Bilateral Ectasia Research Articles

Bilateral Ectasia After SMILE Combined With Accelerated Corneal Cross-linking (SMILE-Xtra)

Purpose To present the first reported case of bilateral ectasia following small incision lenticule extraction (SMILE) associated with corneal cross-linking (CXL). Methods A 20-year-old woman was referred for bilateral corneal ectasia 2 years after uneventful bilateral SMILE combined with accelerated CXL (SMILE-Xtra) for myopic correction. The preoperative refraction was −3.00 −0.75 × 10° in the right eye and −2.50 −0.50 × 165° in the left eye. The preoperative corneal topography showed a minimum corneal thickness of 488 µm in the right eye and 498 µm in the left eye. Results Initial follow-up results showed stable visual acuity, but she presented 24 months later with reduced vision in the left eye, revealing bilateral ectasia. Scheimpflug examination confirmed central ectasia in the left eye and subtle initial ectasia in the right eye. Biomechanical analysis demonstrated altered parameters and epithelial mapping revealed epithelial thinning. Conclusions This study challenges previous assertions about the efficacy of SMILE-Xtra in preventing ectasia, because it presents the first documented case of this complication. The findings emphasize the importance of exercising caution in treating corneas at risk, regardless of the association of CXL, especially when the cornea is considered suspicious. This highlights a broader concern that all refractive surgeries may carry a risk of inducing ectasia, underscoring the necessity for careful patient selection and continuous refinement of surgical protocols for optimal safety outcomes. [ Journal of Refractive Surgery Case Reports. 2024;4(4):e40–e45.]

Inter-zonal epithelial thickness differences for early keratoconus detection using optical coherence tomography

PurposeTo develop and test a parameter for early keratoconus screening by quantifying the localized epithelial thickness differences in keratoconic eyes.MethodsThe cross-sectional study included 189 eyes of 116 subjects in total: 86 eyes of 54 keratoconus patients with bilateral ectasia and 40 eyes of 20 healthy subjects in the parameter-development dataset and 42 eyes of 21 keratoconus patients with asymmetric ectasia and 21 eyes of 21 healthy subjects in the parameter-validation dataset. Epithelial thickness maps were obtained using anterior segment optical coherence tomography and the inter-zonal epithelial thickness differences were calculated. The developed parameter was tested in keratoconus patients with asymmetric ectasia.ResultsCompared to healthy controls, the inferior-temporal and global inter-zonal epithelial thickness differences were higher not only in eyes with tomographically significant keratoconus (median [interquartile range] of 4.42 [3.13] µm vs. 0.78 [0.42] µm, p < 0.001, and 3.05 [1.51] µm vs. 1.07 [0.26] µm, p < 0.001, respectively), but also in tomographically normal keratoconus fellow eyes (1.36 [0.85] µm vs. 0.78 [0.42] µm, p = 0.005, and 1.31 [0.32] µm vs. 1.07 [0.26] µm, p = 0.01, respectively). The inferior-temporal inter-zonal epithelial thickness differences had an area under the receiver operating characteristic curve (95% confidence interval) of 0.991 (0.972–1) for detecting tomographically significant keratoconus and 0.749 (0.598–0.901) for differentiating between tomographically normal keratoconus fellow eyes and healthy controls.ConclusionsThe inter-zonal epithelial thickness differences are increased in keratoconus fellow eyes which still have a normal Scheimpflug corneal tomography, and therefore may serve as a useful parameter to detect early ectatic changes.

Long-term follow-up of bilateral ectasia after laser-assisted Small-Incision Lenticule Extraction (SMILE) with known risk factors.

To report the long-term follow-up of bilateral ectasia after laser-assisted small-incision lenticule extraction (SMILE) with known risk factors. We report the case of a 23-year-old woman. Preoperative refraction was - 7.25 -2.00 × 20 in the right eye and -7.25 -1.50 × 155 in the left eye. Maximal keratometry was 47.32 diopters and 48.37 diopters, respectively, which was a contraindication to Laser Assisted In Situ Keratomileusis (LASIK) and a SMILE was proposed in 2015. One year after surgery, ectasia developed in the left eye and crosslinking (CXL) was performed. Two years after surgery, ectasia also developed in the right eye and CXL was also performed, leading to stabilization in both eyes five years after surgery. Known contraindications for LASIK are also contraindications for the performance of refractive surgery with SMILE. CXL is an efficient treatment of post-SMILE corneal ectasia.

Surgical treatment of corneal ectasia with motowa′s trephine and selective suturing technique

A 40-year-old male presented with bilateral ectasia, contact lens intolerance, and astigmatism >10 D in both eyes. The patient had end-stage pellucid marginal degeneration that warranted surgical treatment. We present a unique surgical technique to stabilize the cornea, minimize astigmatism, improve vision and corneal status, and avoid penetrating keratoplasty.

Bilateral corneal ectasia after laser in situ keratomileusis in patient with isolated difference in central corneal thickness between eyes

A patient was treated bilaterally for myopia using laser in situ keratomileusis (LASIK). Preoperatively, there was no known risk factor for ectasia but a 20 microm between-eye difference in central mean corneal thickness was seen on the optical pachymetry map. Two years postoperatively, bilateral ectasia was diagnosed. This case suggests that abstention or surface ablation treatment may be a safer option than LASIK in patients showing central thickness asymmetry between eyes.

Correction of Severe Ectasia After LASIK With Intracorneal Ring Segments

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). 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). 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. Implantation of intracorneal ring segments can be considered as a treatment option in patients with severe ectasia after LASIK.

Bilateral Keratectasia After Photorefractive Keratectomy

To report the clinical features, management, and outcome of a patient who developed bilateral ectasia after photorefractive keratectomy (PRK). Case report of a 35-year-old man who underwent bilateral PRK. Preoperative uncorrected visual acuity was 20/200 in the right eye and 20/100 in the left eye. The patient's history was unremarkable and he denied a family history of ocular disorders. Two weeks after surgery, the patient presented with loss of visual acuity in both eyes. Uncorrected visual acuity was 20/80 in the right eye and 20/200 in the left eye. Objective refraction could not be obtained. Slit-lamp microscopy showed corneal thinning in both eyes. After examining the patient's family, his sister was found to have clinical and topographic keratoconus. Ectasia is a rare complication of PRK. We report the occurrence of bilateral ectasia after PRK in a patient with asymmetric bowtie topographies. We recommend that refractive surgery, even surface techniques such as PRK, be avoided in patients with a family history of keratoconus.

Late Bilateral Keratectasia After LASIK in a Low Myopic Patient

ABSTRACT PURPOSE: To report a rare case of late bilateral ectasia developing after LASIK for low myopia without preoperative risk factors. METHODS: A 21-year-old man underwent bilateral uneventful LASIK for low myopia of -2.75 diopters in both eyes. Preoperative corneal pachymetry was 531 µm in the right eye and 526 µm in the left eye. The total ablation depth was 46.8 µm in the right eye and 42.2 µm in the left eye. Preoperative corneal topography was normal and did not reveal forme fruste keratoconus. RESULTS: Twenty-four months postoperatively, the patient developed bilateral inferior keratectasia of +0.50 -3.00 × 72° in the right eye and +1.00 -2.75 × 99° in the left eye. CONCLUSIONS: Late keratectasia may follow LASIK for low myopia despite a thorough preoperative work-up. [J Refract Surg. 2005;21:494-496.]

Late Bilateral Keratectasia After LASIK in a Low Myopia Patient/Reply

To report a rare case of late bilateral ectasia developing after LASIK for low myopia without preoperative risk factors. A 21-year-old man underwent bilateral uneventful LASIK for low myopia of -2.75 diopters in both eyes. Preoperative corneal pachymetry was 531 microm in the right eye and 526 microm in the left eye. The total ablation depth was 46.8 microm in the right eye and 42.2 microm in the left eye. Preoperative corneal topography was normal and did not reveal forme fruste keratoconus. Twenty-four months postoperatively, the patient developed bilateral inferior keratectasia of +0.50 -3.00 x 72 degrees in the right eye and +1.00 -2.75 x 99 degrees in the left eye. Late keratectasia may follow LASIK for low myopia despite a thorough preoperative work-up.