LASIK for post penetrating keratoplasty astigmatism and myopia.
AIMS: To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia. METHODS: 26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was -5.20D and the mean preoperative astigmatism was 8.67D. RESULTS: The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were -0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are -1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suffered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA. CONCLUSIONS: LASIK after penetrating keratoplasty is a relatively safe and effective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed. (+info)
Corneal wound healing following laser in situ keratomileusis (LASIK): a histopathological study in rabbits.
AIMS: To investigate the histopathological changes of rabbit corneas after laser in situ keratomileusis (LASIK) and to evaluate the corneal wound healing process. METHODS: A LASIK was performed on white rabbit eyes. Postoperatively, rabbits were killed on days 1 and 7, and at 1, 3, and 9 months. RESULTS: Periodic acid Schiff (PAS) positive material and disorganised collagen fibre were seen along the interface of the corneal flap even 9 months after operation. CONCLUSIONS: The wound healing process still continued at 9 months after LASIK indicating that a much longer time than expected was required for corneal wound healing following LASIK. (+info)
Corneal stromal changes induced by myopic LASIK.
PURPOSE. Despite the rapidly growing popularity of laser in situ keratomileusis (LASIK) in correction of myopia, the tissue responses have not been thoroughly investigated. The aim was to characterize morphologic changes induced by myopic LASIK in human corneal stroma. METHODS: Sixty-two myopic eyes were examined once at 3 days to 2 years after LASIK using in vivo confocal microscopy for measurement of flap thickness, keratocyte response zones, and objective grading of haze. RESULTS: Confocal microscopy revealed corneal flap interface particles in 100% of eyes and microfolds at the Bowman's layer in 96.8%. The flaps were thinner (112 +/- 25 microm) than intended (160 microm). The keratocyte activation in the stromal bed was greatest on the third postoperative day. Patients with increased interface reflectivity due to abnormal extracellular matrix or activated keratocytes at > or = 1 month (n = 9) had significantly thinner flaps than patients with normal interface reflectivity (n = 18; 114 +/- 12 versus 132 +/- 22 microm, P = 0.027). After 6 months the mean density of the most anterior layer of flap keratocytes was decreased. CONCLUSIONS: Keratocyte activation induced by LASIK was of short duration compared with that reported after photorefractive keratectomy. The flaps were thinner than expected, and microfolds and interface particles were common complications. The new findings such as increased interface reflectivity associated with thin flaps and the apparent loss of keratocytes in the most anterior flap 6 months to 2 years after surgery may have important clinical relevance. (+info)
Effect of myopic LASIK on corneal sensitivity and morphology of subbasal nerves.
PURPOSE: To investigate whether the morphology of the subbasal nerves corresponds to corneal sensitivity after laser in situ keratomileusis (LASIK). METHODS: In a case series study, 59 patients were examined at 2 to 4 hours, 3 days, 1 to 2 weeks, 1 to 2 months, 3 months, or 6 or more months after undergoing LASIK for myopia, by using a Cochet-Bonnet esthesiometer and an in vivo confocal microscope, and were compared with control subjects. Corneal sensitivity and confocal images of subbasal nerves were obtained centrally and 2 mm nasally and temporally. Subbasal nerve fiber bundles (NFBs) were grouped as follows: corneas with no nerve images; corneas with short (<200 microm), unconnected NFBs; corneas with long (> or =200 microm) NFBs without interconnections; and corneas with long NFBs with interconnections. RESULTS: Corneal sensitivity was at its lowest at 1 to 2 weeks after LASIK. Sensitivity of the hinge area was higher than temporal or central areas at every time point. At 6 or more months the sensitivity values were comparable with the values observed in control subjects. The central area showed mainly short, unconnected subbasal NFBs, even at 6 months. In general, the temporal area presented with long NFBs from 3 months onward, whereas the nasal area showed long NFBs at every time point. CONCLUSIONS: The results suggest that the corneal areas with no nerve images or short, unconnected NFBs are associated with lower sensitivities than corneal areas with long NFBs with or without interconnections. In vivo confocal microscopy reveals LASIK-induced alterations of subbasal nerve morphology and thus enables a direct comparison of corneal sensory innervation and sensitivity. (+info)
Six-month results of hyperopic and astigmatic LASIK in eyes with primary and secondary hyperopia.
PURPOSE: To assess the safety and efficacy of laser in situ keratomileusis (LASIK) for hyperopia and hyperopic astigmatism and develop a LASIK nomogram for primary hyperopia or hyperopia secondary to myopic refractive surgery using the VISX STAR S2. METHODS: Prospective evaluation of LASIK in 46 primary eyes and 29 secondary eyes with fogged manifest sphere from +0.5 diopters (D) to +6.0 D and cylinder from 0 to +5.0 D. RESULTS: Mean manifest spherical equivalent (SE) in patients with primary hyperopia was +2.50 D +/- 0.93 preoperatively and +0.70 D +/- 1.19 at 6 months. At 6 months, 79% of primary hyperopes had uncorrected visual acuity (UCVA) of 20/40 or better; 63% were within +/- 1 D of emmetropia. One primary hyperope lost 2 lines of best spectacle-corrected vision (BCVA) at 1 month. Complications included transient epithelial defect (6.5%), epithelial cells in the interface (4.3%), diffuse lamellar keratitis (4.3%), haze (2.2%), and mild irregular astigmatism (2.2%). In those with secondary hyperopia, mean manifest SE was +1.70 D +/- 0.82 preoperatively and -0.27 D +/- 0.95 at 6 months. At 6 months, 83% of secondary hyperopes had UCVA of 20/40 or better; 74% were within +/- 1 D of emmetropia. No secondary hyperope lost > or = 2 lines of BCVA. Complications included intraoperative bleeding (3.4%), intraoperative epithelial defect (3.4%), transient interface debris (3.4%), significant dry eye (3.4%), blood in interface (3.4%), irregular astigmatism (6.9%), slight decentration (6.9%), trace haze (6.9%), mild epithelial ingrowth not requiring removal (3.4%), or corneal irregularity (3.4%). CONCLUSION: These early data suggest that LASIK for hyperopia from +0.5 to +6 D and astigmatism from 0 to +5 D using the VISX STAR S2 benefits from a nomogram adjusted for preoperative refraction, age, and prior refractive surgery and is safe and effective. Patients with secondary hyperopia achieved more correction than those with primary hyperopia, although the accuracy and predictability of LASIK in both groups has improved with the nomogram adjustments. (+info)
Long-term results of laser in situ keratomileusis for high myopia.
The objective of this study was to evaluate the results of laser in situ keratomileusis (LASIK) for high myopia after a follow-up of two years. A total of 42 eyes from 33 patients with high myopia (range: -9.00 D to -25.50 D) were studied. LASIK was performed using an automated microkeratome (Steinway, USA) and OmniMed II excimer laser with the standard MKM program (Summit Technology, Inc., Waltham, MA) in all patients. The patients were followed up at one, three, six, 12 and 24 months. During follow-up manifest refraction and best corrected and uncorrected visual acuity were measured. Any complications were also analyzed. The two-year follow-up results were as follows. The mean postoperative manifest spherical equivalents (MSE) were -0.51 D at one month, -1.09 D at three months, -1.78 D at six months, -2.17 D at 12 months and -2.61 D at 24 months. Myopic regression continued during the two-year follow-up (p < 0.05). The accuracy of the intended postoperative correction within +/- 2.00 D was 73.8% at one month, 69.1% at three months, 52.4% at six months, 52.4% at 12 months, and 45.2% at 24 months. The best corrected visual acuity (BCVA) was unchanged or increased in 35 eyes (83.3%). Only three eyes (7.2%) lost two or more lines of BCVA. This was due to irregular astigmatism in one eye, macular degeneration in one eye, and rhegmatogenous retinal detachment in one eye. In this study, LASIK was effective and safe in the correction of high myopia, however continuous myopic regression was seen over the two-year follow-up. Refining the nomogram to adjust for progressive myopic regression will be necessary in order to obtain better results. (+info)
Corneal flap dimensions in laser in situ keratomileusis using the Innovatome automatic microkeratome.
To evaluate the thickness and size consistency of the corneal flap created with the Innovatome automatic microkeratome and to determine any correlation between preoperative variables and these corneal flap dimensions, we performed a prospective study comprising of 268 eyes of 143 patients having laser in situ keratomileusis. Either No. 170 or No. 190 blade was used, and preoperative variables including the central corneal thickness, keratometry (K) reading, spherical equivalent, and the blade type were measured. The mean central corneal flap thickness was 138.8 +/- 23.5 microns (range, 71.6-193.7 microns) in blade 170 group, and 148.3 +/- 25.4 microns (range, 80.3-211.7 microns) in blade 190 group. No relationship was found between the corneal flap thickness and the preoperative K reading or the spherical equivalent, but the corneal flap thickness increased with the preoperative central corneal thickness. The mean vertical flap diameter was 9.18 +/- 0.25 mm (range, 8.50-9.75 mm) in blade 170 group, and 9.50 +/- 0.31 mm (range, 8.75-10.00 mm) in blade 190 group. No relationship was found between the corneal flap diameter and the preoperative central corneal thickness or the spherical equivalent, but the corneal flap size increased with the preoperative K reading. (+info)
Ocular deviation after unilateral laser in situ keratomileusis.
Laser keratomileusis and excimer laser photorefractive keratectomy in situ are widely used therapies for treating myopia. The corrections of refractive error by glasses or contact lens result in a relatively equal refractive correction on both eyes. However, refractive surgery on a single eye can cause a focus disparity between both eyes and may result in the impairment of fusion leading to strabismus. This article aims to report a case where diplopia and esotropia occurred 1 month after laser keratomileusis (LASIK) in situ for the correction of myopia. (+info)