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// ═══════════════════════════════════════════════════════════
//  SLIDES
// ═══════════════════════════════════════════════════════════

// 1. Title
addTitleSlide(
  "Keratometry",
  "Principles, Technique, Interpretation & Clinical Applications"
);

// 2. Agenda
addContentSlide(
  "Agenda",
  [
    "1.  What is Keratometry?",
    "2.  Optical Principles & Instrumentation",
    "3.  Manual vs. Automated Keratometry",
    "4.  Performing Keratometry – Step-by-Step",
    "5.  Reading K-Values: Units & Normal Ranges",
    "6.  Interpreting Irregular Mires",
    "7.  Clinical Applications (IOL, LASIK, Keratoconus, CL fitting)",
    "8.  Limitations & Pitfalls",
    "9.  Corneal Topography vs. Keratometry",
    "10. Key Takeaways & Exam Pearls"
  ],
  "Overview of presentation structure"
);

// ─── SECTION 1 ───────────────────────────────────────────
addDivider("Part 1", "Principles & Instrumentation");

// 3. What is Keratometry?
addContentSlide(
  "What is Keratometry?",
  [
    "Measurement of the anterior corneal surface curvature in two principal meridians (steepest and flattest)",
    "Results expressed as radius of curvature (mm) or dioptric power (D)",
    "Conversion: D = (n-1) / r, where n = refractive index of cornea (1.3375) and r = radius in metres",
    "A keratometer measures only the central ~3–4 mm of the cornea — it is not a full corneal map",
    "Classic keratometers use the Mire reflection principle (Helmholtz / Javal-Schiotz designs)",
    "Steepest meridian = K1 (axis of higher power); Flattest = K2 (axis of lower power)"
  ],
  "Keratometry literally means 'corneal measurement'. The cornea provides ~2/3 of the total refracting power of the eye (~43 D out of ~60 D total)."
);

// 4. Optical Principle
addContentSlide(
  "Optical Principle – How It Works",
  [
    "The convex cornea acts as a convex mirror; the size of the reflected image of a target (mire) depends on corneal curvature",
    "Flatter cornea → larger reflected image; Steeper cornea → smaller reflected image",
    "Doubling prism: two slightly displaced images are brought into alignment – eliminates movement artefact and allows precise endpoint",
    "One-position instruments (Bausch & Lomb): two mires aligned simultaneously; measures both meridians in one setting",
    "Two-position instruments (Javal-Schiotz): rotate 90° to measure each meridian separately",
    "Formula: r = 2d × (I/O), where r = radius, d = instrument distance, I = image size, O = object size"
  ],
  "The doubling prism is the key to accurate keratometry — it removes parallax error caused by patient movement."
);

// 5. Instruments
addTwoColSlide(
  "Manual vs. Automated Keratometry",
  "Manual Keratometer",
  [
    "Bausch & Lomb (1-position) or Javal-Schiotz (2-position)",
    "Operator aligns mire rings manually",
    "Skilled operator needed; ~5 min per eye",
    "Resilient — works without power",
    "Gold standard for contact lens fitting verification",
    "Range: typically 36–52 D (5–9 mm radius)"
  ],
  "Automated Keratometer",
  [
    "Autorefractor/keratometer combo (Topcon, Nidek, Huvitz)",
    "Infrared targets; rapid (<30 sec)",
    "Less operator skill required; repeatable",
    "Integrated with biometry units (IOLMaster, Lenstar)",
    "Same central 3-4 mm sampling zone limitation",
    "Can miss irregular astigmatism"
  ]
);

// ─── SECTION 2 ───────────────────────────────────────────
addDivider("Part 2", "Technique & Reading K-Values");

// 6. Technique – Step by Step
addContentSlide(
  "Performing Keratometry – Step by Step",
  [
    "1. Remove contact lenses: soft CLs – 1 week prior; rigid/RGP CLs – minimum 3–6 weeks prior to allow corneal stabilization",
    "2. Position patient at slit-lamp height; instruct to fixate the central target",
    "3. Focus the eyepiece on the mire rings (adjust diopter wheel to clinician's refraction)",
    "4. Align instrument axis with patient's visual axis; ensure the rings are centred",
    "5. Note the two principal meridians and bring mire images into correct alignment",
    "6. Read K1 (flat meridian, lower power) and K2 (steep meridian, higher power) + axis",
    "7. Take 3 readings per eye; accept if ≤0.25 D variation; record mean",
    "8. Note mire quality: regular circles = regular astigmatism; distorted/broken mires = irregular cornea"
  ],
  "CL discontinuation is one of the most commonly tested clinical points. Failure to discontinue leads to false corneal curvature readings."
);

// 7. Reading K-Values
addContentSlide(
  "Reading K-Values – Units & Normal Ranges",
  [
    "Average K: 43.25 D (range ~40–47 D) | radius ~7.8 mm (range 7.2–8.4 mm)",
    "Flat K (K1 / Km): lower diopter, longer radius — corresponds to flattest meridian",
    "Steep K (K2 / KM): higher diopter, shorter radius — corresponds to steepest meridian",
    "Corneal astigmatism = K2 − K1 (in dioptres); cylinder axis recorded with each reading",
    "Regular astigmatism: principal meridians ~90° apart",
    "Rule: with-the-rule (WTR) → steep at 90° ± 30°; against-the-rule (ATR) → steep at 180° ± 30°; oblique → any other axis",
    "Average corneal astigmatism in adults: ~0.5–1.0 D WTR",
    "Keratometric index used: 1.3375 (standard); some instruments use 1.332 — be aware when comparing"
  ],
  "Normal K reading: ~43 D / 7.8 mm. Any reading >47.2 D or <40 D is outside normal range and warrants further investigation."
);

// ─── SECTION 3 ───────────────────────────────────────────
addDivider("Part 3", "Interpretation & Clinical Applications");

// 8. Interpreting Mires
addContentSlide(
  "Interpreting Keratometer Mires",
  [
    "Regular mires (round, smooth): normal cornea or regular astigmatism — predictable refraction",
    "Irregular mires (distorted, oval, broken, doubled): suggests irregular astigmatism → investigate further",
    "Causes of irregular mires:",
    "   - Keratoconus: inferior steepening, mires egg-shaped / displaced inferiorly, K often >47 D",
    "   - Pellucid marginal degeneration: 'butterfly' topography; irregular inferiorly",
    "   - Corneal scar or dystrophy: focal distortion at scar site",
    "   - Dry eye / tear film instability: mires fluctuate with blinking",
    "   - Contact lens warpage: normalises after CL cessation",
    "   - Previous refractive surgery (PRK/LASIK): flat central K, unreliable readings"
  ],
  "Irregular mires are a red flag — never proceed with LASIK or IOL calculation without corneal topography if mires are distorted."
);

// 9. IOL Calculation
addContentSlide(
  "Clinical Application 1 – IOL Power Calculation",
  [
    "Keratometry is one of the two essential inputs in all IOL formulas (the other: axial length)",
    "Modern biometry devices (IOLMaster 700, Lenstar LS900) integrate keratometry measurement",
    "Commonly used formulas: SRK-T, Hoffer Q, Holladay 1 & 2, Haigis, Barrett Universal II, Kane",
    "Short eyes (AL <22 mm): Hoffer Q, Haigis, Hill-RBF, Kane preferred",
    "Long eyes (AL >26 mm): BUII, Holladay, Haigis (optimised constant), Kane preferred",
    "Post-refractive surgery: standard K readings unreliable — use True Net Power, contact lens method, Haigis-L, or Barrett True-K formula",
    "Personalized A-constant: surgeons should optimise constants using their own outcomes data",
    "Goal: 90% of patients within ±1.0 D of target refraction; ~67% within ±0.5 D"
  ],
  "Source: Kanski's Clinical Ophthalmology 10th ed., Biometry chapter. Post-refractive surgery eyes are the highest-yield clinical scenario for exam questions."
);

// 10. Refractive Surgery
addContentSlide(
  "Clinical Application 2 – Refractive Surgery Screening",
  [
    "Preoperative keratometry is mandatory before LASIK, PRK, SMILE",
    "Concerns:",
    "   - K >47 D (steep) or K <41 D (flat): raises suspicion for ectasia risk",
    "   - Asymmetric bowtie or irregular mires: must obtain corneal topography/tomography",
    "   - Central K asymmetry >1 D between eyes: investigate",
    "Contact lens-induced corneal distortion: soft CLs – discontinue 2 weeks; hard/RGP CLs – ≥3 weeks (some recommend 1 week per year of wear)",
    "After LASIK/PRK: flat central K (central flattening by photoablation) — K readings underestimate true corneal power → causes hyperopic surprise if used uncorrected for IOL",
    "Irregular mires = exclude irregular astigmatism, keratoconus, forme fruste keratoconus before surgery"
  ],
  "LASIK candidate screening: any irregular mires on keratometry mandate full topography/tomography before proceeding."
);

// 11. Keratoconus
addContentSlide(
  "Clinical Application 3 – Keratoconus Screening",
  [
    "Keratometry findings in keratoconus:",
    "   - K readings: steep (often >47 D, sometimes >50–55 D in advanced disease)",
    "   - Irregular mires: asymmetric, egg-shaped, inferior displacement",
    "   - Asymmetric astigmatism between eyes",
    "   - Scissors reflex on retinoscopy correlates with irregular mires",
    "Keratometry alone is insufficient — corneal topography/tomography is the gold standard for detection",
    "Topography hallmarks: central/inferior steepening, asymmetric bowtie, KISA index elevated",
    "Tomography (Pentacam/Scheimpflug) adds: posterior elevation, pachymetry, thinnest point displacement",
    "Repeat keratometry during CXL follow-up: flattening of K values indicates treatment response"
  ],
  "Source: Kanski's Clinical Ophthalmology 10th ed. — Keratometry readings steep + irregular mires = keratoconus until proven otherwise."
);

// 12. Contact Lens Fitting
addContentSlide(
  "Clinical Application 4 – Contact Lens Fitting",
  [
    "Keratometry provides base curve guidance for rigid contact lens fitting",
    "Rigid/RGP lens base curve selected relative to flat K (K1):",
    "   - Fit-on-K (aligned): base curve = flat K reading",
    "   - Steeper than K: vaulted fit (for keratoconus)",
    "   - Flatter than K: flatter fit (larger diameter lenses)",
    "Soft CLs: less dependent on K readings; base curve mostly 8.3–8.6 mm for standard CLs",
    "Keratoconus fitting: scleral lenses / speciality RGPs — K only guides initial selection; fluorescein pattern assessment is definitive",
    "Post-surgical corneas (post-LASIK, post-PK): K readings guide initial fitting; require speciality lenses",
    "Orthokeratology: baseline K required to design reverse-geometry lenses"
  ],
  "K readings give the starting base curve for RGP/scleral fitting. Always confirm with fluorescein pattern assessment at the slit lamp."
);

// ─── SECTION 4 ───────────────────────────────────────────
addDivider("Part 4", "Limitations, Topography Comparison & Key Pearls");

// 13. Limitations & Pitfalls
addTwoColSlide(
  "Limitations & Common Pitfalls",
  "Limitations",
  [
    "Samples only central 3–4 mm of cornea",
    "Cannot detect paracentral or peripheral ectasia",
    "Assumes cornea is a sphere — misses asphericity (Q-value)",
    "Uses fixed keratometric index (1.3375) — approximation only",
    "Cannot measure posterior corneal surface",
    "Unreliable after refractive surgery",
    "Poor sensitivity for early keratoconus (topography superior)"
  ],
  "Common Clinical Errors",
  [
    "Not discontinuing CLs before measurement",
    "Accepting irregular mires without further work-up",
    "Using standard K for IOL after LASIK/PRK",
    "Confusing flat vs. steep K axis orientation",
    "Using different instruments between visits (index variation)",
    "Tear film instability — ask patient to blink before reading",
    "Misidentifying ATR vs WTR astigmatism"
  ]
);

// 14. Topography vs Keratometry
addContentSlide(
  "Corneal Topography vs. Keratometry",
  [
    "Keratometry: measures 2 points (steepest & flattest meridians), central 3–4 mm only",
    "Corneal Topography (Placido-disc): maps ~8,000–10,000 points, anterior surface, 9–11 mm zone",
    "   → Better at: detecting irregular astigmatism, screening keratoconus, monitoring ectasia",
    "Corneal Tomography (Scheimpflug / Pentacam, Orbscan): adds posterior surface + pachymetry",
    "   → Best for: comprehensive pre-refractive surgery screening, posterior elevation, ectasia risk",
    "Simulated K (SimK) from topography ≈ keratometry K-values but derived from more data points",
    "Anterior segment OCT (MS-39, Anterion): highest resolution; images all corneal layers",
    "When to upgrade from keratometry to topography/tomography:",
    "   - Pre-LASIK/PRK/SMILE screening",
    "   - Irregular mires on keratometry",
    "   - Suspected keratoconus or ectasia",
    "   - Post-keratorefractive cornea before cataract surgery"
  ],
  "The hierarchy: Keratometry → Topography → Tomography, in increasing diagnostic depth."
);

// 15. IOL Formula Table
addTableSlide(
  "IOL Formula Selection – Quick Reference",
  ["Formula", "Best for", "Inputs Required", "Notes"],
  [
    ["SRK-T", "Normal eyes (AL 22–26 mm)", "K, AL, A-constant", "Most widely used historically"],
    ["Hoffer Q", "Short eyes (AL <22 mm)", "K, AL, ACD", "May overestimate power in long eyes"],
    ["Holladay 1 & 2", "Normal to long eyes", "K, AL, ACD ± WTW", "H2 adds more parameters"],
    ["Haigis", "Wide range; post-refractive", "K, AL, ACD", "3 constants; optimised for post-Rx"],
    ["Barrett Universal II", "Long eyes (>26 mm)", "K, AL, ACD, LT, WTW", "Current best-performer"],
    ["Kane", "Short + long eyes", "K, AL, ACD, LT, WTW, gender", "AI-enhanced; strong evidence"],
    ["Hill-RBF", "Short eyes", "Multiple biometry inputs", "Machine learning-based"]
  ]
);

// 16. Key Pearls / Takeaways
addContentSlide(
  "Key Takeaways & Exam Pearls",
  [
    "Normal K: ~43.25 D / 7.8 mm radius; range 40–47 D",
    "K >47.2 D → suspicious for keratoconus; K <40 D → unusually flat",
    "Mire distortion is a red flag — always investigate with topography/tomography",
    "Soft CL cessation: 1 week before; RGP CL cessation: 3–6 weeks before keratometry",
    "Post-refractive surgery K is systematically underestimated → use special IOL formulas",
    "IOL formulas: short eyes → Hoffer Q / Kane; long eyes → BUII / Kane",
    "Keratometry ≠ corneal topography — know when to escalate the investigation",
    "Personalized A-constant optimisation improves refractive outcomes over time",
    "Astigmatism axis: WTR (steep at 90°) natural with youth; ATR shift common with age",
    "Always confirm 3 consistent readings; repeat if range >0.25 D"
  ],
  "These are the highest-yield clinical and examination points from this topic."
);

// 17. Final Thank You slide
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