Transcript الشريحة 1
Schiotz tonometer Schiotz tonometer Professor Hjalmar Schiøtz, the first Director of the Eye Department at the Rikshospitalet, Oslo, from 1897 devised his impression tonometer, originally for use against the sclera of the eye, in 1905. For the next half century the Schiøtz was generally accepted as a reliable means of measuring IOP and became the first tonometer to achieve mass sales. Various fakes also hit the market Professor Hjalmar Schiøtz Schiotz tonometer The Schiotz Tonometer is an instrument that measures ocular tension by indicating the ease with which the cornea is indented * Receive an Estimate prior to doing work. * Most Schiotz Tonometers repaired and shipped back in ten business days. * We have the ability to repair Schiotz Tonometers from any manufacturer. * Our Technicians are specialists in Schiotz Tonometer instruments. * Technicians with over 30 years experience examine all Schiotz Tonometers. * All Schiotz Tonometer parts cleaned and adjusted. * Quality control evaluation for Schiotz Tonometer repair. . The Schiøtz was still offered as a ‘traditional’ instrument (with a choice of straight or oblique scale) in Keeler catalogues of the 1980s but it is now rarely used in the developed world. Before the procedure could begin the footplate had to be sterilised with absolute alcohol or by heating. The practitioner then had to wait for evaporation or cooling to occur. The patient had to be placed in a supine position, without any pillow, and undergo corneal anaesthesia (using Xylocaine). Application of an antibiotic ointment was necessary after the procedure was complete. Impression tonometers can only record a relative measurement and various unavoidable errors might occur due to contraction of the extra-ocular muscles or an eye having a particularly rigid outer coating. Accommodation (which causes IOP to drop) was also a problem, as the patient would somewhat naturally attempt to focus on the instrument heading straight for his eye. Applanation (Goldmann) tonometry This type of tonometry uses a small probe to gently flatten part of your cornea to measure eye pressure and a microscope called a slit lamp to look at your eye. The pressure in your eye is measured by how much force is needed to flatten your cornea. This type of tonometry is very accurate. advantages are: • • Easy handling • Elegant design • Anodized scale mount which is highly resistant to sterilizing wear • Independence of sources of current • Delivered in smart padded metal cases, easy to carry with The tonometer with the curved, titled scale is a special favourite, as the values can be read from the top much more easily. If glaucoma is diagnosed early, treatment can • then be given that may preserve vision. Although raised intraocular pressure (IOP) is not the only sign of glaucoma, the IOP should be checked routinely on all adults attending eye care facilities. Applanation tonometry, is the most accurate method to measure IOP, but Schiötz tonometry is also a useful screening test. If Schiötz tonometry reveals a high IOP, this result should be checked and confirmed by applanation tonometry and the patient referred to the senior clinician at the eye clinic. You will need 1*Schiötz tonometer, weights, and scale card. 2*local anaesthetic drops0 3*clean cotton wool or gauze swabs . 4*isopropyl alcohol 70 per cent (methylated spirit) or impregnated ‘Mediswabs’. Preparation Test the tonometer using the spherical mould • in the box and the 5.5 g weight. The pointer should immediately reach the ‘O’ marking Clean the plunger and disc of the tonometer • with a gauze swab (or cotton wool) and the methylated spirit (or a Mediswab). Wipe dry with a clean dry gauze swab (or cotton wool). Lie the patient flat with his or her head • supported on a pillow. Method Wash and dry your hands. • Position yourself correctly: stand upright, behind the head of the patient, • with your hands level with the patient's head. Note the health worker's good posture and the awkward position of the health worker in . Bad posture can affect the tonometry reading. Instil local anaesthetic eye drops and wait about 30 seconds. • Ask the patient to look at a fixed object (the patient's own thumb or finger • held directly in front of his or her eyes may work) and to keep absolutely still. With the thumb and index finger of one hand, gently hold open the patient's • eyelids, taking care not to put any pressure on the eye . With the other hand, hold the tonometer (with the 5.5 g weight) between • the thumb and index finger and place the plunger on the central cornea Allow the disc to lower gently onto the corneal surface. • Note the scale reading. • If the scale reading is ‘2’ or less, remove the • tonometer, replace the 5 g weight with the 7.5 g weight, and repeat the procedure. Note the scale reading again and remove the • tonometer. Tell the patient not to rub the eye - the anaesthetic will • last for about five minutes. Clean and dry the tonometer head. • Repeat the whole procedure for the other eye. • Clean and dry the tonometer again and store it safely • in the box. Using the scale card, convert the noted scale readings • and record the IOP in the patient's records. The instrument must be held perpendicular • to the eye to allow the plunger to move freely, indenting the cornea. The degree of indentation is measured by movement of a needle on a scale. Fine oscillations of the needle represent ocular pulsations, indicating free movement of the plunger and good technique. The midpoint of the needle excursion is taken as the pressure measurement. The standard force on the plunger • producing corneal indentation is a 5.5 g weight. Globes with elevated intraocular pressure will be resistant to denting by the plunger, resulting in inaccurate measurements. Three larger plunger weights are provided with the instrument and, when added to the standard 5.5 g weight, increase the total plunger weight to 7.5, 10, or 15 g. The extra weights should be used whenever the pressure reading on the instrument scale is 4 or less Since the Schiotz tonometer does not • measure pressure directly, conversion tables, supplied with the instrument, are used to translate scale readings into estimates of intra-ocular pressure. In patients with known or suspected ocular • infection, trauma, or known sensitivity to the topical anesthetic, Schiotz tonometry should not be performed by a primary-care physician. The procedure is further contraindicated in patients who cannot inhibit their blinking, because of the increased risk of corneal abrasion. The actual complication rate of tonometry is quite small, estimated from large screening programs to be less than 1 %, and includes corneal abrasions, infections, and drug sensitivity.