Table 1.
Classifications of Stargardt Disease. The Groups Proposed Do Not Always Correspond to Different Progressive Stages of the Disease but Have Important Implications in the Clinical and Functional Assessment of the Patients
| Fishman Classification43 | Lois Classification44 | FAF45 | Early Onset STGD Fundus Grading System46 | Genotype45 |
|---|---|---|---|---|
| 1. Flecks confined to the fovea, with pigmentary changes; “beaten-metal” or “snail-slime” appearance. EOG and both scotopic and fotopic ERG) normal (Figure 1) | 1. PERG abnormality with normal full-field ERG | 1. Localized low foveal FAF signal surrounded by a homogeneous background with or without perifoveal foci of high or low signal | 1. Normal fundus | A. Patients with ≥2 severe/null variants |
| 2. Flecks, extending anterior to the vascular arcades and/or nasally to the optic disc. Flecks might be partially or totally resorbed. Subnormal cone and rod responses on EOG and ERG, delayed dark adaptation (Figure 2) | 2. PERG abnormality with cone ERG abnormality | 2. Focal low FAF signal at the macula encircled by heterogeneous background and foci of high or low FAF signal anteriorly to the vascular arcades | 2. Macular and/or peripheral flecks without central atrophy | B. Patients with 1 severe/null variant and ≥1 variant that are missense or in-frame insertion/deletion. |
| 3. Flecks reabsorbed, atrophy of RPE and CC. EOG testing subnormal; ERG severely altered | 3. Pattern ERG abnormality with generalized cone and rod dysfunction | 3. Multiple areas of low FAF signal in macular area with heterogeneous background and/or foci of high or low signal | 3a. Central atrophy without flecks 3b. Central atrophy with macular and/or peripheral flecks 3c. Paracentral atrophy with macular and/or peripheral flecks, without central atrophy |
C. Patients with no severe/null variant, but ≥2 variants that are missense or in-frame insertion/deletion. |
| 4. Further worsening of stage 3, complete reabsorption of flecks, extensive CC and RPE loss. ERG responses extinguished | 4. Multiple extensive atrophic changes of the RPE, extending beyond the vascular arcades | D. Patients with 1 missense or in-frame insertion/deletion variant or with only variants predicted as less likely pathogenic or uncertain. |
Abbreviations: CC, choriocapillaris; FAF, fundus autofluorescence; EOG, electrooculogram; ERG, electroretinogram; PERG, pattern electroretinogram; RPE, retinal pigment epithelium.