Table 3.
Type of study and outcome for observational studies
| Reference | Type of study | Number of participants, group (and age). | Method | Outcome | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
Fern 198624 |
Cross-sectional |
N = 105 Children NV (2-7y) |
Stimulus: Isolated Landolt C/Landolt C with flanking bars at 3 m. |
Contour interaction area |
||||||
| Children showed the same contour interaction effects as adults at 2.5 × MAR. | ||||||||||
| N = 16 Adults NV | ||||||||||
|
Threshold symbol size: 75% | ||||||||||
|
Flanker spacing: 2.5 MAR | ||||||||||
|
Foveal/Eccentric: foveal | ||||||||||
|
Manny 198721 |
Cross-sectional |
N = 13 Children NV (3-4y) |
Stimulus: Isolated Landolt C/Landolt C with flanking bars at 3 m. |
Contour interaction area (see Figure 2). |
||||||
| N = 5 Adults NV | ||||||||||
|
Threshold symbol size: 90-95% | ||||||||||
|
Flanker spacing: 0–8.52 MAR | ||||||||||
|
Foveal/Eccentric: foveal | ||||||||||
|
Chung 19959 |
Case- control |
N = 4 Adults CN |
Stimulus: Isolated Landolt C/Landolt C with flanking bars at 4.1 m. |
Contour interaction area (see Figure 3). |
||||||
| N = 6 Adults NV | ||||||||||
|
Threshold symbol size: 50% | ||||||||||
|
Flanker spacing: 1, 2, 5, or 10 MAR | ||||||||||
|
Foveal/eccentric: foveal | ||||||||||
|
Pascal 19948 |
Case- control |
N = 6 Adults NV |
Stimulus: Isolated Landolt C/Landolt C with flanking bars (3 m or 6 m). |
Contour interaction area (see Figure 3). |
||||||
| N = 6 Adults idiopathic CN | ||||||||||
|
Threshold optotype size: 50% | ||||||||||
| N = 6 Adults with albinism | ||||||||||
|
Flanker spacing: 1, 5 MAR | ||||||||||
|
Foveal /eccentric: foveal | ||||||||||
|
Semenov 200020 |
Cross- sectional |
N = 140 Children NV (3-9y) |
Stimulus: Isolated Landolt C/Landolt C with flanking bars at 4.3 m. |
Contour interaction area (see Figure 2). |
||||||
| N = 4 Adults NV | ||||||||||
|
Threshold optotype size: 75% | ||||||||||
|
Flanker spacing: 3.75-10 MAR | ||||||||||
|
Foveal/eccentric: foveal. | ||||||||||
|
Bondarko 200522 |
Cross- sectional |
N = 292 Children NV (8-17y) |
Stimulus: Isolated Landolt C, E-letters, Gratings/Landolt C with flanking bars, E-letters with E-letters, Gratings by Gratings at 4.3 m. |
Contour interaction |
||||||
| The maximum inhibition separation significantly decreased from approximately 2 MAR to 1.5MAR from age 8 to age 17. | ||||||||||
|
Threshold optotype size: 75% | ||||||||||
|
Flanker spacing: 0–7 MAR. | ||||||||||
|
Foveal/eccentric: foveal | ||||||||||
|
Jeon 20107 |
Cross- sectional |
N = 59 Children NV (5-, 8-, 11y) |
Stimuli: Single Sloan E/Sloan E with gratings at 4.2 m. |
Contour interaction area (see Figure 2). |
||||||
|
Threshold optotype size: 79.1% | ||||||||||
| N = 19 Adults NV | ||||||||||
|
Flanker spacing: started at 20MAR (10 reversals) | ||||||||||
|
Foveal/eccentric: foveal | ||||||||||
|
Atkinson198526 |
Cross- sectional |
Study 1: N = 14 Children NV (5;3–6;2y) N = 9 Mothers Study 2: N = 13 Children NV (3;1–4;1y) N = 8 Mothers |
Stimulus: Single Landolt C/Landolt C surrounded by Os and Cs at 1.5-8.3 m.Interoptotype spacing: 50% (line/circular configuration) Foveal/eccentric: foveal |
Crowding ratio (see Figure 5). |
||||||
|
Atkinson 198827 |
Cross- sectional |
N = 47 Children NV (3-4y) N = 12 Adults NVN = 12 Children NV (5-7y) |
Stimulus: Single Sheridan Gardener card/5-letter Sheridan Gardener card at 3 m and 6 m.Interoptotype spacing: 50%Foveal/eccentric: foveal |
Crowding ratio (see Figure 5). |
||||||
|
Kothe 199023 |
Cross-sectional |
N = 90 Children NV (4-11y) |
Stimulus: Isolated acuity/Regan Repeat Letter acuity/Snellen acuity at 6 m.Interoptotype size: 100%Foveal/eccentric: foveal. |
Crowding ratio (see Figure 4). |
||||||
|
Jacobson 19966 |
Cross-sectional |
N = 13 Children CVI (5-14y) |
Stimulus: LH single /LH line at 3 m.Interoptotype spacing = :100%Foveal/eccentric =: foveal |
Crowding ratio (see Figure 4). |
||||||
|
Pike 199411 |
Cross-sectional |
N = 42 Children CVI (2-9y) |
Stimulus: Single Sheridan Gardener /7-letter Sheridan Gardener at 6 m.Interoptotype spacing:50%Foveal/eccentric: foveal |
Crowding ratio (see Figure 5). |
||||||
|
Pardhan 199710 |
Case–control |
N = 18VI Adults (42-85y)N = 25 Adults NV (42-85y) |
Stimulus: Isolated visual /Regan Repeat Letter Chart, Snellen Line chart at 6 m.Interoptotype spacing: 100% Foveal/eccentric: foveal |
Crowding ratio (see Figure 4). |
||||||
|
Norgett 201125 |
Cross-sectional |
N = 103 Children NV (4-9y) |
Stimulus: Single: Kay Picture Single, Single Sheridan Gardiner. 50%: Log MAR crowded acuity, Kay Picture Crowded Log MAR100%: Sonkson Log MAR at 6 m.Interoptotype spacing: see above.Foveal/eccentric: foveal |
Crowding ratio (see Figure 4 and 5) |
||||||
| Huurneman 201215 | Case–control | N = 75 Children NV (4-8y) N = 20VI children without CNN = 38 VI children with CN | Stimulus: C-test, LH-version C-test, LH line test with 25%, 50% and 100% spacing at 40 cm.C-test at 5 m.Interoptotype spacing: see above.Foveal/eccentric: foveal | Crowding ratio |
||||||
| |
C2.6′ |
C (LH)2.6′ |
C2.6′ far (5m) |
LH25% |
LH50% |
LH100% |
||||
| NV |
1.39 |
1.38 |
1.22 |
1.19 |
1.12 |
1.12 |
||||
| VI without CN |
1.52 |
1.56 |
1.17 |
1.12 |
1.12 |
1.11 |
||||
| VI with CN | 1.76 | 1.78 | 1.53 | 1.25 | 1.22 | 1.11 | ||||