Ala®sil chemical characterization and toxicity evaluation: an example of the need for the Medical Device Regulation 2017/745

Introduction: Ala®sil infusion was on the market for clinical use under the Medical Devices Directive (MDD) 93/42/EEC as an irrigating solution based on polydimethylsiloxane (PDMS). The product was withdrawn in 2016, and to the best of our knowledge, it did not cause any health damage. Methods: A bibliographic review and experimental analysis were conducted to evaluate whether this CE-marked product could have been used in patients under the current Medical Device Regulation (MDR) 2017/745. Analytical results from gas chromatography-mass spectrometry (GC-MS) and matrixassisted laser desorption ionization (MALDI) were performed. Citotoxicity studies were also carried out. Results: Only one study related to Ala®sil clinical use was found, describing a pilot series of five patients. The authors rated the product as not helpful in three out of the five cases for internal searching of retinal breaks and in four out of the five cases for drainage of subretinal fluid. No other scientific papers or documentation was found regarding Ala®sil's safety. Nevertheless, the product was introduced in the market after achieving the CE marking. GC-MS and MALDI showed that the polymer has a low molecular weight of 1,000 g/mol. Several linear and cyclic low-molecular-weight components (LMWCs) were identified as impurities ranging from L3 to D8, with a molecular weight below 600 g/mol. The Ala®sil sample was found to be cytotoxic after 24 h of cell culture but non-cytotoxic after 72 h, probably due to the cellular regeneration capacity of an immortalized cell line. Tissular cytotoxicity revealed an increased apoptosis rate but without morphological modifications. Discussion: Although Ala®sil cannot be classified as cytotoxic, this substance appears to increase retinal cell death processes. This study supports the notion that the MDDwas not functioning adequately to ensure the safety of medical devices. However, the current MDR 2017/745 imposes stricter standards to prevent the commercialization of medical devices without high-quality preclinical and clinical information, as well as precise clinical verification for their use, information not available for Ala®sil infusion.

Reporting serious incidents in medical devices used in intraocular surgery: Proposing ideas

The entry into force of the regulation on medical devices obliges clinicians to identify and report to the Health Authorities possible serious incidents arising from their use. In view of the doubts that may arise as to whether or not it may be considered a serious incident, a working group, set up by members of the Spanish Society of Retina and Vitreo and the cluster of ophthalmology and vision sciences (Cluster4Eye) have prepared a document that aims to guide ophthalmologists about some of the incidents that, in the experience of the work team, are not common or can cause serious damage to the patient's function.

Oncological monitoring after transanal total mesorectal excision (TaTME) for rectal neoplasia

BACKGROUND

The surgical treatment of choice for rectal neoplasia is total mesorectal excision (TME). The transanal approach enables a better approach in male and obese patients and/or those with a narrow pelvis and in patients with small tumors. Short-term results are comparable with those for laparoscopy or the open approach, but the medium- and long-term oncological data are sparse. The aim of the present study was to evaluate our early experience with transanal TME (TaTME).

METHODS

This was a retrospective study conducted on patients who underwent TaTME at our center between August 2013 and April 2017 with a follow-up ≥ 3 years. Histopathology, complications, mortality, neoplastic recurrence and disease-free survival were analyzed.

RESULTS

One hundred patients (68 men and 32 women,, median age 66.8 years [range 29.6-91.2 years]) were included. There were 67 T3 cases (67%) with 74 N0 cases (74%), the mesorectal quality was graded optimal for 87.6% and only 2 cases of radial margin involvement were detected (2%). The median follow-up period was 47.6 months (range 11.8-78.9 months). Eighteen cases of recurrence were diagnosed, of which 3 (3%) recurred locally with an average disease-free period of 43.1 months. Overall survival was 80% and mortality due to progression of disease was 13%.

CONCLUSIONS

TaTME is a safe surgical procedure with surgical, anatomopathological and oncological results at 3 years (medium-term) comparable with those for the laparoscopic and open approaches. Better monitoring is required with studies of the long-term functional and quality of life outcomes, i.e., at 5 or 10 years.

INTRAOCULAR EMULSION OF SILICONE OIL (ITEMS) GRADING SYSTEM: An Evidence-Based Expert-Led Consensus

PURPOSE

To propose the InTraocular EMulsion of Silicone oil (ITEMS) grading system for the assessment of silicone oil (SiO) emulsion, applicable in a routine clinical setting and validated through an expert-led consensus procedure.

METHODS

Seven experts on intraocular liquid tamponades, led by a facilitator, performed a literature review on the detection of SiO emulsion. Based on the proposed ideas, a questionnaire was developed and submitted to the experts on the methods to detect SiO emulsion and the items to grade. After 2 rounds of individual ranking using a 9-point scale and related discussion, the final grading system was developed including items that reached consensus (score ≥7 from ≥75% of members).

RESULTS

The agreed ITEMS grading system includes the identification of SiO microbubbles and large SiO bubbles through slit-lamp biomicroscopy, gonioscopy, fundus examination under mydriasis, or ultra-wide-field fundus photography. Moreover, macular and disk optical coherence tomography are used to detect SiO-associated hyperreflective dots.

CONCLUSION

An evidence-based expert-led consensus was conducted to develop grading system of SiO emulsion, allowing, for the first time, homogenous collection of data on SiO emulsion. This has the potential to improve the understanding of the role and clinical relevance of SiO emulsion, allowing comparisons between different studies.

Quantification of Microvascular Lesions in the Central Retinal Field: Could It Predict the Severity of Diabetic Retinopathy?

Diabetic retinopathy (DR) is a neurodegenerative disease characterized by the presence of microcirculatory lesions. Among them, microaneurysms (MAs) are the first observable hallmark of early ophthalmological changes. The present work aims to study whether the quantification of MAs, hemorrhages (Hmas) and hard exudates (HEs) in the central retinal field could have a predictive value on DR severity. These retinal lesions were quantified in a single field NM-1 of 160 retinographies of diabetic patients from the IOBA's reading center. Samples included different disease severity levels and excluded proliferating forms: no DR (n = 30), mild non-proliferative (n = 30), moderate (n = 50) and severe (n = 50). Quantification of MAs, Hmas, and HEs revealed an increasing trend as DR severity progresses. Differences between severity levels were statistically significant, suggesting that the analysis of the central field provides valuable information on severity level and could be used as a clinical tool to assess DR grading in the eyecare routine. Even though further validation is needed, counting microvascular lesions in a single retinal field can be proposed as a rapid screening system to classify DR patients with different stages of severity according to the international classification.

Mercury intoxication and ophthalmic involvement: An update review

Human intoxication after mercury exposure is a rare condition that can cause severe damage to the central nervous, respiratory, cardiovascular, renal, gastrointestinal, skin, and visual systems and represents a major public health concern. Ophthalmic involvement includes impaired function of the extraocular muscles and the eyelids, as well as structural changes in the ocular surface, lens, retina, and optic nerve causing a potential irreversible damage to the visual system. Although, there are many pathways for poisoning depending on the mercury form, it has been suggested that tissue distribution does not differ in experimental animals when administered as mercury vapor, organic mercury, or inorganic mercury. Additionally, visual function alterations regarding central visual acuity, color discrimination, contrast sensitivity, visual field and electroretinogram responses have also been described widely. Nevertheless, there is still controversy about whether visual manifestations occur secondary to brain damage or as a direct affectation, and which ocular structure is primarily affected. Despite the use of some imaging techniques such as in vivo confocal microscopy of the cornea, optical coherence tomography (OCT) of the retina and optic nerve, and functional tests such as electroretinography has helped to solve in part this debate, further studies incorporating other imaging modalities such as autofluorescence, OCT angiography or adaptive optics retinal imaging are needed. This review aims to summarize the published structural and functional alterations found in the visual system of patients suffering from mercury intoxication.

Rho-Kinase Inhibitors for the Treatment of Refractory Diabetic Macular Oedema

Diabetic macular oedema (DMO) is one of the leading causes of vision loss associated with diabetic retinopathy (DR). New insights in managing this condition have changed the paradigm in its treatment, with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) having become the standard therapy for DMO worldwide. However, there is no single standard therapy for all patients DMO refractory to anti-VEGF treatment; thus, further investigation is still needed. The key obstacles in developing suitable therapeutics for refractory DMO lie in its complex pathophysiology; therefore, there is an opportunity for further improvements in the progress and applications of new drugs. Previous studies have indicated that Rho-associated kinase (Rho-kinase/ROCK) is an essential molecule in the pathogenesis of DMO. This is why the Rho/ROCK signalling pathway has been proposed as a possible target for new treatments. The present review focuses on the recent progress on the possible role of ROCK and its therapeutic potential in DMO. A systematic literature search was performed, covering the years 1991 to 2021, using the following keywords: "rho-Associated Kinas-es", "Diabetic Retinopathy", "Macular Edema", "Ripasudil", "Fasudil" and "Netarsudil". Better insight into the pathological role of Rho-kinase/ROCK may lead to the development of new strategies for refractory DMO treatment and prevention.

Matrix Metalloproteinases in Age-Related Macular Degeneration (AMD)

Age-related macular degeneration (AMD) is a complex, multifactorial and progressive retinal disease affecting millions of people worldwide. In developed countries, it is the leading cause of vision loss and legal blindness among the elderly. Although the pathogenesis of AMD is still barely understood, recent studies have reported that disorders in the regulation of the extracellular matrix (ECM) play an important role in its etiopathogenesis. The dynamic metabolism of the ECM is closely regulated by matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs). The present review focuses on the crucial processes that occur at the level of the Bruch’s membrane, with special emphasis on MMPs, TIMPs, and the polymorphisms associated with increased susceptibility to AMD development. A systematic literature search was performed, covering the years 1990–2020, using the following keywords: AMD, extracellular matrix, Bruch’s membrane, MMPs, TIMPs, and MMPs polymorphisms in AMD. In both early and advanced AMD, the pathological dynamic changes of ECM structural components are caused by the dysfunction of specific regulators and by the influence of other regulatory systems connected with both genetic and environmental factors. Better insight into the pathological role of MMP/TIMP complexes may lead to the development of new strategies for AMD treatment and prevention.

Early prevention of diabetes microvascular complications in people with hyperglycaemia in Europe. ePREDICE randomized trial. Study protocol, recruitment and selected baseline data

Objectives

To assess the effects of early management of hyperglycaemia with antidiabetic drugs plus lifestyle intervention compared with lifestyle alone, on microvascular function in adults with pre-diabetes.

Methods

Trial design: International, multicenter, randomised, partially double-blind, placebo-controlled, clinical trial.

Participants

Males and females aged 45–74 years with IFG, IGT or IFG+IGT, recruited from primary care centres in Australia, Austria, Bulgaria, Greece, Kuwait, Poland, Serbia, Spain and Turkey.

Intervention

Participants were randomized to placebo; metformin 1.700 mg/day; linagliptin 5 mg/day or fixed-dose combination of linagliptin/metformin. All patients were enrolled in a lifestyle intervention program (diet and physical activity). Drug intervention will last 2 years. Primary Outcome: composite end-point of diabetic retinopathy estimated by the Early Treatment Diabetic Retinopathy Study Score, urinary albumin to creatinine ratio, and skin conductance in feet estimated by the sudomotor index. Secondary outcomes in a subsample include insulin sensitivity, beta-cell function, biomarkers of inflammation and fatty liver disease, quality of life, cognitive function, depressive symptoms and endothelial function.

Results

One thousand three hundred ninety one individuals with hyperglycaemia were assessed for eligibility, 424 excluded after screening, 967 allocated to placebo, metformin, linagliptin or to fixed-dose combination of metformin + linagliptin. A total of 809 people (91.1%) accepted and initiated the assigned treatment. Study sample after randomization was well balanced among the four groups. No statistical differences for the main risk factors analysed were observed between those accepting or rejecting treatment initiation. At baseline prevalence of diabetic retinopathy was 4.2%, severe neuropathy 5.3% and nephropathy 5.7%.

Conclusions

ePREDICE is the first -randomized clinical trial with the aim to assess effects of different interventions (lifestyle and pharmacological) on microvascular function in people with pre-diabetes. The trial will provide novel data on lifestyle modification combined with glucose lowering drugs for the prevention of early microvascular complications and diabetes.

Registration

- ClinicalTrials.Gov Identifier: NCT03222765

- EUDRACT Registry Number: 2013-000418-39

Evaluation of Potential Pain Biomarkers in Saliva and Pain Perception After Corneal Advanced Surface Ablation Surgery

Purpose

To evaluate the evolution of a set of proposed pain biomarkers in the saliva of subjects following Advanced Surface Ablation (ASA), in order to determine their validity as objective pain measures.

Methods

A multicenter, prospective, and descriptive study was carried out to assess the variations between biomarkers and perceived pain. The Inclusion criteria were healthy subjects who underwent a bilateral, alcohol-assisted surface ablation with epithelial removal (ASA). Pain intensity before and after surgery was assessed by Visual Analog Scale (VAS) and the Numeric Pain Rating Scale (NPRS). Cortisol, sAA, sIgA, testosterone, and sTNFαRII were assayed at four-time points (V0, baseline; V1, pre-surgery; V2, 1 hr post-surgery, and V3, 72 hrs post-surgery). Comorbidities and Hospital Anxiety and Depression (HADS) questionnaires were administrated before and at 6 hrs after the surgery. All patients were treated with cold patches, topical steroids, topical cold antibiotics, and benzodiazepines after ASA surgery. A descriptive analysis of biomarkers and pain intensity evolution and the agreement between biomarkers and pain was performed.

Results

Concentration of sIgA and sTNFαRII post-surgery was significantly higher at each visit compared to baseline (p-value: 0.053, p-value: <0.001, respectively). Relations between VAS scale score and putative biomarker variations were not statistically significant except for the sIgA but only at visit 0 (p-value: 0.024). The HADS questionnaire showed anxiety scores between 0 and 7 in all patients before and at 6 hrs after surgery.

Conclusion

In this study, sIgA and sTNFαRII are the two potential biomarkers that present correlation with the VAS and these salivary substances showed acceptable levels of reproducibility in healthy subjects.

Chemical compounds causing severe acute toxicity in heavy liquids used for intraocular surgery

Perfluorocarbon liquids (PFCLs) have been considered safe for intraocular manipulation of the retina, but since 2013 many cases of acute eye toxicity cousing blindness have been reported in various countries when using various commercial PFCLs. All these PFCLs were CE marked (Conformité Européenne), which meant they had been subjected to evaluation complying with the International Organization for Standardization (ISO) guidelines. These dramatic events raised questions about the safety of PFCLs and the validity of some cytotoxicity tests performed under ISO guidelines. Samples from toxic batches were analyzed by gas chromatography-mass spectrometry combined with Raman and infrared spectrometry. Perfluorooctanoic acid, dodecafluoro-1-heptanol, ethylbenzene and tributyltin bromide were identified and evaluated by a direct contact cytotoxicity test using ARPE-19 cell line, patented by our group (EP 3467118 A1). Perfluorooctanoic acid at a concentration of >0.06 mM and tributyltin bromide at a concentration of ≥0.016 mM were shown to be toxic, whereas the concentration found in the toxic samples reached 0.48 mM, and 0.111 mM, respectively. These finding emphasized the idea that determination of partially fluorinated compounds are not enough to guarantee the safety of these medical devices.

Retinal Toxicity of Medical Devices Used during Vitreoretinal Surgery: A Critical Overview

Retinal toxicity/biocompatibility of medical devices in direct contact with the retina is an important subject for clinicians and scientists. As these effects are not very frequent, there is also a relative lack of information for many clinicians. The past has taught us multiple times that there is a significant safety problem associated with severe loss of vision in affected patients. In this review, we want to classify medical products that are used in the back of the eye, describe recent examples of toxicity, critically reflect on the regulations that exist and suggest improvements that can be done to ensure patient safety without hindering innovation.

METHODS

Critical review of the recent papers and personal experience of the authors in this issue. Medical devices used in the back of the eye and recent examples of toxicity are described, regulations that exist are critically reflected and improvements suggested that can ensure patient safety without hindering innovation.

RESULTS

There is clear evidence of toxicity after intraocular surgery in any category. Some cytotoxic indirect methods have failed in detecting this toxicity. Some ISO rules do not seem appropriate. Postmarketing safety is missing. There is little data on this issue.

CONCLUSIONS

The absence of a clear regulation of the production, purification and evaluation of the toxic effects of the medical devices supposes the possibility that products are not sufficiently safe to obtain the CE mark.

Clinical Consequences of the Use of Highly Purified Silicone Oil: Comparative study of highly and less purified silicone oil

Purpose

To compare the ocular toxicity caused by the use of highly purified silicone oil to less purified silicone oil in humans.

Methods

Fifty-six eyes received 2,000 centistokes (cs) purified silicone oil (group 1) and 42 eyes received 2,000 cs fractionated (highly purified) silicone oil (group 2) after pars plana vitrectormy. Follow-up ranged from 6 to 48 months.

Results

Six months after injection, the following complications were found in groups 1 and 2, respectively: ocular hypotension (<13mmHg), 39.3% and 31%, sustained ocular hypertension (>23mmHg), 19.6% and 19%; acute hypertensive peaks (>30mmHg), 23.2% and 11.9%; corneal alterations, 19.6% and 14.3%; emulsification, 1.8% and 2.4%; silicone oil cloudiness, 28.6% and 0%; preretinal reproliferation, 14.3% and 4.8% and total or partial retinal reattachment, 78.6% and 90.5%.

Conclusions

Highly purified silicone oil was better tolerated than the less purified oil and caused fewer complications. Poorly purified silicone oils should be avoided in clinical practice.

Comparison between direct contact and extract exposure methods for PFO cytotoxicity evaluation

A series of recent acute blindness cases following non-complicated retinal detachment surgery caused the release of several health alerts in Spain. The blindness was attributed to certain lots of perfluoro-octane (PFO; a volatile and transient medical device). Similar cases have been reported in other countries. This has raised questions regarding the validity of cytotoxicity test methods currently used to certify the safety of PFO lots. The tests were performed according to the International Organization for Standardization (ISO) norms, using the extract dilution method or the indirect contact method as applied to L929 cells, a line derived from mouse fibroblasts. The limitations of those methods have been resolved in this study by proposing a new cytotoxicity test method for volatile substances. The new method requires direct contact of the tested substance with cells that are similar to those exposed to the substance in the clinical setting. This approach includes a few new technical steps that are crucial for detecting cytotoxicity. Our new method detected toxic PFO lots that corresponded to the lots producing clinical blindness, which previous methods failed to detect. The study suggests applying this new method to avoid occurrence of such cases of blindness.

Classifications for Proliferative Vitreoretinopathy (PVR): An Analysis of Their Use in Publications over the Last 15 Years

Purpose. To evaluate the current and suitable use of current proliferative vitreoretinopathy (PVR) classifications in clinical publications related to treatment. Methods. A PubMed search was undertaken using the term "proliferative vitreoretinopathy therapy". Outcome parameters were the reported PVR classification and PVR grades. The way the classifications were used in comparison to the original description was analyzed. Classification errors were also included. It was also noted whether classifications were used for comparison before and after pharmacological or surgical treatment. Results. 138 papers were included. 35 of them (25.4%) presented no classification reference or did not use any one. 103 publications (74.6%) used a standardized classification. The updated Retina Society Classification, the first Retina Society Classification, and the Silicone Study Classification were cited in 56.3%, 33.9%, and 3.8% papers, respectively. Furthermore, 3 authors (2.9%) used modified-customized classifications and 4 (3.8%) classification errors were identified. When the updated Retina Society Classification was used, only 10.4% of authors used a full C grade description. Finally, only 2 authors reported PVR grade before and after treatment. Conclusions. Our findings suggest that current classifications are of limited value in clinical practice due to the inconsistent and limited use and that it may be of benefit to produce a revised classification.

A novel coculture model of porcine central neuroretina explants and retinal pigment epithelium cells

PURPOSE

To develop and standardize a novel organ culture model using porcine central neuroretina explants and RPE cells separated by a cell culture membrane.

METHODS

RPE cells were isolated from porcine eyes, expanded, and seeded on the bottom of cell culture inserts. Neuroretina explants were obtained from the area centralis and cultured alone (controls) on cell culture membranes or supplemented with RPE cells in the same wells but physically separated by the culture membrane. Finally, cellular and tissue specimens were processed for phase contrast, cyto-/histological, and immunochemical evaluation. Neuroretina thickness was also determined.

RESULTS

Compared to the neuroretinas cultured alone, the neuroretinas cocultured with RPE cells maintained better tissue structure and cellular organization, displayed better preservation of photoreceptors containing rhodopsin, lower levels of glial fibrillary acidic protein immunoexpression, and preservation of cellular retinaldehyde binding protein both markers of reactive gliosis. Neuroretina thickness was significantly greater in the cocultures.

CONCLUSIONS

A coculture model of central porcine neuroretina and RPE cells was successfully developed and standardized. This model mimics a subretinal space and will be useful in studying interactions between the RPE and the neuroretina and to preclinically test potential therapies.

Comparative study for the efficacy and safety of percutaneous nefhrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) for the treatment of 2-3,5 cm kidney stones

OBJECTIVES

Retrograde intrarenal surgery (RIRS) has become an important alternative for the treatment of kidney stones due to its increased safety and efficiency. The purpose of this study is to compare efficacy and safety features of RIRS against percutaneous nephrolithotomy (PCNL) for the treatment of 2 - 3.5 cm kidney stones.

METHODS

142 cases (106 RIRS and 36 PCNL) encompassing 2 - 3.5 cm kidney stones that have been treated in our center between December 2009 and December 2011 have been considered. Demographic variables, stone characteristics, surgical stay and surgical time have been evaluated. Additionally, the complication prerate and success rate after one and two procedures (retreatment) have also been assessed. Student's T, Mann-Whitney U y Chi² - V Cramer (p=0.05) tests were used for statistical analysis.

RESULTS

There are not statistically significant differences in demographic or stone variables. The calculated mean surgical time was lower for PCNL (85 min) than for RIRS (112 min). Mean hospital stay was statistically significantly shorter in RIRS (16 h vs. 98 h in RIRS, p=0.001). PCNL exhibited a higher global complication rate of 19.4% vs. 6.6% for RIRS (p=0.001). PCNL also showed a higher successful rate (80.6% vs. 73.6% for RIRS), although this difference was not statistically significant (p=0.40). When comparing the success rate after a second procedure, PCNL results in 94.3% vs. 93.5% for RIRS (p=0.88).

CONCLUSION

RIRS was found to be a safe and efficient procedure with a short hospital stay. Overall, RIRS can be considered as an alternative to PCNL for the treatment of renal stones smaller than 3.5 cm.

Loss of Visual Acuity after Successful Surgery for Macula-On Rhegmatogenous Retinal Detachment in a Prospective Multicentre Study

Purpose. To quantify the frequency of visual loss after successful retinal detachment (RD) surgery in macula-on patients in a multicentric, prospective series of RD. Methods. Clinical variables from consecutive macula-on RD patients were collected in a prospective multicentric study. Visual loss was defined as at least a reduction in one line in best corrected visual acuity (VA) with Snellen chart. The series were divided into 4 subgroups: (1) all macula-on eyes (n = 357); (2) macula-on patients with visual loss at the third month of follow-up (n = 53) which were further subdivided in (3) phakic eyes (n = 39); and (4) pseudophakic eyes (n = 14). Results. Fifty-three eyes (14.9%) had visual loss three months after surgery (n = 39 phakic eyes; n = 14 pseudophakic eyes). There were no statistically significant differences between them regarding their clinical characteristics. Pars plana vitrectomy (PPV) was used in 67.2% of cases, scleral buckle in 57.7%, and scleral explant in 11.9% (36.1% were combined procedures). Conclusions. Around 15% of macula-on RD eyes lose VA after successful surgery. Development of cataracts may be one cause in phakic eyes, but vision loss in pseudophakic eyes could have other explanations such as the effect of released factors produced by retinal ischemia on the macula area. Further investigations are necessary to elucidate this hypothesis.

Proliferative vitreoretinopathy: A new concept of disease pathogenesis and practical consequences

During the last four decades, proliferative vitreoretinopathy (PVR) has defied the efforts of many researchers to prevent its occurrence or development. Thus, PVR is still the major complication following retinal detachment (RD) surgery and a bottle-neck for advances in cell therapy that require intraocular surgery. In this review we tried to combine basic and clinical knowledge, as an example of translational research, providing new and practical information for clinicians. PVR was defined as the proliferation of cells after RD. This idea was used for classifying PVR and also for designing experimental models used for testing many drugs, none of which were successful in humans. We summarize current information regarding the pathogenic events that follow any RD because this information may be the key for understanding and treating the earliest stages of PVR. A major focus is made on the intraretinal changes derived mainly from retinal glial cell reactivity. These responses can lead to intraretinal PVR, an entity that has not been clearly recognized. Inflammation is one of the major components of PVR, and we describe new genetic biomarkers that have the potential to predict its development. New treatment approaches are analyzed, especially those directed towards neuroprotection, which can also be useful for preventing visual loss after any RD. We also summarize the results of different surgical techniques and clinical information that is oriented toward the identification of high risk patients. Finally, we provide some recommendations for future classification of PVR and for designing comparable protocols for testing new drugs or techniques.

The value of simple microbiological studies for on-site screening of acute neonatal conjunctivitis in Angola

BACKGROUND

Neonatal conjunctivitis or ophthalmia neonatorum (ON) is an acute bacterial conjunctivitis contracted by newborns during delivery. In non-industrialized countries, detection of the etiological agent is difficult due to the unavailability of modern diagnostic resources. Therefore, we analyzed the effectiveness of Gram and methylene blue staining techniques, which are simple microbiological methods in suspecting the aetiology of ON in a maternity ward in Luanda, Angola.

FINDINGS

Neonatal conjunctival smears (n = 95), maternal data, and perinatal factors were collected. Slides were air-dried and sent to the Microbiology Department of the Hospital Clinico Universitario, Valladolid, Spain, where trained personnel performed Gram and methylene blue staining methods. Findings were interpreted by two expert microbiologists. Ophthalmological examination of all children showed five newborns with clinical signs of ON. Fourteen mothers reported were suspected with vulvo-vaginitis, and 27 had a urinary infection during pregnancy. Gram staining revealed the presence of epithelial cells in 87.6% and leukocytes in 15% of the conjunctival smears. These values were significantly higher than those shown by methylene blue staining. No rods, cocci, or yeasts were identified by either staining method. Chlamydia trachomatis DNA was also undetected in a small sub-sample with clinical suspicion of ON. There was no correlation among the presence of ON, ON microbes, maternal data, or perinatal factors.

CONCLUSIONS

Basic microbiological techniques did not provide enough information for screening cases of ON in Angola. Therefore, the use of molecular biology or other techniques is warranted for this purpose.

Adipose derived mesenchymal stem cells partially rescue mitomycin C treated ARPE19 cells from death in co-culture condition

Age-related macular degeneration is a retinal disease with important damage at the RPE layer. This layer is considered a target for therapeutical approaches. Stem cell transplantation is a promising option for retinal diseases. Adipose derived mesenchymal stem cells secret growth factors which might play a significant role in RPE maintenance. This study aimed to evaluate human AD-MSCs ability to rescue mitomycin C treated dying ARPE19 cells in co-culture condition. ARPE19 cells were treated with MMC (50 μg/ml, 100 μg/ml and 200 μg/ml) for 2 hours to induce cell death. These treated cells were co-cultured with hAD-MSCs in indirect co-culture system for 3 days and 3 weeks. Then the viability, growth and proliferation of these ARPE19 cells were evaluated by a cell viability/cytotoxicity assay kit and Alamar Blue (AB) assay. Untreated ARPE19 cells and human skin fibroblasts (HSF) were used as controls. MMC blocked ARPE19 cell proliferation significantly in 3 days and cells were almost completely dead after 3 weeks. Cell toxicity of MMC increased significantly with concentration. When these cells were co-cultured with hAD-MSCs, a significant growth difference was observed in treated cells compared to untreated cells. hAD-MSCs rescue capacity was also significantly higher than HSF for treated ARPE19 cells. This study showed that hAD-MSCs rescued MMC treated ARPE19 cells from death. It probably occurred due to undefined growth factors secreted by hAD-MSCs in the medium, shared by treated ARPE19 cells in co-culture conditions. This study supports further evaluation of the effect of hAD-MSCs subretinal transplantation over the RPE degeneration process in AMD patients.

Variations in Functional and Anatomical Outcomes and in Proliferative Vitreoretinopathy Rate along a Prospective Collaborative Study on Primary Rhegmatogenous Retinal Detachments: The Retina 1 Project-Report 4

Purpose. To analyse variations in the anatomical and functional outcomes and in proliferative vitreoretinopathy (PVR) rate of a prospective multicentric study that was primarily designed for identification of clinical risk factors for PVR. Methods. 1,046 retinal detachment (RD) cases were analysed. Cases were divided into two series based upon variation in PVR rate determined by logistic regression analysis. Series 1 (S1) included RD treated during 2004-2005 (n = 481) and Series 2 (S2) during 2006–2008 (n = 565). Pre-, intra-, and postoperative characteristics were recorded. Results. There were few differences in the preoperative characteristics. S2 had more vitrectomies and scleral bands and fewer explants and associated cataract extractions than S1. Anatomic reattachment improved from 87.9% to 92.9% in S1 and S2, respectively, (P = 0.006). Visual acuity at 3 months ≥20/40 increased from 36.5% of S1 to 44.2% in S2 (P = 0.049). PVR rate diminished from 14.1% in S1 to 8.1% in S2 (P = 0.002). Centres with higher rates of PVR in S1 showed the greatest reductions in S2. Conclusion. An improvement in anatomical and functional outcome and PVR rate occurred in participating centres cannot be attributed to the learning curve of surgeons. We speculated that it could be an effect of their participation in the study.

Detecting amblyogenic diseases with the photographic Bruckner test

The authors evaluated the photographic Brückner test for its ability to detect the main causes of amblyopia. One hundred four patients divided into four groups underwent this test: Group I, small deviation esotropia; Group II, large deviation esotropia; Group III, anisometropia; and Group IV, healthy controls. The results show high sensitivity (82%), specificity (91%), and accuracy (84%), indicating that this test could be a potential way to mass-screen pre-verbal and pre-school children to facilitate early detection of the main causes of amblyopia, when treatment is still possible.

Original papers: Prevalence of amblyogenic diseases in a preschool population sample of Valladolid, Spain

OBJECTIVES

Amblyopia is the leading cause of monocular vision loss in people under 40 years, and especially in children. The purpose of the present investigation is to determine the prevalence of amblyopia and ocular pathology, specially the most common causes of amblyopia, in a population of 3-to 6-year-old children.

PATIENTS AND METHODS

From a total of 8167 children, a geographically defined population of 3-to 6-year-old children, 2000 were randomly selected, and 1179 (58.9%) examined. Ophthalmologic examination included: Personal and familial history, visual acuity, extraocular motility, cover test at near distance, cycloplegic refraction with autorefractometer and fundus eye examination. Amblyopia was considered when corrected visual acuity was < 0.5 with Marquez optotypes and difference in visual acuity of 0.2 or more between eyes. Pathology considered as amblyogenic were strabismus, visual acuity asymmetry and anisometropia.

RESULTS

The family history showed amblyopia in 249 (21.1%), strabismus in 227 (19.2%), and refractive errors in 808 (65.5%). Cover test was positive in 78 children (6.7%). A visual acuity difference of 0.2 or more between eyes was present in 88 (7.5%) children, and anisometropia over 1.5 diopters (in spherical equivalent) was present in 17 (1.4%) subjects. One hundred and twenty-two (10.35%) children did not achieve a normal visual acuity: visual acuity in the better eye was less than 0.5 in 55 children under 5 years and less than 0.6 in 67 children over 5 years. The prevalence of amblyopia was 7.5%.

CONCLUSIONS

The data support the importance of early detection and treatment of amblyopia and the need for visual screening at an early age.

[Surgical therapy of lithiasis in horseshoe kidney]

OBJECTIVE

To present our centre's experience in the surgical treatment of lithiasis in patients with horseshoe kidney.

MATERIAL AND METHODS

From October 2007 to March 2011 we treated 10 patients with renal lithiasis in their horseshoe kidneys. Retrospectively, we reviewed the symptoms, medical and surgical history, the characteristics of the stones (size, location, composition) and treatments that were carried out. In all the cases, the study was carried out by CT, with volume reconstruction and with an angiographic study. A percutaneous nephrolithotomy (PCNL) or an endoscopic retrograde intrarrenal surgery (RIRS) was carried out, depending on the size and location of the stone.

RESULTS

Three percutaneous nephrolithotomies were carried out (2 on staghorn lithiasis stones, 1 pseudocoraliform stone) with a combined rigid and flexible single-access nephroscopy. In one case there was haemorrhage that required treatment by selective embolization. In the rest, RIRS was carried out, all with stones < 30 mm in their greatest diameter without any complications. The mean surgical times were 120 (60-180) minutes for the percutaneous route and of 105 (65-160) minutes for the retrograde route. In all the cases the treatment achieved a complete elimination of the stones or remains of less than 5 mm.

CONCLUSIONS

The treatment of renal lithiasis in horseshoe kidneys is complex, given their peculiar anatomy. The usual surgical techniques can be reproduced in these cases with good results. We opt for PCNL in complete staghorn stone and pseudocoraiform stones, whereas RIRS is a valid option in cases with stones < 3 cm.

Training and professional profile of retinologists in Spain: Retina 2 project, Report 4

Background:

Uniform postresidency systems to train medical specialists have not been developed in most European countries. Before developing a framework for such a system, we established the learning and professional profiles of Spanish ophthalmologists dedicated to medical retina and vitreoretina subspecialties.

Methods:

After identification of presumed subspecialists by experts from different autonomous regions, a self-administered questionnaire was mailed in 2006. A reminder was sent three weeks later. Postal mail was used. Nonresponder bias was determined.

Results:

Of 492 possible retina subspecialists, 261 replied to the questionnaires. While about 86% received specific retinal training, standardized fellowship programs were uncommon for both medical retina and vitreoretina (around 10%). Of the responders, 24.5% performed only medical retina, 11.8% vitreoretina, and 63.6% both. Most (60.5%) practiced anterior segment surgery, and 78.7% declared skills in vitrectomy.

Conclusion:

We have developed a database of Spanish ophthalmologists dedicated to retinal pathologies and identified some characteristics of their professional profile. Although most of them have received specific retinal training, standardized mastership programs are still uncommon. These data will be useful in creating a standardized Retina Mastership, an important goal of the European Higher Education Area.

A Brief Review and Re-thinking of Proliferative Vitreoretinopathy

Prevention of proliferative vitreoretinopathy (PVR) continues to be a challenge for retinologists despite almost 30 years of research history. New diagnostic tools, based on the genetic profiles of patients with retinal detachment (RD), are now available. In addition, clinical trials in humans are about to begin of new pharmacological approaches, based on so-called ‘biological agents’. Thus, it might be that, in the near future, it will be possible to reduce the incidence of PVR, which currently accounts for 8–10 % of all cases of RD.

[Training and clinical activity of Spanish retinologists: a preliminary approach. Retina 2 project. Descriptive analysis]

PURPOSE

To create a database of Spanish ophthalmologists mainly dedicated to retinal pathology care, describing their training period characteristics and their daily activity (clinical and surgical).

METHODS

A postal questionnaire was sent to 504 possible retinologists identified through the information supplied by the Spanish Ophthalmological Society and the Spanish Vitreous-Retina Society, with a minimum of 3 retinologists per Autonomous Region.

RESULTS

267 (52.9% of the sample population) responses were collected and processed. Most of the respondents had started their residency after 1980 (82.4%). Ninety-four percent had received specific training in retinal pathology, mostly during the residency period (82.1%) and from more experienced colleagues (62.9%). Official fellowships were held in a minority of cases (around 12%). Twelve percent of retinologists performed retinal surgery only, 14.6% performed anterior segment surgery, and 60.7% performed both types of surgery.

CONCLUSIONS

Despite not having taken into consideration non-response bias, this study provides the first reported data on the professional profile of Spanish retinologists.

Development of predictive models of proliferative vitreoretinopathy based on genetic variables: the Retina 4 project

PURPOSE

Machine learning techniques were used to identify which of 14 algorithms best predicts the genetic risk for development of proliferative vitreoretinopathy (PVR) in patients who are experiencing primary rhegmatogenous retinal detachment (RD).

METHOD

Data from a total of 196 single nucleotide polymorphisms in 30 candidate genes were used. The genotypic profile of 138 patients with PVR following primary rhegmatogenous RD and 312 patients without PVR RD were analyzed. Machine learning techniques were used to develop statistical predictive models. Fourteen models were assessed. Their reproducibility was evaluated by an internal cross-validation method.

RESULTS

The three best predictive models were the lineal kernel based on the Support Vector Machine (SMV), the radial kernel based on the SVM, and the Random Forest. Accuracy values were 78.4%, 70.3%, and 69.3%, respectively. The more accurate, although complex, algorithm uses 42 SNPs, whereas the simpler one uses only two SNPs, which makes them more suitable for routine diagnostic work. The radial kernel based on SVM uses 10 SNPs. The best individually predictor marker was rs2229094 in the tumor necrosis factor locus.

CONCLUSION

Genetic variables may be useful to predict the likelihood of the development of PVR. The predictive capabilities of these models are as good as those observed with clinical approaches. These results need external validation to estimate the true predictive capability and select the most appropriate ones for clinical use.

Non-complicated retinal detachment management: variations in 4 years. Retina 1 project; report 1

AIMS

To assess variations in the characteristics and management of two series of non-complicated rhegmatogenous retinal detachments (RD) carried out 4 years apart in Spain.

METHODS

Prospective, multicentric, non-randomised comparative study. 339 consecutive cases of RD treated in five hospitals were included. Group 1 (G1) (n = 186) included cases operated on from 1999 to 2001; group 2 (G2) (n = 153) included cases from 2004 to 2006. 83 variables related to preoperative characteristics of RD, surgical management and postoperative evolution were recorded. Surgeons were allowed to treat patients following their personal criteria. Differences in preoperative characteristics, rate of vitrectomy and anatomical outcome were studied. Quantitative variables were compared by Mann-Whitney U test and qualitative variables by standard contingency tables. Multivariate analysis was carried out by logistic regression analysis.

RESULTS

G1 showed a significantly longer delay in performing surgery, since the first symptoms appeared (G1: 29 (SD 50) days; G2: 22 (55); p<0.001) and more RD without visible retinal break than G2 (G1: 17.4%; G2: 9.2%; p = 0.028). In G2, cases with multiple retinal breaks (G1: 31.6%; G2: 44.6%) were more frequent (p = 0.022). No significant differences in other preoperative variables were observed. Vitrectomy was performed in 30.1% in G1 and in 78.4% in G2 as a primary surgical approach (p<0.001). Regardless of the characteristics of the RD, the rate of vitrectomy was higher in G2. The reattachment rate was over 94% in both groups (p = 0.833). Pseudophakic RD showed better anatomical outcomes in G2 (G1: 83.9%; G2: 96.4%; p = 0.028).

CONCLUSION

There is an increasing tendency to treat RD with primary vitrectomy, which is related to neither a higher complexity of cases nor better anatomical results.

[Urgent retinal detachment management by the National Health System of Spain. Project Retina 2]

OBJECTIVE

To identify problems in the urgent management of retinal detachments (RD) in hospitals of the Spanish National Health System (NHS).

METHODS

A questionnaire was submitted confidentially to the heads of Ophthalmic Departments of 217 hospitals of the NHS to obtain information on the management of urgent RD during the last year. Data was stored in a Microsoft Access database and statistically analyzed by Excel and Statgraphics. Qualitative variables were analyzed by Chi-Square and Fisher exact tests and quantitative variables by the Kruskall-Wallis test.

RESULTS

A global response rate of 54.8% was achieved with higher participation of the Teaching Hospitals (TH). District Hospital and non-Teaching Hospital responses were similar and grouped as non-TH. Eighteen percent of centers, mostly non-TH, had no ophthalmologist on duty. Thirty-six percent had a vitreoretinal specialist on call. Eighty percent of centres admitted to have problems handling urgent RD during weekends. Twenty-four had no ophthalmic surgical theatre available. Fifty percent referred to have problems having an anaesthesiologist available and only 22% had ophthalmic trained personnel (nurses) available. Sixty-four percent of centres performed pars plana vitrectomy (PPV) and 77% of those were able to perform an urgent PPV. Ninety percent admitted that a patient with a macula-threatening RD occurring at the beginning of the week-end would not be treated until at least 24 hours had elapsed, although 84% considered this to be inadequate.

CONCLUSION

Despite the methodological problems and bias of this questionnaire, we did identify several important problems in the management of urgent RD by NHS hospitals. The data obtained provides useful information to enable the quality of the NHS care of RD to be improved, particularly that available at the week-end.

[Correction of secondary anisometropia after retinal detachment and LASIK surgery]

CASE REPORT

A male with cylindrical anisometropia secondary to retinal detachment (RD) surgery in the right eye (OD) was referred for contact lens (CL) fitting. His refraction was OD -1.25 -2.75 x 60 degrees VA 1.0 and OS +0.25 VA 1.2. He was complaining of diplopia with spectacles. Seven years prior to the RD surgery, he had undergone LASIK without complications. The diplopia was eliminated after a CL was fitted according to his corneal topography.

DISCUSSION

RD surgery can cause anisometropic refractive changes. In patients with diplopia and asthenopia, spectacles are not well tolerated. CL fitting according to post-LASIK corneal geometry succeeded in refractive correction with less anisometropic symptoms.

[National survey on vitreo-retinal surgery and the management of rhegmatogenous retinal detachments in Spain. Project retina 2]

PURPOSE

To obtain information throughout Spain on the current management of vitreo-retinal surgical diseases, the number of ophthalmologists involved in retinal surgical diseases care, and the urgent management of retinal detachments.

METHODS

A 30 item questionnaire was sent by mail, on two separate occasions, to the heads of Ophthalmology Departments of 276 centers in Spain.

RESULTS

A total response rate of 48.2% was achieved, however the answers from private centers represented only 9.4% of the total so these were excluded from the analysis. The centers most likely to respond were those in Teaching Hospitals (TH) (52.3%). Of these, 64% of hospitals responded that, in the last year, they performed pars plana vitrectomies (PPV) and 70% performed more than 100 PPVs in the year. In all, 77% of the centers that performed PPVs had also performed them urgently. A total of 75% of hospitals indicated that they had ophthalmologists mainly dedicated to retinal diseases care, with a median of 2 specialists per center, with this representing 23% of their total staff. Retinal surgery was performed by general ophthalmologists in 11.5% of centres. Only 40.3% of hospitals audit their results (37.5% TH).

CONCLUSIONS

Despite the existence of a relatively low response rate, as well as some biases and methodological problems, data on the management of retinal surgical disease has been obtained for the first time at a national level. This data will facilitate later studies and must be taken into consideration in improving the planning and adequate management of these diseases in Spain.

Intraretinal immunohistochemistry findings in proliferative vitreoretinopathy with retinal shortening

To report the major intraretinal pathological changes in retinas with proliferative vitreoretinopathy (PVR) and retinal shortening, 13 human retinal samples from postoperative PVR after primary surgery for retinal detachment were immunostained for vimentin, glial fibrillary acidic protein (GFAP), cytokeratins, and CD68. One more sample was studied with electron microscopy. Retinal disorganization, neuronal loss, and gliosis were observed in 12 out of 13 samples, but all 13 were positive for GFAP. Muller cell processes showed different degrees of intermediate filament hyperplasia. CD68-positive cells were present in 11 of 13 retinal samples.

CONCLUSION

A gliotic response plays a major role in retinal shortening in PVR. In addition, the presence of macrophage-like cells in retinal tissues suggests a possible role of these cells in the pathogenesis of this variety of PVR.

[Cholesterol, alpha-tocopherol, and retinoid concentrations in silicone oil used as a vitreous substitute]

OBJECTIVE

To verify the existence of organic lipophylic compounds in silicone oil extracted from human eyes following its use for previous retinal detachment, and to determine the intraocular permanence time of these substances in the oil.

METHODS

Concentrations of retinoic acid, retinol, retinal, cholesterol and alpha-tocopherol were detected by HPLC in 23 samples of silicone oil extracted from patients with complicated retinal detachments. The time interval between the time of injection of the silicone oil and the subsequent assessment varied from 3 to 50 months (the permanence time).

RESULTS

All tested compounds were found in the samples, but these were most commonly cholesterol and less frequently alpha-tocopherol. There was an inverse relationship between retinoic acid concentration and age (p=0.023), and a direct relationship between cholesterol concentration and permanence time (p=0.0008) at least up to 20 months.

CONCLUSIONS

These findings confirm that silicone oil is not an inert substance but is capable of extracting lipophylic compounds from the intraocular tissues. There is a clear linear elevation of cholesterol levels with increased intraocular permanence time. This finding could be used to further establish a safe permanence time for intraocular silicone oil used in ophthalmologic surgery. More studies with larger samples are warranted to evaluate this further.

Interaction between surgical procedure for repairing retinal detachment and clinical risk factors for proliferative vitreoretinopathy

PURPOSE

To asses risk factors of proliferative vitreoretinopathy (PVR) and a model for predicting it.

METHODS

Observational, case-control. 335 patients with non-complicated retinal detachment (RD) were included: 134 developed PVR (Cases); 201 patients did not (Controls). Risk factors for PVR were identified by multivariate analysis. Influence of variables was assayed according to the surgical approach. By logistic regression analysis a model to predict the risk of developing PVR and odds ratio (OR) values for each clinical factor were estimated.

RESULTS

Risk was higher in patients > 70 years and with intraocular pressure lower than 14 (OR: 3.84; CI 95%: 2.04-7.30) and in retinal breaks larger than "1 clock hour" (OR: 2.54; CI: 1.28-5.05), extended retinal detachments (OR: 4.01; CI: 1.98-8.10) and reinterventions (OR: 1.55; CI: 1.14-9.22). Scleral surgery also was a risk factor (OR: 3.89; CI: 2.12-7.14) and aphakia/pseudophakia when scleral surgery is performed (OR: 3.33; CI: 1.54-7.22). A model to predict PVR was proposed with these results.

CONCLUSIONS

Surgical approach modifies risk factors of PVR, and should be taken into account to improve the models for predicting it.

[Retinal shortening: the most severe form of proliferative vitreoretinopathy (PVR)]

PURPOSE

To identify the clinical characteristics of patients developing retinal shortening due to intraretinal PVR.

METHODS

Observational and retrospective cohort study on 110 PVR patients operated on between 2000 and 2001. During surgery, after removing epiretinal membranes and ruling out the presence of subretinal membranes, a perfluorocarbon liquid was injected. Those cases in which retinal flattening was not accomplished, were considered intraretinal PVR (group 1). Those in which retinal flattening allowed endolaser application, were taken as the control group (group 2). Clinical features of both groups were compared by chi-square test.

RESULTS

60 cases (54.5%, CI 95%: 40.5-68.5) showed retinal shortening (group 1). In 24 cases (21.8%, CI 95%: 12.9-30.7) complete retinal flattening was accomplished (group 2). In 26 cases (23.6%), evaluation was inconclusive. In 9 out of the 60 cases of group 1 (15%) a retinectomy was necessary to reattach the retina. Differences between both groups were not statistically significant for any of the clinical variables. However, the number of retinal detachments of more than 60 days of evolution was significantly higher in retinectomized eyes (20.7%) than in group 1 (3.7%) (p=0.04).

CONCLUSIONS

Retinal shortening is a relatively frequent phenomenon in PVR. Further studies are necessary to characterize this clinical presentation of PVR and its pathogenesis.

Proliferative vitreoretinopathy: cytologic findings in vitreous samples

PURPOSE

To compare the cellularity of vitreous samples obtained from patients with rhegmatogenous retinal detachment complicated by proliferative vitreoretinopathy (PVR) and from patients with uncomplicated rhegmatogenous retinal detachment (RD) to detect possible variations in cellularity over time.

METHODS

One hundred and twenty-five vitreous specimens collected from patients with RD (n = 41) and PVR (n = 84) were processed through direct paraffin embedding and cytospin. Different cell types were identified by light-microscopy (hematoxylin-eosin and Papanicolaou stain) according to their morphologic features, and a scale of cellular density was established for each cell type. Student's t test was used to analyze differences in the cellularity of RD versus PVR. A quadratic model was used to identify variations in the density of each cellular type in the PVR group, based on its evolution time.

RESULTS

During the first months after surgery, more macrophages and fibroblast-like cells were observed in the PVR group, but at other times no differences were found.

CONCLUSIONS

There are some differences in vitreous cellularity in PVR specimens when compared with RD. Especially relevant could be the large number of macrophages in earlier stages and their constant presence over time in PVR samples. The cytology of vitreous samples may shed light on the chronology of PVR cell pathobiology.

[Clinical risk factors for postoperative proliferative vitreoretinopathy (PVR). A prospective study]

PURPOSE

To identify clinical risk factors for development of postoperative PVR, to determine the incidence of this complication and its time of onset by a prospective multicentric study.

METHODS

A multicentric and prospective study of 223 patients with rhegmatogenous retinal detachment (RD) was conducted. Logistic regression analysis was used to identify risk factors for PVR among 83 variables related to preoperative, intraoperative and postoperative characteristics.

RESULTS

22 out of 223 RD developed PVR (incidence 9.9%, confidence interval 95%: 5.9-13.9). After logistic regression analysis, four variables showed an odds ratio higher than 1.0 (RD affecting 4 quadrants, cryopexy, aphakia/pseudophakia and those RD in which an encircling band was implanted). None of these factors showed a <<p>> value lower than 0.05. Most of postoperative PVR (77.2%) appeared in the first month after surgery.

CONCLUSIONS

This study establishes the incidence of PVR, and its time of onset, but it was not effective to identify clinical risk factors with a high level of confidence.

[Ghost cell detection in vitreous cytology: clinico-pathological correlation]

PURPOSE

To determine the prevalence of detection of ghost cells (GCs) in vitreous hemorrhages (VHs) and correlate it with the development of ghost cell glaucoma. To compare our results with those previously reported.

METHODS

Retrospective analysis of clinical records and vitreous cytology reports (cytospin and direct paraffin embedding) from patients undergoing vitrectomy for VH at Instituto Universitario de Oftalmobiología Aplicada and University Hospital, Valladolid, for the last 2 years.

RESULTS

76 VHs have been analysed; 45 corresponded to proliferative diabetic retinopathy and the remainder to several pathologies. GCs have been detected in 18 cases (25%) (4 out of 76 specimens were excluded): 14 were phakic and 4 pseudophakic. Most of 76 VHs lasted more than 2 months. No case of ghost cell glaucoma was detected, neither previously nor after vitrectomy.

CONCLUSIONS

The frequency of detection of GCs in vitreous cytology may vary according to the cytologic technique. In contrast with the information previously reported, ghost cell glaucoma is an unfrequent disease, particularly after vitrectomy, probably because of a better removal of hemorrhagic debris from the vitreous cavity nowadays. Nevertheless, this diagnosis should not be overlooked.

[Glutathione-related enzymes activity during vitrectomy. Effect of BSS Plus(R) in retinal tissue]

PURPOSE

To determine changes in the retinal activity of two enzymes related to the glutathione metabolism (Glutathione synthetase -GSHS- and glutathione reductase -GSSGR-) after vitrectomy using BSS Plus(R).

MATERIAL AND METHODS

Forty-five pigmented rabbits were distributed in 6 groups: group I (GSHS control in retinal tissue); Group II (analysis of GSHS at 3 hours post-vitrectomy); Group III (determination of GSHS at 48 hours after vitrectomy); Group IV (GSSGR control in retinal tissue); Group V (measurement of GSSGR at 3 hours post-surgery) and Group VI (study of GSSGR at 48 hours post-vitrectomy). Statistical analysis was done by a parametric test (ANOVA of single factor) (p<0.05).

RESULTS

The activity of these enzymes was: Group I (n=5, basal GSHS). 2785,63 D.S. 419,51 U/g; Group II (n=4, GSHS at 3 hours). 6053,50 D.S. 2788,84 U/g; Group III (n=4, GSHS at 48 hours). 7424,30 D.S. 997,47 U/g; Group IV (n=10, basal GSSGR). 150,86 D.S. 24,40 mU/mL; Group V (n=7, GSSGR at 3 hours). 212,03 D.S. 53,30 mU/mL; Group VI (n=8, GSSGR at 48 hours). 210,84 D.S. 46,03 mU/mL.

CONCLUSIONS

At retinal tissue, BSS Plus(R) intraocular irrigating solution increases GSHS activity without modifications of GSSGR levels. It seems to be related to the <<novo>> synthesis of glutathione.