Table 1 Comparison of Cyp4v3^−/− and HFD-Cyp4v3^−/− mouse models to BCD in humans

Blindness

Yes

No

No

Visual function (ERG pathologic findings):¹⁵

- Early stage (preceding loss of central vision): diminished ERG.

- Intermediate stage (long before legal blindness occurrence): Extinction of ERG occurs already.

Visual acuity^9,12,16

- Continuous decline till legal blindness.

Visual function (ERG): normal

- 24-week-old⁶

- 12- and 18-month-old³⁵

Visual acuity (OKN): normal

- 12- and 18-month-old: normal³⁵

Visual function (ERG): unlike in BCD.

- No ERG extinction

- ERG stabilized after initial decline and improved over time,

- Reduced ERGs were also reported in WT-HFD mice^45,46.

Severe retinal degeneration

Yes

No

No

Retinal structure (OCT, FAF and other imaging modalities^10–14, see also Fig. 1):

- Extensive RPE atrophy

- Loss of the outer retina.

- Pigment clumps

- Near total degeneration of all functional elements of the retina leaving only structural astrocytes.

Retinal structure: normal

- OCT: 12- and 18-month-old³⁵

- Histology: retinal tissue structures⁵.

Retinal structure (OCT and histology):

- No evidence of extensive RPE atrophy or severe retinal degeneration as seen in BCD.

- Retinal lesions are not unique to HFD-Cyp4v3^−/− mouse. HFD also causes retinal lesions in WT mice⁵¹.

Retinal crystals

Yes

Yes but unlike in BCD

No

Retinal crystals^11,13,16,17

- Numerous.

- Disappearing in advanced stage.

- Are not unique to BCD. A variety of diseases, such as other types of crystalline retinopathy, chronic retinal detachment, or even high dose of tamoxifen or lutein can cause retinal crystals^18–20

Retinal crystals

- Non-pathological: do not affect vision.

- Are not unique to BCD^18–20.

- Not in all mice⁶

- Less numerous than in BCD.

- Do not disappear in advanced stage.

Retinal crystals

- No retinal crystals.

- only large, patchy lesions were observed, similar to the lesions seen in HFD-WT mice⁵¹