The effects of irradiation on the eye and optic nerve

Late effects of irradiation of the eye and optic nerve in 74 patients are reviewed. Time-dose analyses are performed for lacrimal apparatus, retinal, and optic nerve injuries. Management of radiation complications is discussed. Recommendations are made regarding radiation treatment techniques and methods of reducing the risk of late injury.     

Studies on the Production and Radioactive Labeling "2-C14"of Aflatoxin B1 by the Chlamydospore Growth Phase of Aspergillus parasiticus

Summary: A significant yield of aflatoxin B₁ was produced by the chlamydospore growth phase of Aspergillus parasiticus grown on a synthetic liquid medium. Morphology and structure of the fungus growth is fully described. The two stage addition of 2-C¹⁴-acetate to the medium proved to improve dramatically the efficiency of labeling the toxic metabolite.
Zusammenfassung: Eine signifikante Ausbeute an Aflatoxin B₁ konnte aus der Chlamydosporen-Wuchsphase von Aspergillus parasiticus auf einem synthetischen flüssigen Medium gewonnen werden. Die Morphologie des Pilzwachstums wird ausführlich beschrieben. Die Zugabe von Natriumacetat-2-C¹⁴ zu dem Medium in zwei Stufen ergab eine dramatische Steigerung der Ausbeute an markierten Toxin.     

Topical application of penicillin into hippocampal in vitro slices: A methodological study using benzyl (14C) penicillin

A gas pressure system is employed for topical application of pico/nanolitre volumes of 9 mmol/1 benzyl (¹⁴C) penicillin into guinea-pig in vitro transverse hippocampal slices. Control of pressure pulse parameters enables ejectates, computed after liquid scintillation, from 10 μm, 5 μm and 2 μm pipettes with high reliability of ejection. A detailed study was done on the ejection performance of 5 μm and 2 μm pipettes. It shows that for the 5 μm tips, with the chosen ejection parameters, feeding pressure=0.5 MPa, feeding pulse duration 50 ms, a 99% ejection incidence was obtained (n= 200). The mean volumes ejected were 0.12 and 0.5 nl (n= 50) for one and four pulses delivered respectively. The corresponding ejectate means obtained from five 2 μm pipettes given a feeding pressure of 1.5 MPa, and a feeding pulse duration of 70 ms, were 0.04 and 0.13 nl. Statistical evaluation of the individual pipette ejection performances gave characteristic regression slopes within each pipette group. A comparison between visually controlled injection into oil and injection into slice, showed a close correspondence. The applicability of the ejection method is discussed in relation to functional studies on the conversion of single neurones into “epileptic” ones.     

Panrefinal Photocoagulation Influence on Vitrectomy Results for Complications of Diabetic Retinopathy

Despite panretinal photocoagulation (PRP), some diabetic eyes develop complications that are correctable with vitrectomy. The results of vitrectomy performed on 80 eyes having previtrectomy PRP are compared with 402 eyes without photocoagulation. The preoperative findings and operative procedures were almost identical, except the PRP cases had a slightly higher incidence of preoperative iris rubeosis and traction macular detachments, and more surgical membrane peeling. Six months after vitrectomy, the PRP eyes had slightly better visual acuities and fewer detached maculas, but were otherwise almost identical to the non-photocoagulated eyes. There was no evidence that pre-vitrectomy PRP prevents postoperative iris rubeosis.     

Diabetic Retinopathy as a Cause of Blindness in the Province of Turin,North-west Italy,in 1967–1991

Diabetes is known to be a major contributor to blindness in industrialized countries but few data are available on the situation in Italy. As an introductory step to the implementation of permanent screening for diabetic retinopathy, a search was carried out on the causes of visual loss in the provincial territory surrounding Turin, the main city of North-West Italy. The case notes of all 4549 residents in the province who were certified blind between 1967 and 1991 were examined with regard to cause, age at onset, and year of onset of visual acuity 1/20. Diabetic retinopathy was the second commonest cause of bilateral blindness (13.1 % of cases), preceded by cataract (26.7%) and followed by myopia (11.1%), optic atrophy (8.9%), glaucoma (8.9%), retinitis pigmentosa (7.2%), and senile macular degeneration (4.1%). Diabetic retinopathy was the commonest eye disease among those who became blind between the ages of 50 and 70 and remained the leading cause of visual loss when the age groups 20 to 70 were pooled together. The incidence of diabetic retinopathy-related blindness did not show any trend to decrease over the 25 years investigated. It is concluded that, in spite of widespread availability of facilities for its assessment and treatment, diabetic retinopathy remains a leading cause of blindness in North-West Italy. This fully justifies the implementation of screening programmes and efficient referral chains for the early detection and prompt treatment of this complication of diabetes.     

Diabetic dense premacular hemorrhage. A possible indication for prompt vitrectomy

A review was undertaken of nine eyes of nine patients who suffered tightly bound dense premacular hemorrhage as a complication of proliferative diabetic retinopathy. Patients who did not receive vitrectomy within four weeks of the onset of the hemorrhage all progressed to late macular traction and visual acuity no better than 6/30. Of the five patients who received vitrectomy within four weeks of the onset of the hemorrhage, none developed significant late macular traction and all achieved visual acuity of 6/12 or better. It is possible that the tightly bound dense premacular hemorrhage represents an indication for vitrectomy within one month of its onset.     

The retinopathy of prematurity: medicolegal aspects

The incidence of medicolegal claims based on retinopathy of prematurity (ROP) diminished in the 1960s after the role of oxygen was presumed to be understood. It has since increased again for a number of reasons. More very premature infants are being saved. The causes of ROP are multifactorial, not well understood, and the role of oxygen as a significant factor is not always clear. Moreover, the risk/benefit ratio of supplemental oxygen is not always easy to evaluate. The morphologic features of ROP are common to a number of disorders, which may be misdiagnosed as ROP. In the series of 500 medicolegal claims that I have studied, no ophthalmologists have been sued in cases concerning ROP. However, they are routinely called as expert witnesses and it is to guide them in that role that I am reviewing the subject.     

The efficacy of additional argon laser photocoagulation for persistent, severe proliferative diabetic retinopathy

Twenty-three eyes with severe proliferative diabetic retinopathy had failed to show a satisfactory response to initial panretinal photocoagulation of approximately 3000 burns. A satisfactory response was defined as two or less retinopathy risk factors as defined by the diabetic retinopathy study (DRS). These eyes were treated with additional, extensive ablative laser therapy. Twelve of the 23 eyes showed a satisfactory response after an average of 7550 burns. Eleven eyes failed to show a satisfactory response after an average of 7985 burns. Forty-five percent of eyes that failed to show a satisfactory response suffered a severe decrease in visual acuity to count fingers or less. Additional extensive laser therapy can induce a satisfactory response in approximately 50% of resistant nonresponder eyes. Failure to respond to such therapy indicates a poor prognosis.     

Alterations in Blood Elements in the Pathogenesis of Diabetic Retinopathy

The role of altered blood elements in the pathogenesis of retinal ischemia and diabetic retinopathy and the relationship to abnormal carbohydrate metabolism and to elevated levels of growth hormone are discussed. These changes involve red blood cells, platelets, plasma proteins, fibrinolytic response, and vascular endothelium. The significance of blood elements mediated by plasma is noted with aggregation of normal red cells when cross-matched with diabetic plasma and with intensive plasmapheresis, which caused red cell disaggregation and improvement of retinopathy. The relationship of metabolic control to diabetic retinopathy is reviewed and is evident by improvement of retinopathy occurring eight weeks after continuous subcutaneous infusion of insulin. A hypothesis is presented which integrates the multifactorial processes involved in the pathogenesis of diabetic retinopathy. Only through future research can one prove the implicated mechanisms in the pathogenesis of diabetic retinopathy and the role of strict metabolic control in altering the progression of retinopathy.     

Hypertensive Retinal Vascular Changes: Relationship to Left Ventricular Hypertrophy and Arteriolar Changes Before and After Treatment

Eye-ground-photos were taken in twenty-eight previously untreated men with mild to moderate essential hypertension. The same eye was evaluated before and after 26 weeks of double-blind treatment with Enalapril or Hydrochlorothiazide. The vascular changes were assessed by using a more elaborate and refined grading than the Keith-Wagener-Barker scale. All photos were examined by the same observer without knowledge of blood pressure, type of treatment or the order in which the photos had been taken. There were significant positive correlations between the vascular alterations in the retina in the untreated state and left ventricular wall thickness (echocardiography), minimal vascular resistance in the calf (plethysmography) and blood pressure respectively. Treatment with Enalapril decreased the reflection of the retinal arterial wall significantly and reduced the narrowing of arteries and arterio-venous crossing phenomena non-significantly. Hydrochlorothiazide did not affect any of the retinal vascular changes. It can be concluded that this relatively simple technique of evaluating eye-ground-photos with a new grading scale, when used in non-malignant hypertension, gives a useful assessment of the degree of hypertensive target organ damage in the retina as well as in other important target organs, i.e. the heart and vascular beds. In addition, Enalapril positively affects hypertensive retinopathy in contrast to Hydrochlorothiazide, reflecting what happens to structural cardiovascular changes in the rest of the body.