Tonometry applanation

Applanation tonometry elevated IOP (greater than 21 mm Hg) may be present however, a patient can have signs of optic neuropathy without elevated IOP. 

Topical anesthesia is necessary for applanation tonometry and gonioscopy. Proparacaine and benoxinate are most... 

Figure l6-6 Cornea partially flattened by applanation tonometer. The apices of the fluorescein-stained wedges above and below the flattened area are too dilute to be visible. The 3.06-mm end point of applanation appears to have been reached but in reality consists of a smaller flattened area. (Modified and reprinted with permission from Moses RA. Fluorescein in applanation tonometry. Am J Ophthalmol 1960 49 1149-1155.)... 

Reprinted with permission from Bright DC, Potter JW, Allen DC, et al. Goldmann applanation tonometry without fluorescein. Am J Optom Physiol Optics 1981 58 1120-1126. 

Goldmann H. Applanation tonometry. In Newell FW, ed. Glaucoma. New York Josiah Mach, Jr. Foundation, 1956 167-220. 

Applanation tonometry A-scan ultrasonography B-scan ultrasonography Contact lens fitting Cultures Cytology... 

Instilling topical anesthesia before the mydriatic enhances patient comfort and reduces tearing from the stinging caused by the mydriatic drops. In addition, if applanation tonometry has been performed immediately before dilation, then the patient is already anesthetized, and any corneal epithelial disruption caused by the tonometer can enhance the dilation. 

The cocaine test is valid only if the cornea is intact, so it is important that the clinician not perform applanation tonometry before the test. In addition, the test is not as effective on darkly pigmented irides as it is on lighter irides.The patient should be informed that he or she may have a positive urine test for cocaine for 24 hours after the test. 

The careful monitoring of lOP with applanation tonometry at each follow-up visit is an important aspect of postoperative management. lOPs that are either elevated or depressed outside the expected range for a particular patient are considered to be a postoperative complication and should be managed accordingly (see Managing Complications, below). 

The patient may report episodes of watering or tenderness. When reduced lOP is fc>imd by applanation tonometry, a careful examination of the woimd is necessary.This inspection is achieved by painting sodium fluorescein over the cataract incision to observe for Seidel s sign. Occasionally, the auxiliary incisions can leak, so they should also be examined. The clinician should note the appearance of the cornea, which often shows endothelial folds. After the instillation of sodium fluorescein, a waffled appearance of the cornea is generally apparent if the lOP is markedly reduced (Figure 30-3). In addition, the anterior chamber depth should be assessed as well as the presence of inflammation. The pupils should be dilated and a retinal examination should be performed to rule out serous or hemorrhagic choroidal separations or a retinal break or detachment. 

To obtain applanation tonometry readings that are relatively unaffected by contact lens-induced or diurnal variations, contact lens wearers should remove their contacts on the day of their examination and leave them out for at least 2 hours before the tonometry measurement. For patients who are scheduled for appointments near the time of their awakening, it is advisable to obtain applanation tonometry readings after the patient has been awake for at least 2 hours. 

New Aftematives to Applanation Tonometry. In an effort to address the biomechanical variables associated with the measurement of lOP, new lOP measuring devices have been developed and introduced.Two notable instruments are the dynamic contour (Pascal) tonometer and the ocular response analyzer (Reichert) tonometer. These technologies... 

The applanation tonometry reading should be obtained after the patient has been awake fc>r at least 2 hours. 

Induction of ocular hypertension after corticosteroid administration depends on the specific drug, the dose, the route and frequency of administration, and the corticosteroid responsiveness of the patient. Generally, patients with elevated lOP are asymptomatic, so examination with applanation tonometry is the key to diagnosis. If the patient shows a steroid responsiveness, the onset of lOP elevations is not immediate but occurs after approximately 2 weeks of use. However, it can occur many weeks later, and this time to onset is generally longer for systemic steroids. In responsive patients the level of lOP rise with systemic steroids averages approximately 60% of that produced by topically applied steroids. 

Ehlers N, Bramsen T, Sperling S (1975) Applanation tonometry and central corneal thickness. Acta Ophthalmol (Copenh) 53 1974-1983. 

Ballantyne, B., Gazzard, M.F., and Swanston, D.W., Applanation tonometry in ophthalmic toxicology, in Current Approaches in Toxicology, Ballantyne, B., Ed., John Wright, Bristol, 1977a, pp. 158-192. 

Ballantyne, B., Applanation tonometry and corneal pachymetry for prediction of eye irritating potential. The Pharmacologist, 28, 173, 1986. 

The effect of solutions of CR in PEG 300 on rabbit corneal thickness was studied in vivo (optical pachymeter) in the range 0.05 to 10%. Peak increases in thickness were measured between 1 and 6 h post-instillation and returned to normal between 2 and 10 days, depending on concentration. The effect on IOP of solutions of CR in PEG (0.5 to 5%) was investigated in the rabbit eye in vivo (applanation tonometry). Peak increases in IOP were measured at 10 min post-instillation for concentrations of 1% and above, ranging 20 to 40% and concentration-dependent (Ballantyne et al., 1975). 

The effects of solutions of CR on IOP in humans was studied in carefully controlled volunteer studies in which 0.04 ml of either 0.05% or 0.1% CR dissolved in PEG 300 was applied to the surface of the cornea. IOP was measured by applanation tonometry before application of CR... 

Fluorescein, a dye, is nsed as a diagnostic aid in corneal abrasions and foreign bodies for fitting hard contact lenses lacrimal patency fundns photography and applanation tonometry. 

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