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Optic Disc Area Calculator

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<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Calculate D</title>

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<h3>Estimate Disc Area from the Heidelberg Spectralis OCT optic nerve report</h3>
<form id="calc-form">
  <label for="a">Measure ring diameter (mm):</label>
  <input type="number" id="a" step="any" placeholder="Enter Ring Diameter" required><br><br>
  <label for="b">Measure horizontal disc diameter (mm):</label>
  <input type="number" id="b" step="any" placeholder="Enter Horizontal Disc Diameter" required><br><br>
  <label for="c">Measure vertical disc diameter:</label>
  <input type="number" id="c" step="any" placeholder="Enter Vertical Disc Diameter" required><br><br>
  <button type="button" onclick="calculateD()">Calculate</button>
</form>
<br><br>
<p id="result"></p>
<script>
  function calculateD() {
    // Get input values
    const a = parseFloat(document.getElementById("a").value);
    const b = parseFloat(document.getElementById("b").value);
    const c = parseFloat(document.getElementById("c").value);
    // Check for valid input and ensure A is not zero
    if (isNaN(a) || isNaN(b) || isNaN(c) || a === 0) {
      document.getElementById("result").textContent = "Please enter valid numbers for ring diameter, horizontal and vertical disc diameters. Values must not be zero.";
      return;
    }
    // Calculate D using the formula D = π * (3.0625 * B * C) / (A^2)
    const d = Math.PI * (3.0625 * b * c) / (a * a);
    // Display the result in bold
    document.getElementById("result").innerHTML = `The estimated disc area is: <strong>${d.toFixed(2)} mm2</strong>`;
  }
</script>

</body> </html>

Test Procedure

1. Obtain the Heidelberg Spectralis optic nerve report. The report must show an image of the optic nerve head and the superimposed peripapillary ring where peripapillary segmentation was performed.

2. Measure ring diameter
3. Measure horizontal optic nerve diameter
4. Measure vertical optic nerve diameter

See Normative Data for Optic Disc Area

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