Evaluation of a rebound tonometer (Tonovet®) in clinically normal cat eyes

Objective  To determine the accuracy of and to establish reference values for a rebound tonometer (Tonovet^®) in normal feline eyes, to compare it with an applanation tonometer (Tonopen Vet^®) and to evaluate the effect of topical anesthesia on rebound tonometry.
Procedures  Six enucleated eyes were used to compare both tonometers with direct manometry. Intraocular pressure (IOP) was measured in 100 cats to establish reference values for rebound tonometry. Of these, 22 cats were used to compare rebound tonometry with and without topical anesthesia and 33 cats to compare the rebound and applanation tonometers. All evaluated eyes were free of ocular disease.
Results  Both tonometers correlated well with direct manometry. The best agreement with the rebound tonometer was achieved between 25–50 mmHg. The applanation tonometer was accurate at pressures between 0 and 30 mmHg. The mean IOP in clinically normal cats was 20.74 mmHg with the rebound tonometer and 18.4 mmHg with the applanation tonometer. Topical anesthesia did not significantly affect rebound tonometry.
Conclusions  As the rebound tonometer correlated well with direct manometry in the clinically important pressure range and was well tolerated by cats, it appears suitable for glaucoma diagnosis. The mean IOP obtained with the rebound tonometer was 2–3 mmHg higher than that measured with the applanation tonometer. This difference is within clinically acceptable limits, but indicates that the same type of tonometer should be used in follow-up examinations in a given cat.     

Effect of nitrogen and potassium fertilizer on growth,herbage and oil yield of irrigated palmarosa (Cymbopogon martinii [roxb.] wats. var. motia burk) in a semi-arid tropical climate

The world's agricultural production is increasing by 1 to 2 per cent annually and has been enough to satisfy the growing world population's need for food. Breeding, fertilisation and crop protection have decidedly contributed to that progress in productivity. But since the 1960s, agriculture has been more and more conceived by the public as an environment-contaminating industry. The public is concerned about water contamination with nitrate as a result of the use of fertilisers, and about harmful effects of chemical plant protection products on soil, water, air, animals and wild plants. The public discussion has not remained without consequences. Sustainability of development has become a central political objective in all spheres of social life, and in all world regions. Sustainable development concerns economic, ecological as well as social objectives, and is also the guideline for a renovation of agriculture. Any concepts and strategies integrating environmental aspects into agricultural production are linked with the objective of sustainable development. Discussion on sustainable agriculture has become more concrete on the basis of the Brundtland Report and Agenda 21 , as well as the various follow-up meetings of the 1992 Conference of Rio. Although efforts towards sustainable development in agriculture encounter widespread scepticism, clear progress is to be noted since that discussion has intensified. Farmers have paid more attention to new farming practices. Environmental aspects now play an important role when extension services advise farmers on fertilisation and crop protection. Research has contributed essentially to the change in agriculture towards sustainable production. Sustainability in agriculture has also been expressed in new legal regulations. Principles of good professional practice in applying fertilisers, as it is required by the Fertilisers Act from the year 1989, have been spelled out more clearly in a legal regulation issued on 26 January 1996 (Federal Law Gazette part I of 06 February 1996, p. 118). Principles of good professional practice in crop protection were published in Bundesanzeiger (Federal Gazette) No. 220 a of 21 November 1998. Principles of integrated crop protection were first discussed by representatives of agriculture, environment protection offices and researchers at a workshop at Biologische Bundesanstalt für Land- und Forstwirtschaft (BBA, Federal Biological Research Centre for Agriculture and Forestry) in Kleinmachnow on 23° March 2000. The debate on sustainability centres around the aspects of economic and social efficiency of measures taken, and their effects on the environment. The following article deals with some basic aspects of efficiency on the one hand, and effects/emission on the environment on the other, of fertilisers and crop protection products as important input factors in agriculture. Crop husbandry always is an interference with nature. The Lüneburger Heide cropping region is a memorial of ecologically out-dated land management. Today, sustainable and at the same time efficient agriculture can only be realised with modern methods based on sound knowledge. This includes mineral fertilisation and chemical crop protection. Cropping permanently draws nutrients from the soil-plant system. They have to be refilled by fertilisation. If no fertilising measures are taken at all, the humus layer of the soil declines and soil degrades. The decline in fertility will result in yield losses of between 70 and 90%. In contrast, combination of organic and mineral fertilisers has continually added to soil fertility. This is reflected in the humus content of the soil, which is by about a quarter higher than it was a hundred years ago. Farmers resorting solely to mineral fertilisation produce yields lower by 5-10% than those combining mineral and organic fertilisers. If only organic fertilisers are used, this may reduce yields by between 10 and 40%, depending on the site. Unwanted side-effects of fertilisation (such as leaching of nitrates) may be reduced to a tolerable level by precise input of nutrients, improved methods such as precise fertiliser input depending on the condition of certain field patches, and by integrated crop protection, which relies on synergetic effects of various measures. Germany has for these reasons witnessed a relaxation of environmental pressure from excessive nutrient input. If crop protection measures were abandoned, pests and diseases would reduce yields by between 40 and 80 per cent. Our own trials about energy input-output proportions have shown a ratio of 1:4.6 with use of fertilisers (100kg N/ha), and a ratio of 1:8.6 with use of fertiliser and chemical plant protection products. The risk potential of modern chemical plant protection products has permanently decreased over the past few decades and is generally about one tenth of the values of 15 years ago. Integrated crop protection, which combines various methods of crop protection and reduces the use of chemical crop protection products to a necessary minimum, is the "optimal solution for the future" and "contributes to the sustainability of agriculture", as it is said in the Agenda 21 programme adopted by the 1992 environmental conference in Rio.     

Corneal esthesiometry in the healthy horse

Objective To determine corneal sensitivity in healthy adult horses in order to establish reference values. Animals studied One hundred eyes of 50 healthy adult horses. Procedure Corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) in five different corneal regions using a Cochet‐Bonnet esthesiometer. Results Comparing CTT values (in mm filament length) of the five prescribed corneal regions revealed regional variations in corneal sensitivity, with the central region (21.15 ± 6.23 mm) being the most sensitive, followed by the nasal (20.75 ± 5.14 mm), temporal (20.70 ± 5.37 mm), ventral (20.15 ± 5.88 mm) and dorsal (15.85 ± 3.70 mm) region. However, differences between the central, nasal, temporal and ventral regions were not statistically significant, whereas the dorsal region was significantly (P < 0.0001) less sensitive compared to the other regions. Division of the horses into three age groups revealed an insignificant decrease in corneal sensitivity with age in the nasal, temporal, ventral and central region, and an insignificant increase with age in the dorsal region. Correlation of corneal sensitivity with age was statistically significant in the central, ventral and temporal region. No statistically significant difference in the CTT was found between left and right eyes and between males and females. Conclusions CTT values in 100 eyes of 50 healthy adult horses evaluated with a Cochet‐Bonnet esthesiometer generated reference values. Reference values are necessary to determine alterations of corneal sensation accompanying various eye diseases or systemic diseases.