refractive components were collected from patients' medical records. The biomechanical properties of patients were measured using the Corvis ST (Oculus, Inc, Weltzar, Germany). Corneal topography and aberrometry parameters were also recorded from the Pentacam HR device (Oculus). RESULTS: Both UCVA and CDVA increased in both groups after ICR implantation; however, this improvement was more significant in the ICR plus CXL group (P = 0.002 and P = 0.001, respectively). The mean improvement of CDVA in patients with ICR implantation with and without CXL was 0.56 ± 0.67 and 0.33 ± 0.61, respectively. A comparison of the long-term postoperative Tomographic and Biomechanical Index between 2 groups showed a better result in the ICR plus CXL group (P = 0.012). Topographic findings of the anterior corneal surface (flat-K, steep-K, mean-K, and astigmatism) after surgery were significantly better than before surgery in both groups (P < 0.05). CONCLUSIONS: Although ICR implantation alone might halt the KCN progression with acceptable visual, topographic, and biomechanical outcomes, the combination of ICR and CXL has an adjuvant and synergistic effect, especially in long-term follow-up.

Infiltrados estériles tras cross-linking / Sterile infiltrates after cross-linking

Caso clínico: Mujer de 20 años que acude diagnosticada de queratocono bilateral asimétrico. Debido a las características topográficas y paquimétricas del queratocono del ojo derecho se decidió realizar la técnica de cross-linking. Tres días después del procedimiento, la paciente acude con unos infiltrados blanquecinos que resultaron ser estériles. Discusión: El cross-linking es una técnica eficaz a la par que segura. Sin embargo, en ocasiones pueden ocurrir ciertas complicaciones. Los infiltrados estériles han sido descritos aunque su procedencia sigue sin estar aclarada (AU)

Case report: A 20 year-old woman presented with an asymmetric bilateral keratoconus. Cross-linking of the right eye was performed due of its topographic and pachymetric conditions. Three days after the procedure, the patient presented with some corneal infiltrates that where classified as sterile. Discussion: Cross-linking is known for its efficacy and safety. Nevertheless, there can be complications. Sterile infiltrates have already been described, although their aetiology is still not clear (AU)

Combined application of prophylactic corneal cross-linking and laser in-situ keratomileusis - a review of literature.

Laser in-situ keratomileusis (LASIK) is safe and effective laser refractive procedures in treating refractive errors. However, regression of treatment and iatrogenic keratectasia remain to be a major concern, especially in treating thin cornea with high ametropia. Collagen cross-linking (CXL) is an effective method in stopping keratoconus progression through increasing the biomechanical strength of the cornea. Adjuvant cross-linking to refractive procedures can theoretically help prevent regression and reduce the risk of keratectasia development by increasing the mechanical stability of cornea. During the procedure, riboflavin is directly applied to the corneal stroma, thereby reducing the need of de-epithelialization as in the conventional protocol for keratoconus. Currently, there is still no consensus regarding the indication of CXL during refractive procedure, nor any standardized treatment protocol. This article aims to summarize the current evidence regarding the use of adjuvant CXL in LASIK.

Corneal collagen cross-linking (CXL) combined with refractive procedures for the treatment of corneal ectatic disorders: CXL plus.

PURPOSE: To discuss current combined corneal collagen cross-linking (CXL) and refractive surgical techniques (herein termed "CXL plus") for the treatment of corneal ectatic disorders to improve functional visual acuity in addition to corneal stability from CXL alone. METHODS: Literature review. RESULTS: Efficacious combined treatments with CXL include: photorefractive keratectomy, transepithelial phototherapeutic keratectomy, intrastromal corneal ring segments implantation, phakic intraocular lens implantation, and multiple combined procedures. Some uncertainty remains as to the optimal strategies for each patient. A decision tree is proposed to facilitate optimal patient management. CONCLUSIONS: With multiple adjuvant techniques, CXL plus is likely to benefit many patients with corneal ectatic disorders. The appropriate combined procedure will depend on multiple factors, such as refraction, corneal thickness, and degree of irregular astigmatism.

Big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children.

To report the early results of big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children. Five eyes of 5 pediatric patients were enrolled in the study; 3 had keratoconus and 2 corneal opacities. An IntraLase 60 KHz femtosecond laser (Abbott Medical Optics, Inc) was used to create mushroom incisions on both donor and recipient corneas. All patients were evaluated for best-corrected visual acuity, spherical equivalent, refractive astigmatism, keratometric astigmatism, mean K value, and corneal thinnest point. The big bubble was always achieved, and all eyes were treated successfully without intraoperative complications. The follow-up was of 10 months. At 10 months (at least 3 months after complete suture removal), the mean postoperative best-corrected visual acuity was 20/30 (range, 20/25 to 20/30), mean spherical equivalent was -1.8 ± 1.2 diopters (D) (range, -0.25 to 1.25 D), mean refractive astigmatism was 1.8 ± 1.4 D (range, 0 to 4.0 D), mean keratometric astigmatism was 5.1 ± 2.1 D (range, 3.5 to 8.59 D), mean K value was 46.2 ± 0.8D, and mean corneal thinnest point was 581 ± 46 µm (range, 511-638 µm). Our early findings suggest that the big-bubble technique in deep anterior lamellar keratoplasty assisted by femtosecond laser is safe and effective also in pediatric patients in the attempt to decrease the rejection percentage, improve the refractive outcome, and then provide an antiamblyopic effect.

Femtosecond laser (WaveLight FS200) customized keratoplasty for keratoconus: case report.

PURPOSE: To describe a case of a 52-year-old man with severe keratoconus who underwent femtosecond laser-assisted keratoplasty with the WaveLight FS200 femtosecond laser (Alcon Laboratories Inc). METHODS: The donor and recipient corneas were cut in a mushroom-shaped pattern. The laser parameters used on this platform for the donor and recipient corneas are described. RESULTS: Corrected distance visual acuity improved by 3 weeks postoperatively. Mean keratometry decreased from 60.00 to 46.00 diopters. CONCLUSIONS: This patient underwent a mushroom-shaped keratoplasty with the femtosecond laser to maximize preservation of his own endothelium. Increased energy and/or decreased spot line separation may be required depending on the degree of corneal edema or scarring involved.

Refractive outcome of keratoconus treated by combined femtosecond laser and big-bubble deep anterior lamellar keratoplasty.

PURPOSE: To report 1-year follow-up in 11 of 13 eyes with keratoconus treated by deep anterior lamellar keratoplasty with a combined femtosecond laser lamellar resection followed by a big-bubble dissection. METHODS: Thirteen eyes with keratoconus were treated. Recipient and donor were prepared with the 60-kHz IntraLase femtosecond laser (Abbott Medical Optics). In the recipient, the femtosecond laser, after performing a lamellar cut 100 µm above the thinnest corneal point (measured by Pentacam [Oculus Optikgeräte GmbH]), was used to make a mushroom-shaped resection (anterior diameter, 9 mm; posterior diameter, 8 mm) from the same depth. In the donor, the mushroom lamellar thickness was calculated according to an original model based on the recipient preoperative corneal thickness. Upon removal of the recipient lamella, air was injected into the residual stroma to achieve a big bubble. The keratectomy was continued up to Descemet membrane. The donor was fit into place and sutured using interrupted sutures, which were removed by 8 months postoperative. Corrected distance visual acuity (CDVA) and refractive astigmatism were calculated by manifest refraction, whereas topographic astigmatism and corneal thickness were measured by Pentacam. RESULTS: A big bubble was successfully achieved in 11 eyes. Twelve months after surgery, mean CDVA was 0.52±1.2 (decimal), and refractive sphere and cylinder were -1.50±1.70 diopters (D) and 2.00±2.60 D, respectively. Three (27%) of 11 eyes at 1 year had a manifest refraction spherical equivalent within 1.00 D of emmetropia. Topographic astigmatism was 2.90±1.60 D. The thinnest corneal point was 519±27 µm. CONCLUSIONS: This combination of a femtosecond laser lamellar dissection with a big-bubble technique can improve the standardization of deep anterior lamellar keratoplasty for keratoconus.

Eye rubbing as an apparent cause of recurrent keratoconus.

PURPOSE: To report a case of recurrent keratoconus after penetrating keratoplasty (PKP) because of allergic conjunctivitis. METHOD: Case report. RESULTS: A 23-year-old woman who had successful bilateral PKP presented with complaints of visual impairment 3 years after the last examination. She also complained of severe ocular itching and hyperemia, and she reported a history of vigorous eye rubbing. The diagnosis of recurrent keratoconus was confirmed based on clinical findings and topographic features. CONCLUSIONS: A recurrence of keratoconus can occur because of itch-provoked rubbing of the eyes. Patients who had PKP should be evaluated for a history of ocular allergies.

Bilateral recurrent self-induced keratoconus.

The observational case describes bilateral recurrent keratoconus in corneal transplants performed in a patient with self-induced keratoconus secondary to compulsive eye rubbing. Slitlamp findings demonstrated corneal stromal thinning and scarring in the patient's right eye and temporal corneal hydrops in his left eye. Videokeratography of the right eye confirmed the presence of corneal steepening and irregular astigmatism, consistent with the diagnosis of keratoconus involving each transplant. Together with the history of ongoing compulsive eye rubbing, these findings support the concept that chronic mechanical trauma to the cornea may contribute to the development of keratoconus.

Long-term follow-up of intraocular pressure after penetrating keratoplasty for keratoconus and Fuchs' dystrophy: comparison of mechanical and Excimer laser trephination.

PURPOSE: In the literature, the incidence of "secondary glaucoma" after penetrating keratoplasty (PK) is reported to range from 10% to 42%, depending on the diagnosis and the complexity of surgery. The purpose of this study was to assess the impact of the trephination method and simultaneous cataract surgery on the early and long-term intraocular pressure (IOP) after PK in eyes without previous surgery and glaucoma. METHODS: Inclusion criteria for this prospective, randomized, longitudinal clinical study were (1) one surgeon (G.O.H.N.), (2) primary central PK, (3) Fuchs' dystrophy (7.5/7.6 mm) or keratoconus (8.0/8.1 mm), and (4) 16-bite double running diagonal suture. Exclusion criteria were (1) previous intraocular surgery, (2) preoperative glaucoma, and (3) postoperative trauma or endophthalmitis. In 170 patients (mean age, 51 +/- 18 years), PK was performed with use of either a 193-nm excimer laser (Excimer patients) along metal masks with eight orientation teeth/notches (50 keratoconus, 32 Fuchs') or motor trephination (Control patients; 53 keratoconus, 35 Fuchs'). In 27% of Excimer patients and 29% of Control patients a triple procedure was performed. The perioperative systemic acetazolamide application and the postoperative topical steroid therapy were standardized. RESULTS: Maximal IOP during the first week after PK was 15.7 +/- 3.6 mm Hg (7% > 21; maximum, 28) in the Excimer group and 16.2 +/- 3.5 mm Hg (7% > 21; maximum, 30) in the Control group. During a mean follow-up of 3.4 +/- 1.3 years (maximal, 6.0), an IOP >21 mm Hg and/or application of topical antiglaucomatous medication was documented in 9% of Excimer patients versus 15% of Control patients (p = 0.32), in 15% of Fuchs' dystrophy versus 11% of keratoconus cases (p = 0.41), and in 11% of PK-only versus 15% of triple-procedure cases (p = 0.68). The IOP elevation started an average of 3.7 +/- 2.8 months (1 week to 9 months) after PK and ended an average of 6.5 +/- 3.1 months (6 weeks to 12 months) after PK. Mean maximal IOP during follow-up was 16.6 +/- 3.5 mm Hg (12-38) in the Excimer group and 17.2 +/- 3.2 mm Hg (12-30) in the Control group. Only one patient, who had undergone a triple procedure for Fuchs' dystrophy and had an elevated IOP, needed topical medication, from 32 months after PK to the end of follow-up. Glaucomatous optic disc damage was clinically detected in none of the patients. CONCLUSIONS: Temporary secondary ocular hypertension after PK is rare in eyes with keratoconus or Fuchs' dystrophy without previous surgery. There was no detectable impact from the trephination method, the diagnosis, or simultaneous cataract surgery. With meticulous microsurgical technique, careful suturing, and peripheral iridotomy, the development of secondary glaucoma with disc cupping seems to be the exception.