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At least 1,423 records · Page 79Linked to original sources
PubMed2005

Pachymetric evaluation prior to laser in situ keratomileusis.

PURPOSE: To determine whether deviations in the localization of the cornea's thinnest point or the magnitude and localization of posterior corneal ectasia is associated with deviations in the spherical equivalent, the astigmatism, or the magnitude of an anterior corneal ectasia and whether corneas at risk for iatrogenic keratectasia can be identified without a pachymetry map of the cornea. SETTING: University hospital eye clinic. METHODS: Three hundred eight eyes of 156 healthy volunteers with various refractive errors were examined with Orbscan II and autorefractometer-keratometer. The corneal thickness was registered at the fixation point, at the geometrical center, and at the thinnest point of the cornea. Keratometry and refraction were determined for all subjects. RESULTS: The thinnest point of the cornea was predominantly located in the inferotemporal quadrant, and was significantly thinner than the fixation point (539.6 +/- 35.8 microm and 548.0 +/- 35.4 microm, respectively, P<.001). Interestingly, the larger this difference was, the longer the distance between these points. No relationship was found between the refractive or external surface measurements and the internal surface measurements. CONCLUSIONS: The absence of a clear relationship between the shape of the anterior corneal surface or the refractive error, and the shape of the posterior corneal surface, necessitates a thorough pachymetric evaluation of the cornea before a laser in situ keratomileusis procedure, with special attention to the inferotemporal area.

Adult↗
PubMed2005

Treatment-induced shifts of ocular reference axes used for measurement centration.

PURPOSE: To determine the shifts of the main corneal reference points in dependence of the chosen centration axis for the treatment. SETTING: Federal Institute of Technology Zurich, Institute of Biomedical Engineering, Zurich, Switzerland. METHODS: Computer simulations were performed on several variants of the Gullstrand-Emsley schematic eye, which was modified by an off-axis fovea. Refractive corrections were simulated by centering Munnerlyn's formula on each of the 4 corneal reference points determined in the preoperative eye: the optical axis, the line of sight, the visual axis, and the first corneal reflex. Subsequently, the postoperative locations of these axes were determined and compared with the preoperative values. RESULTS: The postoperative line of sight was found to depend least on the choice of the preoperative centration axis for both myopic and hyperopic treatments. It undergoes a maximum movement of 0.040 mm when centering a +5 diopter correction on the preoperative line of sight, whereas the corneal reflex, which is used for centering most topography systems, can move by more than 0.10 mm. CONCLUSIONS: Centration of the correction on the preoperative line of sight enabled good comparability between preoperative and postoperative measurements that use the line of sight as a reference axis. Yet, centration of the treatment on the preoperative line of sight does not ensure comparability between preoperative and postoperative measurements that use the corneal reflex as a reference axis such as most corneal topography systems. Axis shifts might lead to misinterpretation of data such as a wrong diagnosis of a decentered ablation or changes in the Zernike representation.

Computer Simulation↗
PubMed2005

Posterior corneal surface changes after hyperopic laser in situ keratomileusis.

PURPOSE: To evaluate posterior corneal surface topographic changes after hyperopic laser in situ keratomileusis (H-LASIK) using Orbscan I (Orbtek, Inc.). SETTING: Department of Ophthalmology, Nara Medical University, Nara, Japan. METHODS: In 25 eyes of 15 patients who had H-LASIK, the posterior corneal surface was measured with slit-scanning corneal topography (Orbscan I) preoperatively and 1 year postoperatively. The center as a fit zone and calculated posterior corneal surface changes were taken at 4 points: nasal, temporal, superior, and inferior sides in the 5.0 mm diameter. The posterior corneal topographic changes were analyzed using an analysis of variance. The postoperative:preoperative magnification ratio of the posterior corneal surface was calculated in a theoretical eye model. RESULTS: When a "+" reading was defined as the forward displacement and "-" was defined as the backward displacement, the mean posterior corneal topographic changes were -2.8 microm +/- 27.9 (SD) at the nasal side, -4.5 +/- 27.8 microm at the temporal side, -3.9 +/- 20.1 microm at the superior side, and -2.3 +/- 20.1 microm at the inferior side. The posterior corneal surface between any 2 examined points showed no significant difference after H-LASIK. In addition, the hypothetical change in the posterior cornea was -8.3 microm after +3.0 diopter H-LASIK, which was approximately closer to the study results. In each side, the amount of the attempted correction was significantly correlated with the posterior corneal topographic change. CONCLUSIONS: Clinical measurement of the posterior corneal displacement after H-LASIK with Orbscan revealed a backward shift. This change corresponded to the hypothetical artifactual changes with Orbscan; that is, changes in the magnification ratio.

Adult↗
PubMed2005

Elevated intraocular pressure in secondary piggyback intraocular lens implantation.

We report 2 cases of postoperative intraocular pressure (IOP) elevation in secondary piggyback intraocular lens (IOL) implantation without history of glaucoma or ocular hypertension. A 74-year-old woman with myopic pseudophakia and a 68-year-old man with hyperopic pseudophakia received secondary piggyback AcrySof IOL implantation in their left eyes. In both patients, the left IOP gradually increased and sustained around 30 mm Hg for about 1 year. In the first, IOP continued elevating despite topical and systemic medications. There was an episode of pupillary block in the second. Gonioscopically, heavier trabecular meshwork pigmentation in their left eyes was observed. Because of this, the 2 IOLs implanted were removed and replaced by an adequate IOL and trabeculotomy was performed in the former. The AcrySof IOL has a truncated optic edge, which increases the risk for chafing the iris, resulting in pigment dispersion syndrome; thus, it would be a poor choice for a sulcus-placed piggyback implantation.

Acrylic Resins↗
PubMed2005

Enhancement outcomes after photorefractive keratectomy and laser in situ keratomileusis using topographically guided excimer laser photoablation.

PURPOSE: To evaluate the efficacy and safety of topographically guided excimer laser photoablation to retreat unsuccessful myopic and hyperopic photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Eye Clinic, San Salvatore Hospital, University of L'Aquila, L'Aquila, Italy. METHODS: At least 3 months after primary PRK (Group A) or primary LASIK (Group B), 48 eyes of 42 patients were submitted to PRK or LASIK enhancements. The eyes were treated with an excimer laser linked to a computerized videokeratography unit with a topographically supported customized ablation workstation. RESULTS: The mean follow-up was 27.8 months +/- 8.2 (SD). In Group A, the uncorrected visual acuity (UCVA) changed from 0.5 +/- 0.7 logarithm of the minimum angle of resolution (logMAR) (range 20/600 to 20/200) to 0.1 +/- 0.7 logMAR (range 20/60 to 20/20); the mean best spectacle-corrected visual acuity (BSCVA) changed from 0.1 +/- 0.7 logMAR (range 20/50 to 20/20) to 0 +/- 0.7 logMAR (range 20/50 to 20/20) after the enhancement. In Group B, the UCVA changed from 0.7 +/- 0.8 logMAR (range 20/600 to 20/40) to 0.1 +/- 0.7 logMAR (range 20/40 to 20/20); the mean BSCVA improved from 0.2 +/- 0.8 logMAR (range 20/30 to 20/20) to 0 +/- 1.3 logMAR (range 20/25 to 20/20) after surgery. CONCLUSIONS: The enhancements using topographically guided excimer laser photoablation with a topographically supported customized ablation method resulted in satisfactory and stable visual outcome with good safety and efficacy after unsuccessful PRK and LASIK.

Adult↗
PubMed2006

Two-year follow-up of conductive keratoplasty for the treatment of hyperopic astigmatism.

PURPOSE: To evaluate the safety, efficacy, predictability, and stability of conductive keratoplasty (CK) for the treatment of hyperopic astigmatism. SETTING: University of Crete Medical School, Vardinoyannion Eye Institute of Crete, Heraklion, Greece. METHODS: In this prospective nonrandomized noncontrolled single-center study, 47 eyes of 34 patients (15 women and 19 men) were treated for hyperopic astigmatism (up to + 3.50 diopters [D]) with a Refractec ViewPoint CK system and followed for 24 months +/- 0.6 (SD). The treatment consisted of 4 to 36 spots applied to the periphery of the cornea. Mean age was 48.5 years +/- 9.7 years, range 25 to 68 years. All the treated eyes were analyzed for safety, efficacy, predictability, and stability. RESULTS: The mean patient age was 48.5 +/- 9.7 years (range 25 to 68 years). Preoperatively, the mean manifest refraction spherical equivalent (MRSE) was +2.11 +/- 0.88 D (range -0.50 to + 4.13 D); at 12 months, it was -0.52 +/- 0.73 D and at 24 months, -0.50 +/- 0.77 D. At 24 months, the mean MRSE was within +/-0.50 D in 61% of eyes, within +/-1.00 D in 83%, and within +/-2.00 D in all eyes. At 24 months, the uncorrected visual acuity was 20/20 or better in 37% of eyes and 20/40 or better in 97%. By the end of the follow-up period, no eye had lost > or =2 Snellen lines or had an induced cylinder > or =1.50 D. CONCLUSIONS: Conductive keratoplasty for low hyperopic astigmatism was a safe, effective, and stable procedure. Nomogram adjustments and careful patient selection should contribute to higher levels of predictability when treating hyperopic astigmatism.

Adult↗
PubMed2006

Confocal assessment of the corneal response to intracorneal lens insertion and laser in situ keratomileusis with flap creation using IntraLase.

PURPOSE: To assess the response of the cornea to hydrogel intracorneal lens (ICL) insertion or laser in situ keratomileusis (LASIK) with IntraLase (IntraLase Corp.) at the cellular level. SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: Twenty patients (29 eyes) were evaluated by in vivo confocal microscopy 1 to 6 months postoperatively: 20 eyes had LASIK with flap creation by IntraLase, and 9 eyes had ICL insertion (8 following IntraLase). RESULTS: For LASIK with IntraLase, keratocyte activation and/or interface haze was detected in 8 of 20 eyes. The remaining eyes had interface particles but no cell activation. Keratocyte activation was generally limited to a few cell layers adjacent to the interface. However, 2 patients exhibited multiple layers of activation and increased extracellular matrix (ECM) reflectivity (haze) surrounding the interface by confocal microscopy. Both patients also had clinical haze and photophobia. For ICLs, following insertion, 5 of 9 eyes had activated keratocytes adjacent to the implant surfaces. The largest amount of cell activation and ECM haze detected by confocal microscopy was in 2 patients with significant clinical haze. Structures with an epithelioid morphology were detected on some implant surfaces. Epithelial thickness was 33.3 microm +/- 2.3 (SD) in the ICL eyes and 49.2 +/- 6.5 microm in the LASIK with IntraLase eyes. CONCLUSIONS: Both LASIK with IntraLase and ICL insertion following IntraLase induced keratocyte activation, which may underlie clinical observations of haze in some patients. Intracorneal lens implant also induced thinning of the overlying corneal epithelium.

Biocompatible Materials↗
PubMed2006

Iridocyclitis associated with angle-supported phakic intraocular lenses.

PURPOSE: To evaluate incidence, features, risk factors, and prognosis of iridocyclitis after angle-supported phakic intraocular lens (IOL) implantation. SETTING: Private practice, Siena, Italy. METHODS: This retrospective analysis comprised 356 consecutive eyes of 212 patients. In myopic eyes, the ZSAL-4 IOL (205 eyes of 125 patients) or the ZSAL-4 Plus IOL (106 eyes of 63 patients) was used. In hyperopic eyes (45 eyes of 24 patients), the Type 54 IOL was implanted. Haptic posterior angulation was 19 degrees (ZSAL-4), 23 degrees (ZSAL-4 Plus), and 14 degrees (Type 54). RESULTS: Clinically significant iridocyclitis occurred in 11 eyes (3.1%) of 11 patients. Mean patient age was 37.3 years +/- 9.4 (SD). Sixty-four percent were male (odds ratio [OR], 3.0; 95% confidence interval [CI], 0.8 to 7.4, not statistically significant). Iridocyclitis was observed in 4.4% of hyperopic eyes (OR, 1.6; 95% CI, 0.3 to 7.4; not statistically significant) and in 2.9% of myopic eyes. In myopic eyes, it followed the implantation of ZSAL-4 IOL in 3.9% of eyes (OR, 4.1; 95% CI, 0.5 to 33.6; not statistically significant), and of ZSAL-4 Plus IOL in 1%. Mean time from surgery was 8.5 +/- 10.6 months). Presentation included aqueous flare (100%), posterior synechiae (82%), blurred vision (82%), redness (36%), pain (27%), IOL precipitates (18%), and angular synechiae (9%). Only 1 patient had recurrences, leading to IOL explantation and cataract surgery. After topical therapy, best spectacle-corrected visual acuity was fully recovered in 9 of 11 eyes. CONCLUSION: Iridocyclitis can occur months or years after the implantation of angle-supported phakic IOLs. No statistically significant risk factors were identified. Functional prognosis is generally good.

Adult↗
PubMed2006

One thousand consecutive IntraLase laser in situ keratomileusis flaps.

PURPOSE: To measure laser in situ keratomileusis (LASIK) flap dimensions created with the IntraLase FS (IL) laser (Intralase Corporation). SETTING: Private practice, San Diego, California, USA. METHODS: Consecutive LASIK flaps created with the IL were measured with subtraction ultrasound at primary and enhancement surgeries. Data were stored in Outcomes Analysis Software and analyzed using MS Excel (Microsoft Corporation) and SSPS software. RESULTS: The mean achieved flap thickness exceeded the attempted by 9.4 to 34.3 mum. The standard deviation varied from +/-10.2 to +/-21.7 mum. Preoperative corneal thickness and power did not affect achieved flap thickness. Seventy-three percent of mate eye flaps were within +/-15 mum of each other for the 90 mum attempted. The same flaps measured at enhancement were thicker than the primarily measured flaps (n = 58). Diffuse lamellar keratitis and slipped flaps were eliminated with experience. There were no decentered or irregular flaps, epithelial defects, or flap perforations. CONCLUSIONS: Compared with published results of mechanical microkeratomes, the IL reduced the standard deviation of flap thickness as well as the achieved range. It eliminated physical complications associated with mechanical flap creation, and the impact of preoperative pachymetry and corneal power, thereby permitting more myopia to be corrected without risking deep ablations.

Adult↗
PubMed2006

Intraocular lens pupillary capture after neodymium:YAG laser treatment of interlenticular opacification of posterior chamber piggyback intraocular lenses.

A hyperopic 73-year-old woman had bilateral phacoemulsification with primary implantation of piggyback AcrySof intraocular lenses (IOLs) (Alcon) in the capsular bag. Interlenticular opacification (ILO) developed after 6 months in the left eye and after 2 years in the right eye. Treatment of the ILO in the left eye with a neodymium:YAG (Nd:YAG) laser resulted in pupillary capture of the optic of the anterior IOL. This case shows that despite using low energy levels, pupillary capture of the anterior IOL can occur after Nd:YAG laser treatment for ILO in piggyback IOLs.

Acrylic Resins↗