Ticks transmit more than Lyme. A bite can introduce more than one pathogen at a time — Borrelia burgdorferi (Lyme), Babesia microti (a malaria-like blood parasite), Anaplasma phagocytophilum, an Ehrlichia species, and in some discussions Bartonella henselae. Rickettsia rickettsii, the cause of Rocky Mountain spotted fever, is carried by a different tick but sits in the same clinical universe of acute, antibiotic-treatable tick-borne infection.
Several have documented ophthalmologic findings. Bartonella has the densest ocular literature; Rocky Mountain spotted fever has well-described retinal manifestations in severe disease; the others are case-report rarities. Lyme is covered in a separate post on Lyme disease and vision changes, and we will not re-narrate the Borrelia literature here.
A note on framing. Some patient communities — particularly those that grew out of the Lyme-literate clinical network — treat persistent Bartonella, Babesia, and other co-infections as chronic systemic illnesses, sometimes pairing them with a chronic-Lyme framework. Mainstream infectious disease holds that acute disease is antibiotic-responsive and that persistent post-infectious symptoms are real but not consistently linked to ongoing infection. We will not adjudicate. We will lay out what is published, name where the camps disagree, and stay neutral.
The major non-Lyme tick-borne infections
A brief anchor of names to pathogens before turning to the ocular literature.
Babesiosis (Babesia microti, less commonly Babesia duncani) is a protozoal red-blood-cell parasite producing a malaria-like illness — fever, chills, fatigue, anaemia — that can be severe in patients without a functioning spleen, on immunosuppression, or over age 50. The standard recent review is Vannier and Krause, 2012, New England Journal of Medicine.
Bartonellosis in tick-related discussions usually refers to Bartonella henselae, the cause of cat-scratch disease. The dominant transmission route is cat-scratch and flea exposure rather than tick bite, but the bacterium appears in the tick-borne literature because tick transmission is documented and because Bartonella turns up as a co-infection in tick-illness clinics.
Anaplasmosis (Anaplasma phagocytophilum) and ehrlichiosis (Ehrlichia chaffeensis and relatives) are intracellular bacterial infections of white blood cells. Both produce acute febrile illness, both respond to doxycycline, and ocular involvement is uncommon.
Rocky Mountain spotted fever (RMSF, Rickettsia rickettsii) is the most severe of the classical United States tick-borne illnesses. The pathogen invades vascular endothelial cells, producing a systemic vasculitis that explains both the rash and the more serious complications. RMSF is a medical emergency: untreated case fatality is substantial, and early empirical doxycycline is standard of care.
Tick-borne encephalitis (TBE), a flavivirus rare in the Americas and more relevant in Europe and Asia, can include optic-pathway findings in severe disease.
What's documented in mainstream ophthalmology
The most-cited recent overview is Raja, Starr, and Bakri's 2016 Survey of Ophthalmology review of ocular manifestations of tick-borne diseases (Raja, Starr & Bakri, 2016). Its calibration is worth quoting carefully: vision-threatening ophthalmologic manifestations are relatively common in Lyme disease and Rocky Mountain spotted fever; ocular involvement is rare in babesiosis, ehrlichiosis, anaplasmosis, tick-borne relapsing fever, and the more unusual North American tick-borne infections. The bulk of the published ocular literature in this space is on Bartonella and RMSF, with everything else sitting at the case-report end of the evidence.
Bartonella
The single most-documented ocular finding across the non-Lyme tick-borne infections is Bartonella neuroretinitis with macular star — optic disc oedema accompanied by a fan-shaped pattern of exudates radiating from the fovea, classically called a macular star. The seminal case series is Reed et al., 1998, Ophthalmology 105(3):459–466, describing seven consecutive patients with neuroretinitis and cat-scratch disease. Solley et al., 1999, Ophthalmology 106:1546–1553, extended that work to broader posterior-segment manifestations.
Recognised posterior-segment findings include neuroretinitis, focal retinitis (small white retinal lesions, in some series the most common finding), branch retinal artery occlusion, choroiditis and chorioretinitis, exudative retinal detachment involving the macula, optic neuritis, and rare vitritis. Anterior involvement (conjunctivitis, uveitis) is also described. Visual outcomes are generally favourable with appropriate antibiotics, though residual optic-nerve pallor is a documented sequela.
If this post has a single concrete claim, it is that Bartonella-associated neuroretinitis is a real, well-documented, treatable ophthalmologic finding that deserves urgent ophthalmology referral when suspected.
Rocky Mountain spotted fever
Retinal manifestations of RMSF were described in Smith and Burton, 1977, American Journal of Ophthalmology 84(2):259–262, which documented papilloedema, cotton-wool spots, dilated tortuous retinal veins, and fluorescein-angiographic capillary non-perfusion in a child with severe disease. Subsequent literature has extended the picture: petechial conjunctivitis, anterior uveitis, retinal haemorrhages, vascular engorgement, branch arteriolar occlusion, and rare neuroretinitis with macular star. The mechanism is the same systemic small-vessel vasculitis that produces the rash. Most ocular findings appear in moderate-to-severe disease and respond to prompt antibiotic treatment.
Babesia, anaplasmosis, ehrlichiosis
The ocular literature here is genuinely thin. The foundational babesia paper is Ortiz and Eagle, 1982, American Journal of Ophthalmology 93(3):307–311 — "Ocular Findings in Human Babesiosis (Nantucket Fever)" — describing retinal haemorrhages, nerve-fibre-layer infarcts, and papillitis. Later case reports add scattered cotton-wool spots, often in severe anaemia or co-infection. A recent retinal-integrity pilot study found most acute-babesiosis patients had unremarkable retinal exams, consistent with the Raja/Starr/Bakri placement of babesiosis ocular involvement as rare. For anaplasmosis and ehrlichiosis the literature is limited to scattered case reports: ehrlichiosis-associated optic neuritis is documented, anaplasmosis retinal findings rarely. Neither has a substantial published case series.
Where the contested framing lives
A subset of clinicians and patient communities — overlapping with the "Lyme-literate" network described in our Lyme post — treat persistent Bartonella and Babesia as chronic systemic illnesses producing a multi-system symptom picture (fatigue, cognitive complaints, pain, autonomic symptoms, sometimes visual complaints). Within this framework, extended antibiotic and antiparasitic regimens are used, sometimes for months. Mainstream infectious disease does not endorse it: acute disease is recognised as antibiotic-responsive, persistent post-treatment symptoms are recognised as real, but the link to ongoing infection is not established to the standard mainstream guidelines require.
The disagreement is structurally similar to the IDSA/ILADS disagreement over chronic Lyme but not identical. Bartonella has its own chronic-infection literature including ongoing work on biofilm and intracellular persistence in animal models. The Babesia question is partly bound up with documented relapsing babesiosis in immunocompromised patients — a recognised mainstream entity — and partly with the broader patient-community framing, which is not. We will not pick a side. What both camps would agree on at the careful end: the documented acute ocular findings above are real and merit prompt ophthalmologic care. The disagreement is about what happens after treatment.
CSF in tick-borne co-infections: plausible, not established
Direct contrast-sensitivity-function studies in well-defined Bartonella, Babesia, Anaplasma, Ehrlichia, or RMSF cohorts are essentially absent from the peer-reviewed literature. Where the optic pathway is acutely involved — Bartonella optic neuritis, RMSF retinitis with optic-pathway involvement, rare neuro-rickettsial or neuro-bartonellosis disease — CSF reduction is part of what one would expect, just as in any optic-nerve condition. But studies establishing a population-level CSF signature in any of these conditions have not been published. Plausible is not established. A reduced CSF result in a patient with documented Bartonella neuroretinitis is consistent with the diagnosis; it is not specific to it, and no contrast sensitivity result on its own tells you which tick-borne infection (or whether any) you have.
What an online contrast sensitivity test can do
If you have a documented tick-borne infection or are being worked up for one, an at-home CSF test can provide a baseline on a calibrated setup, track change over time on the same setup (the trend is more informative than any single absolute number), and give you one piece of objective data to bring to a physician — whether infectious disease, ophthalmology, or primary care. What it does not do is identify any tick-borne infection. Diagnosis is through history, exposure, clinical findings, and standard serology — sometimes paired with blood smear (Babesia), PCR, or histopathology.
What it cannot tell you
Note. A contrast sensitivity test is a screening and tracking measurement, not a diagnosis.
A CSF test does not diagnose Bartonella, Babesia, Anaplasma, Ehrlichia, Rocky Mountain spotted fever, tick-borne encephalitis, or any other tick-borne infection. None of these are diagnosed by a vision test; all are diagnosed by a clinician using history, examination, and laboratory testing.
A CSF test does not distinguish among the tick-borne infections, or tell you which pathogen you might have, or whether you have one at all.
A CSF test does not distinguish active infection from post-infectious symptoms, or adjudicate between the mainstream and patient-advocacy framings of persistent illness.
A reduced CSF result is consistent with many things. Cataract, glaucoma (early), multiple sclerosis, optic neuritis, diabetic retinopathy, post-concussion vision changes, uncorrected refractive error, dry eye, fatigue, certain medications, and normal aging can all reduce contrast sensitivity.
A single reading is a snapshot. Test-retest variation is real even with clinical-grade instruments — the Pelli-Robson chart has a test-retest repeatability of about ±0.15 log units, and the smallest clinically meaningful change is generally taken to be about ±0.30 log units (Pelli, Robson & Wilkins, 1988). A consumer-screen test, however carefully calibrated, is noisier than that.
A normal result does not rule out any tick-borne infection. The relevant test for ruling in or out is serology, not a vision measurement.
Practical next steps
If you have a known tick exposure and current systemic symptoms — fever, characteristic rash, unexplained anaemia, severe fatigue, neurological symptoms — see a clinician promptly. Standard of care is empirical antibiotic treatment when the clinical picture warrants. Ophthalmology is not the first stop unless there are eye-specific findings.
If you have acute visual symptoms — sudden vision loss, a fan-shaped pattern of exudates radiating from the fovea (the classic "macular star"), eye pain, or new floaters with a febrile illness — those are urgent ophthalmology findings regardless of cause. The ophthalmologist will examine the fundus and can order serology if a tick-borne infection is suspected.
If you have persistent symptoms after treatment and you are in the contested territory above: continuing care with whichever clinician you trust is the framework. We make no recommendation about which to choose. A longitudinal CSF record is data either kind of clinician can read.
If you are wondering whether your fatigue or vague symptoms are a tick-borne co-infection: a contrast sensitivity test cannot answer that. The pathway is clinical evaluation with appropriate serology. An eye exam belongs in the picture independently — refractive error, dry eye, and early cataract are routine findings worth ruling out before any vision change is attributed to a less-common cause.
Take the test
Take the test now. Three minutes for the quick mode, around seven for the full curve. Calibration happens at the start so the numbers are comparable across sessions on the same device.
If you are managing post-treatment symptoms after a documented tick-borne infection, save the baseline, retake if symptoms persist, and bring the trend to your clinician. The curve joins the rest of the picture rather than replacing any of it.
References
- Raja, H., Starr, M. R., & Bakri, S. J. (2016). Ocular manifestations of tick-borne diseases. Survey of Ophthalmology, 61(6), 726–744. The most-cited recent comprehensive review of tick-borne ocular involvement, and the anchor for the calibration that Lyme and RMSF have relatively common vision-threatening manifestations while babesiosis, ehrlichiosis, and anaplasmosis are rare.
- Reed, J. B., Scales, D. K., Wong, M. T., Lattuada, C. P., Dolan, M. J., & Schwab, I. R. (1998). Bartonella henselae neuroretinitis in cat scratch disease: diagnosis, management, and sequelae. Ophthalmology, 105(3), 459–466. Seminal case series of seven patients — the most-cited primary source for the Bartonella neuroretinitis finding that anchors this post.
- Solley, W. A., Martin, D. F., Newman, N. J., King, R., Callanan, D. G., Zacchei, T., et al. (1999). Cat scratch disease: posterior segment manifestations. Ophthalmology, 106, 1546–1553. Extended the Reed et al. series to a broader range of posterior-segment findings — focal retinitis, branch retinal artery occlusion, choroiditis, exudative retinal detachment.
- Ortiz, J. M., & Eagle, R. C., Jr. (1982). Ocular findings in human babesiosis (Nantucket fever). American Journal of Ophthalmology, 93(3), 307–311. The foundational paper on the sparse ocular literature in babesiosis — retinal haemorrhages, nerve-fibre-layer infarcts, papillitis.
- Smith, T. W., & Burton, T. C. (1977). The retinal manifestations of Rocky Mountain spotted fever. American Journal of Ophthalmology, 84(2), 259–262. The foundational paper on RMSF retinal findings; the vasculitic mechanism it describes underpins the wider rickettsial ocular literature.
- Vannier, E., & Krause, P. J. (2012). Human babesiosis. New England Journal of Medicine, 366, 2397–2407. Standard recent review — epidemiology, transmission, clinical features, diagnosis, treatment.
- Pelli, D. G., Robson, J. G., & Wilkins, A. J. (1988). The design of a new letter chart for measuring contrast sensitivity. Clinical Vision Sciences, 2, 187–199. Source for the ±0.15 log test-retest repeatability and ±0.30 log clinically-meaningful-change figures.
A note on what we did not cite
The patient-advocacy clinical literature on chronic Bartonella and chronic Babesia, the Lyme-literate-clinician-network publications, and the broader chronic-co-infection framework sit outside the references above. That literature exists; selectively quoting from it without the methodological framing a fair evaluation requires risks misrepresenting either side. We recommend reading the relevant primary sources directly if those frameworks bear on your decisions.