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At least 1,135 records · Page 63Linked to original sources
PubMed2005

[LASIK using a scanning spot excimer laser for the treatment of myopia and myopic astigmatism 3-Jahresergebnisse].

PURPOSE: The correction of refractive errors using laser in situ keratomileusis (LASIK) has become the primary refractive procedure worldwide. The purpose of this study was to evaluate LASIK within a retrospective cohort. PATIENTS AND METHODS: The mean preoperative spherical equivalent for the 34 consecutively treated eyes was -6.67+/-2.69 D. The LASIK operations were performed by a Hansatome microkeratome (Bausch and Lomb) and a scanning spot excimer laser (Technolas Keracor 217, Bausch and Lomb). For pre- and postoperative analysis the Datagraph med software (Version 2.7) was used. RESULTS: None of the treated eyes lost 2 or more lines of best-corrected visual acuity (BCVA). At the 36-month examination the spherical equivalent had changed to -0.47 D (mean increase of myopia: 0.13 D). No long-term complications were found in the study period. CONCLUSION: LASIK with superior hinge and scanning spot excimer ablation is an effective treatment for the correction of myopia and myopic astigmatism in the refractive range described above.

Adolescent↗
PubMed2001

[Photorefractive/photo-astigmatic refractive keratectomy in low myopia and myopic astigmatism. Broad beam versus scanning spot laser technology].

PURPOSE: The results of photorefractive/photoastigmatic refractive keratectomy (PRK/PARK) were compared between two patient groups treated consecutively with either broad-beam or scanning-spot technology. PATIENTS AND METHODS: PRK/PARK was performed with a broad-beam excimer laser VISX 20/20 in 46 eyes and with the scanning-spot laser system Keracor 217 in 49 eyes. Preoperative spherical equivalent (subjective manifest refraction) was < or =-6.0 diopter in both groups. Safety, efficacy, predictability, stability, and complications were investigated after 1,4 and 12, months postoperatively. RESULTS: In the broad-beam laser group no eye lost two or more lines of best-corrected visual acuity;in the scanning-spot laser group one eye lost two lines 12 months postoperatively. Efficacy, predictability, and stability were comparable between the two groups. CONCLUSIONS: Both the broad-beam and the scanning-spot laser provided good results after PRK/PARK for low myopia and myopic astigmatism. This study found no fundamental differences between the two laser systems.

Adult↗
PubMed1987

Scleral flap surgery for modification of corneal astigmatism.

We performed resections and recessions of scleral flaps on human cadaver eyes in order to measure the induced change in keratometric astigmatism. We prepared 3-mm scleral flaps that were 3, 5, 7, or 10 mm long and resected or recessed these flaps up to 1 mm in 0.25-mm increments. Scleral flap resection resulted in up to 10.1 D of net corneal steepening along the meridian of the incision. Scleral flap recessions resulted in up to 7.7 D of net corneal flattening along the meridian of the incision; the effect increased with increasing flap length in the recessed eyes. There was a tendency toward mean corneal flattening with resections and mean corneal steepening with recessions.

Astigmatism↗
PubMed1989

Corneal topography of transverse keratotomies for astigmatism after penetrating keratoplasty.

We used a topography system to evaluate retrospectively the pattern of power distribution seen preoperatively and postoperatively in six patients with high postkeratoplasty astigmatism. The relaxing incisions had all been placed based on visual inspection of keratoscope mires alone. Computer analysis of keratoscope photographs showed considerable individual variation in the degree of surface irregularity in preoperative topography. Our data suggest that the steep axis of the postkeratoplasty graft is better conceptualized as two steep hemimeridians. These hemimeridians were separated by an angle other than 180 degrees (two of six cases), and often showed fairly large changes in power from the most central to peripheral areas of the graft analyzed (three of six cases). Asymmetry of power between the two steep hemimeridians was seen in all cases. Areas of maximum steepening were often present in the peripheral portions of the graft in areas other than the major hemimeridians. Individual variation in preoperative corneal irregularity and asymmetry appeared to have an effect on the success of the relaxing incisions.

Adult↗
PubMed1982

Meridional variations in acuity and CSF's in monkeys (Macaca nemestrina) reared with externally applied astigmatism.

Infant macaque monkeys have been raised under such conditions that all visual experience was obtained while looking through a cylindrical lens. When tested at older ages, these monkeys were found to have meridional differences in acuity and contrast sensitivity. The direction of the differences were predictable on the basis of the defocus produced by the rearing condition. The data support the theory, previously suggested on the basis of clinical and correlational studies, that astigmatism is a major cause factor in the occurrence of meridional amblyopia.

Accommodation, Ocular↗
PubMed1982

Astigmatic visual and deprivation in cat: behavioral, optical and retinophysiological consequences.

Kittens were deprived of clear vision in one eye only by +7D or -7D cylindrical lenses worn from eye opening until 7.5 months of age. Behavioral measurements subsequently demonstrated diminished acuity through the affected eye relative to the opposite control eye. However, single unit recordings at 3.5 years of age from retinal ganglion cells located within 1-11 degrees of the centre of the area centralis showed neither loss of grating resolution nor any abnormal orientation bias. Furthermore, the astigmatic rearing had minimal effect on the development of the cat's natural optics to the emmetropic state. The experiments indicate that the amblyopic defect induced by the cylindrical lenses occurs in the brain rather than the eye.

Age Factors↗
PubMed1983

Astigmatism of oblique incidence in the human model eye.

Two cylindrical lenses of equal power, one positive and one negative, were used to correct astigmatism of oblique incidence in a wide-angle optical model of the human eye. Tangential and sagittal vergences were calculated at different visual angles from the posterior pole to the peripheral retina. The positive cylinder was placed with its axis parallel to the tangential meridian while the negative cylinder was placed with its axis parallel to the sagittal meridian. Improvement in the quality of the retinal image at different angles of incidence was obtained by varying the angle between the axes of the correcting cylinders. Corresponding gains in resolution have been calculated and confirmed by peripheral fundus photography.

Astigmatism↗
PubMed2004

Recurrent interface infiltration with hypopyon after astigmatic laser in situ keratomileusis on a penetrating corneal graft.

A 56-year-old woman was referred with recurrent interface infiltration and hypopyon after astigmatic laser in situ keratomileusis (LASIK) on a corneal graft. Pseudomonas aeruginosa was isolated as the causative pathogen. Penetrating keratoplasty had been performed 2 years before refractive surgery. After the antibiotic medication was tapered, 3 recurrences of interface infiltration with hypopyon were observed. Penetrating rekeratoplasty was deemed appropriate. Histological examination of the explanted corneal graft revealed anterior stromal neutrophil infiltration. This case illustrates that microbial pathogens brought underneath the flap by LASIK can persist months later despite antimicrobial treatment.

Anti-Bacterial Agents↗
PubMed2005

Laser in situ keratomileusis outcomes following radial keratotomy, astigmatic keratotomy, photorefractive keratectomy, and penetrating keratoplasty.

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) to enhance refractive status following other corneal surgical procedures. SETTING: Clinical office-based practice. METHODS: Seventy-one eyes of 57 patients had LASIK for refractive errors following radial keratotomy (n = 22), astigmatic keratotomy (n = 13), photorefractive keratectomy (n = 18), and penetrating keratoplasty (n = 18). A Moria LSK-1 microkeratome was used with a Visx S2 or Wavelight Allegretto excimer laser. Data were acquired by retrospective chart review of all appropriately qualified patients. RESULTS: The mean preoperative manifest refractive spherical equivalent (MRSE) was -3.93 diopters (D) +/- 2.83 (SD) in myopic eyes and +1.43 +/- 1.79 D in hyperopic eyes. The mean time from the initial corneal surgical procedure to LASIK was 65.0 months. The mean post-LASIK follow-up was 9.40 months (range 1 to 42 months). Postoperatively, the mean MRSE was -0.85 +/- 1.42 D in myopic eyes (P<.0001) and -0.16 +/- 1.09 D in hyperopic eyes (P<.0001). Enhancement by LASIK was required in 14% of eyes. CONCLUSION: In eyes that have had a variety of previous corneal surgeries, LASIK offers a safe and predictable method for enhancing refractive results.

Astigmatism↗
PubMed2000

Comparison of visual results in initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism.

PURPOSE: To report the results of initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism. METHODS: A total of 1161 consecutive inital and retreatment laser in situ keratomileusis procedures in 697 patients performed between September 19, 1996, and June 20, 1998, were retrospectively analyzed. Baseline and postoperative best spectacle-corrected visual acuity, uncorrected visual acuity, spherical and cylindrical refractions, computerized video keratography, and biomicroscopy were measured or performed on each eye. RESULTS: Of 1,071 eyes, 900 (84%) underwent a single-laser in situ keratomileusis procedure, and 171 of 1,071 eyes (16%) underwent one or two re-treatment procedures. The preoperative mean +/- SD spherical equivalent was -5.09 +/- 3.15 diopters (range, -0.75 to -14.38 diopters) and the cylinder was 0.97 +/- 1.09 diopters (range, 0.00 to 3.25 diopters) in the group that underwent a single laser in situ keratomileusis treatment. The preoperative mean +/- SD spherical equivalent was -6.26 +/- 3.04 diopters (range, -1.75 to -12.88 diopters) and the cylinder was 1.53 +/- 1.11 diopters (range, 0.00 to 3.50 diopters) in the group that underwent re-treatment. Before re-treatment, 110 eyes (64.3%) in the group that underwent re-treatment achieved 20/40 or better uncorrected visual acuity and 23 eyes (13.5%) achieved 20/25 or better. Three months after re-treatment, 155 eyes (90.6%) achieved 20/40 or better, and 80 eyes (46.8%) achieved 20/25 or better. In the single-procedure group, uncorrected visual acuity at 3 months revealed 20/40 vision or better in 856 eyes (95.1%) and 20/25 vision or better in 572 eyes (63.6%). In this study group, 23.6% of eyes with a preoperative spherical equivalent greater than -6.0 diopters underwent re-treatment compared with 11.8% of eyes with a preoperative spherical equivalent of -6.0 diopters or less. CONCLUSIONS: Laser in situ keratomileusis appears to be an effective procedure for mild, moderate, and severe myopia. In eyes with residual refractive error, re-treatment laser in situ keratomileusis procedures can result in good visual outcomes.

Astigmatism↗
PubMed1994

Photorefractive keratectomy for the correction of myopia and astigmatism.

Photorefractive keratectomy corrects myopia with or without astigmatism by decreasing the refractive power of the central cornea. The Colliac matrix formula determines the anterior corneal radius of curvature expected to achieve emmetropia. We used the formula as an algorithm for the computer-controlled delivery of the laser beam. The formula was evaluated by using theoretical and clinical cases. We examined the relationship between the correction induced by photorefractive keratectomy, the diameter of ablation zone, and the thickness of the ablated corneal lenticule on the optical axis. Comparison between attempted and achieved keratometric readings showed the accuracy of the formula to be in the order of +/- 0.75 diopter.

Adult↗
PubMed1989

Corneal compression sutures for the reduction of astigmatism after penetrating keratoplasty.

We placed interrupted 9-0 nylon sutures across the graft-host interface of ten eyes with more than 5 diopters of keratometric cylinder after penetrating keratoplasty in order to steepen the flattest corneal meridian and reduce the amount of corneal cylinder. Placement of compression sutures reduced corneal cylinder by an average of almost 6 diopters one week later. Average corneal cylinder was 5.1 diopters nine to 12 months after surgery. Best-corrected visual acuity with spectacles improved by an average of two Snellen lines (20/60 to 20/40) and uncorrected visual acuity improved by an average of one line (20/300 to 20/200). There were no complications related to placement of the sutures. This procedure provides a rapid and simple method for reducing astigmatism after penetrating keratoplasty.

Astigmatism↗
PubMed1982

Bullous keratopathy after anterior-posterior radial keratotomy for myopia for myopic astigmatism.

Of 281 eyes that had had Sato's anterior-posterior radial keratotomy for myopia or myopic astigmatism, 80 (50 patients) underwent follow-up examinations ten to 20 years later. Sixty of the 80 eyes had bullous keratopathy. The onset of this disease occurred when the patient was about 40 years old, regardless of the patient's age at the time of surgery. Seven corneal buttons were obtained from patients with bullous keratopathy who required penetrating keratoplasty. Light and electron microscopy disclosed subepithelial bullae, degenerate or absent Bowman's zone, and thickened Descemet's membrane. Flattened fibroblastic endothelial cells were observed in three of the seven cases. This type of radial keratotomy surgery seems to produce severe corneal decompensation many years later, possibly as a result of damage from the corneal incisions in combination with endothelial losses from aging.

Adolescent↗
PubMed1984

Episodic astigmatism heralding generalized myopathy: report of a case managed with a new type of soft contact lens.

A 29-year-old woman presented with marked variations in refraction. A few minutes of physical exertion or reading at a close distance induced up to 2D of myopia and 2D of myopic astigmatism, which regressed upon resting with closed eyes. Cycloplegic agents did not affect the refractive changes, which were shown to be due to variations in corneal curvatures. The eyes were otherwise clinically normal. A few months later the patient developed signs of a progressive, generalized myopathy of unknown origin. The muscular disease was resistant to treatment. The refractive changes were effectively controlled by means of a new type of soft contact lens, with a semi-rigid center.

Adult↗
PubMed1985

Selective suture removal can reduce postkeratoplasty astigmatism.

Two hundred four consecutive eyes underwent penetrating keratoplasty by a single surgeon using eight interrupted 10-0 monofilament nylon sutures in the cardinal position combined with a continuous 11-0, 16-bite monofilament nylon suture technique. The interrupted 10-0 monofilament nylon sutures were selectively removed postkeratoplasty based on central keratometry readings and corneal topography. Sutures were removed in 56 eyes in Group I as early as six to eight weeks after surgery and in 148 eyes in Group II as early as three weeks after surgery. The mean astigmatism for all groups decreased from 7.5 diopters in the first postoperative month to 2.6 diopters 14 to 16 months after surgery. Sutures were completely removed in 75 eyes in this study between 2 and 46 months after surgery without producing significant changes in corneal curvature. The complications associated with this suturing technique were no different from those associated with other suturing techniques. The selective removal of interrupted sutures postkeratoplasty can improve the recovery of vision after corneal transplantation without subjecting the eyes to increased risks.

Aphakia↗
PubMed1991

Refractive surgery for graft-induced astigmatism after penetrating keratoplasty for keratoconus.

Of a series of 201 corneal transplants for keratoconus over a 20-year period, 42 grafts (39 eyes of 38 patients) required further surgery because of intolerable astigmatism (range, -3 diopters [D] to -18 D; mean, 8.9 D). Relaxing incisions, compressive resuturing, and augmented relaxing incisions were the techniques used. All procedures resulted in a similar mean reduction in cylinder -3.6 to 5 D, but the outcome with augmented relaxing incisions was less predictable. Six grafts required two or more procedures for a satisfactory outcome. All patients had corrected visual acuity of 20/30 or better after surgery, and 75% had visual acuity of 20/20 or better. The cumulative time until 90% of the grafts had useful vision was 32 months after refractive surgery. Relaxing incisions offer the prospect of more rapid visual rehabilitation than compressive resuturing.

Astigmatism↗
PubMed1996

Clinical and surgical factors influencing corneal graft survival, visual acuity, and astigmatism. Corneal Transplant Follow-up Study Collaborators.

PURPOSE: To quantify clinical and operative factors that influence corneal graft outcome. METHODS: A multifactorial analysis was done on 2242 corneal grafts registered by the United Kingdom Transplant Service from July 1987 to June 1991. RESULTS: There was an increased risk of graft failure in patients with preoperative diffuse and other noncentral stromal edema, less-common eye diseases, small trephine size, difference in donor and recipient sizes greater than 0.25 mm, and use of mixed continuous and interrupted sutures. Visual acuity 3 months after surgery was poorer in patients who had glaucoma and low visual acuity preoperatively, small trephine size, and combined vitreous surgery. Use of interrupted sutures resulted in higher astigmatism at 3 months. CONCLUSIONS: After allowing for the effects of recipient factors, surgical factors significantly affected corneal graft outcome. No factors that showed significant benefits for graft survival also adversely affected visual performance. Details of medical history, clinical condition, and surgical method failed to predict more than a small proportion of observed variability in visual performance of functioning grafts.

Astigmatism↗