Thickness and immunohistochemistry of LASIK flaps created by different femtosecond lasers in eye-bank corneas / Espessura e imunohistoquímica de flap de LASIK criado com diferentes laseres de femtosegundo em córneas de banco de olhos

ABSTRACT Purpose: The aim of this study was to compare the corneal cell viability and thickness of LASIK flaps created by 3 femtosecond lasers in eye-bank human corneas. Methods: Forty-five eye-bank human sclerocorneal buttons (15 corneas in each group) were examined after the creation of 120 mm-thick laser-assisted keratomileusis (LASIK) flaps with 150kHz iFS In­traLase™ (IL), Z6 Femto LDV™ (LDV), or 200kHz Wavelight™ FS200 (FS200). The thickness of the flaps was measured using anterior segment optical coherence tomography (AS-OCT; Visante™). Cell viability was blindly evaluated with immunohistochemistry for keratocyte apoptosis using anti-caspase 3 antibodies. Results: The standard deviation from the intended flap thickness was less than 10 mm in all the groups. There was a statistically significant difference in corneas treated with LDV and IL with regard to the flap thickness horizontally at +3.00 mm (p=0.0124), -0.5 mm (p=0.0082), and -1.00 mm (p=0.0425) from the corneal vertex and +0.5 mm from the flap edge (p=0.0240), and those treated with LDV and FS200 with regard to the flap thickness horizontally at -0.5 mm from the corneal vertex (p=0.0082). The mean keratocyte apoptosis numbers were 13.09 ± 1.10, 15.59 ± 3.28, and 17.72 ± 1.49 in corneas treated with IL, FS200, and LDV, respectively (p<0.001). Conclusion: All 3 assessed femtosecond lasers provided predictable LASIK flap thickness. The mean stromal keratocyte apoptosis number was low in all groups.

RESUMO Objetivos: Comparar a viabilidade celular e a espessura do disco de LASIK confeccionado por três laseres de femtosegundo, em córneas humanas de banco de olhos. Métodos: Quarenta e cinco botões córneo-esclerais humanos de banco de olhos (15 córneas em cada grupo) foram examinados, após a criação de disco de LASIK com 120 mm de espessura, utilizando-se o iFS IntraLase® 150kHz (IL), o Femto LDV® Z6 (LDV), ou o Wavelight® FS200 200kHz (FS200). Tomografia de coerência óptica do seguimento anterior (OCT Visante®) foi usada para medir a espessura dos discos. A viabilidade celular foi avaliada por meio de imuno-histoquímica para apoptose dos ceratócitos, com anti-caspase 3. Resultados: O desvio padrão da espessura planejada do disco foi inferior a 10 mm em todos os grupos. Houve diferença estatisticamente significante da espessura do disco horizontalmente a +3,00 mm (p=0,0124), -0,5 mm (p=0,0082) e -1,00 mm (p=0,0425), a partir do vértice corneal, e a +0,5 mm (p=0,0240), a partir da borda do disco, em córneas tratadas por LDV e IL, e horizontalmente a -0,5 mm a partir do vértice corneal, entre LDV e FS200 (p=0,0082). A média de apoptose dos ceratócitos foi (13,09 ± 1,10), (15,59 ± 3,28) e (17,72 ± 1,49), em córneas tratadas pelo IL, FS200 e LDV, respectivamente (p<0,001). Conclusão: Todos os três laseres de femtosegundo estudados produziram disco de LASIK com predictibilidade de espessura. A média de apoptose dos ceratócitos foi baixa em todos os grupos.

Thickness and immunohistochemistry of LASIK flaps created by different femtosecond lasers in eye-bank corneas.

PURPOSE: The aim of this study was to compare the corneal cell viability and thickness of LASIK flaps created by 3 femtosecond lasers in eye-bank human corneas. METHODS: Forty-five eye-bank human sclerocorneal buttons (15 corneas in each group) were examined after the creation of 120 mm-thick laser-assisted keratomileusis (LASIK) flaps with 150kHz iFS In-traLase™ (IL), Z6 Femto LDV™ (LDV), or 200kHz Wavelight™ FS200 (FS200). The thickness of the flaps was measured using anterior segment optical coherence tomography (AS-OCT; Visante™). Cell viability was blindly evaluated with immunohistochemistry for keratocyte apoptosis using anti-caspase 3 antibodies. RESULTS: The standard deviation from the intended flap thickness was less than 10 mm in all the groups. There was a statistically significant difference in corneas treated with LDV and IL with regard to the flap thickness horizontally at +3.00 mm (p=0.0124), -0.5 mm (p=0.0082), and -1.00 mm (p=0.0425) from the corneal vertex and +0.5 mm from the flap edge (p=0.0240), and those treated with LDV and FS200 with regard to the flap thickness horizontally at -0.5 mm from the corneal vertex (p=0.0082). The mean keratocyte apoptosis numbers were 13.09 ± 1.10, 15.59 ± 3.28, and 17.72 ± 1.49 in corneas treated with IL, FS200, and LDV, respectively (p<0.001). CONCLUSION: All 3 assessed femtosecond lasers provided predictable LASIK flap thickness. The mean stromal keratocyte apoptosis number was low in all groups.

Descemet Membrane Detachment in Femtosecond Laser-Assisted Cataract Surgery.

PURPOSE: To report a case series of 4 patients with Descemet membrane detachment (DMD) after undergoing femtosecond laser-assisted cataract surgery incisions. METHODS: Case report. RESULTS: DMD was noted at the secondary incision (n = 2) or at the main incision (n = 2). All the secondary incision and 1 main incision DMD were resolved with intraoperative maneuvers. Delay in recognizing DMD intraoperatively at the principal incision in 1 case led to inadvertent aspiration of a part of it and persistent postoperative corneal edema. This complication was handled with Descemet membrane endothelial keratoplasty 1 month after initial surgery. CONCLUSIONS: DMD can occur after femtosecond laser-assisted cataract surgery, although it is a rare complication as it is in traditional phacoemulsification. The surgeon must be prepared to recognize it, manage it intraoperatively, and treat it postoperatively to reduce the risk of permanent damage to the eye.

Toric intraocular lens misalignment inducing astigmatism after refractive surgery.

PURPOSE: To report the unexpected induction of astigmatism after phacoemulsification and toric intraocular lens (IOL) implantation in an eye with previous corneal refractive surgery. METHODS: Case report of a 46-year-old man with bilateral nuclear cataract and previous photorefractive keratectomy. Because corneal topography identified regular corneal astigmatism at the central optical zone, phacoemulsification and implantation of a one-piece hydrophobic acrylic toric IOL were performed. RESULTS: Unexpected induction of astigmatism occurred in the first operated eye despite proper alignment of the IOL according to the preoperative calculations using simulated K values to determine toric IOL power and alignment. A retrospective qualitative analysis of corneal topography showed mismatching of the steepest meridian, leading to an off-axis IOL. Secondary IOL rotation improved both uncorrected and corrected distance visual acuity. CONCLUSIONS: Qualitative analysis of the corneal topography is mandatory during the assessment of toric IOL alignment in eyes with previous corneal refractive surgery to identify the actual location of the steepest meridian.

Corneal suture for the correction of hyperopia following radial keratotomy.

PURPOSE: To report the visual and refractive changes observed after double concentric corneal suture to correct hyperopic shift after radial keratotomy (RK). METHODS: This retrospective consecutive case series comprised 17 eyes (15 patients) that underwent two concentric corneal sutures (modified Grene Lasso suture) to correct hyperopic shift after RK. All surgeries were performed by the same surgeon between 2000 and 2003. RESULTS: The mean time after RK was 11.6 +/- 3.2 years. The mean follow-up was 20.3 +/- 11.3 months. The spherical equivalent refraction was reduced from a preoperative mean of +4.38 +/- 2.87 diopters (D) to -0.54 +/- 2.59 D at last postoperative follow-up (P < .001). No statistically significant difference was observed in mean refractive astigmatism before and after the corneal suture (P = .15). Before surgery, no eye presented with best spectacle-corrected visual acuity (BSCVA) > or = 20/20. At final follow-up, 3 (17.6%) eyes attained this level. Seven (41.2%) eyes improved their BSCVA by > or = 2 Snellen lines. One (5.9%) eye lost 2 Snellen lines of BSCVA. CONCLUSIONS: Corneal suture can be used to correct RK-induced hyperopia, improving the corneal asphericity in an attempt to stabilize these corneas. It appeared to be effective even for high degrees of hyperopia and in cases with associated irregular astigmatism or open incisions.

Flap-induced refraction change in LASIK after penetrating keratoplasty.

PURPOSE: To further analyze the refractive and topographic changes occurring with microkeratome lamellar keratotomy and to investigate possible factors associated in eyes with previous penetrating keratoplasty (PK). METHODS: The Hansatome microkeratome was used to create a lamellar corneal flap in 21 eyes of 19 patients after PK. The laser ablation was not performed in the first stage. Pre- and postoperative refractions and corneal topographies were compared to evaluate possible changes induced by the keratotomy. RESULTS: Twenty-one eyes were analyzed in this study. Mean time between PK and lamellar keratotomy was 36.63 +/- 28.23 months (range: 12 to 120 months). No microkeratome-related flap complications occurred. Previous to the keratotomy, the mean spherical equivalent refraction was -4.26 +/- 3.41 diopters (D), mean refractive astigmatism was -4.71 +/- 2.27 D, and mean topographic astigmatism was 5.28 +/- 2.94 D. After keratotomy, eyes showed statistically significant changes in spherical equivalent refraction from preoperative values (P = .025), with 3 eyes showing changes > 2.00 D. Average refractive and topographic astigmatism did not change significantly from before to after keratotomy. However, surgically induced astigmatism (SIA) calculated through vector analysis was > 1.01 in 11 (52.4%) eyes. A statistically significant correlation was found between the SIA values and preoperative refractive astigmatism (P = .025). CONCLUSIONS: Lamellar keratotomy as part of two-stage LASIK in eyes with prior PK led to refractive changes that justify the use of this technique, especially in eyes with high degrees of preoperative astigmatism.

Comparison of topographic corneal irregularity after LASIK and intrastromal corneal ring segments in the same patients.

PURPOSE: To retrospectively compare the irregularity of the corneal surfaces of 14 patients after LASIK in 1 eye and placement of intrastromal corneal ring segments (ICRS) in the other eye. METHODS: In a within-patient comparison, Orbscan corneal topography was used to retrospectively compare the corneal surface irregularity of LASIK-treated and ICRS-treated eyes at an outpatient tertiary-care ophthalmology clinic in Sao Paulo, Brazil. For the anterior corneal surface, irregularity measurements were compared for both the central and peripheral areas of the cornea. The differences between each group were analyzed for statistical significance. RESULTS: The corneal surfaces of eyes treated with ICRS were found to be more irregular than the corneal surfaces of eyes treated with LASIK, the mean irregularity being 1.91 for LASIK-treated eyes and 3.12 for ICRS-treated eyes in the anterior corneal surface and 0.51 for LASIK-treated eyes and 0.87 for ICRS-treated eyes in the posterior corneal surface. A statistically significant difference was noted only in the posterior surfaces. CONCLUSIONS: When measured with Orbscan topography, ICRS-treated eyes show more corneal surface irregularity than LASIK-treated eyes. The difference in outcome for the two types of treatment may be due to the mechanical effect of the ICRS on the shape of the cornea.

Ceratoplastia lamelar profunda com viscodissecçäo da membrana de Descemet / Deep lamellar keratoplasty with viscodissection of Descemet's membrane

Objetivo: Avaliar a eficácia da técnica de ceratoplastia lamelar profunda preservando a membrana de Descemet e as células endoteliais do paciente, com a utilizaçäo de botäo esclero-corneano. Métodos: Foram realizadas 14 ceratoplastias lamelares com viscodissecçäo da membrana de Descemet do receptor usando sulfato de condroitina 4 por cento e hialuronato de sódio 3 por cento. Dez (10) pacientes apresentavam ceratocone avançado, 3 tinham leucoma por herpes simples eem 1 havia irregularidade corneana pós-ceratotomia radial. O acompanhamento pós-operatório variou de 12 a 48 meses (média 24 ñ10,5 meses). Resultados: Após a retirada de todas as suturas a média do equivalente esférico no último exame oftalmológico foi de -2,0 ñ 3,6 dioptrias (D) (-10,3 D a +4,74 D). O astigmatismo final variou de -6,0 DC a-0,75 DC com média de -3,3 ñ 1,9 DC. Dos 14 pacientes 12 apresentaram na visita final acuidade visual com correçäo de 20/40 ou melhor. Todos os pacientes ganharam linha de visäo pela tabela de Snellen. Näo houve presença de edema corneano, descompensaçäo endotelial ou rejeiçäo. Nenhuma opacidade ou depósito na interface foi observado. Dois pacientes apresentaram dobras na membrana de Descemet com baixa da acuidade visual. Conclusäo: Apesar das dificuldades técnicas relacionadas à ceratoplastia lamelar e viscodissecçäo da membrana de Descemet, acreditamos que este seja um procedimento de escolha em pacientes cuja populaçäo de células endoteliais esteja preservada. Esta técnica resulta em melhor acuidade visual final quando comparada ao transplante lamelar tradicional e menor reaçäo imunológica quando comparada a ceratoplastia penetrante. Independentemente da qualidade do tecido doador, conseguimos córneas transparentes como resultado, pois o endotélio do receptor foi preservado.