Preoperative vitreous hemorrhage associated with rhegmatogenous retinal detachment: a risk factor for postoperative proliferative vitreoretinopathy?

BACKGROUND: We conducted a prospective clinical study to elucidate the role of preoperative vitreous hemorrhage in the development of postoperative proliferative vitreoretinopathy (PVR) in primary rhegmatogenous retinal detachment. MATERIALS AND METHODS: We prospectively evaluated 409 eyes of 390 patients affected by primary rhegmatogenous retinal detachment referred before any failed attempt to reattach the retina. Single and multiple logistic regression analysis were used to test 14 categories of variables. RESULTS: Postoperative PVR occurred in 48 (11.7% of 409 eyes). Postoperative PVR developed in 41 (11.8%) of the 347 eyes with no preoperative vitreous hemorrhage, and 7 (11.3%) of the 62 eyes with preoperative vitreous hemorrhage (P = 0.90). The results of multiple logistic regression analysis showed that only four variables were significant factors which had independently and jointly an effect on the risk of postoperative PVR: (1) 90 degrees or greater circumferential extent of the retinal tears; (2) preoperative PVR grade B; (3) preoperative PVR grade C-D; and (4) the use of cyrotreatment as the method of retinopexy. CONCLUSION: With the surgical techniques currently used, mild preoperative vitreous hemorrhage is not an independent risk factor for postoperative PVR in primary rhegmatogenous retinal detachment. The role of moderate and severe vitreous hemorrhage remains to be fully evaluated in a larger series of eyes.     

Results of vitreous surgery for proliferative vitreoretinopathy

During the past four years, we performed vitreous surgery on 73 eyes with rhegmatogenous retinal detachments complicated with severe proliferative vitreoretinopathy (PVR). We analyzed the surgical outcome of PVR according to the revised classification of PVR Grade C (1991). After a mean follow-up period of 19 months, the retinas were successfully reattached in 62 of 73 eyes (85%). The reattachment rate in the eyes with only posterior proliferation was high (96%), regardless of the extent of posterior proliferation. However, the reattachment rate in the eyes associated with anterior proliferation was markedly low (57%), depending on the extent of anterior proliferation. Among 62 eyes with successfully reattached retinas, 39 eyes (63%) had an improved postoperative visual acuity. These results demonstrated that the eyes with anterior PVR have a worse reattachment rate than the eyes with only posterior PVR. Using the revised classification of PVR, we were able to analyze the surgical outcome of PVR which could not be classified by the old classification.     

Silicone oil tamponade in the treatment of retinal detachment with proliferative vitreoretinopathy

Over 2 months in 1995, 235 assault patients attended the accident and emergency department of the Royal Alexandra Hospital, Paisley (2.4% of total new attendances). 80% were male and their mean age was 28 years (range 6-64); men were the assailants in over 90% of attacks. Alcohol had been consumed by 69% of the victims and 9% admitted to taking illicit drugs. The commonest place of assault was the street (44%) but women were more likely to be assaulted in their homes. Penetrating weapons were used in 23% of assaults. 60% of all injuries were to the head and neck. 27% of the victims were admitted to hospital. Paisley has an assault rate similar to that of other UK centres but the use of penetrating weapons is much higher than elsewhere.     

Natural history of posterior vitreous detachment with early management as the premier line of defense against retinal detachment

PURPOSE: This study was designed to elucidate various aspects of the natural history of posterior vitreous detachment (PVD), in particular the relation between symptomatology and prognosis as it relates to management of patients with the earliest symptoms of PVD. METHODS: A prospective study of 350 consecutive patients with PVD was performed, excluding all patients referred from an ophthalmologist, those with symptoms of more than 3 months in duration, and those with a history of ocular trauma, except for cataract surgery. Aphakia was present in 21 eyes, and 50 patients were bilaterally involved. RESULTS: Of 163 patients who had one to two floaters as their presenting symptom, with or without light flashes, a retinal tear developed in 12 (7.3%). Of 31 phakic eyes with secondary retinal tears on initial examination, 9 (29%) had one to two floaters and light flashes as the only symptoms. Of eight phakic eyes that initially, or eventually, had a retinal detachment, three (37%) had an interval of 2 1/2 to 3 weeks before visual field loss, during which they noticed only one to three visual floaters plus light flashes as their only symptoms. This early stage in which symptoms are detectable is crucial in terms of providing an opportunity for early treatment that might prevent retinal detachments. CONCLUSIONS: The prompt and conscientious vitreoretinal examination of each patient older than 45 years of age who experiences vitreous floaters, even though limited to one or two, should be undertaken without delay. This practice, combined with expeditious treatment of any secondary retinal tears, provides the most effective known means of preventing rhegmatogenous retinal detachment, and currently it appears to be neglected. A national public educational effort should be pursued to publicize the importance of these symptoms.     

Repair of a complex retinal detachment with proliferative vitreoretinopathy in an eye with extreme scleral thinning

Two new withanolides (steroidal lactones) named coagulin F [27-hydroxy-14,20-epoxy-1-oxo-(22R)-witha-3,5,24-trienolide] (1) and coagulin G [17beta,27-dihydroxy-14,20-epoxy-1-oxo-(22R)-witha-2,5, 24-trienolide] (2) were isolated from the whole plant of Withania coagulans, and their structures were deduced by spectral analysis.     

A prospective study of matrix metalloproteinases in proliferative vitreoretinopathy

PURPOSE: The migration, proliferation, differentiation, and adhesion of cells and other cellular functions are influenced by the surrounding extracellular matrix, in normal and wound-healing conditions. The matrix metalloproteinases (MMPs) are a family of enzymes that degrade and remodel the extracellular matrix and, thus, play a central role in the wound-healing process. Proliferative vitreoretinopathy (PVR), a wound-healing process in the retina, is a major cause of the failure of retinal detachment surgery. The role of MMPs in the pathobiology of PVR is unknown. We have investigated the presence of MMPs in the vitreous of patients with retinal detachment and the predictive value of MMPs for the future development of PVR. METHODS: A prospective study was conducted on 140 consecutive patients with a rhegmatogenous retinal detachment in whom vitrectomy was considered necessary because of a giant retinal tear and the presence of preoperative PVR, among other reasons. Vitreous samples were obtained and analyzed by zymography for the presence of MMPs. The patients were then followed up for the development of postoperative PVR (mild and severe). RESULTS: Two species of MMPs were detected in the vitreous: MMP-2 and MMP-9. MMP-2 was detected in all of the vitreous samples obtained, whereas MMP-9 was found in only 64 (47%) of 136 samples. The levels of MMPs detected were not significantly associated with the presence of preoperative PVR (P > 0.05), but they were significantly associated (P < 0.05) with the development of postoperative PVR (mild and severe). CONCLUSIONS: The results from this prospective study suggest that MMPs may be an important predictor and may also play a role in the development of postoperative PVR.     

Development of a multiple-drug delivery implant for intraocular management of proliferative vitreoretinopathy

A prototype multiple-drug delivery implant has been developed for the intraocular management of proliferative vitreoretinopathy (PVR). Because of the recurrent nature of the disease, PVR causes blindness in approximately 7% of patients who have undergone retinal re-attachment surgery. The poly(dl-lactide-co-glycolide) 50/50 (PLGA) implant consists of three cylindrical segments, each of which contains one of the following drugs: 5-fluorouridine (5FUrd, an antimetabolite), triamcinolone (Triam, a corticosteroid), and human recombinant tissue plasminogen activator (t-PA, a thrombolytic agent). The device can be inserted through a 20-gauge syringe needle into the vitreous body of the eye. The implant also possesses a PLGA coating over the t-PA-containing terminal segment, which creates a lag-time to deliver t-PA when most needed and to decrease the risk of postoperative bleeding. Two methods of cylinder fabrication were investigated: heat and solvent extrusion. The release behavior of several drugs was examined as a function of the processing variables including: extrusion method, drug loading, polymer molecular weight, and drug particle size. The presence of either the organic solvent (acetone) during processing or a highly water-soluble drug (5FUrd) in the formulation increased the polymer porosity, which in turn, increased the drug release-rate. Drug loading effects were consistent with percolation concepts, and a low-molecular-weight PLGA (e.g., Mw=42000 for inherent viscosity=0.58 dl/g) was desirable to produce controlled release close to one month. Based on pharmacological and pharmacokinetic data of these compounds and our clinical experience with this disease, several design criteria for a combined implant were devised. Optimal cylindrical segments from the formulation studies were selected and combined in series to form a contiguous implant. After successful combination and coating procedures were developed, prototype implants were prepared. From the 3-drug prototype, 5FUrd and Triam were released approximately 1 microgram/day for over 4 weeks and 10-190 microgram/day over 2 weeks, respectively. The solvent-extrusion procedure did not significantly alter the stability of the encapsulated t-PA (>94+/-5% serine protease activity after preparation). After a lag-time of approximately 2 days, t-PA was released active at a rate of approximately 0.2-0.5 microgram/day in approximately 2 weeks. The release characteristics from the combined implant largely met our initial design criteria. Hence, controlled-release implants of this kind may have potential use for intraocular treatment of PVR.     

The effect of posterior vitreous detachment on the prognosis of branch retinal vein occlusion

PURPOSE: Two important complications causing visual loss in retinal branch vein occlusions are vitreous hemorrhage due to retinal neovascularization and persistent macular edema. The aim of this study was to identify the effect of the total posterior vitreous detachment on the disease prognosis. METHODS: Fifty-three patients with temporal branch vein obstruction were followed for eighteen months on average. The vitreous conditions of all patients were established, and the effect on persistent macular edema and retinal neovascularization development was statistically investigated. RESULTS: This prospective study shows that total posterior vitreous detachment has a clear preventive effect on both complications. CONCLUSION: Careful vitreous examinations of all patients with branch retinal vein occlusion give us important information about the prognosis and patient management.     

Hypertension as a risk factor for diabetic neuropathy: a prospective study

The pathogeneses of diabetic neuropathy is still unclear. This study prospectively investigated the risk factors for distal symmetrical polyneuropathy (DSP) in a cohort of childhood-onset IDDM patients. Subjects from the Epidemiology of Diabetes Complications (EDC) Study were clinically examined at baseline and then biennially. DSP was diagnosed by a combination of clinical criteria, symptoms and signs (Diabetes Control and Complications Trial [DCCT] exam), and quantitative sensory threshold (QST). Among the 463 (70.4%) subjects who were free of DSP at baseline, 453 (97.8%) participated in at least one biennial reexamination during the first 6 years of follow-up and were included in the current analysis. A total of 68 (15.0%) subjects developed DSP in 6 years, giving a cumulative probability of 0.29. The Cox proportional hazards model shows that longer IDDM duration, hypertension, poor glycemic control, height, and smoking were all independent predictors of the incidence of DSP (all P < 0.0001, except for smoking for which P = 0.03). Hypertension showed the greatest impact on the development of DSP for individuals with either short or long IDDM duration. This study confirms some risk factors for DSP found in cross-sectional studies and suggests a strong relationship between hypertension and DSP. The results indicate that in addition to good glycemic control, avoidance of smoking and good blood pressure control may be helpful in preventing or delaying the onset of DSP in IDDM patients.     

Inhibition of experimental proliferative vitreoretinopathy by retroviral vector-mediated transfer of suicide gene. Can proliferative vitreoretinopathy be a target of gene therapy?

PURPOSE: To determine the potential of somatic gene transfer as a treatment for proliferative vitreoretinopathy (PVR), experimental PVR was induced in rabbits by intraocular injection of fibroblasts bearing the herpes simplex virus thymidine kinase (HStk) gene. These transduced cells should be susceptible to cytotoxicity by exposure to ganciclovir (GCV). MATERIALS AND METHODS: Rabbit fibroblasts were transduced with retroviral vectors bearing an HStk gene. Proliferative vitreoretinopathy was induced by injection of 5 x 10(4) normal or HStk gene-transduced fibroblasts (HStk fibroblasts) into rabbit eyes. Ganciclovir (100 micrograms per eye) or saline was injected into the vitreous on days 0 and 4. Experimental animals were divided into three groups: group A received HStk fibroblasts with GCV; group B, normal fibroblasts with GCV; group C, HStk fibroblasts with saline. Proliferative vitreoretinopathy also was induced in several other groups of eyes, some receiving GCV and different proportions of HStk fibroblasts to normal fibroblasts, others receiving only normal fibroblasts and GCV. The eyes were examined by indirect ophthalmoscopy on days 4, 7, 14, and 28, and PVR was classified into six stages (0-5). RESULTS: Proliferative vitreoretinopathy was induced and progressed over time in each group. On day 28, PVR was most severe in animals in group B (average stage, 4.6) and group C (average stage, 4.4). Proliferative vitreoretinopathy was inhibited in group A (average stage, 1.0). The groups that received mixed injection of HStk fibroblasts and normal fibroblasts had intermediate PVR. Results of histologic study showed no apparent toxic or pathologic reaction in the retinochoroidal tissue of group A animals. CONCLUSIONS: Severity of experimental PVR clearly was reduced by transfer of the HStk gene and administration of GCV. This inhibitory effect also was produced by a combination of 10% HStk fibroblasts and 90% normal fibroblasts, indicating a significant bystander effect. These data suggest the potential of somatic gene therapy for the treatment of PVR.     

Radon as a risk factor for extra-pulmonary tumours

Most divers and diving medicine specialists know that application of normobaric oxygen as first aid after a bubble disease incident is highly effective. However, as yet technical difficulties acted as a deterrent to using normobaric oxygen at the diving site. This can now be overcome by a newer technique. To be efficient, any therapy of bubble disease should follow three main principles: maximal partial pressure of inhaled oxygen (i.e. 100 kpa in normobaric, and 280 kpa in hyperbaric conditions); minimal partial pressure of inhaled nitrogen, which should ideally be near zero; immediate start of therapy, if possible at the diving site, but not later than 2 hours after the onset of the first symptoms. However, it has to be borne in mind that for an efficient normobaric oxygenation (100%), the standard apparatus design without oxygen reservoir is obsolete, for it offers at most 40% oxygen to the lungs. Currently the following technical approaches for an efficient normobaric oxygenation are available: open one-way systems with tightly fitting mask and oxygen reservoir bag (type Ambu or Leardal, etc.); open systems with on-demand regulation and tightly fitting mouth piece (type SCUBA, or Bird-respirator); closed systems with CO2 absorber (type oxygen rebreathing diving gear). The closed system is a genuine technical advance, because it needs 15 times less oxygen than open systems (about 90 liters oxygen for a 3-hours oxygenation run). Such an apparatus is thus of light weight, far less cumbersome, and nevertheless highly efficient. The therapy should start immediately at the site of the mishap and be maintained during the transport to the next HBO-unit (usually 3 to 6 hours).(ABSTRACT TRUNCATED AT 250 WORDS)     

Parity as a risk factor for cancer cervix

PURPOSE: To analyze the likelihood of perioperative transfusion using the data of the abstracted patient discharge records. MATERIAL AND METHODS: It was studied the data of the records of the pediatric patients in whom were done surgical procedures for 1996. The abstracted patient discharge records are codified according the ICD-9-CM codes. RESULTS: 1,166 pediatric patients were operated, of whom were transfused 25 (2.1%). The transfusion rate was higher in patients less than 3 years old, who were operated with three o more surgical procedures simultaneously, who were admitted newly after the admittance here studied, and patients operated of spine, dorsolumbar spine, pharynx, thorax and mediastinum, central nervous system, colon, vessels and hip. CONCLUSIONS: Given the variability of the transfusion rate, to know it will allow a better planning of the surgical transfusions, the policy of the hospital blood bank and to increase the information to patient about the risk of the elective surgery.     

Destruction of the posterior hyaloid membrane in rhegmatogenous detachment of the vitreous body (author''s transl)

Five yearling wether sheep were maintained on total intravenous, fat-free feeding for periods in excess of 4 weeks. Analysis of plasma total lipid, neutral lipid, and phospholipid fatty acid patterns showed a decrease in linoleic acid during the first week, after which levels tended to stabilize. Rate of decrease in linoleic acid content of plasma phospholipids of two sheep was different. Changes in nonessential fatty acids were variable. 5,8,11- and 8,11,14-Eicosatrienoic acids were not detected in any of the sheep.     

Silicone assisted, argon laser confinement of recurrent proliferative vitreoretinopathy related retinal detachment: a technique to allow silicone oil removal in problem eyes

AIMS/BACKGROUND: Recurrent peripheral retinal detachments may occur in eyes treated with vitrectomy and silicone oil for retinal detachments complicated by proliferative vitreoretinopathy (PVR). The aim of this study was to assess whether laser photocoagulation could be used in the presence of silicone oil to confine and stabilise recurrent PVR related peripheral retinal detachments enabling the timely removal of the oil. METHODS: 10 patients with recurrent peripheral retinal detachments after vitrectomy and silicone oil insertion were treated with posturing and subsequent focal argon laser to circumscribe the area of recurrent detachment. RESULTS: This technique alone was sufficient to limit the area of retinal detachment in seven of the cases. The remaining three cases required relieving retinotomies because of increasing retinal detachment despite the laser. In all 10 cases the silicone oil was later removed without progression of the detached areas. CONCLUSION: Silicone assisted argon laser 'confinement' can be effective in stabilising eyes with peripheral retinal detachments allowing the subsequent removal of silicone oil.     

Blood transfusion as a risk factor for non-Hodgkin lymphoma

In a case-control study of 280 out of 426 consecutive patients with a recent diagnosis of non-Hodgkin lymphoma (NHL) and 1827 control subjects, 53 (19%) and 230 (13%) respectively had received blood transfusions 1 year or more before the interview. Using an age- and sex-stratified analysis the odds ratio (OR) for transfusion was 1.74 (95% CI 1.24-2.44). ORs were also determined for transfusions received in the intervals 1-5, 6-15, 16-25 and > or = 26 years before diagnosis. In the interval 6-15 years, the OR for transfusion was 2.83 (95% CI 1.60-4.99) whereas ORs for transfusions received in other intervals were lower and not significantly elevated. Histological diagnoses (Kiel classification) and results of staging procedures were known for 185 patients. For low-grade NHL of nodal B-cell chronic lymphocytic leukaemia (B-CLL) or immunocytoma type, the OR for transfusions was 4.15 (95% CI 1.92-9.01). For low-grade nodal lymphomas of follicle centre cell type and high-grade nodal lymphomas, no relation to transfusions could be demonstrated. For high-grade extranodal lymphoma as sole manifestation, OR for transfusions was 3.27 (95% CI 1.30-8.24). It is concluded that blood transfusion may be a risk factor for NHLs especially those of B-CLL or immunocytoma type and for high-grade extranodal lymphoma.     

Obesity as a metabolic risk factor

On the basis of the results of clinico-experimental examinations and of animal experiments the importance of obesity as metabolic factor of risk is confirmed and hereby the diabetes mellitus as well as cardiovascular effects are particularly taken into consideration. Conclusions are made relevant to practice and it is particularly referred to the central position of the B-cells for the pathogenesis of diabetes as well as to prophylactic and early therapeutic measures.     

Chronically elevated proliferation as a risk factor for neoplasia

Chronic disease conditions that are associated with elevated proliferation are well established as risk factors for cancer development. These may be due to viruses (for example, in the case of hepatitis and liver cancer), bacterial infections, parasite infestation or physical trauma. In addition to these exogenous agents there are also metabolic abnormalities that can contribute, caused by genetic or epigenetic influence. In the latter case, an increase in serum levels of the hormones oestrogen, testosterone and insulin may be of special importance. The present review concentrates attention on factors that induce elevated cell turnover and for which there is epidemiological and/or experimental evidence of a link with neoplasia, with particular stress on the individual organ or tissue level.     

Obesity as a risk factor for certain types of cancer

In conclusion, obesity has been associated with increased risk for a number of different types of cancer. The evidence has been most consistent for endometrial cancer, breast cancer in postmenopausal women, and renal cell cancer. More variable results have been reported for colorectal, prostate and pancreatic cancer. Possible mechanisms by which obesity may influence cancer risk include alteration in hormonal patterns, including sex hormones and insulin, and factors such as the distribution of body fat and changes in adiposity at different ages. The increasing prevalence of obesity in many parts of the world emphasizes the importance of learning more about the relationship between obesity and cancer and the mechanisms involved in their interaction.