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. Author manuscript; available in PMC: 2014 Aug 25.
Published in final edited form as: JAMA Ophthalmol. 2013 Jul;131(7):870–879. doi: 10.1001/jamaophthalmol.2013.2313

Table 2.

Baseline Participant and Ocular Characteristics

N=293
Participant-level

Age (years)-Mean±standard deviation (Min, Median, Max) 65±9 (29, 65, 85)
Gender
 Women 171 (58%)
Race/Ethnicity
 White 191 (65%)
 Black 67 (23%)
 Hispanic 26 (9 %)
 Asian 2 (1%)
 Native Hawaiian/ Pacific Islander 3 (1%)
 Unknown/not reported 4 (1%)
Diabetes Type
 Type 1 34 (12%)
 Type 2 242 (83%)
 Uncertain 17 (6%)
Duration of Diabetes- (Years); Mean±STD 21±12
HbA1c*-(%); Mean±STD 7.7±1.5

Ocular-level

Visual Acuity
 Letter Score-Mean±STD (Median) 66±15 (69)
 Snellen Equivalent-Mean (Median) 20/50 (20/40)
 ≥ 69 (20/40 or better)-N (%) 151 (52%)
 68-54 (20/50 to 20/80)-N (%) 97 (33%)
 53-39 (20/100 to 20/160)-N (%) 26 (9%)
 ≤38 (20/300 or worse) N (%) 19 (6%)
Diabetic Retinopathy-N (%)
 Microaneurysms only 63 (22%)
 Mild/moderate NPDR 131 (45%)
 Severe NPDR 15 (5%)
 PDR and/or prior scatter 84 (29%)
Prior History of PRP 71 (24%)
History of DME Treatment-n (%) 128 (44%)
History of Recent Injection for DME ** 29 (10%)
Baseline DME Subgroup
A. No central-involved DME & No non-central
  involved DME
17 (6%)
B. No central-involved DME & Definite/possible if
  non- central involved DME
100 (36%)
C. Possible if central-involved DME and No non-
  central involved DME
5 (2%)
D. Possible if central involved DME and
  Definite/possible if non central involved DME
153 (56%)
OCT- Mean ±STD (Min, Max)
 Time Domain
  CSF Thickness μm (N = 281) 201±26 (114, 249)
  Retinal Volume mm3 §(N = 261) 6.7± 0.6 (4.3, 8.8)
 Spectral Domain
  CSF Thickness μm (N = 12) 244±32 (178, 284)
  Retinal Volume mm3 §(N = 9) 8.97±1.29 (6.96, 10.20)
OCT Machines
 Zeiss Stratus 281 (96%)
 Zeiss Cirrus 8 (3%)
 Optovue RTVue 2 (1%)
 Heidelberg Spectralis 2 (1%)

HbA1c=hemoglobin A1c; NPDR=non-proliferative diabetic retinopathy; PDR=proliferative diabetic retinopathy; PRP=panretinal photocoagulation; DME=diabetic macular edema; OCT=optical coherence tomography; CSF=central subfield;

*

Missing in 13 participants

By clinical exam. Scale: None, Microaneurysms only, Mild/moderate NPDR, Severe NPDR and PDR

**

Intravitreal or peribulbar corticosteroids within the last 4 months prior to surgery or on the day of surgery; anti-VEGF therapy within the last 2 months prior to surgery or on the day of surgery

Missing in 18 (6%); 5 eyes, originally classified in the possible central-involved DME and no non-central involved DME group, were individually examined by the protocol chair due to small numbers in the subgroup and were reclassified into the no central or non-central involved DME (N = 1), no central-involved DME and definite/possible non-central involved DME (N = 1) and the possible central-involved and definite/possible non-central involved DME (N = 3) groups respectively in the analysis.

§

Missing 20 in time domain and 3 spectral domain: non-gradable by the reading central