Optic Nerve Diameter Calculator

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

</head> <body>

<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

Use this test to estimate the optic nerve diameter (in whichever direction) of the Heidelberg Spectralis optic nerve report. This report must show an image of the optic nerve head and the green peripapillary ring

1. Spectralis OCT Optic Nerve Report
2. Measure ring diameter
3. Measure optic nerve diameter

calculator