Joaquim Murta

Keratoconus-integrated characterization considering anterior corneal aberrations, internal astigmatism, and corneal biomechanics

PURPOSE: To evaluate the clinical features of keratoconus taking into consideration anterior corneal aberrations, internal astigmatism, and corneal biomechanical properties and to define a new grading system based on visual limitation. SETTING: Vissum Corporation, Alicante, Spain. DESIGN: Retrospective case series. METHODS: This multicenter study comprised consecutive keratoconic eyes with no previous ocular surgery or active ocular disease. Visual, refractive, corneal topography, and pachymetry outcomes were analyzed. Internal astigmatism was calculated by vectorial analysis. Corneal aberrations and corneal biomechanics characterized by the Ocular Response Analyzer were evaluated in some eyes. Correlations between clinical data and a linear multiple regression analysis for characterizing the relationship between visual limitation and objective clinical data were performed. RESULTS: This study comprised 776 eyes of 507 patients (age range 11 to 79 years) The mean keratometry (K) correlated significantly with logMAR corrected distance visual acuity (CDVA) (r = 0.591, P<.01), internal astigmatism (r = 0.497, P<.01), corneal asphericity (r = −0.647, P<.01), and several corneal higher‐order aberrometric coefficients (r≥0.603, P<.01). Significant correlations were found between some corneal aberrometric parameters and CDVA (r≥0.444, P<.01). Multiple regression analysis showed that CDVA was significantly correlated with the mean K, intraocular pressure, corneal resistance factor, and spherical equivalent (r2 = 0.69, P<.01). There were significant differences in mean K, internal astigmatism, and corneal higher‐order aberrations between 4 groups differentiated by visual limitation (P<.01). CONCLUSION: The visual limitation in keratoconus could be explained by different alterations that occur in these corneas and allowed development of a new grading system for this condition. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Intravitreal ranibizumab for myopic choroidal neovascularization: 12-month results

Purpose: The purpose of this study was to evaluate the safety and efficacy of intravitreal ranibizumab after 12 months in the treatment of choroidal neovascularization secondary to pathologic myopia. Methods: This was a prospective, multicenter, consecutive, nonrandomized, interventional case series. The study included 34 eyes of 32 patients with choroidal neovascularization secondary to pathologic myopia; 13 eyes had previous photodynamic therapy, and 21 eyes had no previous treatment. The patients were followed for ≥12 months. Best-corrected visual acuity, optical coherence tomography, and the presence of metamorphopsia were assessed monthly. Results: Mean visual acuity improved 8 letters from baseline to 12-month follow-up, and the difference was statistically significant (P < 0.001): 100% of the eyes lost <3 lines on the Early Treatment Diabetic Retinopathy Study chart, 24% of the eyes improved ≥3 lines, 44% improved ≥2 lines, 65% improved ≥1 line, and 79% improved ≥0 lines. Central retinal thickness decreased significantly from baseline to the 12-month follow-up (P < 0.01). A mean of 3.6 treatments were performed during the 12-month follow-up, and no systemic or ocular side effects were registered during that time. Conclusion: One-year results of intravitreal ranibizumab for myopic choroidal neovascularization are very promising. Additional prospective studies are necessary to better determine long-term efficacy and safety.

Diabetes and corneal cell densities in humans by in vivo confocal microscopy.

Purpose: Diabetes is accompanied by an increased autofluorescence of the cornea, probably because of accumulation of advanced glycation end products (AGEs). The pathogenic mechanism is still unknown. This study aimed to quantify differences in corneal cell densities between diabetic patients and healthy controls. Methods: The left cornea of 15 patients with non-insulin-dependent diabetes mellitus (NIDDM) with level of retinopathy 20 according to the Early Treatment of Diabetic Retinopathy Study (ETDRS) and of 15 healthy controls were examined by noninvasive in vivo confocal microscopy in an observational prospective study. The cell densities in 6 corneal layers were determined along the optical axis of the cornea by using stereologic methods. Results: The average cell density per unit area in the superficial and basal epithelium and the endothelial layer was 725 ± 171, 5950 ± 653, and 2690 ± 302 cells/mm2 in controls and 815 ± 260, 5060 ± 301, and 2660 ± 364 cells/mm2 in diabetic patients. The cell density per unit volume in the anterior, mid-, and posterior stroma was 26,300 ± 4090, 19,390 ± 3120, and 25,700 ± 3260 cells/mm3 in controls and 27,560 ± 3880, 21,930 ± 2110, and 25,790 ± 3090 cells/mm3 in patients with diabetes. In both groups, the density in the midstroma was significantly lower than in both the anterior stroma and the posterior stroma (P < 0.02). The cell density in the basal layer of diabetic patients was significantly lower than in healthy controls (−15.0%, P < 0.0004). In the other layers, no significant differences between both groups (P > 0.07) were observed. Conclusions: The lower basal cell density found in patients with diabetes may result from a combination of different mechanisms including decreased innervation at the subbasal nerve plexus, basement membrane alterations, and higher turnover rate in basal epithelial cells. The lower cell density in the midstroma of diabetic patients and healthy controls may be attributed in part to differences in oxygen concentration in the stromal layers (depths). Changes in cellular density did not seem to be responsible for the increased autofluorescence in diabetes.

Femtosecond laser versus mechanical microkeratomes for flap creation in laser in situ keratomileusis and effect of postoperative measurement interval on estimated femtosecond flap thickness

PURPOSE: To prospectively compare laser in situ keratomileusis (LASIK) flaps created with a femtosecond laser or a mechanical microkeratome and analyze the effect of the postoperative measurement interval on estimated femtosecond flap thickness using ultrasound (US) pachymetry. SETTING: Department of Ophthalmology, University Hospital of Coimbra, and Coimbra Surgical Centre, Coimbra, Portugal. METHODS: Flaps were created with a Hansatome Zero Compression microkeratome (Group 1), Zyoptix XP keratome (Group 2), or IntraLase 60 kHz femtosecond laser (Groups 3 and 4). Flap thickness was determined by intraoperative US pachymetry immediately after flap creation in Groups 1, 2, and 3. In Group 4, pachymetry was performed 20 minutes after the laser treatment. The main outcome measures were flap thickness and deviation from the target value. RESULTS: Eighty patients had LASIK for myopia or myopic astigmatism. The mean flap thickness was 149.1 μm ± 24.9 (SD) in Group 1, 124.7 ± 23.8 μm in Group 2, 143.1 ± 18.4 μm in Group 3, and 115.5 ± 12.5 μm in Group 4. The difference in flap thickness between Group 3 and Group 4 was statistically significant (P<.01). The flap thickness deviation from the target value was 22.8 μm in Group 1, 19.0 μm in Group 2, 26.1 μm in Group 3, and 10.4 μm in Group 4. CONCLUSIONS: Results indicate that the time of measurement after femtosecond affects the estimated flap thickness. Waiting 20 minutes after laser treatment permitted easier separation and may eliminate the effect of variable corneal dehydration on flap measurement by subtraction pachymetry.

Outcome Analysis of Intracorneal Ring Segments for the Treatment of Keratoconus Based on Visual, Refractive, and Aberrometric Impairment

PURPOSE To analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of keratoconus based on preoperative visual impairment. DESIGN Multicenter, retrospective, nonrandomized study. METHODS A total of 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into 5 different groups: grade I, CDVA of 0.90 or better; grade II, CDVA equal to or better than 0.60 and worse than 0.90; grade III, CDVA equal to or better than 0.40 and worse than 0.60; grade IV, CDVA equal to or better than 0.20 and worse than 0.40; and grade plus, CDVA worse than 0.20. Success and failure indices were defined based on visual, refractive, corneal topographic, and aberrometric data and evaluated in each group 6 months after ICRS implantation. RESULTS Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (P < .05). CDVA significantly decreased in grade I (P < .01) but significantly increased in all other grades (P < .05). A total of 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, whereas 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (P < .01). Spherical equivalent and keratometry readings showed a significant reduction in all grades (P ≤ .02). Corneal higher-order aberrations did not change after the procedure (P ≥ .05). CONCLUSIONS Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notable loss of CDVA lines can be expected in patients with a milder form of keratoconus.

Photodynamic therapy for chronic central serous chorioretinopathy: a 4-year follow-up study.

Purpose: To evaluate the efficacy and safety of standard photodynamic therapy with verteporfin at 48 months in patients with chronic central serous chorioretinopathy. Methods: A retrospective, multicenter, interventional case series analysis in patients with chronic central serous chorioretinopathy, treated with standard photodynamic therapy, and with ≥4 years of follow-up. Evaluations were performed every 3 months in the first year, every 6 months in the second year, and thereafter annually. Optical coherence tomography was performed in all visits. Fluorescein angiography and indocyanine green angiography were performed at baseline and thereafter as necessary. Retinal thickness on optical coherence tomography was measured manually, evaluating central macular thickness and neural retina thickness. Main outcomes included the evolution of best-corrected visual acuity, the resolution of subretinal fluid, documented with optical coherence tomography, the number of treatments, and the evaluation of neural retina thickness during the 48 months of follow-up. Results: The study included 46 eyes of 42 patients, 38 men (90.4%) and 4 women (9.5%), with mean age of 49.19 ± 9.9 years (range, 32–70 years), and the minimal follow-up period was 48 months (mean, 56.8 ±10.3 months). Subretinal fluid was observed in all the included eyes at baseline, and 10 eyes (21.7%) had intraretinal diffuse or cystoid fluid. Concerning the mean best-corrected visual acuity, a statistically significant improvement (P < 0.01, Student t-test) was registered from 58.8 ± 18.3 letters at baseline to 66.9 ± 18.6 letters at 48th month. A complete resolution of subretinal fluid was achieved in 93.4%, and resolution of intraretinal fluid occurred in all 10 cases at 48 months. Neural retina thickness remained stable during the 48 months of follow-up (163.8 ± 47 &mgr;m at baseline and 163.8 ± 46 &mgr;m at 48 months). The mean number of treatments was 1.08 ± 0.3. No systemic or ocular side effects were registered. Conclusion: Standard photodynamic therapy with verteporfin was effective and safe in chronic central serous chorioretinopathy treatment with a significant improvement in the long term, both anatomic and visual, without inducing additional retinal atrophy or systemic adverse effects.

Comparison of visual function after bilateral implantation of inferior sector-shaped near-addition and diffractive–refractive multifocal IOLs

Purpose To compare visual function after bilateral implantation of multifocal Lentis Mplus LS‐312 (Group A) or Acrysof Restor SN6AD1 (Group B) intraocular lenses (IOLs). Setting Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra, and Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal. Design Comparative case series. Methods Patients between 49 years and 76 years had bilateral cataract surgery with multifocal IOL implantation. Patients were evaluated preoperatively and 3 months postoperatively for distance, intermediate, and near visual acuities; static photopic and mesopic contrast sensitivity; and visual acuity under a glare source using the Metrovision contrast sensitivity platform. Color vision was evaluated with the Cambridge Colour Test. Results Group A comprised 56 eyes and Group B, 44 eyes. Visual and refractive results were comparable between the 2 groups. Photopic contrast sensitivity was significantly better in Group B at intermediate (2.2 cycles per degree [cpd] and 3.4 cpd) and high (7.1 cpd and 23.6 cpd) spatial frequencies. Under low mesopic conditions (0.08 candelas/m2), differences were significant at 1.1 cpd and 2.2 cpd spatial frequencies. There were no differences in visual acuity under a glare source or in color vision. Conclusions Both IOLs provided good distance, intermediate, and near visual acuities. Visual acuity under a glare source and color vision were similar in the 2 groups. However, photopic and low mesopic contrast sensitivities were better in Group B, particularly for intermediate spatial frequencies, which are important for night driving. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Astigmatism after penetrating keratoplasty. Role of the suture technique.

The Authors retrospectively evaluated the evolution of corneal astigmatism 6, 12 and 24 months after penetrating keratoplasty in 75 eyes by comparing 2 suture techniques: running suture (RS) in 14 cases vs interrupted suture (IS) in 61 cases. The mean keratometric astigmatism in patients with RS was 7.75 ± 3.10 D at 6 months, 5.89 ± 2.50 D at 12 months and 3.90 ± 1.70 D at 24 months. In patients with IS these values were 4.82 ± 4.00 D at 6 months, 2.81 ± 1.60 D at 12 months and 2.77 ± 1.34 D at 24 months. A significant lower astigmatism (P < 0.05) was noted after using IS at 6 and 12 months. At 24 months, however, this difference was no longer statistically significant (P > 0.3). The IS suture allowed a better control ot the post-surgical astigmatism, and a more rapid recovery of the visual acuity.

Plasticity in the Human Visual Cortex: An Ophthalmology-Based Perspective

Neuroplasticity refers to the ability of the brain to reorganize the function and structure of its connections in response to changes in the environment. Adult human visual cortex shows several manifestations of plasticity, such as perceptual learning and adaptation, working under the top-down influence of attention. Plasticity results from the interplay of several mechanisms, including the GABAergic system, epigenetic factors, mitochondrial activity, and structural remodeling of synaptic connectivity. There is also a downside of plasticity, that is, maladaptive plasticity, in which there are behavioral losses resulting from plasticity changes in the human brain. Understanding plasticity mechanisms could have major implications in the diagnosis and treatment of ocular diseases, such as retinal disorders, cataract and refractive surgery, amblyopia, and in the evaluation of surgical materials and techniques. Furthermore, eliciting plasticity could open new perspectives in the development of strategies that trigger plasticity for better medical and surgical outcomes.

Clinical characterization of corneal ectasia after myopic laser in situ keratomileusis based on anterior corneal aberrations and internal astigmatism.

PURPOSE: To evaluate and characterize the clinical features of corneal ectasia after myopic laser in situ keratomileusis (LASIK) considering internal astigmatism and corneal aberrations and their correlation with other clinical data. SETTING: Vissum‐Instituto de Oftalmológico de Alicante, Alicante, Spain. DESIGN: Retrospective comparative case series. METHODS: In this multicenter study, eyes were divided into 2 groups. The study group comprised eyes that had corneal ectasia after myopic LASIK. The control group comprised eyes that had successful LASIK to correct high myopia. The clinical outcomes were analyzed and compared. Internal astigmatism was calculated using vectorial analysis. RESULTS: The study enrolled 91 eyes (48 study group; 40 control group) of 81 patients (age 18 to 67 years). Uncorrected and corrected (CDVA) distance visual acuities and the refractive status were significantly worse in the study group (P≤.01). Corneas in the study group had a significantly higher steepest keratometry (K) reading and a more negative central asphericity (P<.01). Internal astigmatism and corneal aberrations were also significantly higher in the study group (P<.01). The CDVA was significantly correlated with primary spherical aberration (r = −0.561, P=.01) and primary coma root mean square (r = 0.451, P=.04). Age was significantly correlated with mean K (r = −0.44, P=.01) and internal astigmatism (r = −0.34, P=.04). CONCLUSION: Larger levels of internal astigmatism and anterior corneal aberrations leading to a visual deterioration were present in eyes with corneal ectasia after myopic LASIK. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.