The accuracy of the double-K adjustment for third-generation intraocular lens calculation formulas in previous keratorefractive surgery eyes.

PURPOSE: To evaluate the effect of the double-K (DK) modification on third-generation formulas. METHODS: Thirty-eight previously myopic and 24 previously hyperopic eyes that underwent phacoemulsification with intraocular lens (IOL) insertion after Laser in situ keratomileusis (LASIK) were evaluated. Pre-LASIK refraction and keratometry, post-LASIK topography, axial length (AL), IOL type and power, and 1-month postphacoemulsification refraction were recorded spherical equivalent after phacoemulsification (SE(postphaco)). Measured corneal power was adjusted using published and validated methods for postmyopic and posthyperopic LASIK. For each eye, and using SE(postphaco), different DK-IOL formulas were used to calculate the corresponding IOL power, the outcome measure, which was compared with the implanted IOL. RESULTS: DK-Holladay 1 yielded the highest Pearson correlation coefficient (PCC), 0.955 for myopes and 0.943 for high myopes (AL>26 mm). Mean error (ME) and mean absolute error (MAE) for myopes for DK Sanders-Retzlaff-Kraff theoretical formula [DK-SRK/T] were 0.44±0.84 D and 0.75±0.61 D for DK-SRK/T compared with -0.04±0.67 D and 0.52±0.40 D for DK-Holladay 1 (P<0.001 and P=0.016, respectively), and 0.03±0.88 and 0.64±0.58 for DK-Hoffer Q. For high myopes, ME and MAE were 0.75±0.81 D and 0.84±0.69 D for DK-SRK/T, and -0.05±0.74 D (P<0.0001) and 0.57±0.45 D (P=0.019) for DK-Holladay 1. About 29% of DK-SRK/T eyes with large AL had MAE>1.5 D, compared with 0% for DK-Holladay 1 and 14% for DK-Hoffer-Q. Eyes with previous hyperopic LASIK faired similarly for all formulas, with similar PCCs, and only 8% in each category with MAE>1.5 D. CONCLUSIONS: DK-SRK/T overestimates IOL power in eyes with large AL, especially with concomitant steep pre-lasik keratometry. Among third-generation formulas, DK-Holladay 1 seems more accurate to use in postmyopic LASIK eyes.

Corneal higher-order aberrations after Descemet's stripping automated endothelial keratoplasty.

PURPOSE: To compare the corneal higher-order aberration (HOA) after Descemet's stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty (PKP), and in age-matched controls. DESIGN: Cross-sectional, non-comparative interventional case series. PARTICIPANTS: Thirty-one eyes of 28 patients who underwent DSAEK, 20 eyes of 16 patients who underwent PKP, and 31 eyes of 31 control patients. INTERVENTION: The corneal topography and HOAs of the central 4- and 6-mm zones from anterior and posterior corneal surfaces were evaluated postoperatively with the Scheimpflug rotating imaging system (Oculus Gmbh, Wetzlar, Germany). MAIN OUTCOME MEASURES: Anterior and posterior corneal HOAs. RESULTS: The mean anterior corneal total HOAs of the central 4 and 6 mm were 0.599+/-0.288 microm and 1.215+/-0.496 microm, respectively, in eyes that underwent DSAEK; 1.730+/-0.826 microm and 3.349+/-1.490 microm, respectively, in eyes that underwent PKP; and 0.439+/-0.163 microm and 0.921+/-0.300 microm, respectively, in controls. Although the mean anterior corneal total HOAs of the central 4 and 6 mm were significantly higher in eyes that underwent PKP than in eyes that underwent DSAEK and in controls (P<0.01), there was no significant difference in anterior corneal total HOAs of the central 4 and 6 mm between eyes that underwent DSAEK and controls. The mean posterior corneal total HOAs of the central 4 and 6 mm were 3.680+/-1.586 microm and 7.142+/-3.011 microm, respectively, in eyes that underwent DSAEK; 2.957+/-1.238 microm and 5.314+/-2.095 microm, respectively, in eyes that underwent PKP; and 0.818+/-0.193 microm and 1.609+/-0.344 microm, respectively, in controls. Although there was no significant difference in posterior corneal total HOAs of the central 4 mm between the DSAEK group and the PKP group, the posterior corneal HOAs of the central 6 mm were significantly higher in the DSAEK group than in the PKP group (P<0.01). CONCLUSIONS: Although posterior corneal HOAs are significantly higher in eyes that underwent DSAEK, anterior corneal HOAs are not significantly different in eyes that underwent DSAEK than those of age-matched controls.

Risk factors for intraocular pressure elevation after descemet stripping automated endothelial keratoplasty.

PURPOSE: To identify the incidence of and risk factors for intraocular pressure (IOP) elevation after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Retrospective review was conducted of 68 consecutive DSAEK procedures alone, or in combination with phacoemulsification with intraocular lens implantation or exchange, performed by two surgeons at the University of Texas Southwestern Medical Center between 2005 and 2009. Eyes that developed IOP elevation above 21 mm Hg after DSAEK and requiring initiation or escalation of glaucoma therapy were evaluated. RESULTS: Thirty-seven (54%) eyes showed IOP elevation responsive to medical treatment by a mean follow-up of 11.38 +/- 7.81 months. Six (8.8%) eyes required glaucoma surgery. In the eyes, which developed elevated IOP, gonioscopy did not reveal any new peripheral anterior synechiae formation. Prolonged topical steroid usage, rebubbling, combined DSAEK/cataract surgery, or repeat DSAEK were not significant factors (P>0.05) for development of elevated IOP, but history of previous glaucoma or ocular hypertension (OHTN) was significant (P=0.007). CONCLUSIONS: Intraocular pressure elevation is not uncommon in eyes after DSAEK, but most cases can be controlled with conservative management. Intraocular pressure elevation post-DSAEK occurred by mechanisms other than peripheral anterior synechial angle closure. The only significant risk factor for development of elevated IOP in our series was a previous history of glaucoma or OHTN.

Corneal refractive power estimation and intraocular lens calculation after hyperopic LASIK.

PURPOSE: To identify key independent variables in estimating corneal refractive power (KBC) after hyperopic LASIK. DESIGN: Retrospective study. PARTICIPANTS: We included 24 eyes of 16 hyperopic patients who underwent LASIK with subsequent phacoemulsification and posterior chamber intraocular lens (IOL) implantation in the same eye. METHODS: Pre-LASIK and post-LASIK spherical equivalent (SE) refractions and topographies, axial length, implant type and power, and 3-month postphacoemulsification SE were recorded. Using the double-K Hoffer Q formula, corneal power was backcalculated for every eye (KBC), regression-based formulas derived, and corresponding IOL powers calculated and compared with published methods. MAIN OUTCOME MEASURES: The Pearson correlation coefficient (PCC) and arithmetic and absolute corneal and IOL power errors. RESULTS: Adjusting either the average central corneal power (ACCP(3mm)) or SimK based on the laser-induced spherical equivalent change (DeltaSE) resulted in an estimated corneal power (ACCP(adj) and SimK(adj)) with highest correlation with KBC (PCC=0.940 and 0.956, respectively) and lowest absolute corneal estimation error (0.37+/-0.45 and 0.38+/-0.39 diopter [D], respectively). The ACCP(adj) closely mirrored published DeltaSE-based adjustments of central corneal power on different topographers, whereas DeltaSE-based SimK adjustments varied across platforms. Using ACCP(adj) or SimK(adj) in the double-K Hoffer Q, using ACCP(3mm) or SimK in single-K Hoffer Q and adjusting the resultant IOL power based on DeltaSE, or applying Masket's formula all yielded accurate and similar IOL powers. The Latkany method consistently underestimated IOL power. The Feiz-Mannis and clinical history methods yielded poor IOL correlations and large IOL errors. CONCLUSION: After hyperopic LASIK, adjusting either corneal power or IOL power based on DeltaSE accurately estimates the appropriate IOL power.

Outcomes of LASIK and PRK in previous penetrating corneal transplant recipients.

OBJECTIVE: To evaluate the safety and efficacy of excimer laser refractive surgery in correcting refractive error in eyes that have undergone previous penetrating keratoplasty (PK). METHODS: Twenty-three keratorefractive procedures on 16 eyes from 16 consecutive subjects were evaluated between 2002 and 2008. Each patient presented a previous history of a PK with subsequent postoperative myopia and astigmatism. Keratometric value, manifest refraction, best-corrected visual acuity, uncorrected visual acuity, and complications were determined. RESULTS: There were a total of 14 photorefractive keratectomy (PRK) procedures performed on 11 eyes and 9 laser in situ keratomileusis (LASIK) procedures performed on 5 eyes. In the PRK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -6.22 +/- 6.23 diopter and 5.23 +/- 2.26 D, respectively. The PRK postoperative manifest refractive spherical equivalent and cylindrical error were -3.61 +/- 4.23 D (P=0.25) and 3.21 +/- 1.78 D (P=0.02), respectively. In the LASIK group, the preoperative post-PK manifest refractive spherical equivalent and cylindrical error were -3.05 +/- 3.29 D and 4.11 +/- 2.38 D, respectively. The LASIK postoperative manifest refractive spherical equivalent and cylindrical error were -1.51 +/- 2.02 D (P=0.24) and 2.08 +/- 1.26 D (P=0.03), respectively. There was a 2-line or greater improvement of uncorrected visual acuity in 8 of the 14 PRK treatments and 5 of the 9 LASIK treatments. There were two episodes of acute graft rejection. One of the episodes resolved with topical and oral corticosteroids, and the other episode required a repeat corneal transplantation. CONCLUSIONS: PRK and LASIK are effective tools in reducing surgically induced astigmatism after penetrating corneal transplantation in most patients in this case series. The reduction of astigmatism may allow improved contact lens or spectacle fitting to achieve best-corrected binocular visual acuity.

Quality of life changes after myopic wavefront-guided laser in situ keratomileusis.

OBJECTIVE: To evaluate the changes in quality of life in patients undergoing wavefront-guided laser in situ keratomeilusis (WG-LASIK). METHODS: Thirty candidates undergoing WG-LASIK were enrolled in a prospective study at the University of Texas Southwestern Medical Center at Dallas, TX. The patients were asked to fill out a questionnaire which had questions pertaining to their quality of life, preoperatively and 3 months postoperatively. The average patients' age was 41.4 +/- 12.45 years, and the preoperative manifest refractive spherical equivalent was -3.62 +/- 1.60 D (-1.00 to -7.50 D). RESULTS: The total quality-of-life score improved from 3.70 +/- 0.91 to 3.90 +/- 0.97 (P = 0.01). Most of the psychologic well-being items like energy level, stress level, self-confidence, sense of safety, and the social role subscale items such as ability to communicate with others, job performance, and sex life showed significant improvement in mean scores (P < 0.05). The postoperative visual function and visual symptom scores, however, were overall similar to preoperative levels. CONCLUSIONS: Consistent with previous studies with conventional LASIK, there is a significant improvement in quality of life after WG-LASIK. The main changes pertain to psychologic well-being and social role, more than the changes in visual function per se. However, the latter did not show evidence of deterioration, nor of worsening of visual symptoms, contrary to some studies with conventional LASIK.

Assessment of keratocyte activation following LASIK with flap creation using the IntraLase FS60 laser.

PURPOSE: To assess the response of corneal keratocytes to the IntraLase FS60 femtosecond laser using attenuated steroids. METHODS: Thirty patients (30 eyes) who underwent LASIK with the IntraLase FS60 were assessed by clinical examination and confocal microscopy 3 months postoperatively. Postoperative steroid regimen was Econopred Plus (Alcon Laboratories Inc) every hour for 1 day and four times daily for 7 days. RESULTS: No cornea had clinically significant flap interface haze. Two corneas had trace haze at the interface detected by slit-lamp examination; both showed significant keratocyte activation by confocal microscopy. Overall, some degree of keratocyte activation was detected at the flap interface in 10 of 30 eyes. The measured interface reflectivity was 328.8 +/- 85.0 confocal backscatter units (CBU) in eyes with activated keratocytes and 88.9 +/- 74.5 CBU for the remaining 19 eyes (P < .001). CONCLUSIONS: With attenuated steroids, keratocyte activation was found in a significant number of eyes, although interface haze was subclinical. A higher steroid dosage might therefore be indicated.

Intraocular lens power calculation after myopic laser in situ keratomileusis: Estimating the corneal refractive power.

PURPOSE: To derive regression-based formulas and identify essential dependent variables to estimate refractive corneal power after myopic laser in situ keratomileusis (LASIK). SETTING: University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA. METHODS: A retrospective data review of 30 eyes (23 patients) having myopic LASIK followed by phacoemulsification and posterior chamber intraocular lens (IOL) implantation in the same eye gathered the following: pre-LASIK and post-LASIK refractions and topographies, axial length, IOL type and power, and spherical equivalent (SE) refraction 3 months after phacoemulsification. Using the double-K Holladay 1 formula, the refractive corneal power in each eye was back-calculated. Regression formulas were derived and compared with current corneal power estimation methods. RESULTS: The multiple regression formula based on the average corneal power in the central 3.0 mm area (ACCP3 mm) and the change (Delta) in SE (SEpostLASIK-SEpreLASIK) was simplified to ACCPadj=ACCP3mm-0.16DeltaSE, with the highest Pearson correlation coefficient (r=0.989) and lowest absolute corneal power estimation error (0.30 diopter [D]+/-0.30 (SD)). Regression based on ACCP3 mm alone yielded 0.980 and 0.49+/-0.40 D, respectively. Using SimK with DeltaSE resulted in a lower r value (0.971) and larger absolute corneal power estimation error (0.65+/-0.44 D) (P=.0014). The clinical history methods yielded 0.909 and 1.09+/-0.868 D, respectively (P=.0005). CONCLUSION: The regression formula based on ACCP3mm and DeltaSE was very accurate in predicting refractive corneal power after myopic LASIK followed by formulas based on ACCP3mm alone and SimK and DeltaSE, all of which consolidate the validity of similar previously suggested methods, including EffRPadjusted.

Wavefront-guided LASIK for myopia using the LADAR CustomCornea and the VISX CustomVue.

PURPOSE: To evaluate the objective and subjective visual outcomes and refractive results of wavefront-guided LASIK with LADAR CustomCornea and VISX CustomVue. METHODS: This prospective randomized single-institution multisurgeon study comprised 100 eyes of 58 patients (50 eyes on each laser platform). Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and manifest refraction were measured postoperatively at 1 day, 1 week, 1 month, and 3 months. Contrast sensitivity, higher order aberrations measurement, and a subjective vision questionnaire were performed preoperatively and at 3 months. RESULTS: Preoperatively, the CustomCornea group had a mean manifest sphere of -3.58 +/- 1.61 diopters (D) (range: -0.50 to -7.25 D), cylinder of +0.64 +/- 0.45 D (range: 0 to +1.75 D), and manifest refractive spherical equivalent (MRSE) of -3.26 +/- 1.56 D. The CustomVue group had a manifest sphere of -4.00 +/- 1.69 D (range: -1.50 to -7.50 D), cylinder of +0.60 +/- 0.52 D (range: 0 to +2.00 D), and MRSE of -3.70 +/- 1.64 D. At 3 months, 94% of CustomCornea eyes and 84% of CustomVue eyes had UCVA > or = 20/20 (P = .20). Twenty-four percent of CustomVue eyes and 22% of CustomCornea eyes gained 1 line of BSCVA. In both groups, 96% of eyes were within 0.50 D of emmetropia. Mean CustomCornea glare contrast sensitivity improved (P = .04) whereas more eyes improved than worsened in both groups. Spherical aberration and total higher order aberrations increased, and trefoil decreased in both groups. A decrease in coma was noted in 70% of CustomCornea eyes. CONCLUSIONS: Wavefront-guided LASIK with both platforms is safe, effective, and delivers excellent visual results. CustomCornea improves contrast sensitivity under glare conditions.

Prospective evaluation of PermaVision intracorneal implants using in vivo confocal microscopy.

PURPOSE: To report effects of the PermaVision intracorneal lens at the cellular level using in vivo confocal microscopy. METHODS: Four eyes implanted with intracorneal lenses beneath an IntraLase flap for correction of hyperopia were evaluated preoperatively and 1 to 6 months postoperatively. RESULTS: Intracorneal lenses were tolerated in three eyes with little or no haze observed clinically and good visual results. Minimal keratocyte activation was detected by confocal microscopy, and cell density was decreased posterior to the implants. Epithelial thinning was observed 1 month after implantation. Thickness stabilized by 6 months but remained thinner than baseline (33 +/- 2 microm vs 48 +/- 8 microm, P < .01). The fourth eye had a complicated course with early flap displacement followed by diffuse lamellar keratitis. Confocal microscopy revealed activated keratocytes throughout the anterior stroma. The implant was removed, and recovery was promising. CONCLUSIONS: Implantation of intracorneal lenses can induce side effects of epithelial thinning, keratocyte loss, and keratocyte activation.

Intraocular lens power calculation after radial keratotomy: estimating the refractive corneal power.

PURPOSE: To evaluate the most accurate method for corneal power determination in patients with previous radial keratotomy (RK). SETTING: University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA. METHODS: A retrospective review of data for 16 eyes of 14 patients with a history of RK and subsequent phacoemulsification and posterior chamber intraocular lens (IOL) implantation was performed. Outcome measures included axial length, postoperative topography, type and power of IOL implanted, and postoperative spherical equivalent (SE) refraction at 3 to 6 months. Average central corneal power (ACCP) was defined as the average of the mean powers of the central Placido rings. For each eye, simulated K-readings and different values of ACCP computed corresponding to different central corneal diameters were used in each case, along with the implanted IOL power, to back-calculate the SE refraction (Ref) via the double-K adjusted Holladay 1 IOL formula. The predicted refractive error was hence computed as (Ref - SE), both in algebraic and absolute values. RESULTS: The ACCP over the central 3.0 mm (ACCP(3mm)) yielded the lowest absolute predicted refractive error (0.25 +/- 0.38 diopters [D]), which was statistically lower than the error for ACCP(1mm) (P<.001) and for the simulated K-value (P = .033). It also resulted in 87.5% of eyes being within +/-0.50 D and 100% within +/-1.00 D of the actual postoperative refraction. CONCLUSIONS: Corneal refractive power after RK was best described by averaging the topographic data of the central 3.0 mm area. Applying this method, together with a double-K IOL formula, achieved excellent IOL power predictability.

Comparison of the corneal response to laser in situ keratomileusis with flap creation using the FS15 and FS30 femtosecond lasers: clinical and confocal microscopy findings.

PURPOSE: To compare the response of the cornea to laser in situ keratomileusis (LASIK) with flap creation using the IntraLase FS15 or FS30 femtosecond laser (IntraLase Corp.). SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: Twenty-three patients (31 eyes) who had LASIK with flap creation using the FS15 or FS30 laser were assessed by clinical examination and confocal microscopy in a nonrandomized parallel treatment group comparative trial. Eight FS15 patients (15 eyes) were examined preoperatively and 3 months postoperatively, and 14 FS30 patients (15 eyes) were examined 3 months postoperatively. RESULTS: No patient in either group had clinically significant flap interface haze. One FS15 eye and 1 FS30 eye had significant keratocyte activation at the flap interface. The mean difference between the actual flap thickness and intended flap thickness was 16.8 microm +/- 11.1 (SD) and 13.9 +/- 7.1 microm in the FS15 group and FS30 group, respectively (P = .49). The mean measured interface reflectivity was 156.4 +/- 88.6 confocal backscatter units (CBU) and 104.8 +/- 91.2 CBU, respectively (P = .15). The mean density of interface particles was 21.4 +/- 14.8 particles/mm(2) in the FS15 group and 11.0 +/- 7.1 particles/mm(2) in the FS30 group (P<.05). CONCLUSIONS: Both the FS15 and FS30 lasers provided more reproducible flap thickness and fewer interface particles than previously observed using microkeratomes. The response of corneal keratocytes to intra-LASIK was reduced compared with previous results in which higher raster energies were used. Compared with the FS15, there was an apparent reduction in overall interface reflectivity and fewer interface particles with the FS30 laser.

Tandem scanning confocal corneal microscopy in the diagnosis of suspected acanthamoeba keratitis.

OBJECTIVE: To evaluate the role of in vivo corneal tandem scanning confocal microscopy (TSCM) in the definitive diagnosis of suspected Acanthamoeba keratitis (AK). DESIGN: Noncomparative interventional single-institution case series. METHOD: A retrospective case review of patients consecutively referred with suspected AK and undergoing corneal TSCM was performed. RESULTS: A total of 63 cases that met the inclusion criteria for the study were referred for diagnostic evaluation. Tandem scanning confocal microscopy demonstrated Acanthamoeba cysts/trophozoites in 54 cases and fungal hyphae in 2, whereas 1 case was positive for both Acanthamoeba and fungus. Culture of the cornea or contact lenses was carried out in 35 cases, 9 of which were positive for Acanthamoeba. Six of the TSCM-positive cases also underwent corneal biopsy, being positive for Acanthamoeba in only 2. Six patients were negative for Acanthamoeba on TSCM, the etiology being fungal in 1 case, as shown by subsequent culture. One patient was positive on culture for Acanthamoeba but falsely negative by TSCM, which was limited by poor cooperation during the examination. Two cases initially masqueraded as Acanthamoeba keratitis but showed fungus on TSCM. Mean follow-up was 14 months. CONCLUSION: In vivo corneal TSCM can establish the diagnosis of Acanthamoeba keratitis rapidly and noninvasively, particularly when conventional microbiology is inconclusive.

Ocular surface restoration using non-surgical transplantation of tissue-cultured human amniotic epithelial cells.

PURPOSE: To assess the effect of tissue-cultured human amniotic epithelial cells (AECs) in restoring the ocular surface, transplanted using a collagen shield seeded with AECs supported by a soft contact lens. DESIGN: Prospective interventional single-institutional case series with crossover controls. METHODS: Three eyes in three patients were identified with persistent corneal epithelial defects (PEDs) refractory to medical therapy. Two cases were secondary to neurotrophic keratopathy, while one case was attributable to longstanding alkali injury. AECs were isolated from serologically screened donor human placenta, seeded onto collagen corneal shields, and incubated in tissue culture medium for 7 days. These collagen shields were placed over the PED and supported by an overlying soft contact lens. The collagen shields dissolved by 72 hours, and the contact lenses were removed after this time. This cycle was repeated every week until healing was achieved. As a crossover control, collagen shields without AECs were placed in the same eye 1 week before placing collagen shields containing AECs. The PED was assessed by vital staining and slit-lamp color photography. RESULTS: The PEDs had a mean duration of 4 months and involved 20% to 37% of the corneal surface area, one case secondary to longstanding alkali injury and two cases attributable to neurotrophic keratopathy. No change in PED size was observed in those control eyes receiving collagen shields without AECs. Complete resolution of the PED was seen after two cycles of AEC-seeded collagen shield in one case, and four cycles in two cases, from 7 to 12 weeks following treatment in all patients. No loss of visual acuity was seen and clinical improvement was maintained in all cases, with a mean follow-up of 6.3 months. CONCLUSIONS: Nonsurgical transplantation of tissue-cultured AECs on a collagen shield provides a promising approach to restoring the ocular surface in cases of PED.

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.

Perioperative Corneal Abrasion: Updated Guidelines for Prevention and Management.

Corneal abrasion is the most common ocular complication in surgery. Treatment requires pain control, antimicrobial prophylaxis, and close monitoring. Pain improves significantly after 24 hours and should be resolved by 48 hours. Persistent, worsening, or new symptoms warrant immediate specialist consultation. The authors review the pathophysiology of perioperative corneal abrasion, and propose updated evidence-based guidelines for improved patient care.

Results of penetrating keratoplasty for visual rehabilitation after Acanthamoeba keratitis.

PURPOSE: To assess the results of penetrating keratoplasty in quiet eyes after resolution of Acanthamoeba keratitis. DESIGN: A retrospective interventional case series. METHODS: Penetrating keratoplasty was undertaken in 13 eyes of 13 patients with an average age of 29 +/- 13 years and a history of Acanthamoeba keratitis that was diagnosed by culture and/or confocal microscopy between January 1995 and September 2004. All eyes were observed for at least 3 months (average, 5 months) after the discontinuation of antiamebic therapy that had been administered for at least 4.5 months. In vivo confocal microscopy was used to ensure that no residual amoeba were present before the operation. Two keratoplasties were combined with a valve insertion; five keratoplasties were combined with cataract extraction, and one keratoplasty was preceded by a ciliary laser ablation. RESULTS: Postoperative best-corrected visual acuity ranged from 20/40 to 20/15, with the exception of one eye with advanced glaucoma that did not improve from a preoperative vision of light perception. No eye experienced rejection or amoebic recurrences, and 12 grafts remained clear throughout the follow-up period (8 months to 9 years; median, 23 months). One graft failed at 4 months because of uncontrolled glaucoma. The eye was regrafted, and the graft remained clear during the 28 months of follow-up evaluation. Two eyes with preoperatively diagnosed glaucoma needed subsequent surgery to control their intraocular pressure. CONCLUSION: Penetrating keratoplasty for visual restoration after Acanthamoeba keratitis appears to have an excellent long-term prognosis, provided amoebic infection has resolved and concurrent glaucoma is controlled.

A comparison of induced astigmatism in conventional and wavefront-guided myopic LASIK using LADARVision4000 and VISX S4 platforms.

PURPOSE: To evaluate and compare the surgically induced astigmatism in myopic eyes undergoing conventional and wavefront-guided LASIK. METHODS: A retrospective review was performed of the charts of 200 myopic eyes of 121 patients who underwent either custom or conventional treatments via the VISX S4 or LADARVision4000 platforms (50 consecutive eyes in each of the four groups). The primary outcome measure was manifest refraction, which was evaluated preoperatively and at 3 months postoperatively. The magnitude and axis of the unintended surgically induced astigmatism were calculated using vector analysis. The Student t test was used to compare the magnitudes of the surgically induced astigmatism and the absolute angle of error. RESULTS: The mean preoperative manifest cylinder was 0.66 +/- 0.38 diopters (D) for conventional VISX S4 and 0.68 +/- 0.39 D for VISX CustomVue (P = .795), and 0.76 +/- 0.56 D for LADARVision and 0.61 +/- 0.36 D for LADAR CustomCornea (P = .114). The success index was 0.19 +/- 0.41 for VISX S4 and 0.49 +/- 0.49 for VISX CustomVue (P = .0013), and 0.25 +/- 0.47 for LADARVision and 0.20 +/- 0.39 for LADAR CustomCornea (P = .5721). The absolute mean angle of error was 4.4 +/- 13.9 degrees for VISX S4 versus 14.9 +/- 23.9 degrees for VISX CustomVue (P = .0085), and 6.1 +/- 12.30 for LADARVision versus 3.9 +/- 11.1 degrees for LADAR CustomCornea (P = .3501). Of the VISX CustomVue eyes, 32% had an absolute angle of error > 10 degrees, as compared to 10% for both the VISX S4 and LADAR CustomCornea eyes (P = .013), and 16% for the LADARVision group (P = .056). CONCLUSIONS: Wavefront-guided ablation is associated with higher surgically induced astigmatism and larger astigmatic axis shift on the VISX platform as compared to the LADAR CustomCornea and the LADAR and VISX conventional platforms. Care should be emphasized mainly during registration/alignment to minimize surgically induced astigmatism in wavefront-guided LASIK.

Hyperopic laser in situ keratomileusis in eyes with previous radial keratotomy.

PURPOSE: To assess the safety and efficacy of hyperopic laser in situ keratomileusis (LASIK) in eyes with previous radial keratotomy (RK). SETTING: Zale Lipshy University Hospital Laser Center for Vision, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: Thirty-eight eyes of 25 patients were treated with LASIK for secondary hyperopia after RK using a Visx Star S2, S3, S4, or LADARVision excimer laser. Retreatment was done in 7 eyes. The main outcome measures were manifest refraction spherical equivalent (MRSE), uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), predictability of treatment, and complications. RESULTS: Preoperative mean MRSE was +2.39 diopters (D) +/- 1.28 (SD) (range +0.87 to +6.00 D). At the last visit (25 eyes with minimum follow-up of 12 months, including retreatments), the mean follow-up was 23.3 +/- 7.3 months (range 12 to 34 months), the mean MRSE was +0.11 +/- 0.71 D, and the UCVA was 20/40 or better in 24 eyes (96%). Although no significant change in the mean MRSE was observed, the postoperative mean refractive cylinder showed a gradual increase over the follow-up period. No eye lost more than 2 lines of BSCVA. CONCLUSIONS: Laser in situ keratomileusis was a safe and effective treatment with good predictability for the correction of consecutive hyperopia after RK. Cylindrical errors were difficult to correct, and astigmatic correction tended to regress over time. Retreatments are safe when old flaps were relifted.

Effect of phacoemulsification on corneal thickness.

PURPOSE: To determine the immediate effect on corneal thickness of cataract extraction using phacoemulsification. DESIGN: Prospective consecutive nonrandomized humans undergoing standard small-incision phacoemulsification and intraocular lens insertion. METHODS: Corneal thickness was measured immediately preoperative and postoperatively in 58 consecutive patients undergoing phacoemulsification in the absence of other ocular abnormalities. Corneal thickness was determined centrally and in the midperiphery of four quadrants. The last 17 eyes were also evaluated for the effect of pressure from a Honan balloon on corneal thickness. SETTING: Faculty practice in medical school and university hospital. The cornea thinned in all five of the measured locations, with statistical significance being reached only in the four midperipheral quadrants. Pressure from the Honan balloon resulted in a negligible increase in corneal thickness preoperatively. CONCLUSIONS: Corneas were found to have thinned statistically significantly immediately after phacoemulsification; however, the degree of thinning has doubtful clinical significance and does not represent a significant dehydration of the cornea during the surgical procedure.