1/20. Delayed onset keratectasia following laser in situ keratomileusis.We present a case of unilateral iatrogenic keratectasia developing 10 months after bilateral laser in situ keratomileusis (LASIK) involving enhancement surgery using a broad-beam excimer laser (Summit Apex) to treat 6.6 diopters (D) of myopia. The ectasia progressed rapidly over the subsequent 12 months. The surgeon did not measure preoperative pachymetry, but preoperative topography and corneal measurements did not reveal underlying keratoconus or forme fruste keratoconus. corneal transplantation was required for final visual rehabilitation. light microscopy of the button revealed no underlying inflammation, which suggests biomechanical corneal weakening as the cause of the ectasia. Scanning electron microscopy showed the dramatic thinning seen clinically. latrogenic keratectasia appears to be a possible complication of LASIK.- - - - - - - - - - ranking = 1keywords = myopia (Clic here for more details about this article) |
2/20. Corneal ectasia detected after laser in situ keratomileusis for correction of less than -12 diopters of myopia.We report 2 cases of corneal ectasia detected after laser in situ keratomileusis (LASIK) for the correction of less than -12.0 diopters (D) of myopia. patients were evaluated before and after LASIK by corneal topography and pachymetry. After treatment, visual acuity temporarily improved but was followed by visual impairment, with corneal ectasia detected by topography. There may be a risk of corneal ectasia after LASIK in cases of myopia of less than -12.0 D. Despite thelow incidence, we recommend that LASIK be restricted to cases in which more than half the original corneal thickness and more than 250 microns of the stromal bed can be preserved. Careful examination, including preoperative serial topographic evaluation and measurement of posterior stromal thickness, should be performed to improve the quality and predictability of corneal refractive surgery.- - - - - - - - - - ranking = 6keywords = myopia (Clic here for more details about this article) |
3/20. Iatrogenic keratectasia after laser in situ keratomileusis for less than -4.0 to -7.0 diopters of myopia.PURPOSE: To study 13 eyes with less than -4.0 to -7.0 diopters of myopia that developed central or inferior keratectasia after laser in situ keratomileusis (LASIK). methods: The progress of the ectasia was determined by a series of pre- and post-LASIK topographies and the case histories. RESULTS: Progressive ectasia developed from 1 week to 27 months after LASIK. This necessitated the wearing of hard contact lenses or penetrating keratoplasty. One eye improved for some months after photorefractive keratectomy retreatment. Two eyes in 1 patient and 1 eye in a second patient had latent keratoconus before surgery. CONCLUSION: Laser in situ keratomileusis can cause permanent weakening and ectasia of the cornea even in eyes with low myopia.- - - - - - - - - - ranking = 6keywords = myopia (Clic here for more details about this article) |
4/20. Contact lens fitting in a patient with keratectasia after laser in situ keratomileusis.We present a case of unilateral iatrogenic keratectasia developing 15 months after bilateral laser in situ keratomileusis using a broad-beam excimer laser (Bausch & Lomb Keracor 116) to treat -3.5 -1.5 x 85 diopters of myopia. Preoperative pachymetry in the eye measured 450 microm without topographical changes suggesting keratoconus or forme fruste keratoconus. Contact lens fitting to provide 20/25 visual acuity is described.- - - - - - - - - - ranking = 1keywords = myopia (Clic here for more details about this article) |
5/20. Early onset ectasia following laser in situ keratomileusus: case report and literature review.PURPOSE: Laser in situ keratomileusis (LASIK) has been associated with the development of postoperative corneal ectasia. We present a case of early onset ectasia after LASIK, review known risk factors in development, and discuss possible strategies for prevention. methods: A 39-year-old man underwent bilateral LASIK for moderate myopia. Preoperative cycloplegic refractions were -9.00 0.25 x 140 degrees OD and -7.75 sphere OS. corneal topography demonstrated mild inferior steepening bilaterally although definite evidence of keratoconus by either the Klyce/Maeda and Smolek/Klyce keratoconus screening tests was not present. Following the creation of flaps with 160-microm plates, ablations of 93 microm OD and 80 microm OS were performed, estimated to leave residual stromal beds of at least 314 microm OD and 330 microm OS. RESULTS: On the first postoperative day, uncorrected visual acuities were 20/400 OD and 20/40 OS. On the fifth postoperative day, the patient's uncorrected visual acuity was 20/400 OD, and 20/300 OS. corneal topography of the right eye showed profound inferior steepening with an apical corneal power in excess of 57 D; topography of the left eye showed mild inferior steepening. Eighteen months after surgery best corrected visual acuity was 20/40 OD and 20/30 OS with rigid gas permeable contact lenses. CONCLUSIONS: This case highlights the need for a high index of suspicion when one notes an asymmetric bow-tie pattern on preoperative LASIK corneal topography, despite seemingly safe estimates of residual stromal bed thickness.- - - - - - - - - - ranking = 1keywords = myopia (Clic here for more details about this article) |
6/20. Latrogenic keratectasia following laser in situ keratomileusis.PURPOSE: To evaluate keratectasia after laser in situ keratomileusis (LASIK) for high myopia. methods: A 49-year-old male patient with myopia of -23.50 D in both eyes underwent LASIK with a Summit technology Apex Plus excimer laser. A Moria manually-guided MDSC microkeratome was used. Preoperative corneal topography in both eyes did not reveal underlying or fruste form of keratoconus. Four months after LASIK, a progressive keratectasia occurred in right eye and after 12 months, in left eye. corneal transplantation was performed in both eyes. RESULTS: Histological and ultrastructural examinations were performed on one corneal button. The analysis showed regular stromal morphology and cellularity, with no sign of inflammation. The morphometric analysis showed an overall thickness of 334 microm, with a flap of 262 microm and a stromal residual bed of 72 microm, in the center of the button. CONCLUSION: A LASIK corneal flap made with a planned 120-microm plate turned out histologically to be approximately 260 microm thick, in an eye with a refractive correction of -23.50 D. The excessive flap thickness and excessive ablation produced progressive keratectasia requiring a penetrating keratoplasty.- - - - - - - - - - ranking = 2keywords = myopia (Clic here for more details about this article) |
7/20. Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis.PURPOSE: To evaluate the potential of using intrastromal corneal ring technology (Intacs, KeraVision) to correct posterior ectasia after laser in situ keratomileusis (LASIK) for myopia. SETTING: Department of Cornea and Refractive Surgery, Instituto Oftalmologico de Alicante, and Miguel Hernandez University School of medicine, Alicante, spain. methods: In this prospective noncomparative intervention case series, Intacs segments were implanted in 3 eyes that developed posterior ectasia after myopic LASIK with clear central corneas. Posterior ectasia and corneal thickness were tested using the Orbscan II Slit Scanning corneal topography/Pachymetry System (Orbtek Inc.). Segment thickness varied based on corneal topography analysis and refraction. The mean follow-up was 8.3 months (range 7 to 11 months). RESULTS: The cases showed marked improvement after Intacs segment implantation. Postoperatively, there was a reduction in the magnitude of the posterior and anterior corneal surface steepening or ectasia and an increase in the topographical regularity index. In addition, the significantly enlarged optical zones resulted in a favorable visual outcome. In 2 eyes, the uncorrected visual acuity (UCVA) was 20/40 postoperatively. In the third eye, there was a residual refractive error; the UCVA was 20/50 and the best spectacle-corrected visual acuity, 20/40. CONCLUSIONS:Intacs intrastromal corneal rings used as a mechanical device may alter the biomechanical properties of the cornea for the correction of iatrogenic keratectasia and the associated residual myopia.- - - - - - - - - - ranking = 2keywords = myopia (Clic here for more details about this article) |
8/20. Histological and immunohistochemical findings after laser in situ keratomileusis in human corneas.PURPOSE: To describe histopathological and immunohistochemical findings in human corneas after myopic laser in situ keratomileusis (LASIK) followed by iatrogenic keratectasia and after hyperopic LASIK. SETTING: Department of ophthalmology, University of Innsbruck, Innsbruck, austria. methods: Clinical, histological, and immunohistochemical investigations were performed of 1 human cornea with iatrogenic keratectasia following myopic LASIK and 1 human cornea with irregular astigmatism and central scar formation after hyperopic LASIK. Corneal buttons were obtained during penetrating keratoplasty in both patients. RESULTS: Histopathological examination showed thinning of the central stroma with a posterior residual thickness of 190 microm in the patient with iatrogenic keratectasia after myopic LASIK and significant midperipheral thinning in the patient who had hyperopic LASIK. However, this characteristic ablation profile of the stroma after hyperopic LASIK was partially mitigated and compensated by the epithelium, which was significantly thinned in the center and markedly thickened in the midperiphery. Traces of wound healing with minimal scar tissue were present at the flap margin after myopic and hyperopic LASIK. In a few sections of the cornea with keratectasia after myopia LASIK, only a few collagen lamellae were visible crossing between the posterior residual stroma and the superficial flap. Immunohistochemical examination revealed minimally increased staining of dermatan sulfate proteoglycan within the stroma adjacent to the interface of the microkeratome incision. Increased staining of hepatocyte growth factor was found on keratocytes/fibroblasts at the flap margin in both corneas. CONCLUSIONS: The wound-healing response is generally poor after LASIK, which may result in significant weakening of the tensile strength of the cornea after myopic LASIK, probably due to biomechanically ineffective superficial lamella. After LASIK in patients with high hyperopia, compensatory epithelial thickening in the annular midperipheral ablation zone might be partly responsible for regression.- - - - - - - - - - ranking = 1keywords = myopia (Clic here for more details about this article) |
9/20. Corneal ectasia detected 32 months after LASIK for correction of myopia and asymmetric astigmatism.We report a case of corneal ectasia detected 32 months after laser in situ keratomileusis (LASIK) for correction of -4.25 diopters (D) of myopia associated with -2.00 D of regular but slight asymmetric astigmatism. The patient retained stable visual acuity for 15 months postoperatively. The preoperative corneal thickness was 540 microm, and the postablation untouched stroma was assumed to be 290 microm. Although a rare complication of LASIK, corneal ectasia can occur, and there is no consensus regarding how much stroma should be left intact to avoid it. Until we have a better understanding of corneal strength, we think surface photorefractive keratectomy or laser-assisted subepithelial keratectomy ablations should be considered instead of LASIK in borderline cases.- - - - - - - - - - ranking = 5keywords = myopia (Clic here for more details about this article) |
10/20. Corneal bed perforation by laser ablation during laser in situ keratomileusis.A 34-year-old man was referred to our department with corneal perforation after multiple laser in situ keratomileusis procedures for myopia. corneal perforation occurred at the time of laser application during the fourth surgery, and the anterior chamber became completely flat. The perforation was sealed shortly thereafter and the corneal edema disappeared in 3 weeks, but there was an 86 microm forward shift of the cornea associated with an 8.0 diopter myopic shift during the subsequent 6 months. No further forward bulging of the cornea was observed. The refraction had stabilized up to 2 years postoperatively, but corneal irregular astigmatism limited the patient's best spectacle-corrected visual acuity.- - - - - - - - - - ranking = 1keywords = myopia (Clic here for more details about this article) |
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