Temporal association is not the same as medical causation. A patient may first notice blurred vision after an accident, injection, surgery, or medication change, yet the timing alone does not establish that the event produced the deficit. Ophthalmic causation requires a plausible mechanism supported by objective findings and a clinical course that fits the clinical picture.
This distinction is especially important because many eye diseases develop silently. Glaucoma is the perfect example. I warn my patients who have it that it is a sinister disease that never sleeps and that is why they need careful follow-up. It can cause progressive field loss before a patient recognizes it. Other conditions can do the same thing: diabetic retinopathy, macular degeneration, epiretinal membrane, cataract, amblyopia in children, high myopia in adults, and prior retinal disease may all limit vision or make an eye more vulnerable. The event in dispute may be the cause, a contributing factor, a trigger that made an existing condition symptomatic, or merely the occasion on which the condition was discovered.
Build the visual baseline
The best starting point is the patient's pre-event visual baseline. Prior eye records may document best-corrected acuity, refraction, intraocular pressure, optic nerve appearance, visual fields, OCT imaging, retinal photographs, lens status, or prior complaints. Even routine optometry records can be decisive. Without that baseline, an expert must be careful not to assume that pre-event vision was normal. As my freshman sociology professor explained as he spelled the word "assume" on the chalkboard: "When we assume we often make an A-S-S out of U and M-E."
Post-event findings should then be tested against the proposed mechanism. Direct ocular trauma may produce hyphema, angle recession, lens damage, retinal tears, commotio retinae, choroidal rupture, optic neuropathy, or globe injury. A medication claim should be compatible with known ocular toxicity, dose, duration, and pattern of damage. A delayed-diagnosis claim should identify how the untreated disease progressed during the period of delay.
Use chronology, anatomy, and probability
A defensible causation analysis aligns three elements. First is chronology: Did symptoms and objective changes arise in a medically coherent sequence? Second is anatomy: Do the location and pattern of injury match the alleged mechanism of injury? Third is probability: Are competing explanations more or less likely when we consider the patient's age, disease burden, risk factors, and prior records?
The opinion should also distinguish aggravation from creation. An incident may exacerbate a pre-existing condition without being responsible for the entire impairment. Apportionment is not always possible with mathematical precision, but uncertainty should be acknowledged rather than hidden behind an absolute conclusion.
Serial testing can strengthen or weaken the proposed relationship. OCT scans may show whether retinal or optic nerve damage was already present, stable, or progressive. Visual fields may reveal a pattern consistent with glaucoma, neurologic disease, or unreliable performance. Fundus photographs, corneal topography, ultrasound, and operative findings can provide similar clues. Objective change over time is usually more persuasive than a single test obtained after litigation has already begun.
Authoritative references
Disclaimer: This article is provided solely for general educational purposes. It does not constitute legal or medical advice, establish an attorney-client, physician-patient, or expert-client relationship, or provide an expert opinion concerning any particular matter. The discussion is general, may not reflect later changes in the law or medicine, and should not be relied upon in making litigation, legal, or clinical decisions. Attorneys should independently verify the governing law and consult qualified counsel in the applicable jurisdiction. Medical conclusions require review of the complete facts and records of the individual case.