Clinical Evaluation of a New Spectral-Domain Optical Coherence Tomography-Based Biometer.

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

Surgical Approaches to Optic Disc Pit Maculopathy: A Clinical Case Series.

The purpose of this study was to compare the clinical outcomes of 13 patients with optic disc pit maculopathy (ODP-M) - progressive visual loss, serous macular detachment, and/or intraretinal fluid - who underwent different surgical approaches. This was a retrospective study including a consecutive sample of 13 patients aged 13-74 years (mean 35.38 ± 19.66 years) diagnosed with ODP-M and submitted to vitreoretinal surgery between 2005 and 2021. All patients underwent pars plana vitrectomy, posterior hyaloid detachment, and gas tamponade. Endolaser photocoagulation was applied to the temporal margin of the optic disc in 8 cases; internal limiting membrane (ILM) peeling was performed in 9 cases; and ILM inverted flap technique in 5 cases. Stuffing of the pit with an ILM flap was performed in 3 cases. Mean best-corrected visual acuity improved from 20/200 (1.04 ± 0.56 LogMAR) to 20/50 (0.43 ± 0.54 LogMAR) within 4-36 months. Central retinal thickness decreased from 587.5 ± 158.01 µm to 253.9 ± 33.55 µm, and 7 out of 10 patients had complete resolution of intraretinal fluid. All patients had complete retinal reattachment; however, a few years after surgery, 4 patients had recurrence of serous retinal detachment. The only adjunctive technique associated with greater visual improvement was endolaser (p = 0.033) and not performing peeling of the ILM was also associated with better visual results (p = 0.013), independently of preoperative visual acuity or age at the time of surgery. None of the adjunctive procedures was a significant predictor of better anatomical outcomes. In conclusion, all of these approaches for the surgical management of ODP-M were safe and effective. In this study, vitrectomy with endolaser was a good option for management of ODP-M.

Characterization of the Portuguese population diagnosed with retinoblastoma.

The purpose of this study is to characterize demographically and genetically the Portuguese population with retinoblastoma; to report the clinical stage at presentation and its impact on survival and ocular preservation rate and, finally, to assess the incidence of retinoblastoma in Portugal. Retrospective observational study including children consecutively diagnosed with retinoblastoma at the Portuguese National Referral Center of Intraocular Tumors, between October 2015 and October 2020. Twenty-eight children were diagnosed with retinoblastoma at our center, 15 hereditary from which 12 presented with bilateral retinoblastoma and 3 were unilateral. The overall mean age at diagnosis was 13.6 ± 11.1 months with hereditary retinoblastomas diagnosed slightly earlier at 9.6 ± 6.3 months. A familial history of retinoblastoma was found in only 4 (14.3%) of the cases. A pathogenic mutation in the RB1 gene was found in 13 (46.4%) of the children. The most frequent sign at referral was leukocoria in 71.4% of patients. Considering the ICRB classification of the tumors, 84.6% of non-hereditable hereditary retinoblastomas were referred to our center in advanced stages. In the group of hereditable retinoblastomas 86.7% presented with one of the eyes with advanced intraocular retinoblastoma. Fourteen children had one eye enucleated due to retinoblastoma. No deaths were registered during the study period. Considering the incidence analysis, we registered a year-of-birth controlled incidence analysis of 4.04 per 100.000 living births (IC 95% 1.59-6.49). This is the first characterization of the Portuguese Population diagnosed with Retinoblastoma in the National Reference Center.

Urinary Mass Spectrometry Profiles in Age-Related Macular Degeneration.

We and others have shown that patients with different severity stages of age-related macular degeneration (AMD) have distinct plasma metabolomic profiles compared to controls. Urine is a biofluid that can be obtained non-invasively and, in other fields, urine metabolomics has been proposed as a feasible alternative to plasma biomarkers. However, no studies have applied urinary mass spectrometry (MS) metabolomics to AMD. This study aimed to assess urinary metabolomic profiles of patients with different stages of AMD and a control group. We included two prospectively designed, multicenter, cross-sectional study cohorts: Boston, US (n = 185) and Coimbra, Portugal (n = 299). We collected fasting urine samples, which were used for metabolomic profiling (Ultrahigh Performance Liquid chromatography-Mass Spectrometry). Multivariable logistic and ordinal logistic regression models were used for analysis, accounting for gender, age, body mass index and use of AREDS supplementation. Results from both cohorts were then meta-analyzed. No significant differences in urine metabolites were seen when comparing patients with AMD and controls. When disease severity was considered as an outcome, six urinary metabolites differed significantly (p < 0.01). In particular, two of the metabolites identified have been previously shown by our group to also differ in the plasma of patients of AMD compared to controls and across severity stages. While there are fewer urinary metabolites associated with AMD than plasma metabolites, this study identified some differences across stages of disease that support previous work performed with plasma, thus highlighting the potential of these metabolites as future biomarkers for AMD.

A Comparison of Intraocular Lens Power Calculation Formulas in High Myopia.

PURPOSE: To comparatively evaluate the accuracy of newer intraocular lens (IOL) calculation formulas and common third-generation formulas after Wang-Koch adjustment in the prediction of postoperative refraction in highly myopic eyes. METHODS: This was a retrospective study including eyes with high myopia that had uncomplicated cataract surgery with implantation of an AcrySof MA60MA IOL (power range: -5.00 to +5.00 diopters [D]) (Alcon Laboratories, Inc). All patients underwent optical biometry (Carl Zeiss IOLMaster 500 and IOLMaster 700, and Allegro Biograph) and the postoperative spherical equivalent for the implanted IOL was estimated using SRK/T, Holladay 1 (both Wang-Koch adjusted), Haigis, Barrett Universal II, Kane, Ladas, and Hill-RBF v2.0 formulas. Outcomes included the median absolute prediction error (MedAE) and the proportion of eyes within ±0.25, ±0.50, and ±1.00 D of the preoperative prediction. RESULTS: Eighty-two eyes with a mean axial length of 30.89 ± 1.85 mm were included. The MedAE in ascending order was Hill-RBF v2.0 0.31 D, Kane 0.33 D, Barrett 0.36 D, Holladay Iwk 0.37 D, SRK/Twk 0.37 D, Holladay Iwk 0.43 D, HaigisULIB 0.54 D, and Ladas 0.61 D. The formula with the lowest MedAE (Hill-RBF v2.0) yielded a prediction error within ±0.25, ±0.50, and ±1.00 D in 43.1%, 70.6%, and 94.1% of cases, respectively. CONCLUSIONS: Recent formulas such as Barrett Universal II, Kane, and Hill-RBF v2.0 and Wang-Koch adjusted formulas perform well in this subset of patients with high myopia. The Hill-RBF v2.0 formula had the lowest MedAE and highest proportion of eyes within ±0.25, ±0.50, and ±1.00 D of the predicted target. [J Refract Surg. 2021;37(3):207-211.].

Treatment of Advanced Retinoblastoma in Children Evacuated from Low-Income Countries: Experience from a National Referral Center in Portugal.

OBJECTIVE: The aim of our study was to characterize the evacuated African patients diagnosed with retinoblastoma and referred to the Portuguese national referral center (Centro Hospital e Universitário de Coimbra, University of Coimbra), identifying inequalities in the stage of diagnosis and prognostic results. DESIGN: Retrospective observational study of evacuated African patients diagnosed with retinoblastoma and referred to the Portuguese National Referral Center (Centro Hospital e Universitário de Coimbra, University of Coimbra). RESULTS: The study included 15 patients between October 2015 and October 2020 from Angola, Cape Verde, Guinea-Bissau and São Tomé and Príncipe. Seven (46.7%) children presented bilateral retinoblastoma. The median age at the time of diagnosis was 20.9 (interquartile range, 16-41) months. The presenting symptoms were leukocoria (86.7%), strabism (53.3%) and buphthalmus (40%). In terms of tumor staging, five (33.3%) children presented with extraocular retinoblastoma and 10 (66.7%) children presented with intraocular retinoblastoma. At presentation, no pineal involvement was diagnosed but two (13.3%) children presented with central nervous system involvement at the time of the first observation. Children were treated with enucleation, exenteration, systemic chemotherapy, intra-arterial chemotherapy and/or supportive palliative care. During the follow-up period (mean 27.2 ± 18.2 months), the overall survival was 73.3%. CONCLUSION: A small proportion of African children are being referred to our center, when considering the expected incidence of retinoblastoma in these countries, and referred children arrive at advanced stages of the disease, compromising treatment outcomes. Considering retinoblastoma is now a curable disease, national and international interventions are required to attempt a better management of children born in low-income countries.

T and genetic variations between Asian and Caucasian polypoidal choroidal vasculopathy.

PURPOSE: To compare phenotypic and genetic variations in polypoidal choroidal vasculopathy (PCV) between Caucasian and Asian patients. METHODS: We analysed phenotypic and genotypic data from two sites, Association for Innovation and Biomedical Research on Light and Image, Portugal and Singapore National Eye Centre, Singapore. Baseline fundus photography, spectral domain-optical coherence tomography, indocyanine green and fluorescein angiography scans were analysed by respective reading centres using a standardised grading protocol. Single nucleotide polymorphisms across 8 PCV loci were compared between cases and controls selected from each population. RESULTS: One hundred and forty treatment-naïve PCV participants (35 Portuguese and 105 Singaporean) were included. The Portuguese cohort were older (72.33±8.44 vs 68.71±9.40 years, p=0.043) and were comprised of a lower proportion of males (43% vs 71%, p=0.005) compared with the Singaporean cohort. Differences in imaging features include higher prevalence of soft drusen (66% vs 30%, p=0.004), lower prevalence of subretinal haemorrhage (14% vs 67%, p<0.001), smaller polypoidal lesion (PL) area (0.09±0.09 vs 0.76±0.93 mm2, p<0.001), lower ratio of PL to branching vascular network area (3% vs 38%, p<0.001) and lower central retinal thickness (346.48±93.74 vs 493.16±212.92 µm, p<0.001) in the Portuguese cohort. CETP rs3764261 (OR 2.467; 95% CI 1.282 to 4.745, p=0.006) in the Portuguese population was significantly associated with PCV and CFH rs800292 (OR 1.719; 95% CI 1.139 to 2.596, p=0.010) in the Singaporean population, respectively. CONCLUSION: Among Asian and Caucasian patients with PCV, there are significant differences in the expression of phenotype. We also identified different polymorphisms associated with PCV in the two populations.

Design, development and deployment of a web-based interoperable registry for inherited retinal dystrophies in Portugal: the IRD-PT.

BACKGROUND: The development of multicenter patient registries promotes the generation of scientific knowledge by using real-world data. A country-wide, web-based registry for inherited retinal dystrophies (IRDs) empowers patients and community organizations, while supporting formal partnerships research. We aim to describe the design, development and deployment of a country-wide, with investigators and stakeholders in the global aim to develop high-value, high-utility web-based, user-friendly and interoperable registry for IRDs-the IRD-PT. RESULTS: The IRD-PT is a clinical/genetic research registry included in the retina.pt platform ( https://www.retina.com.pt ), which was developed by the Portuguese Retina Study Group. The retina.pt platform collects data on individuals diagnosed with retinal diseases, from several sites across Portugal, with over 1800 participants and over 30,000 consultations to date. The IRD-PT module interacts with the retina.pt core system which provides a range of basic functions for patient data management, while the IRD-PT module allows data capture for the specific purpose of IRDs. All IRDs are coded accordingly to the International Statistical Classification of Diseases and Related Health Problems (ICD) 9, ICD 10, ICD 11, and Orphanet Rare Disease Ontology (ORPHA codes) to make the IRD-PT interoperable with other IRD registries across the world. Furthermore, the genes are coded according to the Ontology of Genes and Genomes and Online Mendelian Inheritance in Man, whereas signs and symptoms are coded according to the Human Phenotype Ontology. The IRD-PT module pre-launched at Centro Hospitalar e Universitário de Coimbra, the largest reference center for IRDs in Portugal. As of April 1st 2020, finalized data from 537 participants were available for this preliminary analysis. CONCLUSIONS: In the specific field of rare diseases, the use of registries increases research accessibility for individuals, while providing clinicians/investigators with a coherent data ecosystem necessary to boost research. Appropriate design and implementation of patient registries enables rapid decision making and ongoing data mining, ultimately leading to improved patient outcomes. We have described here the principles behind the design, development and deployment of a web-based, user-friendly and interoperable software tool aimed to generate important knowledge and collecting high-quality data on the epidemiology, genomic landscape and natural history of IRDs in Portugal.

Urine Nuclear Magnetic Resonance (NMR) Metabolomics in Age-Related Macular Degeneration.

Biofluid biomarkers of age-related macular degeneration (AMD) are still lacking, and their identification is challenging. Metabolomics is well-suited to address this need, and urine is a valuable accessible biofluid. This study aimed to characterize the urinary metabolomic signatures of patients with different stages of AMD and a control group (>50 years). It was a prospective, cross-sectional study, where subjects from two cohorts were included: 305 from Coimbra, Portugal (AMD patients n = 252; controls n = 53) and 194 from Boston, United States (AMD patients n = 147; controls n = 47). For all participants, we obtained color fundus photographs (for AMD staging) and fasting urine samples, which were analyzed using 1H nuclear magnetic resonance (NMR) spectroscopy. Our results revealed that in both cohorts, urinary metabolomic profiles differed mostly between controls and late AMD patients, but important differences were also found between controls and subjects with early AMD. Analysis of the metabolites responsible for these separations revealed that, even though distinct features were observed for each cohort, AMD was in general associated with depletion of excreted citrate and selected amino acids at some stage of the disease, suggesting enhanced energy requirements. In conclusion, NMR metabolomics enabled the identification of urinary signals of AMD and its severity stages, which might represent potential metabolomic biomarkers of the disease.

Neurotrophic Keratopathy: Therapeutic Approach Using a Novel Matrix Regenerating Agent.

PURPOSE: To evaluate the efficacy and tolerance of a new matrix-regenerating agent (RGTA), Cacicol®, a polymer that mimics heparan sulfates bound to extracellular matrix proteins, avoiding its proteolysis, to treat neurotrophic keratopathy (NK). METHODS: Uncontrolled prospective clinical study performed between January 2014 and May 2016. Twenty-five patients (25 eyes) with corneal neurotrophic ulcers, nonresponsive to at least 2 weeks of conservative therapy, were treated with Cacicol, instilled once/twice a week. During follow-up, slit-lamp examination, anterior segment photography, fluorescein-dye testing, and best-corrected visual acuity were analyzed. Ulcer evolution was evaluated using image analysis software (ImageJ®) and healing defined as decrease of the corneal ulcer area. An independent observer measured ulcer area. RESULTS: All patients had complete corneal healing within an average of 4.13 ± 2.32 weeks. Mean ulcer area decreased significantly (P = 0.001) from 16.51% ± 18.56% (1st day) to 8.68% ± 11.25% at the 7th day and to 4.73% ± 10.75% at the 14th day. Compared with day 1, mean ulcer area decreased 60.24% after 7 days (P = 0.001), 54.92% after 14 days (P = 0.059), and 83.00% after 21 days (P = 0.003). Two cases of recurrence (8.0%) were registered. No systemic or local side effects were noticed. CONCLUSIONS: The new regenerating agent, Cacicol, represents an effective and safe therapy to treat NK.

Phakic Intraocular Lens Implantation: Refractive Outcome and Safety in Patients with Anterior Chamber Depth between 2.8 and 3.0 versus ≥3.0 mm.

PURPOSE: To compare endothelial cell (EC) variation after anterior chamber phakic intraocular lens (AC-pIOL) implantation in highly myopic patients with a preoperative anterior chamber depth (ACD) between 2.8 and 3.0 versus ≥3.0 mm. METHODS: A total of 280 eyes submitted to primary AC-pIOL implantation were analyzed. Pre- and postoperative values for uncorrected distance visual acuity, corrected distance visual acuity, spherical equivalent, ACD (endothelial surface), and EC count were collected. The eyes were divided into 2 groups: group A - ACD between 2.8 and 3.0 mm; group B - ACD ≥3.0 mm. Mean global EC loss (ECL) and loss for each ACD group, according to pIOL type, were analyzed. RESULTS: Significant improvement of the spherical equivalent (-11.38 ± 4.57 vs. -0.49 ± 0.79; p = 0.000) and a significant decrease in EC density (2,810.95 ± 343.88 vs. 2,584.09 ± 374.88 cells/mm2; p = 0.000) were noted. The mean annual ECL was -2.19 ± 3.97%. Regarding group A (n = 80), a mean annual ECL of -2.06 ± 3.88% was registered, higher for the Acrysof Cachet® subtype, while group B (n = 200) showed -2.25 ± 4.01% ECL, higher for the Verisyse® subtype. There was no significant difference between the groups (p = 0.96). CONCLUSIONS: AC-pIOL implantation significantly improves the spherical equivalent in myopic patients. The mean annual ECL after pIOL implantation was higher in the larger ACD group, but this value was not statistically significant. A 2.8-mm ACD value seems to be a safe cutoff for AC-pIOL implantation.

Development of the Portuguese version of a standardized reading test: the Radner-Coimbra Charts.

PURPOSE: To develop 27 short sentence optotypes for the Portuguese version of the Radner Reading Charts. METHODS: Thirty-four Portuguese sentences were constructed following the concept of the Radner Reading Charts to obtain highly comparable sentences in terms of lexical difficulty, syntactical complexity, word length, number of syllables, and position of words. A long text (106 words) at the 5th grade reading level was also tested to assess the validity of the reading speeds obtained with the short sentences. The short sentences and long text were tested in 50 volunteers with similar educational backgrounds (mean age 30.98 years ± 6.99 years, range 19-47 years). Reading speeds were measured with a stop-watch and reported as words per minute (wpm). The reading time for each of the short sentences to be selected for the chart was defined as falling within the range of the mean ± 0.40 × standard deviation (SD). RESULTS: The overall mean reading speed for each of the short sentences was 235.43 ± 36.39 wpm. The 27 sentences with a mean between 220.8 and 250.0 wpm (overall mean ± 0.40 × SD) were selected for construction of the reading charts. The mean reading speed for the long text was 212.42 ± 26.20 wpm. Correlation between the selected short sentences and long text was high (r =0.86). Reliability analysis yielded an overall Cronbach's alpha coefficient of 0.97. CONCLUSIONS: The 27 short Portuguese sentences were highly comparable in terms of syntactical structure, number, position and length of words, lexical difficulty, and reading length. This reading test can overcome the limitations of the current tests for homogeneity and comparability, reducing subjectivity in the evaluation of the functional outcomes of medical and surgical ophthalmologic treatments.

Development of the Portuguese version of a standardized reading test: the Radner-Coimbra Charts / Desenvolvimento da versão portuguesa do teste padronizado de leitura: tabelas Radner-Coimbra

ABSTRACT Purpose: To develop 27 short sentence optotypes for the Portuguese version of the Radner Reading Charts. Methods: Thirty-four Portuguese sentences were constructed following the concept of the Radner Reading Charts to obtain highly comparable sentences in terms of lexical difficulty, syntactical complexity, word length, number of syllables, and position of words. A long text (106 words) at the 5th grade reading level was also tested to assess the validity of the reading speeds obtained with the short sentences. The short sentences and long text were tested in 50 volunteers with similar educational backgrounds (mean age 30.98 years ± 6.99 years, range 19-47 years). Reading speeds were measured with a stop-watch and reported as words per minute (wpm). The reading time for each of the short sentences to be selected for the chart was defined as falling within the range of the mean ± 0.40 × standard deviation (SD). Results: The overall mean reading speed for each of the short sentences was 235.43 ± 36.39 wpm. The 27 sentences with a mean between 220.8 and 250.0 wpm (overall mean ± 0.40 × SD) were selected for construction of the reading charts. The mean reading speed for the long text was 212.42 ± 26.20 wpm. Correlation between the selected short sentences and long text was high (r =0.86). Reliability analysis yielded an overall Cronbach's alpha coefficient of 0.97. Conclusions: The 27 short Portuguese sentences were highly comparable in terms of syntactical structure, number, position and length of words, lexical difficulty, and reading length. This reading test can overcome the limitations of the current tests for homogeneity and comparability, reducing subjectivity in the evaluation of the functional outcomes of medical and surgical ophthalmologic treatments.

RESUMO Objetivo: Desenvolver 27 frases-optotipo para a versão em português das tabelas de leitura de Radner. Métodos: Trinta e quatro frases em português foram elaboradas de acordo com o conceito das tabelas de leitura de Radner, de forma a obter frases-optotipo, altamente comparáveis em termos dificuldade lexical, complexidade sintática, tamanho das palavras, número de sílabas e posição das palavras. Foi também avaliado um texto longo (106 palavras) ao nível do 5o ano de escolaridade para determinar a validade dos resultados obtidos com as frases curtas. As frases curtas e o texto longo foram testados em 50 voluntários de nível acadêmico semelhante e média de idades de 30,98 anos ± 6,99 (intervalo de 19-47 anos). A velociade de leitura foi medida com cronômetro, de forma a obter o número de palavras por minuto (wpm). O intervalo válido para tempo de leitura das frases curtas foi definido como a média ± 0,40 x desvio padrão (SD). As frases mais semellhantes foram estatisticamente selecionadas para a construção das tabelas de leitura Radner-Coimbra. Resultados: A velocidade média de leitura obtida com as frases curtas foi 235,43 ± 36,39 wpm. As frases com velocidade média entre 220,8 e 250,0 palavras por minuto (média ± 0,40 x SD) foram selecionadas. Vinte e sete frases cumpriram este critério. A velocidade média de leitura do texto longo foi 212,42 ± 26,20 wpm. A correlação entre as frases curtas selecionadas e o texto longo foi alta (r=0,86). A análise de fiabilidade originou um coeficiente alfa de Cronbach de 0,97. Conclusões: As 27 frases em português são altamente semelhantes em termos de estrutura sintática, número, posição e comprimento das palavras, dificuldade lexical e duração da leitura. Este teste permite ultrapassar as limitações dos testes existentes em termos de homogeneidade e comparabilidade, reduzindo a subjetividade na avaliação dos resultados de terapêuticas médicas e cirúrgicas.

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/m(2)), 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.

Femtosecond laser and microkeratome-assisted Descemet stripping endothelial keratoplasty: first clinical results.

AIM: To perform Descemet stripping automated endothelial keratoplasty (DSAEK) using a novel technique to obtain very thin (<100 µm) posterior corneal disks. METHODS: Twenty five DSAEK grafts were prepared with two sequential cuts: the first cut, of variable thickness, was made with a femtosecond laser and the second with a 300 µm microkeratome head. Spectacle corrected visual acuity, endothelial cell density evaluation with specular microscopy and anterior segment optical coherence tomography to measure central and peripheral graft thickness was performed preoperatively and postoperatively at 1, 3 and 6 months. RESULTS: There were no irregular cuts or perforations during tissue preparation. Central graft thickness was 79.6 µm (SD ± 14.5; range 54-98) and 69.3 µm (SD ± 14.2; range 49-96) at 3 and 6 months. Corrected distance visual acuity improved from 0.91 logMAR preoperatively to 0.11 logMAR at 6 months. Donor endothelial cells averaged 2675 cells/mm(2) preoperatively and 1729 cells/mm(2) at 6 months. There were no graft detachments. CONCLUSIONS: This new technique consistently yielded very thin grafts (<100 µm), excellent visual acuity results and good endothelial cell counts. No donor tissue was wasted.

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/mm in controls and 815 +/- 260, 5060 +/- 301, and 2660 +/- 364 cells/mm 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/mm in controls and 27,560 +/- 3880, 21,930 +/- 2110, and 25,790 +/- 3090 cells/mm 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.