Baseline demographic data are listed in Table 1. Comparison of the 2 groups (resolved SRF vs persistent SRF) showed no significant difference in mean age (9 vs 6 years, P = 0.15), sex [male: 97 (88%) vs 57 (85%), P = 0.55], or race [Caucasian: 79 (72%) vs 45 (67%), P = 0.79].
Clinical features are listed in Table 2. Common presenting signs and symptoms included xanthocoria [17 (15%) vs 21 (32%)], strabismus [27 (25%) vs 21 (32%)], and vision loss [41 (37%) vs 15 (23%)] (P = 0.03). Among patients who were able to verbally report vision, baseline visual acuity was more frequently 20/200 or better in patients with resolved SRF [38 (35%) vs 8 (12%), P = 0.003]. Patients were classified into stage 3A1 [20 (18%) vs 11 (16%)], stage 3A2 [43 (39%) vs 9 (13%)], stage 3B [47 (43%) vs 40 (60%)], and stage 4 [0 (0%) vs 7 (11%)] (P < 0.001). There were no stage 5 eyes seen in our practice during this time period. Eyes with resolved SRF presented with less NVI [2 (2%) vs 8 (12%), P = 0.01], fewer clock hours of telangiectasia (mean: 5 vs 7 clock hours, P < 0.001), light bulb aneurysms (mean: 5 vs 7 clock hours, P < 0.001), exudation (mean: 7 vs 10 clock hours, P < 0.001), and SRF extent (mean: 7 vs 10 clock hours, P < 0.001).
Imaging features are listed in Table 3. On FA, comparison of the 2 groups (resolved SRF vs persistent SRF) revealed no significant difference in retinal nonperfusion presence [79 (90%) vs 31 (78%), P = 0.06] or mean number of clock hours (6 vs 6 clock hours, P = 0.57). Eyes with resolved SRF had fewer clock hours of telangiectasia (mean: 6 vs 7 clock hours, P = 0.01), light bulb aneurysms (mean: 5 vs 7 clock hours, P = 0.004), and NVI [1 (1%) vs 8 (20%), P < 0.001]. On US, eyes with resolved SRF presented with fewer open funnel [19 (24%) vs 21 (43%), P = 0.03], or closed funnel RD [1 (1%) vs 11 (22%), P < 0.001], and less SRF elevation by US (mean: 2.3 vs 8.5 mm, P < 0.001).
Treatment modalities are listed in Table 4. Fewer eyes with resolved SRF were observed [2 (2%) vs 10 (15%), P = 0.002], whereas more eyes with resolved SRF were treated with argon laser photocoagulation [65 (61%) vs 18 (34%), P = 0.003] and cryotherapy [97 (91%) vs 40 (75%), P = 0.02] but fewer intravitreal corticosteroid injections [2 (2%) vs 6 (11%), P = 0.03]. There was no difference in those treated with photodynamic therapy, sub-Tenon's corticosteroid therapy, or intravitreal anti-VEGF therapy.
Binomial logistic regression was performed to adjust for potential confounders, with results listed in Table 5. Factors predictive of SRF resolution included absence of NVI on FA [OR 0.05 (0.01–0.60), P = 0.02] and less SRF elevation by US [OR 0.84 (0.76–0.95), P = 0.004]. With each 1-mm decrease in SRF, the likelihood of SRF resolution increased by 16%.
Coats disease is an idiopathic retinal vascular disease characterized by retinal telangiectasia, exudation and RD.4,6–8 Longstanding RD in these patients can lead to profound loss of visual acuity. Levinson and Hubbard9 reviewed the outcomes of 17 cases of Coats disease treated with 577-nm yellow laser photocoagulation of which 8 cases (47%) had RD, classified as “high” (75%) or “low” (25%). A comparison (high vs low RD) regarding visual acuity outcomes revealed 20/50 or better (17% vs 27%), 20/60 to 20/200 (17% vs. 9%), and worse than 20/200 (66% vs 64%) indicating reduced visual prognosis for eyes with high RD.9 Gupta et al10 in a review of spectral domain optical coherence tomography (SD-OCT) features of 27 cases of Coats disease found macular SRF in 10 eyes (37%), which was associated with worse baseline and final visual acuity. Previous reports from our center4,6 on the correlation between disease staging and visual outcome found that increasing disease severity was associated with poorer visual outcome (20/200 or worse).6 In this report, we explore the specific factors predictive of SRF resolution in eyes with Coats disease.
We found factors associated with resolution of SRF included earlier stage of disease and presentation with fewer clock hours of telangiectasia, fewer light bulb aneurysms, less exudation, and less elevated SRF. Factors predictive of SRF resolution included lack of NVI on FA and less elevated SRF on US. The likelihood of SRF resolution increased by 16% for every 1-mm decrease in SRF. We noticed that most of the eyes with nonresolution of SRF were salvaged and comfortable, with good cosmetic appearance.
Treatments for SRF in Coats disease include laser photocoagulation, cryotherapy, intravitreal corticosteroid injection, anti-VEGF injections, or surgical drainage of SRF.4,6,7,11 Treatments for shallow SRF (subtotal RD in stage 3A) include laser photocoagulation or cryotherapy to target leaking telangiectasias and promote SRF resorption.4,9,11–13
Historically, eyes with highly elevated SRF (total RD in stage 3B or 4) have been treated with cryotherapy or surgical reattachment of the bullous RD.4,9,11–13 Cryotherapy was preferred over laser photocoagulation in eyes with RD,11,14,15 as highly elevated SRF was thought to respond poorly to laser photocoagulation, due to decreased absorption of laser energy by detached retina. Additionally, there was a fear of applying laser to a nonrhegmatogenous RD for risk of inducing full-thickness retinal holes, and converting the detachment to rhegmatogenous.9 However, subsequent studies found favorable absorption of yellow laser in eyes with total exudative RD,9 stimulating interest in laser photocoagulation as an alternate treatment to cryotherapy in some cases.9,14,15 Levinson and Hubbard,9 in a study of 17 eyes with Coats disease of stage 1 (6%), stage 2A (12%), stage 2B (35%), stage 3A1 (12%), stage 3A2 (6%), and stage 3B (29%), found complete disease resolution in 16 eyes (94%) after treatment with 577-nm yellow wavelength laser after a mean of 2.5 treatment sessions and mean time of 11.2 months.9
Other treatments for total RD have been explored. Bergstrom and Hubbard16 used combination intravitreal triamcinolone injection and cryotherapy in 5 cases of severe exudative RD from Coats disease and found successful retinal reattachment in 2 cases (40%), with side effects of elevated intraocular pressure (≥26 mm Hg) requiring topical medications in 4 cases (80%) and cataract in 3 cases (60%). Li et al17 studied anti-VEGF injection in combination with laser photocoagulation and cryotherapy in stage 3A (n = 10) and stage 3B (n = 7) Coats disease and found a decrease in the postoperative RD height by OCT and color Doppler imaging (P < 0.001) in 16 of 17 cases (94%), but no case had complete resolution of SRF. Although we did not report a significant difference in the use of intravitreal anti-VEGF in our 2 groups (resolved SRF vs persistent SRF), other reports have shown that intravitreal anti-VEGF in advanced Coats disease improves SRF absorption and retinal reattachment, thus increasing globe survival.18–21 However, intravitreal bevacizumab can cause vitreoretinal fibrosis and tractional RD, so caution is required.22 Zhang et al23 reviewed the outcomes of 28 cases of Coats disease treated with anti-VEGF and laser photocoagulation of which eyes were stage 3A (n = 21) and 3B (n = 7). After laser photocoagulation (mean 3 sessions) and anti-VEGF injections (mean 3 injections) final visual acuity was improved from logMAR 1.57 ± 0.73 (Snellen equivalent 20/740) at baseline to 1.33 ± 0.81 (Snellen equivalent 20/400) at final follow-up (P < 0.001), with no significant adverse effect.23
Regarding surgery for total RD from Coats disease, the most common surgical method is external drainage of SRF,4,11,12 which is preferred over internal SRF drainage due to a theoretically lower risk of proliferative vitreoretinopathy.24 In recent years, modified external SRF drainage techniques using either transscleral or transconjunctival methods have been described in case series, but further studies are needed to establish efficacy.25,26
Limitations of this study include the single-center retrospective design, with treatment during the course of 45 years by 2 different surgeons. As expected, treatment for Coats disease has evolved over time, so patients in this study were not managed uniformly throughout the study period. Additionally, different surgeons could have favored different treatment algorithms. We acknowledge that eyes with persistent SRF had fewer treatments which could have been a reflection of practice pattern, patient preference, chronic retinal atrophy and fibrosis, or estimated poor visual prognosis on presentation. This could have biased study results as both groups did not receive a uniform treatment regimen. Strengths of this study include manual review of detailed medical and imaging records, with a large number of patients allowing for robust statistical analysis, resulting in the discovery of new information that could be applied to improve patient care in the future.
In summary, in this large cohort study, we found that eyes with resolved SRF were associated with less NVI and fewer clock hours of telangiectasia, light bulb aneurysms, exudation, and SRF involvement. On further analysis with binomial logistic regression, only absence of NVI on FA and less SRF on US was found to be predictive of SRF resolution. Additional studies are required to better assess visual outcomes in patients with persistent SRF and determine whether patients presenting with more advanced Coats disease should be considered for early surgical drainage.
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Keywords:© 2019 by Asia Pacific Academy of Ophthalmology
Coats disease; exudation; retinal detachment; subretinal fluid; telangiectasia