Walton Nosé

Corneal Biomechanical Metrics and Anterior Segment Parameters in Mild Keratoconus

PURPOSE To compare corneal hysteresis (CH), corneal resistance factor (CRF), spherical equivalent (SE), average central keratometry (K-Avg), corneal astigmatism (CA), corneal volume (CV), anterior chamber (AC) depth, and central corneal thickness (CCT) between patients with mild keratoconus and healthy controls and to estimate the sensitivity and specificity of CH and CRF in discriminating mild keratoconus from healthy corneas. DESIGN Comparative case series. PARTICIPANTS Sixty-three eyes (40 patients) with mild keratoconus (group 1) and 80 eyes from 40 gender- and age-matched controls (group 2). METHODS Patients underwent a complete clinical eye examination, corneal topography (Humphrey ATLAS; Carl Zeiss Meditec, Dublin, CA), tomography (Pentacam; Oculus, Wetzlar, Germany), and biomechanical evaluations (ocular response analyzer; Reichert Ophthalmic Instruments, Depew, NY). The receiver operating characteristic (ROC) curve was used to identify cutoff points that maximized sensitivity and specificity in discriminating mild keratoconus from normal corneas. MAIN OUTCOME MEASURES Corneal hysteresis, CRF, SE, K-Avg, CA, CV, AC depth, and CCT. The diagnostic performance of CH and CRF for detecting mild keratoconus was assessed using the ROC curve. RESULTS In group 1 versus group 2, the SE values (mean+/-standard deviation) were -3.55+/-2.87 diopters (D) versus -1.46+/-3.09 D (P = 0); K-Avg, 45.09+/-2.24 versus 43.24+/-1.54 D (P = 0); CA, 3.15+/-1.87 versus 1.07+/-0.83 D (P = 0); CV, 57.3+/-2.12 versus 60.86+/-3.39 mm3 (P = 0); AC depth, 3.19+/-0.35 versus 3.05+/-0.43 mm (P = 0.0416); CCT, 503+/-34.15 versus 544.71+/-35.89 microm (P = 0); CH, 8.50+/-1.36 versus 10.17+/-1.79 mmHg (P = 0); CRF, 7.85+/-1.49 versus 10.13+/-2.0 mmHg (P = 0). The ROC curve analyses showed a poor overall predictive accuracy of CH (cutoff, 9.64 mmHg; sensitivity, 87%; specificity, 65%; test accuracy, 74.83%) and CRF (cutoff, 9.60 mmHg; sensitivity, 90.5%; specificity, 66%; test accuracy, 76.97%) for detecting mild keratoconus. CONCLUSIONS The values for CH, CRF, CV, and CCT were statistically lower and those for SE, K-Avg, CA, and AC depth were statistically higher in patients with mild keratoconus compared with controls. Corneal hysteresis and CRF were poor parameters for discriminating between mild keratoconus and normal corneas. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Intrastromal corneal ring : 12-month sighted myopic eyes

BACKGROUND To evaluate the efficacy, predictability, and stability of the refractive effect produced by the Intrastromal Corneal Ring (ICR), the authors completed a 12-month study on 10 myopic eyes. METHODS Ten patients with preoperative refractive errors ranging from -2.63 diopters (D) to -4.25 D (mean, -3.30 D) participated in the study. The attempted correction was -2.50 D for a 7.0-mm diameter, 0.3-mm thick ICR. One eye of each patient received an ICR. RESULTS The average change in spherical equivalent at 12 months was -2.25 D (SD 0.54 D; range, -1.62 to -3.25 D). All patients maintained a spectacle-corrected visual acuity of 20/20 or better during the 12-month study period, with the exception of patient no. 6 who saw 20/30 at the 6-month examination. Her spectacle-corrected visual acuity returned to 20/20 a few days after the ICR was explanted and remained stable throughout the study. Uncorrected visual acuity had improved to 20/40 or better in all patients on postoperative day 1 and remained in this range for the 9 eyes (90%) during the 12 months of follow up. At postoperative month 12, 9 of 9 eyes (100%) had an uncorrected visual acuity of 20/40 or better with 3 of 9 eyes (33%) seeing 20/20 or better. The remaining patient, no. 6, experienced a tear in Descemets membrane during the procedure and required explantation of the ring after 6 months due to induced astigmatism and deterioration of uncorrected visual acuity. Two patients developed infiltrates that resolved with the use of antibiotics. The most common postoperative ocular findings were peripheral corneal haze in all eyes that diminished over time, minute lamellar channel deposits (7 of 10 eyes, 70%), deep stromal neovascularization (5 of 10 eyes, 50%), and pannus (5 of 10 eyes, 50%). CONCLUSION This preliminary study shows that implantation of an intrastromal corneal ring of this dimension (0.3-mm thick) can reduce approximately 1.50 to 3.00 D of myopia and maintain spectacle-corrected visual acuity.

Laser in situ keratomileusis to correctrefractive errors after keratoplasty

PURPOSE To assess the safety and effectiveness of excimer laser in situ keratomileusis (LASIK) to correct refractive myopia, astigmatism, or both after keratoplasty. SETTING Eye Clinic Day Hospital, São Paulo, Brazil. METHODS Twenty-two eyes that had previously had corneal transplantation were studied. Laser in situ keratomileusis was performed using the Chiron automated microkeratome and the VISX Twenty-Twenty B excimer laser. RESULTS Mean follow-up after LASIK was 10.09 months +/- 3.87 (SD). The spherical equivalent refraction dropped from -4.55 +/- 3.66 D before LASIK to -0.67 +/- 1.24 D after surgery. At the last examination, 72.7% of patients had a refractive error within +/- 1.00 D of emmetropia and 54.5% had uncorrected visual acuity of 20/40 or better. Vector analysis of astigmatic correction showed an index of success of 54.0%. Best spectacle-corrected visual acuity was unchanged in 8 cases, improved in 9, and decreased in 5. Significant endothelial cell loss, keratoplasty wound dehiscence, and other serious complications did not develop in any eye. CONCLUSION The correction of refractive error with LASIK in postkeratoplasty patients proved to be safe, effective, and predictable. Further studies with longer follow-up are needed to determine the methods clinical value.

Ocular response analyzer measurements in keratoconus with normal central corneal thickness compared with matched normal control eyes.

PURPOSE To compare corneal hysteresis (CH) and corneal resistance factor (CRF) in eyes with keratoconus with a central corneal thickness (CCT) ≥ 520 μm with CH and CRF in matched controls, and to estimate the sensitivity and specificity of these parameters for discriminating between the two groups. METHODS This prospective, comparative case series comprised 19 eyes of 19 patients with keratoconus with CCT ≥ 520 μm and 19 eyes of 19 healthy sex-, age-, and CCT-matched patients who underwent a complete clinical eye examination, corneal topography, tomography, and biomechanical evaluation. The receiver operating characteristic (ROC) curve was used to identify cutoff points that maximized the sensitivity and specificity for discriminating between groups. RESULTS Central corneal thickness was 543.1 ± 13.9 μm (range: 520 to 568 μm) in the keratoconus group and 545 ± 12.5 μm (range: 527 to 575 μm) in the control group (P=.6017). Corneal hysteresis was 9.22 ± 1.44 mmHg (range: 6.2 to 11.35 mmHg) in the keratoconus group and 10.58 ± 1.91 mmHg (range: 7.34 to 13.53 mmHg) in the control group (P=.0075). Corneal resistance factor was 8.62 ± 1.52 mmHg (range: 5.60 to 11.20 mmHg) in the keratoconus group and 10.30 ± 1.92 mmHg (range: 6.95 to 14.12 mmHg) in the control group (P=.0049). The ROC curve analyses showed a poor overall predictive accuracy of CH (cutoff, 9.90 mmHg; sensitivity, 78.9%; specificity, 63.2%; test accuracy, 71.05%) and CRF (cutoff, 8.90 mmHg; sensitivity, 68.4%; specificity, 78.9%; test accuracy, 73.65%) for detecting keratoconus in the eyes studied. CONCLUSIONS Corneal hysteresis and CRF were statistically lower in the keratoconus group compared with the control group. Given the large overlap, both CH and CRF had low sensitivity and specificity for discriminating between groups.

Intrastromal corneal ring--one-year results of first implants in humans: a preliminary nonfunctional eye study.

BACKGROUND The Intrastromal Corneal Ring (ICR) is a new investigational medical device designed to alter corneal curvature without surgical intervention in the central cornea. The ring is inserted between the layers of the stroma in the corneas periphery at two-thirds depth through an approximately 2-millimeter incision. METHODS To investigate the safety and refractive effect of implanting an ICR of a given thickness (0.30 mm) and outer diameter (7.70 mm) into human corneas, an ICR was implanted into one nonfunctional eye of each of three patients during the period of March to May, 1991. One predesignated ICR was successfully explanted 5 months after implantation to evaluate the feasibility of ICR removal and to observe the effect of ring removal on corneal curvature. Patients were followed for 1 year after the initial implant procedure. RESULTS The three implant procedures and postoperative courses proceeded without any significant complications. Approximately 2.00 D of central corneal flattening was achieved in all eyes. No adverse reactions or other medically-significant complications were observed over a 1-year follow-up period. The patient who underwent ICR removal experienced no perioperative complications, and the patients cornea has remained stable with a return to its preoperative curvature. CONCLUSION Although this study is preliminary and limited in scope, we have demonstrated that the ICR can be tolerated safely in the human cornea and results in a flattening of the corneal curvature that is stable for up to a year after insertion. The successful removal of the ICR begins to establish reversibility of the procedure and induced refractive effect.

Hyperopic laser-assisted in situ keratomileusis for radial keratotomy induced hyperopia.

PURPOSE To evaluate hyperopic laser in situ keratomileusis (H-LASIK) for radial keratotomy (RK)-induced hyperopia. DESIGN Noncomparative interventional retrospective nonconsecutive case series. PARTICIPANTS Sixty-nine eyes of 47 patients who had undergone RK and were seen with induced hyperopia. METHODS H-LASIK was performed with an excimer laser. MAIN OUTCOME MEASURES The mean refractive error, in spherical equivalents (SE), uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) before and after H-LASIK are reported. Safety was analyzed using a mean follow-up time of 6.6 plus minus 3.24 months. RESULTS Preoperative mean SE was +3.4 plus minus 1.6 diopters (D). Postoperative mean SE was -0.32 plus minus 1.2 D. A high percentage of eyes (79.7%; n = 55) were between plus minus1.0 D of emmetropia and 88% within plus minus 2.0 D. Preoperative BSCVA was 20/20 in 53.6% of eyes (n = 37) and 20/40 or better in 100% (n = 69). Postoperative BSCVA was 20/20 in 55% of eyes (n = 38) and 20/40 or better in 95.6% (n = 66) of eyes. Preoperative UCVA was less-than-or-equal20/50 in 52 cases (75.4%). Postoperative UCVA was 20/20 in 13 cases (18.8%) and greater-than-or-equal20/40 in 45 cases (65.2%). Four eyes lost 2 Snellen lines because of epithelial ingrowth in the interface (n = 3) and diffuse lamellar keratitis (Sands of the Sahara syndrome; n = 2). One of the eyes with Sahara syndrome also had epithelial ingrowth and flap necrosis. Thirteen eyes lost 1 Snellen line, and 50 eyes maintained or gained Snellen lines. The only intraoperative complication was incision opening (n = 8) while the flap was lifted; there were no further complications. These patients did not lose any Snellen lines of their BSCVA. CONCLUSIONS H-LASIK can be used successfully to correct RK-induced hyperopia.

Comparative study of coaxial phacoemulsification and microincision cataract surgery. One-year follow-up.

PURPOSE: To evaluate the amount of ultrasound (US) used, best corrected visual acuity (BCVA), and corneal endothelial cell loss in bimanual microincision cataract surgery (MICS) and coaxial phacoemulsification. SETTING: Department of Ophthalmology, Universidade Gama Filho, Rio de Janeiro, Brazil. METHODS: A prospective randomized study included 30 patients (60 eyes) with bilateral cataract. All patients had coaxial phacoemulsification in 1 eye and MICS in the fellow eye. The US time and the effective US time were measured intraoperatively. The BCVA and central endothelial cell loss were evaluated in both groups over a 1‐year follow‐up. The results between the 2 groups were compared. RESULTS: The total US time was lower in the coaxial phacoemulsification group than in the MICS group; the means were 0.50 minutes ± 0.33 (SD) and 0.82 ± 0.39 minutes, respectively. The mean US power was similar between groups (mean 10.1% ± 3.76% and 10.0% ± 4.0%, respectively). The BCVA was similar between the groups from 24 hours to 1 year. The mean central corneal endothelial cell loss at 3 months was 4.66% ± 6.10% in the coaxial phacoemulsification group and 4.45% ± 5.06% in the MICS group and at 1 year, 6.00% ± 6.72% and 8.82% ± 7.39%, respectively. The only significant difference in the postoperative results between the 2 groups was central endothelial cell loss at the 1‐year follow‐up. CONCLUSIONS: The US time was longer in the MICS group than in the in the coaxial phacoemulsification group, but the mean US power was similar between groups. The BCVA was also similar between groups; however, the MICS group had more central endothelial cell loss at the 1‐year follow‐up.

Outcomes of Iris-Claw Anterior Chamber versus Iris-Fixated Foldable Intraocular Lens in Subluxated Lens Secondary to Marfan Syndrome

PURPOSE To compare the outcome of phacoemulsification using 2 different iris-fixation techniques for intraocular lens (IOL) replacement, a foldable posterior chamber IOL (PCIOL; AcrySof MA60AC, Alcon Laboratories Inc, Fort Worth, TX) and an iris-claw anterior chamber IOL (ACIOL; Artisan, Ophtec BV), for treatment of subluxated lenses in patients with Marfan syndrome (MFS). DESIGN Randomized, controlled trial. PARTICIPANTS A total of 31 eyes of 16 patients with subluxated lenses associated with MFS and a preoperative corrected visual acuity (CVA) < or =20/40 based on the Early Treatment Diabetic Retinopathy Study chart. METHODS Patients were enrolled and the eye with worse visual acuity was randomly assigned to 1 of 2 study arms: phacoemulsification and iris-fixated PCIOL or phacoemulsification and iris-claw ACIOL; the second eye of the same patient received the other IOL type. Preoperative and postoperative ophthalmologic examination, optical coherence tomography, and endothelial cell counts were performed. MAIN OUTCOME MEASURES We recorded CVA results at 3, 6, and 12 months, complications, endothelial cell loss, and central retinal thickness. RESULTS In the iris-fixated PCIOL group, CVA was significantly improved at 3 (P = 0.011; n = 16), 6 (P = 0.006; n = 16), and 12 months (P = 0.002; n = 16). In the iris-claw ACIOL group, CVA was significantly improved at 3 (P = 0.001; n=15), 6 (P = 0.001; n = 15), and 12 months (P = 0.009; n = 12). The CVA results did not differ significantly between groups. Dislocation of the IOL occurred in 3 of 16 (18.75%) eyes in the PCIOL group. Retinal detachment occurred in 3 eyes (2 in the PCIOL group and 1 in the ACIOL group) and was successfully repaired. Postoperative foveal tomograms in both groups revealed a decrease in the mean foveal thickness (MFT; < or =172 microm) in 54.16% of the patients. CONCLUSIONS The iris-sutured PCIOL and iris-claw ACIOL produced comparable improvements in CVA at 3, 6, and 12 months postoperatively. Although IOL dislocation tended to occur more frequently in the iris-fixated PCIOL group, the difference was not significant. At 6 months postoperatively, all study patients tended to have a thinner MFT. None of the patients in either group developed cystoid macular edema.

Biomechanical and Tomographic Analysis of Unilateral Keratoconus

PURPOSE To evaluate and compare tomographic, clinical, and biomechanical data of patients with unilateral keratoconus and healthy controls. METHODS Observational, case-control study. Complete clinical eye examination was followed by topographic (ATLAS), tomographic (Pentacam), and biomechanical (Ocular Response Analyzer) evaluation. Cases were sex- and age-matched with healthy individuals for controls. RESULTS Four patients had unilateral keratoconus, and eight healthy patients served as controls. Central corneal thickness was 508±16 μm in the keratoconus group, 531±12.7 μm in the fellow eye group, and 528.6±40.7 μm in the control group (P>.125, all comparisons). Central keratometry was 43.70±2.70 diopters (D) in the keratoconus group, 42.84±1.43 D in the fellow eye group, and 43.81±1.94 D in the control group (P>.45, all comparisons). Corneal astigmatism was 3.30±2.24 D in the keratoconus group, 1.38±1.49 D in the fellow eye group, and 1.34±1.13 D in the control group (P=.037 between the keratoconus and control groups; P=.25 between the keratoconus and fellow eye groups). Corneal hysteresis was 8.13±2 mmHg in the keratoconus group, 8.96±0.86 mmHg in the fellow eye group, and 9.89±1.33 mmHg in the control group (P>.064, all comparisons). Corneal resistance factor was 7.96±2.43 mmHg in the keratoconus group, 8.92±1.39 mmHg in the fellow eye group, and 9.90±2.24 mmHg in the control group (P>.33, all comparisons). CONCLUSIONS Corneal hysteresis and corneal resistance factor values were not statistically different among the groups; however, a trend for lower values was found for keratoconus and fellow eyes compared to controls. Data should be interpreted with caution because of the small sample.

Higher-order aberrations of age-related cataract

PURPOSE: To analyze higher‐order aberrations induced by different types of lenticular opacities. SETTING: Federal University of São Paulo, São Paulo, Brazil. METHODS: One hundred thirty‐eyes of 65 patients with bilateral cataract, classified according to the Lens Opacities Classification System III (LOCS III), had complete ophthalmic examinations, corneal topography (EyeSys Technologies), and wavefront analysis (LADARWave, Alcon Laboratories). Patients with cataracts that could not be measured by a Hartmann‐Shack sensor or those with coexisting ocular disease were excluded. Higher‐order aberrations were compared between the nuclear, cortical, and posterior subcapsular groups for statistical significance. RESULTS: One hundred five eyes of 65 patients were assessed. Twenty‐eight eyes (23.33%) had predominantly nuclear opacification (NO1‐NO6 and C1‐2), and 13 (10.83%) had mainly cortical opacification (C1‐4). Sixty‐four eyes (65.83%) had a mixed pattern of LOCS III classification, which hindered the establishment of a correlation between the aberrometry and cataract type. Eighteen eyes that presented with dense posterior subcapsular cataract (P4‐5) and 7 eyes with cortical C5 LOCS III classification were excluded. In eyes with nuclear opacification, the mean spherical aberration with a 6.0 mm pupil was 0.45 μm ± 0.17 (SD) and the mean coma was 0.29 ± 0.13 μm. In eyes with predominantly cortical cataract, the mean spherical aberration was 0.12 ± 0.10 μm and the mean coma was 0.49 ± 0.23 μm. The cortical cataract group had statistically significantly higher coma than the other groups (P<.001). The nuclear cataract group had statistically significantly higher spherical aberrations than the other groups (P<.001). CONCLUSIONS: Different types of early lenticular opacities induced different wavefront aberration profiles. Coma predominated in the cortical cataract group, and spherical aberration predominated in the nuclear cataract group.