Conceição Lobo

Macular alterations after small-incision cataract surgery

Purpose: To characterize macular edema that occurs after uneventful cataract surgery. Setting: Centre of Ophthalmology, University Hospital, Institute of Biomedical Research on Light and Image, Faculty of Medicine, University of Coimbra, Coimbra, Portugal. Methods: Thirty‐two eyes of 32 patients had uneventful phacoemulsification with implantation of a foldable intraocular lens. Postoperatively, patients were examined at 3, 6, 12, and 30 weeks. The examinations included retinal leakage analysis (Zeiss CSLO), optical coherence tomography (Humphrey Instruments), and retinal thickness analysis (Talia Technology, Ltd.). Results were compared with those in a control group comprising healthy subjects. Results: Increases in retinal thickness (ie, over the mean ± 2 SD in the control group) reached a maximum at 6 weeks in 13 of 32 eyes (41%), after which recovery was progressive. At 30 weeks, all eyes had good visual acuity, but 7 eyes (22%) still had macular edema. The edema was located primarily in the central macular region. Leaking sites involving the vascular areas of the macula, which indicated areas of abnormal blood–retinal barrier permeability, were a frequent finding. The number of sites remained relatively stable during the first 12 weeks (88%) and decreased to 68% at 30 weeks, indicating a trend toward recovery. Conclusion: Macular edema after cataract surgery occurred primarily in the central region of the macula and was associated with the presence of leaking sites, which were located predominantly in the vascular regions of the central macula.

Digital ocular fundus imaging: a review

Ocular fundus imaging plays a key role in monitoring the health status of the human eye. Currently, a large number of imaging modalities allow the assessment and/or quantification of ocular changes from a healthy status. This review focuses on the main digital fundus imaging modality, color fundus photography, with a brief overview of complementary techniques, such as fluorescein angiography. While focusing on two-dimensional color fundus photography, the authors address the evolution from nondigital to digital imaging and its impact on diagnosis. They also compare several studies performed along the transitional path of this technology. Retinal image processing and analysis, automated disease detection and identification of the stage of diabetic retinopathy (DR) are addressed as well. The authors emphasize the problems of image segmentation, focusing on the major landmark structures of the ocular fundus: the vascular network, optic disk and the fovea. Several proposed approaches for the automatic detection of signs of disease onset and progression, such as microaneurysms, are surveyed. A thorough comparison is conducted among different studies with regard to the number of eyes/subjects, imaging modality, fundus camera used, field of view and image resolution to identify the large variation in characteristics from one study to another. Similarly, the main features of the proposed classifications and algorithms for the automatic detection of DR are compared, thereby addressing computer-aided diagnosis and computer-aided detection for use in screening programs.

Blood-retinal barrier

The blood-ocular barrier system is formed by 2 main barriers: the blood-aqueous barrier and the blood-retinal barrier (BRB). The BRB is particularly tight and restrictive and is a physiologic barrier that regulates ion, protein, and water flux into and out of the retina. The BRB consists of inner and outer components, the inner BRB being formed of tight junctions between retinal capillary endothelial cells and the outer BRB of tight junctions between retinal pigment epithelial cells. The BRB is essential to maintaining the eye as a privileged site and is essential for normal visual function. Methods of clinical evaluation of the BRB are reviewed and new directions using optical coherence tomography are presented. Alterations of the BRB play a crucial role in the development of retinal diseases. The 2 most frequent and relevant retinal diseases, diabetic retinopathy and age-related macular degeneration (AMD), are directly associated with alterations of the BRB. Diabetic retinopathy is initiated by an alteration of the inner BRB and neovascular AMD is a result of an alteration of the outer BRB. Macular edema is a direct result of alterations of the BRB.

Phenotypes and biomarkers of diabetic retinopathy.

Diabetic retinopathy (DR) remains a major cause of blindness as the prevalence of diabetes is expected to approximately double globally between 2000 and 2030. DR progresses over time at different rates in different individuals with only a limited number developing significant vision loss due to the two major vision-threatening complications, clinically significant macular edema and proliferative retinopathy. Good metabolic control is important to prevent and delay progression, but whereas some patients escape vision loss even with poor control, others develop vision loss despite good metabolic control. Our research group has been able to identify three different DR phenotypes characterized by different dominant retinal alterations and different risks of progression to vision-threatening complications. Microaneurysm turnover has been validated as a prognostic biomarker of development of clinically significant macular edema, whereas subclinical macular edema identified by OCT and mfERG appear to be also good candidates as organ-specific biomarkers of DR. Hemoglobin A1c remains the only confirmed systemic prognostic biomarker of DR progression. The availability of biomarkers of DR progression and the identification of different phenotypes of DR with different risks for development of vision-threatening complications offers new perspectives for understanding DR and for its personalized management.

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.

Pseudophakic cystoid macular edema.

Cataract surgery is an efficient procedure, and is generally associated with good visual results. Nevertheless, cystoid macular edema (CME) may develop, and this can result in suboptimal postoperative vision. Many factors are considered to contribute to its development, and although the treatment options depend upon the underlying cause of CME, the usual therapeutic approach for prophylaxis and treatment of CME is directed towards blocking the inflammatory mediators. This article provides a review of possible risk factors, pathogeneses, incidence rates, and methods of diagnosis, as well as the current guidelines for managing CME.

Multimodal macula mapping: a new approach to study diseases of the macula.

Multimodal macula mapping is presented as a combination of a variety of diagnostic tools and techniques to examine the macular region in order to obtain information on its structure and function in a clinical environment. Foundations of macular mapping are reviewed and discussed. New methodologies for multimodal macula mapping based on a combination of scanning laser angiography, retinal leakage analysis, retinal thickness analysis, and visual field testing are presented, demonstrating the potential of macula mapping. Other available detection devices are briefly reviewed considering their potential to be included and utilized in future developments of multimodal macula mapping. Multimodal macula mapping appears to offer unique perspectives and insights that are expected to contribute to improved diagnosis and better understanding of macular diseases.

Three different phenotypes of mild nonproliferative diabetic retinopathy with different risks for development of clinically significant macular edema.

PURPOSE To identify different phenotypes of nonproliferative diabetic retinopathy (NPDR) and their progression to clinically significant macular edema (CSME). METHODS A prospective observational study was designed to follow eyes/patients with diabetes type 2 and NPDR with no prior laser treatment for 2 years or until development of CSME. A total of 410 patients, one eye per patient, fulfilled the inclusion/exclusion criteria and were included in the study. Ophthalmological examinations, including BCVA, fundus photography with Retmarker analysis, and optical coherence tomography (OCT), were performed at baseline, month 6 and month 24, or before laser treatment. Hierarchical cluster analysis was used to identify homogeneous subgroups and clinically significant thresholds of the data collected. RESULTS A total of 376 eyes/patients performed the 6-month visit and were considered for cluster analysis. This mathematical method identified three different phenotypes based on statistically significant differences for the microaneurysm (MA) turnover and for the central retinal thickness (RT): phenotype A (low MA turnover and normal RT, 48.1%); phenotype B (low MA turnover and increased central RT, 23.2%); and phenotype C (high MA turnover, 28.7%). From the 348 eyes/patients that reached the study end point or completed the 24-month visit, 26 developed CSME: 3 from phenotype A (1.8%), 7 from phenotype B (8.5%), and 16 from phenotype C (16.2%). Eyes/patients from phenotype C showed a higher risk for CSME development (OR = 3.536; P < 0.001). CONCLUSIONS Hierarchical cluster analysis identifies three different phenotypes of NPDR based on MA turnover and central macular thickness. Eyes/patients from phenotype C show a higher risk for the development of CSME. (ClinicalTrials.gov number, NCT00763802.)

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.

Alterations of retinal capillary blood flow in preclinical retinopathy in subjects with type 2 diabetes.

Abstract Background. To identify alterations of retinal capillary blood flow in the papillomacular area in preclinical diabetic retinopathy using the Heidelberg scanning laser Doppler flowmeter. Methods.Ten eyes from ten patients with type 2 diabetes and no lesions visible on fundus photography (level 10 of Wisconsin grading) and ten eyes from ten healthy subjects of similar age range were examined with the HRF. Intravisit reproducibility of retinal capillary blood flow measurements was assessed in normal subjects and in type 2 diabetic patients, comparing different measurement areas and different analysis procedures: (a) 10×10 pixel box with original software, (b) 10×10 pixel box with SLDF software, and (c) whole-scan analysis with SLDF software (automatic full-field perfusion image analysis). Results.Intravisit reproducibility for the whole-scan analysis in the papillomacular area was 3.52%, 4.81% and 4.60% for volume (VOL), flow (FLW) and velocity (VEL) respectively. Using this method, mean and SD values for retinal capillary blood-flow are 13.25±2.87, 214.58±55.30 and 0.74±0.17, for VOL, FLW and VEL for healthy eyes, comparing with 19.85±6.22, 360.87±158.70 and 1.20±0.48 in eyes with preclinical diabetic retinopathy (P<0.010, P<0.019 and P<0.015 respectively). Conclusions.The HRF shows acceptable reproducibility when using whole-scan analysis in the papillomacular area. Retinal capillary blood VOL, FLW and VEL were particularly increased in five of the ten diabetic eyes examined, with values over the mean + 2SD of the control population, suggesting that eyes showing increased retinal capillary blood flow may indicate risk of progression.