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Lekha Ravindraraj, Robert D Fechtner, Albert S Khouri; Diode CPC Energy Parameters during Treatment of Refractory Childhood Glaucoma. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5675.
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To study the relationship between energy delivered in diode cyclophotocoagulation (CPC) and efficacy in the treatment of refractory childhood glaucomas.
A retrospective review of children who presented over 10 yrs with primary congenital glaucoma (PCG) or secondary glaucoma (SG) was performed. Inclusion: diagnosis of childhood glaucoma that was refractory to other treatments for IOP control. Exclusion: Lack of follow up (<6 months) and treatments not inclusive of CPC. Data on intraocular pressure (IOP), number of glaucoma medications at baseline and 1 yr after CPC, and laser settings (power, duration, number, and location of treatments) were collected. Total energy (defined as product of power, time, and number of treatment spots) was calculated. Means, p-values, r2 values, and IOP reduction from baseline were determined.
Of 61 patients (101 eyes) with childhood glaucomas, 13 patients (7 with PCG and 6 with SG) yielding 16 eyes (8 with PCG and 8 with SG) that received a total of 33 CPCs (18 for PCG, 15 for SG), were followed for 1 yr. Mean power, duration, number of treatment spots, and total energy were: 1398.5 mW (SD 350.4), 3128.8ms (SD 984.5), 22.8 spots (SD 4.2), and 96.8J (SD 35.3) respectively. Mean IOP, and absolute and % reduction at 1 yr from baseline (n=21) were 25.7mmHg (SD 11.0), 12.3mmHg (SD 14.3) and 28%, respectively. No correlation was noted between total laser energy and absolute or % IOP reduction (r2= 0.024 and 0.042, respectively). Analysis for low energy (<100J) and high energy (>100J) treatments is in Table 1. Treatments that delivered higher energy used significantly longer duration (p<0.001), less power (p<0.05), and more spots (p<0.001) than lower energy CPCs. Significantly more patients with PCG than SG underwent high energy treatment (p<0.01). When comparing outcomes of high and low energy treatments, there was no significant difference in mean IOP, absolute IOP reduction, or number of medications used at 1 yr (p =0.58, 0.84, and 0.14 respectively).
Delivery of more energy during CPC for the treatment of refractory childhood glaucomas did not result in better IOP control in our cohort of patients. Treatment with lower energy was equally effective and may avoid risks associated with high energy treatment. A larger sample size and longer follow-up will further confirm efficacy and safety of low and high energy CPCs.
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