Visual and Refractive Outcomes with a New Topography-integrated Wavefront-guided Lasik Procedure.

PURPOSE: To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) using a new approach for the calculation of the ablation profile based on wavefront vertexing from pupil plane to corneal. METHODS: One hundred eyes of 50 patients (age, 21-41 years) with low and moderate myopia were enrolled in this prospective case series. All of them underwent topography-integrated wavefront-guided (TI-WFG) LASIK using the STAR S4IR excimer laser platform (Johnson & Johnson Vision). Visual, refractive, ocular aberrometric, ocular scattering index (OSI) and patient satisfaction outcomes were evaluated after a 90-day follow-up period. Astigmatic changes were evaluated by vector analysis. RESULTS: A significant reduction in sphere and cylinder (p < .001) was observed, with a significant improvement in uncorrected (UDVA) and corrected distance visual acuity (CDVA) (p < .001). Postoperative spherical equivalent was within ±0.50 and ±1.00 D in 91.1% (82/90) and 98.9% (89/90) of eyes, respectively. UDVA was 20/20 or better in 98.9% (89/90) of eyes. A total of 50.0% (45/90) of eyes gained 1 line of CDVA. Mean postoperative astigmatic correction index and angle of error were 1.01 ± 0.56 and 0.17 ± 0.18º. Postoperative high-order aberrometric coefficients were below 0.50 µm in 92.2% (83/90) of eyes. Mean postoperative OSI was 0.71 ± 0.44. All patients referred to be satisfied with the final outcomes and would recommend the procedure to their friends and relatives. CONCLUSIONS: TI-WFG LASIK is a new approach for myopia and myopic astigmatism correction, with preservation of the ocular optical quality and high level of patient satisfaction associated.

Outcome analysis of intracorneal ring segments for the treatment of keratoconus based on visual, refractive, and aberrometric impairment.

PURPOSE: To analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of keratoconus based on preoperative visual impairment. DESIGN: Multicenter, retrospective, nonrandomized study. METHODS: A total of 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into 5 different groups: grade I, CDVA of 0.90 or better; grade II, CDVA equal to or better than 0.60 and worse than 0.90; grade III, CDVA equal to or better than 0.40 and worse than 0.60; grade IV, CDVA equal to or better than 0.20 and worse than 0.40; and grade plus, CDVA worse than 0.20. Success and failure indices were defined based on visual, refractive, corneal topographic, and aberrometric data and evaluated in each group 6 months after ICRS implantation. RESULTS: Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (P < .05). CDVA significantly decreased in grade I (P < .01) but significantly increased in all other grades (P < .05). A total of 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, whereas 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (P < .01). Spherical equivalent and keratometry readings showed a significant reduction in all grades (P ≤ .02). Corneal higher-order aberrations did not change after the procedure (P ≥ .05). CONCLUSIONS: Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notable loss of CDVA lines can be expected in patients with a milder form of keratoconus.

Clinical characterization of corneal ectasia after myopic laser in situ keratomileusis based on anterior corneal aberrations and internal astigmatism.

PURPOSE: To evaluate and characterize the clinical features of corneal ectasia after myopic laser in situ keratomileusis (LASIK) considering internal astigmatism and corneal aberrations and their correlation with other clinical data. SETTING: Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain. DESIGN: Retrospective comparative case series. METHODS: In this multicenter study, eyes were divided into 2 groups. The study group comprised eyes that had corneal ectasia after myopic LASIK. The control group comprised eyes that had successful LASIK to correct high myopia. The clinical outcomes were analyzed and compared. Internal astigmatism was calculated using vectorial analysis. RESULTS: The study enrolled 91 eyes (48 study group; 40 control group) of 81 patients (age 18 to 67 years). Uncorrected and corrected (CDVA) distance visual acuities and the refractive status were significantly worse in the study group (P ≤ .01). Corneas in the study group had a significantly higher steepest keratometry (K) reading and a more negative central asphericity (P < .01). Internal astigmatism and corneal aberrations were also significantly higher in the study group (P < .01). The CDVA was significantly correlated with primary spherical aberration (r = -0.561, P =.01) and primary coma root mean square (r = 0.451, P =.04). Age was significantly correlated with mean K (r = -0.44, P =.01) and internal astigmatism (r = -0.34, P =.04). CONCLUSION: Larger levels of internal astigmatism and anterior corneal aberrations leading to a visual deterioration were present in eyes with corneal ectasia after myopic LASIK. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Keratoconus-integrated characterization considering anterior corneal aberrations, internal astigmatism, and corneal biomechanics.

PURPOSE: To evaluate the clinical features of keratoconus taking into consideration anterior corneal aberrations, internal astigmatism, and corneal biomechanical properties and to define a new grading system based on visual limitation. SETTING: Vissum Corporation, Alicante, Spain. DESIGN: Retrospective case series. METHODS: This multicenter study comprised consecutive keratoconic eyes with no previous ocular surgery or active ocular disease. Visual, refractive, corneal topography, and pachymetry outcomes were analyzed. Internal astigmatism was calculated by vectorial analysis. Corneal aberrations and corneal biomechanics characterized by the Ocular Response Analyzer were evaluated in some eyes. Correlations between clinical data and a linear multiple regression analysis for characterizing the relationship between visual limitation and objective clinical data were performed. RESULTS: This study comprised 776 eyes of 507 patients (age range 11 to 79 years) The mean keratometry (K) correlated significantly with logMAR corrected distance visual acuity (CDVA) (r = 0.591, P<.01), internal astigmatism (r = 0.497, P<.01), corneal asphericity (r = -0.647, P<.01), and several corneal higher-order aberrometric coefficients (r≥0.603, P<.01). Significant correlations were found between some corneal aberrometric parameters and CDVA (r≥0.444, P<.01). Multiple regression analysis showed that CDVA was significantly correlated with the mean K, intraocular pressure, corneal resistance factor, and spherical equivalent (r(2) = 0.69, P<.01). There were significant differences in mean K, internal astigmatism, and corneal higher-order aberrations between 4 groups differentiated by visual limitation (P<.01). CONCLUSION: The visual limitation in keratoconus could be explained by different alterations that occur in these corneas and allowed development of a new grading system for this condition.

Femtosecond laser-assisted superficial lamellar keratectomy for the treatment of superficial corneal leukomas.

PURPOSE: To determine if superficial lamellar corneal excision with femtosecond laser followed by phototherapeutic keratectomy (PTK) using a masking substance improves visual acuity and optical quality of patients with severe corneal opacities. METHODS: Twelve eyes with corneal haze or scarring underwent confocal microscopy to estimate the opacities' thickness and calculate the excision depth. Femtosecond laser was then used to create a superficial corneal flap. PTK and smoothening with masking substance (0.25% sodium hyaluronate) were done to improve corneal regularity and decrease corneal scarring. Follow-up was performed at 1, 6, and 12 months. RESULTS: Mean logarithm of the minimum angle of resolution of best spectacle-corrected visual acuity improved from 0.62 (mean decimal 0.26) to 0.30 (mean decimal 0.58) at 1 year (P = 0.035). Haze grades improved significantly. Coma-like aberration decreased postoperatively. CONCLUSIONS: Results showed that superficial corneal excision with femtosecond laser augmented with PTK laser smoothening assisted with 0.25% sodium hyaluronate improved visual acuity and could be considered as an alternative to more invasive procedures in patients with severe corneal opacities.

Modeling the intracorneal ring segment effect in keratoconus using refractive, keratometric, and corneal aberrometric data.

PURPOSE: To characterize the refractive, keratometric, and corneal aberrometric effect of a specific type of intracorneal ring segment (ICRS) as a function of its thickness and the preoperative conditions of the cornea. METHODS: A total of 72 consecutive keratoconic eyes of 57 patients ranging in age from 15 to 68 years were retrospectively analyzed and included in the study. All cases had a diagnosis of keratoconus and had undergone implantation of a 160° arc-length KeraRing segment (Mediphacos, Belo Horizonte, Brazil), by femtosecond laser technology. Correlations between ring segment thickness and several clinical parameters were investigated. In addition, a multiple regression analysis was performed to characterize all factors that influence the ring segment effect. RESULTS: Significant reductions in central curvature, corneal astigmatism, and comalike aberrations were found after surgery (P ≤ 0.03). Moderate and limited correlations were found between ring segment thicknesses and changes in mean keratometry and higher order aberrations (r ≤ 0.50, P < 0.01). A consistent linear relationship of the superior ring segment thickness to the induced corneal changes, the preoperative cylinder, and the difference in thickness between inferior and superior segments was found (P < 0.01, R(2) = 0.91). An almost identical model was obtained for the inferior ring segment thickness with the only distinction in the factor being the thickness difference between segments (P < 0.01, R(2) = 0.64). CONCLUSIONS: The selection of the ring segment to implant in keratoconus should be based, not only on refraction and subjective appearance of the corneal topographic pattern but also on corneal aberrometry. This highly customized selection would allow a more predictable outcome.

Refractive and corneal aberrometric changes after intracorneal ring implantation in corneas with pellucid marginal degeneration.

PURPOSE: To evaluate refractive, visual, and aberrometric changes in corneas with pellucid marginal degeneration (PMD) implanted with intracorneal ring segments (ICRS) during a 6-month follow-up. DESIGN: Retrospective, consecutive case series. PARTICIPANTS: We included 21 consecutive eyes of 15 patients ranging in age from 21 to 73 years old and with a diagnosis of PMD. This diagnosis was made on the basis of slit-lamp (inferior corneal thinning), corneal topography ("butterfly" pattern), and refractive findings (significant against-the-rule astigmatism with best spectacle-corrected visual acuity loss). METHODS: A multicenter, retrospective analysis of patients undergoing ICRS implantation for the management of PMD in 4 ophthalmologic centers was performed. Surgery was indicated in all cases because of reduced best spectacle-corrected visual acuity (BSCVA) and/or contact lens intolerance or dissatisfaction. Mechanical corneal tunnelization was performed in 7 eyes and femtosecond laser-assisted tunnelization in 14 eyes. Intacs were implanted in only 3 eyes whereas KeraRings in 18 eyes. Refractive and corneal aberrometric changes were analyzed during a 6-month follow-up. MAIN OUTCOMES MEASURES: Uncorrected corrected visual acuity (UCVA) and BSCVA, refraction, keratometry, and root mean square (RMS) for different kinds of corneal aberrations. RESULTS: The UCVA did not improve at 6 months after surgery (P = 0.11). The BSCVA increased from a mean preoperative value of 0.54 to a mean postoperative value of 0.75 (P = 0.06). At 6 months, 44.44% of eyes gained > or =2 lines of BSCVA. Sphere (P = 0.02), cylinder (P<0.01), and spherical equivalent (P<0.01) were reduced significantly after surgery (P< or =0.02). Mean keratometry decreased significantly from 44.95 diopters (D) preoperatively to 43.19 D at 6 months postoperatively (P<0.01). The RMS values for astigmatism, higher order residual, and coma-like aberrations were significantly reduced with surgery (P = 0.03). In addition, significant negative correlations of preoperative RMS astigmatism (r = -0.90) and primary spherical aberration (r = -0.86) with postoperative BSCVA were also found. Segment ring explantation was performed in a total of 4 eyes owing to poor visual outcome. CONCLUSIONS: Implantation of an ICRS is an effective option for the treatment of 2nd-order and higher aberrations in corneas with PMD. Preoperative corneal astigmatism and spherical aberration seem to be limiting factors for a good visual outcome. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this manuscript.

Intracorneal ring segment implantation in corneas with post-laser in situ keratomileusis keratectasia.

PURPOSE: To evaluate the refractive and aberrometric changes in corneas with post-LASIK keratectasia implanted with intracorneal ring segments (ICRS) during a 2-year follow-up. DESIGN: Retrospective, consecutive case series. PARTICIPANTS: Thirty-four eyes of 25 patients (age range, 20-59 years) with post-LASIK ectasia were included. Ectasia was diagnosed by slit-lamp appearance of corneal thinning, unstable topographic steepening, progressive corneal thinning on ultrasonic pachymetry, decreased visual acuity, and unstable refraction. METHODS: Intracorneal ring segment implantation was performed in all cases by 2 surgeons from 2 different ophthalmologic centers with the aim of correcting the spherocylindrical error and improving the visual quality. Corneal tunnels were created by means of mechanical dissection in 20 eyes and femtosecond laser technology in 14 eyes. Intacs (Addition Technology, Inc, Fremont, CA) were inserted in 24 eyes, and KeraRings (Mediphacos, Belo Horizonte, Brazil) in 10 eyes. In all cases a follow-up of 12 months was completed, with a total of 15 eyes examined 24 months after surgery. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, keratometry, and corneal aberrations. RESULTS: Uncorrected visual acuity did not improve after surgery (P = 0.17). Best spectacle-corrected visual acuity increased significantly at 6 months (P = 0.02). Some 38.89% of eyes gained 2 or more lines of BSCVA at 6 months, and this percentage increased to 60% at 24 months. There was a nonsignificant reduction of sphere at 6 months (P = 0.28). Manifest cylinder was reduced significantly during the postoperative follow-up (P = 0.05, preoperative to 6 months; P = 0.04, 6-12 months). The cornea was on average flatter at 6 months (P<0.01), with a posterior nonsignificant regression of the achieved flattening (P = 0.73). In regard to corneal aberrations, a statistically significant reduction was found in coma-like root mean square (RMS) (P = 0.03) after surgery. Segment ring explantation was performed in 6 eyes, and ring reposition was performed in 2 eyes. The apical curvature gradient was significantly higher in the group of explanted eyes (P = 0.03). CONCLUSIONS: Intracorneal ring segment implantation is a useful option for the treatment of coma-like aberrations and astigmatism in post-LASIK corneal ectasia. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Refractive and aberrometric outcomes of intracorneal ring segments for keratoconus: mechanical versus femtosecond-assisted procedures.

OBJECTIVE: To compare visual, refractive, and corneal aberrometric outcomes in keratoconic eyes implanted with intracorneal ring segments (ICRS) implantation using either a mechanical or a femtosecond laser-assisted procedure. DESIGN: Retrospective, consecutive case series. PARTICIPANTS: A total of 146 consecutive eyes of 106 patients with the diagnosis of keratoconus (68 unilateral and 39 bilateral) were included. Two groups were created according to the surgical technique used for corneal tunnelization: Mechanical group (mechanical tunnelization, 63 eyes) and Femtosecond group (femtosecond laser-assisted tunnelization, 83 eyes). Intracorneal ring segments implantation was indicated because of the existence of reduced best spectacle-corrected visual acuity (BSCVA) or contact lens intolerance. METHODS: Intracorneal ring segments implantations were performed by 6 surgeons following the same protocol except for the incision location. A total of 55 eyes were implanted with Intacs (Addition Technology, Inc, Fremont, CA) and 8 eyes were implanted with KeraRings (Mediphacos, Belo Horizonte, Brazil) in the Mechanical group, and 25 eyes were implanted with Intacs and 58 eyes were implanted with KeraRings in the Femtosecond group. Mean follow-up was 10.66+/-8.20 months, ranging from 1 month to 24 months. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), BSCVA, refraction, keratometry, and root mean square (RMS) for different kinds of corneal aberrations. RESULTS: By reporting only for statistically significant changes, UCVA improved in both groups at 6 months (P< or =0.02) and BSCVA improved in the Femtosecond group (P<0.01). The refraction improved in both groups at 6 months (P< or =0.02). The cornea on average was flatter in both groups at 6 months (P<0.01). Root mean square astigmatism was reduced in the Femtosecond group (P = 0.03), but there was an increase in some higher-order aberrations (P = 0.03). Significant differences were found between the 2 groups for eyes implanted with Intacs for primary spherical aberration, coma, and other higher-order aberrations, favoring the Femtosecond group (P< or =0.01). A significant negative correlation was found between the preoperative corneal aberrations and the postoperative BSCVA in the Mechanical group (r>0.63, P< or =0.04). CONCLUSIONS: Intracorneal ring segments implantation using both mechanical and femtosecond laser-assisted procedures provide similar visual and refractive outcomes. A more limited aberrometric correction is observed for eyes with mechanical implantation. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Correction of severe ectasia after LASIK with intracorneal ring segments.

PURPOSE: To report a case of severe bilateral ectasia after LASIK that was treated with implantation of small-diameter Keraring intrastromal corneal ring segments (Mediphacos Ltd). METHODS: A 31-year-old woman underwent LASIK in 2001 at a different institution. One year after LASIK, the patient complained of decreased vision in the left eye and underwent LASIK retreatment. Three months after retreatment, uncorrected visual acuity (UCVA) was counting fingers and best spectacle-corrected visual acuity (BSVCA) was 0.4 in the left eye; UCVA was 0.1 and BSCVA was 0.3 in the right eye. Corneal topography showed inferior steepening bilaterally, consistent with ectasia, and the patient was fitted with rigid gas permeable contact lenses. The patient presented to our clinic 4 years after bilateral LASIK with severe loss of BSCVA in both eyes. Examination confirmed the diagnosis of severe bilateral ectasia. The patient underwent implantation of small-diameter Keraring segments assisted by femtosecond laser in June 2005 (left eye) and March 2006 (right eye). RESULTS: Best spectacle-corrected visual acuity improved by four lines in both eyes. Postoperative keratometry showed a decrease of seven diopters in the right eye and nine diopters in the left eye. Postoperative refraction and keratometry have remained stable for 18 and 10 months in the left and right eyes, respectively. CONCLUSIONS: Implantation of intracorneal ring segments can be considered as a treatment option in patients with severe ectasia after LASIK.