Factors Influencing Threshold Energy in Subthreshold Photocoagulation for Diabetic Macular Edema

Figures & data

Table 1 Multiple regression results for all surgical procedures (n=150)

	Mean (range)	F	CC
Threshold energy	175.7±41.6 (100–350) (mW)	—	—
Age	65.1±9.3 (51–80) (years)	2.22	−0.13
HbA1c	6.8±0.9 (5.3–8.6) (%)	5.67	0.20
Interval from completion of PRP	26.8±29.9 (2–138) (months)	11.29*	−0.27
Central macular thickness	378.7±118.0 (206–751) (μm)	14.33*	0.30
Upper 6 mm subfield	326.4±56.1 (250–449) (μm)	11.14*	−0.27
Nasal 6 mm subfield	336.0±53.6 (259–512) (μm)	7.57*	0.23
Lower 6 mm subfield	302.0±59.0 (195–512) (μm)	1.57	−0.11
Temporal 6 mm subfield	307.9±55.8 (218–444) (μm)	0.18	0.04
HVC	—	36.76*	−0.46

Notes: *P<0.01

Abbreviations: PRP, panretinal photocoagulation; HVC, history of vitrectomy and cataract surgery; CC, correlation coefficient.

Table 2 Multiple regression analysis results for surgical procedures with HVC (n=116)

	Mean (range)	F	CC
Threshold energy	164.4±34.2 (100–250) (mW)	—	—
Age	64.9±10.3 (51–80) (years)	2.54	0.15
HbA1c	6.6±0.7 (5.3–8.4) (%)	10.02*	0.29
Interval from completion of PRP	25.3±32.4 (2–138) (months)	10.39*	−0.30
Central macular thickness	389.±109.0 (206–751) (μm)	14.85*	0.35
Upper 6 mm subfield	321.1±50.9 (250–445) (μm)	0.05	−0.02
Nasal 6 mm subfield	325.4±45.6 (259–453) (μm)	0.98	0.10
Lower 6 mm subfield	287.2±42.9 (195–388) (μm)	6.36	0.24
Temporal 6 mm subfield	299.8±56.7 (218–444) (μm)	4.21	−0.20
Axial length	23.88±1.29 (22.17–27.43) (mm)	12.77*	0.33

Notes: P<0.01.

Abbreviations: PRP, panretinal photocoagulation; HVC, history of vitrectomy and cataract surgery; CC, correlation coefficient.