post-LASIK Ectasia Research Articles

A modified risk assessment scoring system for post laser in situ keratomileusis ectasia in topographically normal patients.

Purpose:To evaluate and modify the Randleman Ectasia Risk Score System for predicting post-laser in situ keratomileusis (LASIK) ectasia in patients with normal preoperative corneal topography.Methods:In this retrospective study we reviewed data from 136 eyes which had undergone LASIK including 34 ectatic and 102 normal eyes between 1999 and 2009. After determining the sensitivity and specificity of the Randleman system, a modified model was designed to predict the risk of post-LASIK corneal ectasia more accurately. Next, the sensitivity and specificity of this modified scoring system was determined and compared to that of the original scoring system.Results:In our sample, the sensitivity and specificity of the Randleman system was 70.1% and 50.5%, respectively. Our modified model included the following parameters: preoperative central corneal thickness, manifest refraction spherical equivalent, and maximum keratometry, as well as the number of months elapsed from surgery. Sensitivity and specificity rates of the modified system were 74.2% and 76.2%, respectively. The difference in receiver operating characteristic curves between the Randleman and modified scoring systems was statistically significant (P<0.001). The best sensitivity and specificity for our model occurred with a cumulative cutoff score of 4.00; a low risk was considered if the score was ≤4.00, and high risk was defined with a score > 4.00.Conclusion:Our modified ectasia risk scoring system for patients with normal corneal topography can predict post LASIK ectasia risk with acceptable sensitivity and specificity. However, there are still unidentified risk factors for which further studies are required.

Assessment of the posterior corneal surface changes after LASIK treatment of myopia using Pentacam

Aim of the workThe aim of this work is to study the changes that occur in the posterior corneal surface after laser-assisted in-situ keratomileusis (LASIK) for correction of myopia using Pentacam.Patients and methodsIn a prospective interventional case-series study, 50 myopic eyes of 27 patients were subjected to the LASIK procedure. Preoperative, 1 week, and 3 months postoperatively, Pentacam examination was performed at the Elminia Roaa Refractive Center between January and October 2011. Pentacam was used for the assessment of preoperative and postoperative pachymetry, anterior and posterior corneal curvatures, anterior and posterior corneal elevations, and asphericity of the posterior corneal surface.ResultsThis study included 50 eyes of 27 patients, 19 women (70.3%) and eight men (29.7%). Patients' age ranged from 20 to 44 years, mean 27.3 ± 7.03 years. No statistically significant changes were found in the posterior horizontal corneal curvature (Rh). A statistically significant change in the posterior vertical corneal curvature (RV) from 6.1 ± 0.3 to 6.06 ± 0.2 mm 1 week after LASIK was found, but increased after 3 months to 6.2 ± 0.3S mm. No statistically significant changes in the posterior mean corneal curvature (Rm) were observed either at 1 week or 3 months after LASIK. A significant change in the Q-value (asphericity) was found both at 1 week and 3 months postoperatively. There were significant changes in the posterior corneal elevation both at 4 and at 7 mm from the center both at 1 week and 3 months after LASIK.ConclusionPost-LASIK changes of the posterior corneal surface affect mainly the vertical curvature, asphericity, and posterior corneal elevation. Fortunately, no case of post-LASIK ectasia was observed during the follow-up period of this study. Further studies are needed to document posterior corneal surface changes in patients with suspected post-LASIK ectasia.

Unilateral Post-LASIK Ectasia in a Topographical Normal Eye with a Slight Asymmetry in the Contralateral Eye

ABSTRACT Purpose To report a case of post-LASIK unilateral corneal ectasia. Setting Department of anterior segment and Refractive surgery, Rothschild Foundation, Paris. Case report A 33-year-old woman was referred with a history of unilateral post-LASIK ectasia in her left eye, 18 months post operatively. Her best-corrected visual acuity was 20/20 with a manifest refraction of +1.75 (–4.75 × 90). Orbscan ii® revealed an inferior steepening associated with irregular astigmatism. The preoperative Placido topographies revealed a slight skewed radial axis in the right eye associated with an inferior-superior keratometry difference of 1.6 Diopters at 3 mm. in the left eye that developed ectasia, regular symmetric astigmatism was present. Uncorrected visual acuity improved to 20/25 2 weeks after keraRing® segment insertion. How to cite this article Berguiga M, saad a, Gatinel D. Unilateral Post-LASIK Ectasia in a Topographical Normal Eye with a slight asymmetry in the Contralateral Eye. int J kerat Ect Cor Dis 2014;3(1):47-51.

Assessing ectasia susceptibility prior to LASIK: the role of age and residual stromal bed (RSB) in conjunction to Belin-Ambrósio deviation index (BAD-D)

Purpose: To compare the ability to detect preoperative ectasia risk among LASIK candidates using classic ERSS (Ectasia Risk Score System) and Pentacam Belin-Ambrosio deviation index (BAD-D), and to test the benefit of a combined approach including BAD-D and clinical data. Methods: A retrospective nonrandomized study involved preoperative LASIK data from 23 post-LASIK ectasia cases and 266 stable-LASIK (follow up > 12 months). Preoperative clinical and Pentacam (Oculus; Wetzlar, Germany) data were obtained from all cases. Mann-Whitney's test was performed to assess differences between groups. Stepwise logistic regression was used for combining parameters.The areas under the Receiver Operating Characteristic (ROC) curves (AUC) were calculated for all parameters and combinations, with pairwise comparisons of AUC (DeLong's method). Results: Statistically significant differences were found for age, residual stromal bed (RSB), central corneal thickness and BAD-D (p 0.05). ERSS was 3 or more on 12/23 eyes from the ectasia group (sensitivity = 52.17%) and 48/266 eyes from the stable LASIK group (18% false positive). BAD-D had AUC of 0.931 (95% CI: 0.895 to 0.957), with cut-off of 1.29 (sensitivity = 87%; specificity = 92.1%). Formula combining BAD-D, age and RSB provided 100% sensitivity and 94% specificity, with better AUC (0.989; 95% CI: 0.969 to 0.998) than all individual parameters (p>0.001). Conclusion: BAD-D is more accurate than ERSS. Combining clinical data and BAD-D improved ectasia susceptibility screening. Further validation is necessary. Novel combined functions using other topometric and tomographic parameters should be tested to further enhance accuracy.

Rate of ectasia and incidence of irregular topography in patients with unidentified preoperative risk factors undergoing femtosecond laser-assisted LASIK

PurposeTo report the rate of postoperative ectasia after laser-assisted in situ keratomileusis (LASIK) with femtosecond laser-assisted flap creation, in a population of patients with no identified preoperative risk factors.MethodsA retrospective case review of 1,992 eyes (1,364 patients) treated between March 2007 and January 2009 was conducted, with a follow up of over 4 years. After identifying cases of ectasia, all the patient charts were examined retrospectively for preoperative findings suggestive of forme fruste keratoconus (FFKC).ResultsFive eyes of four patients with post-LASIK ectasia were identified. All eyes passed preoperative screening and received bilateral LASIK. One of the five patients developed ectasia in both eyes. Three patients retrospectively revealed preoperative topography suggestive of FFKC, while one patient had no identifiable preoperative risk factors. Upon review of all the charts, a total 69 eyes, including four of the five eyes with ectasia, were retrospectively found to have topographies suggestive of FFKC.ConclusionWe identified four cases of post-LASIK ectasia that had risk factors for FFKC on reexamination of the chart and one case of post-LASIK ectasia with no identifiable preoperative risk factors. The most conservative screening recommendations would not have precluded this patient from LASIK. The rate of purely iatrogenic post-LASIK ectasia at our center was 0.05% (1/1,992), and the total rate of post-LASIK ectasia for our entire study was 0.25% (1/398). The rate of eyes with unrecognized preoperative FFKC that developed post-LASIK ectasia was 5.8% (1/17).

Prognostic Factors for Visual Outcomes after Crosslinking for Keratoconus and Post-LASIK Ectasia

To determine the prognostic factors associated with better visual outcomes 1 year after corneal collagen crosslinking (CXL) for keratoconus and post-laser-assisted in situ keratomileusis (LASIK) ectasia. The study cohort comprised 75 eyes from 50 patients with keratoconus or post-LASIK ectasia who underwent CXL. The outcomes measured were visual response, change of corrected distance visual acuity (CDVA), and CDVA 1 year after CXL. The cohort was divided into groups based on the change in CDVA postoperatively. The visual responders were the patients with visual improvement of at least 1 line Snellen CDVA at 1 year postoperatively, and the visual nonresponders were the patients with a gain of less than 1 line, no change, or loss of Snellen lines CDVA at 1 year postoperatively. Univariate analysis was performed to determine the association between the preoperative parameters and visual response. Correlation analyses and forward stepwise regression analyses were performed to evaluate the effect of the preoperative factors on CDVA and the improvement of CDVA at 1 year. There was significant visual improvement from 0.257 ± 0.29 logMAR to 0.159 ± 0.208 logMAR (p<0.001; paired t test) at 1 year postoperatively with a mean change in CDVA of -0.098 ± 0.151 logMAR. The visual responders (46 cases, 61.3%) had poorer preoperative CDVA (p = 0.023), thinner minimal corneal thickness (p = 0.041), and thinner central corneal thickness (p = 0.012) compared to the visual nonresponders (29 cases, 38.7%). Forward stepwise multiple linear regression analysis indicated that the preoperative CDVA significantly affected both the postoperative change in CDVA (standardized β = 0.614; p<0.001) and the postoperative CDVA (standardized β = 0.893; p<0.001). Crosslinking for keratoconus and post-LASIK ectasia can lead to significant visual improvement 1 year after treatment. The preoperative CDVA was a significant prognostic factor for the visual outcome.

Corneal collagen cross-linking in the stabilization of PRK, LASIK, thermal keratoplasty, and orthokeratology

To describe the use of corneal collagen cross-linking (CXL) and its efficacy in the stabilization of keratorefractive procedures, including PRK, laser in-situ keratomileusis (LASIK), thermal keratoplasty, and orthokeratology. Since its introduction, CXL has quickly gained interest in the treatment of ectactic disorders due to its ability to increase the biomechanical stability of the cornea. In its earliest use, it has shown to be effective in the treatment of both keratoconus and post-LASIK ectasia. More recent studies of CXL in combination with keratorefractive procedures have shown varying degrees of success. CXL with PRK has shown to be effective in slowing or halting the progression of keratoconus, pellucid marginal degeneration, and post-LASIK ectasia, in addition to potentially decreasing or delaying the need for penetrating keratoplasty. Several small case series have also demonstrated improved stability and efficacy of PRK and LASIK when combined with CXL, as well as a potentially decreased risk of postprocedure ectasia. In conjunction with thermokeratoplasty and orthokeratology, CXL has shown improved but only temporary results in the treatment of keratoconus. Future studies are needed to determine the efficacy and long-term stability of CXL in combination with keratorefractive procedures, as well as to address possible complications.

Unilateral Ectasia After LASIK in a Patient With Abnormal Topography but Normal Tomography

To report a case of unilateral ectasia developing after LASIK in a patient with abnormal topography but normal tomographic indices. Case report and literature review. A patient was treated bilaterally for myopia using LASIK. Five years and 5 months postoperatively, unilateral ectasia in the right eye was diagnosed. Preoperatively, anterior curvature (Placido) map of the right cornea showed an asymmetry with 1.8 diopters of steepening when evaluated from upper left to lower right meridians, and a skewing of the steepest radial axes. The calculated KISA% index was 128.4 in the right eye and 5.6 in the left eye. Conversely, posterior elevation map and pachymetry map of the right eye showed no frank abnormalities. This case is interesting because it shows that for this patient, the anterior curvature (Placido) map was more sensitive to detect cornea at risk of post-LASIK ectasia than the tomographic features

Post-LASIK ectasia treated with intrastromal corneal ring segments and corneal crosslinking

Corneal ectasia is a serious complication of laser in situ keratomileusis (LASIK). We report the case of a 29-year-old man who underwent LASIK in both eyes and in whom corneal ectasia developed in the left eye 3 years after surgery. He was treated sequentially with intraocular pressure-lowering medication, intrastromal corneal ring segment (ICRS) implants, and collagen cross-linking. Vision improved and the ectasia stabilized following treatment. Combined ICRS implantation and collagen cross-linking should be considered early in the management of post-LASIK ectasia.

Intacs 210° in Post-lasik Ectasia: Follow-up of Clinical and Biomechanical Changes

ABSTRACT The authors report a case of a post-LASIK corneal ectasia with low refractive defect and progressive decreased visual acuity. INTACS SK 210° arc in 7 central millimeters was implanted, 1 year postoperative showed a decreased in maximum keratometry, vertical coma and improved visual acuity. Two years postoperative topography evidence progression of the ectasia. How to cite this article Nuñez MX, Blanco C. Intacs 210° in Post-lasik Ectasia: Follow-up of Clinical and Biomechanical Changes. Int J Kerat Ect Cor Dis 2013;2(2):89-91.

Abbreviated UVA-riboflavin corneal collagen cross-linking for keratoconus and post-LASIK ectasia

Introduction. To determine the effect of corneal collagen cross-linking treatment on keratoconus and post-LASIK ectasia particularly after an abbreviated exposure to ultraviolet light exposure. Materials and methods. Fifty-one eyes of 34 patients were treated with epithelium-off UVA-riboflavin corneal collagen cross-linking for either 20 minutes or 30 minutes as part of a US.FDA clinical study. The study involved eyes with keratoconus but with no prior operation (virginal), patients who had undergone prior intracorneal ring segments, those with keratoconus regression after keratoplasty, and those with post-LASIK ectasia. We report follow up results from three months to one year. Results. In the virginal keratoconus group all 83% of eyes having 20-minute UVA exposure and 75% of those having 30-minute of UVA exposure experienced corneal flattening or stabilization at 6 months post-operatively with visual improvement in both groups. The average patient age in the virginal keratoconus group was 34.5 years. Seventy five percent of virginal keratoconus eyes of patients under age 40 but only 33% of eyes of patients over age 40 experienced statistically significant corneal flattening at six months postoperatively. Average vision improved at six months post-operatively over pre-operative levels by -0.0744 logMAR units in the 20 minute group, and by -0.0869 logMAR units in the 30 minute group. Post-LASIK ectasia patients, with an average age of 58.2 years, had slight overall curvature flattening of -0.75D but without visual improvement one year post-operatively. No one experienced peri-operative complications. Topographic subtraction mapping revealed variations in the power of the cross-linking effect on different portions of the cornea Conclusion. Cross-linking appears safe. It is effective in most young patients causing corneal flattening and can stabilize eyes with post LASIK ectasia but acts more slowly in older patients. The cross-linking effect may be more pronounced in individuals with darker pigmentation. Cross-linking can produce occasional very significant corneal flattening. The cross-linking effect increases with time.

Corneal Collagen Cross-Linking for Keratoconus and Post-LASIK Ectasia

Corneal collagen cross-linking (CXL) is a novel technology that utilizes a combination of riboflavin (vitamin B2) eye drops, to saturate the cornea, and UV-A light which sets off a chemical reaction to shorten the cross links between and within collagen fibers thereby increasing the biomechanical stability of the corneal stroma (1–4). The objective of this procedure is to halt progression of keratoconus, post-LASIK ectasia, and other corneal ectasias, such as pellucid marginal degeneration. In some cases, there has been improvement in visual acuity, reduction of corneal curvature and improvement in quality of life (5). In the 1970’s Siegel discussed cross-linking reactions whereby lysyl oxidase catalyzed the formation of cross-linking aldehydes in collagen and elastin (6–7). Cross-linking is well known in material sciences and dentistry where this enzymatic process increases molecular bonds to increase the mechanical strength of tissue. Cross-linking can be induced enzymatically by means of aldehydes, chemical fixatives or by photosensitizing radiation. Of the three methods the photosensitizing radiation has been shown to be most effective. In corneal clinical practice, CXL utilizes this method where the riboflavin acts as a photosensitizer for the production of free radicals produced by the interaction of the riboflavin and UV-A light. The production of these reactive oxygen species (singlet oxygen) causes the formation of chemical bonds within the corneal stroma resulting in corneal stiffening (3).

Efficacy of intacs intrastromal corneal ring segment relative to depth of insertion evaluated with anterior segment optical coherence tomography

Aim:To evaluate the effect of implantation depth of Intacs microthin prescription inserts (Addition Technology Inc, Fremont, California) on visual and topographic outcomes in patients with post- laser-assisted in situ keratomileusis (LASIK) ectasias.Settings and Design:Retrospective, observational case series.Materials and Methods:In this case series, 16 eyes of 12 patients were evaluated. All cases were post-LASIK ectasia that had undergone intrastromal corneal ring segment (ICRS) implantation. The planned insertion depth was 70% of stromal thickness using a manual dissector. At least 12 months postoperatively, all eyes underwent Visante (Carl Zeiss Meditec) AS-OCT to determine insertion depth. Cases were categorized into 3 groups based on the measured implantation depth: 40-59% thickness; 60-79% thickness; and ≥80% thickness. Visual, refractive and topographic outcomes were evaluated relative to implantation depth.Results:The lowest improvement in the study parameters ocurred when the implantation depth was ≥80%. In this group, uncorrected visual acuity (UCVA) and best spectacle corrected VA (BSCVA) improved less than 0.5 lines. Manifest refractive spherical equivalent (MRSE) and mean keratometry (Km) change was less than 0.5 diopters (D). The greatest improvements were observed with implantation depth of 60-79% where UCVA and BSCVA increased by 4.5 and 2.5 lines respectively, and MRSE and Km changed by approximately 2.00 D. Less improvement was found when ICRS were implanted between 40-59% of stromal thickness.Conclusion:Implantation of ICRS greater than 80% of stromal thickness may have no effect on visual and topographic status.

Corneal Collagen Crosslinking for Keratectasia after Laser in situ Keratomileusis: A Review of the Literature

ABSTRACT Corneal ectasia is a serious vision-threatening complication of laser in situ keratomileusis (LASIK). It is associated with progressive corneal steepening, an increase in myopia and astigmatism, and decrease in uncorrected visual acuity. Before LASIK presence of risk factors (corneal thickness, refractive error, presence of clinical and subclinical corneal pathologies) should be studied so patients should be risk-stratified. Forme fruste keratoconus or marginal pellucid degeneration should be investigated before LASIK in order to inform the patients of the possibility to develop a corneal complication. Management of post-LASIK ectasia enlists crosslinking, INTACTS, contact lenses and, in the most serious cases, lamellar keratoplasty and corneal transplantation. Crosslinking is a technique to treat and even prevent post-LASIK corneal ectasia. LASIK is a technique that reduces the corneal strength and stability. Crosslinking increases the number of collagen interfibrillar covalent bonds, using ultraviolet A and riboflavin. This result increases stability in corneal strength, reducing the risk to develop corneal ectasia (if performed simultaneously with LASIK) or it treats ectasia (if performed after LASIK keratectasia). How to cite this article Spadea L, Verboschi F, Valente S, Vingolo EM. Corneal Collagen Crosslinking for Keratectasia after Laser in situ Keratomileusis: A Review of the Literature. J Kerat Ect Cor Dis 2013;2(3):113-120.

Unilateral Corneal Ectasia after Bilateral LASIK: The Thick Flap Counts

ABSTRACT Purpose To report a case of post-LASIK corneal ectasia due to a thick flap, while the contralateral eye did not develop ectasia after an incomplete deep flap cut, followed by a thinner flap LASIK procedure. Methods Case report Results This 45 years old female patient had bilateral myopic LASIK in 1999. Preoperative anterior curvature map was regular with no signs of keratoconus. Central keratometry was 42.88 × 44.70 @ 163 in OD and 43.43 × 45.24 @ 175 in OS. Ultrasound central corneal thickness was 586 μm and 619 μm in the right eye and left eye, respectively. Corneal OCT identified a deep meniscus-shaped LASIK flap, with a central thickness of a 392 μm in the right eye, and an incomplete deep peripheral cut in the left eye with a thinner meniscus-shaped LASIK flap. Conclusion Unilateral ectasia after LASIK may occur due to a thick flap which leads to biomechanical failure of the cornea. How to cite this article Valbon BF, Ambrosio R Jr, Glicéria J, Santos R, Luz A, Alves MR. Unilateral Corneal Ectasia after Bilateral LASIK: The Thick Flap Counts. Int J Kerat Ect Cor Dis 2013;2(2):79-83.

Evaluation of corneal changes after myopic LASIK using the Pentacam&amp;reg;

BackgroundIn this study, we used a Pentacam® device to evaluate the corneal changes that occur after laser-assisted in situ keratomileusis (LASIK).MethodsOur study included 60 eyes of 32 patients. All patients were treated for myopia and myopic astigmatism using LASIK. The eyes were examined preoperatively and 3 months postoperatively using a Pentacam to assess corneal changes with regard to curvature, elevation, and asphericity of the cornea.ResultsA statistically significant decrease in mean keratometric power of the anterior corneal surface (P = 0.001) compared with its pre-LASIK value was detected after 3 months, but there was no significant change in keratometric power of the posterior surface (P = 0.836). Asphericity (Q-value) of the anterior and posterior surfaces increased significantly after LASIK (P = 0.001). A significant forward bulge of the anterior corneal surface 4 mm and 7 mm from the central zone was detected 3 months post-LASIK (P = 0.001 for both), but there was no significant increase in posterior elevation at 4 mm and 7 mm from the center (P = 0.637 and P = 0.26, respectively). No cases of post-LASIK ectasia were detected. Correlation between different parameters of the corneal surface revealed an indirect relation between changes in pachymetry and anterior corneal elevation at 4 mm and 7 mm from the central zone (r = −0.27, P = 0.13, and r = −0.37, P = 0.04, respectively), and a direct proportion between changes in pachymetry and mean keratometric power of the anterior and posterior corneal surfaces (r = 0.7, P = 0.001 and r = 0.4, P = 0.028, respectively).ConclusionLASIK causes significant changes at the anterior corneal surface but the effect is subtle and insignificant at the posterior surface.

Indications for intrastromal corneal ring segments in ectasia after laser in situ keratomileusis

To evaluate clinical results of intrastromal corneal ring segments (ICRS) in a large series of post-laser in situ keratomileusis (LASIK) ectasia and determine which clinical parameters were related to the success of this technique. Vissum Corporation and Clínica Baviera Group, Alicante, Spain. Case series. Intrastromal corneal ring segments were implanted to correct the spherocylindrical error and improve visual acuity. Based on a previously described grading system, the best indications for ICRS implantation to treat post-LASIK ectasia were evaluated. The variables related to favorable outcomes over a 12-month follow-up were determined. Patients who lost 2 or more lines due to post-LASIK ectasia had a mean gain of +2.89 lines of corrected distance visual acuity (CDVA) after ICRS implantation (P<.001) and a mean CDVA of 0.81 (95% confidence interval, 0.74-0.88). In contrast, patients who did not lose vision after ectasia had a mean loss of -2.00 lines of CDVA after the ICRS implantation (P<.001). The odds ratio of a gain of at least 1 line of CDVA was 18 times greater for those who had lost 2 or more lines of CDVA after ectasia. The best indications for ICRS were a loss of 2 or more lines of CDVA after ectasia and post-LASIK ectasia grade 4. Patients who do not have vision loss after ectasia and those classified as grade 1 should not be considered candidates for ICRS implantation. No author has a financial or proprietary interest in any material or method mentioned.

Monitoring of Cornea Elastic Properties Changes during UV-A/Riboflavin-Induced Corneal Collagen Cross-Linking using Supersonic Shear Wave Imaging: A Pilot Study

Keratoconus disease or post-LASIK corneal ectasia are increasingly treated using UV-A/riboflavin-induced corneal collagen cross-linking (CXL). However, this treatment suffers from a lack of techniques to provide an assessment in real-time of the CXL effects. Here, we investigated the potential interest of corneal elasticity as a biomarker of the efficacy of this treatment. For this purpose, supersonic shear wave imaging (SSI) was performed both ex vivo and in vivo on porcine eyes before and after CXL. Based on ultrasonic scanners providing ultrafast frame rates (~30 kHz), the SSI technique generates and tracks the propagation of shear waves in tissues. It provides two- and three-dimensional (2-D and 3-D) quantitative maps of the corneal elasticity. After CXL, quantitative maps of corneal stiffness clearly depicted the cross-linked area with a typical 200-μm lateral resolution. The CXL resulted in a 56% ± 15% increase of the shear wave speed for corneas treated in vivo (n = 4). The in vivo CXL experiments performed on pigs demonstrated that the quantitative estimation of local stiffness and the 2-D elastic maps of the corneal surface provide an efficient way to monitor the local efficacy of corneal cross-linking.

Clinical grading of post-LASIK ectasia related to visual limitation and predictive factors for vision loss

To evaluate and characterize the main clinical features of post-laser in situ keratomileusis (LASIK) ectasia, propose a grading system based on visual limitation, and identify predictive factors related to the degree of visual loss. Vissum Corp., Alicante, Spain. Retrospective case series. This study comprised consecutive eyes with corneal ectasia after LASIK from 1996 to 2010. Main outcomes were post-LASIK ectasia corrected distance visual acuity (CDVA), CDVA loss, spherical equivalent (SE), and the corneal bulge (delta K). These outcomes were correlated with the residual stromal bed, ablation depth, ablation ratio (ablation depth:pachymetry), corneal depth (flap + ablation depth), and corneal ratio (corneal depth:pachymetry) to characterize their role in the severity of the disease. The mean post-LASIK ectasia CDVA, CDVA loss, SE, and delta K were 0.20 logMAR ± 0.18 (SD), -0.13 ± 0.15 logMAR, -3.80 ± 3.86 diopters (D), and 4.77 ± 4.23 D, respectively. The ablation ratio had the strongest correlation with post-LASIK ectasia CDVA (ρ = 0.477 and P<.001), whereas the corneal ratio had the strongest correlation with the post-LASIK ectasia SE and delta K (ρ = -0.614 and ρ = 0.453, respectively: P<.001). The ablation ratio was the main predictive factor for post-LASIK ectasia CDVA loss (relative risk, 2.04; P=.049). The grading system based on visual limitation was consistently represented by differences in CDVA loss, SE, and delta K. A high amount of tissue removed by the refractive procedure was associated with greater corneal biomechanical destabilization, increased corneal steepening, and a worse prognosis.

Topography-guided laser refractive surgery

Topography-guided laser refractive surgery seeks to correct vision by altering the major refractive surface of the eye. Whereas results are not significantly different from current treatment options for primary surgery, topography-guided treatment is uniquely effective in eyes with corneal irregularity. This review highlights topography-guided ablations, emphasizing recent advances in treating highly aberrated eyes, including treatment for corneal ectasia in conjunction with collagen cross-linking (CXL). Studies continue to document similar outcomes between topography-guided and wavefront-guided customized corneal ablations while exploring the indications for each modality. Topography-guided ablations demonstrate good outcomes for the correction of astigmatism after penetrating keratoplasty, laser-assisted in-situ keratomileusis (LASIK) flap or interface complications, post-radial keratotomy eyes, and other highly aberrated corneas, many of which are poor candidates for wavefront-guided therapy. The use of topography-guided ablations with CXL seeks to address both the refractive and structural abnormalities of corneal ectasias. This combination therapy has shown promising results for keratoconus, post-LASIK ectasia, and pellucid marginal degeneration. Topography-guided customized corneal ablation is well tolerated and effective. Recent attention has been focused on the unique therapeutic benefits of this treatment for highly irregular and ectatic corneas with encouraging results.