
## Summary Table: causes of erroneous IOP readings on Goldmann
<div className="bg-blue-200 px-4 rounded-md shadow-lg dark:text-gray-700">
  <table>
    <tbody>
      <tr>
        <td>
          <span className="font-semibold">Falsely low</span>
        </td>
        <td>
          <span className="font-semibold">Falsely high</span>
        </td>
      </tr>
      <tr>
        <td>Corneal oedema</td>
        <td>High CCT</td>
      </tr>
      <tr>
        <td>Low CCT</td>
        <td>Digital pressure</td>
      </tr>
      <tr>
        <td>Previous refractive surgery</td>
        <td>Corneal scar</td>
      </tr>
      <tr>
        <td>Too little fluorescein</td>
        <td>Too much fluorescein</td>
      </tr>
      <tr>
        <td>&gt;3D with-the-rule astigmatism</td>
        <td>&gt;3D against-the-rule astigmatism</td>
      </tr>
      <tr>
        <td>High myopia</td>
        <td>&nbsp;</td>
      </tr>
    </tbody>
  </table>
</div>

## Principles
<ul>
  <li>Based on Imbert-Fick principle</li>
  <ul>
    <li>P=F/A</li>
  </ul>
  <li>
    Force of application is directly proportional to the intraocular pressure when the area of
    applanation equals 3.06mm
  </li>
  <ul>
    <li>This area of contact occurs when the mires are aligned at their inner margins</li>
    <li>
      At this area, the additional forces of corneal rigidity and surface tension are balanced
    </li>
  </ul>
  <li>
    The tonometer scale is in &ldquo;dynes&rdquo; so is multiplied by ten to give an IOP in mmHg
  </li>
  <li>
    Prisms are used in the tonometer head to split the operator&rsquo;s view of the tear meniscus
    stained with fluorescein, to allow precise adjustment
  </li>
</ul>
<HotTopic>
  <p>
    <span className="font-semibold">Hot topic</span>: Goldmann relies on the false assumption that there is little
    variability between human eyes in terms of corneal thickness and rigidity
  </p>
</HotTopic>


Summary Table: causes of erroneous IOP readings on Goldmann Falsely low Falsely high Corneal oedema High CCT Low CCT Digital pressure Previous refractive…

Clinical Techniques

Goldmann Tonometry

Intro

FRCOphth Part 1 Study Notes

Orbit and ocular adnexae

Orbit

Extraocular Muscles

Orbital Blood Vessels

Paranasal Sinuses

Lacrimal Glands

Tear Film

Eyelids

Blinking

Anterior segment - ocular surface

Conjunctiva

Conjunctivitis

Sclera

Cornea

Corneal Structure And Development

Corneal Physiology

AC to Lens

Angle

Ciliary Body

Aqueous Humour Dynamics

Iris

Pupil

Lens

Posterior segment

Choroid

Vitreous

Retinal Macrostructure

Neurosensory Retina

Retinal Pigment Epithelium

Neuroanatomy

Venous Sinuses

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Cerebral Blood Supply

Supranuclear Gaze Pathways

Head And Neck Autonomic Nervous Supply

Head And Neck Glands

Osteology

Nerves

Muscles And Pharyngeal Arches

Extraocular Nerves

Sensory Nerves

Physiology

Physics Of Blood Flow

Neuronal Control Of Blood Vessels

Oxygen-Haemoglobin Dissociation Curve

Cytochrome p450

Pituitary Gland

Thyroid Hormone Production

Insulin

Glucagon

Parathyroid Hormone

Corticosteroids

Catecholamines

Cardiac Cycle

Renal Physiology

Fluid Balance

Acid-Base Balance

Muscle Physiology

Sensory Fibres

Cutaneous Receptors

Endocytosis

Glycosaminoglycans

Condensed Ocular Biochemistry

Eye Movements

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Visual Pathway

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Histones

MicroRNA

Hardy-Weinberg Equilibrium

Mutations

Chromosome Defects

Autosomal Inheritance

X-Linked Inheritance

Mitochondrial Inheritance

Multifactorial Inheritance

Falsely low	Falsely high
Corneal oedema	High CCT
Low CCT	Digital pressure
Previous refractive surgery	Corneal scar
Too little fluorescein	Too much fluorescein
>3D with-the-rule astigmatism	>3D against-the-rule astigmatism
High myopia