Eales' disease is an idiopathic retinal periphlebitis that primarily affects the peripheral retina in young adults. Retinal changes include periphlebitis, peripheral capillary nonperfusion and neovascularization.1234 The natural history of Eales' disease is quite variable with temporary or even permanent remission in some cases and relentless progression to blindness in others. Visual loss is characteristically caused by recurrent vitreous hemorrhage and their sequelae.5
Immune-mediated mechanisms6 and enhanced oxidative stress have been proposed in the etiopathogenesis of this condition.
Visual outcome in Eales' disease, based on the disease severity, has not been documented till date. There are no well-documented evidences of treatment effects in Eales'' disease. Recently, a new classification system of Eales' disease was established, based on standard terminology and features.7 A retrospective tertiary care center-based study, based on this new classification system, was undertaken with the hypothesis that patients presenting with earlier stage of the disease would have a significantly better final visual outcome after treatment. The aim of this study was to add further to the available evidences which might have effects on patient care and health policy.
Materials and Methods
One hundred and fifty-nine consecutive cases of Eales' disease (mean age 23.8 ± 6.8 years, range 16 to 32 years) presenting at the retina clinic of this tertiary care center, with a median follow-up of 13 months (range, nine months to 25 months) were included in this retrospective analysis. All the cases were males. Duration of this study was from July 2001 to October 2005. Sample size was not calculated.
Diabetes mellitus, tuberculosis, sickle cell hemoglobinopathy, blood dyscrasias, sarcoidosis and collagen vascular disorders were ruled out after proper history, examination and investigations (fasting and postprandial blood sugar, chest X-ray, Sickle cell preparation, hemoglobin, hematocrit, total red blood cell and white blood cell count, differential count, erythrocyte sedimentation rate, serum angiotensin converting enzyme and antinuclear antibody). All the eyes were staged according to the new classification system [Table 1].
Visual acuity was the primary outcome measure. Initial and final visual acuities were recorded. Visual acuity was graded as follows: Grade I (excellent) 20/20 or better; Grade II (good) 20/30 or 20/40; Grade III (fair) 20/60 to 20/120 and Grade IV (poor) 20/200 or worse.8 A successful visual outcome was defined as maintenance of visual acuity of 20/40 or better or improvement of visual acuity by one or more grades, by the last clinic attendance. Cases that did not fulfill these criteria were defined as having poor visual outcome.
All the cases were managed by medical therapy (oral methotrexate pulsed therapy, 12.5 mg/week for three months),910 laser photocoagulation and/or vitreoretinal surgery, according to the stage of the disease at the time of presentation.
Visual acuity was converted into decimal scale, denoting 20/20=1 and 20/800= 0.01. To see the improvement after intervention, paired t-test was used in case the data was normally distributed otherwise Wilcoxon signed-rank test for the difference was used using statistical package Stata 8.2. P -values less than 0.05 were considered significant.
Overall, 221 eyes with Eales' disease were included. Bilateral Eales' disease was observed in 71.94% cases. Vitreous hemorrhage was found to be the commonest presenting feature (49.32%). Stage 1a and 1b cases (n=35) were managed by medical therapy. Stage 2a cases (n=18) were kept under observation, Stage 2b (n=22) underwent argon laser photocoagulation. Stage 3a cases (n=21) also underwent photocoagulation, whereas, Stage 3b cases (n=109) were kept under observation till clearing of vitreous hemorrhage. Subsequently, 87 cases underwent photocoagulation and 22 cases underwent vitrectomy and laser photocoagulation for non-resolving vitreous hemorrhage. Medical therapy was also administered at any stage of the disease if associated retinal periphlebitis was observed. Stage 4a cases (n=14) underwent vitreoretinal surgery for management of retinal detachment. Eleven cases had macula-off retinal detachment. Three cases had retinal detachment encroaching the macula. In cases with Stage 4b disease, cyclocryotherapy was performed in one case with neovascular glaucoma, whereas, one case underwent cataract extraction with intraocular lens implantation. Initial and final visual acuity at the last follow-up visit, according to the stage of the disease at initial presentation, is shown in . Macular involvement was observed in the form of epiretinal membrane (n=5), macular non-perfusion (n=6), macular edema (n=13), retinal pigment epithelial abnormalities (n=21) and intraretinal hemorrhages (n=26). The majority of the cases (up to Stage 3 disease at the time of initial presentation) achieved good final visual acuity (20/30 to 20/40). Cases with Stage 4a disease achieved fair/poor visual acuity (20/80 to 20/400), whereas cases with Stage 4b disease achieved poor visual acuity (20/200 to 20/400).
Statistical analysis of decimal scale converted visual acuities is shown in . Statistically significant improvement in visual acuities was observed in all the stages of the disease except Stage 1a and 4b.
Eales' disease is a distinct clinical entity comprising characteristic fundoscopic and fluorescein angiographic features.11 A new classification system has been established recently at the international level, based on standard terminology and features. This classification system provides a method to categorize Eales' disease, based on both fundoscopic and fluorescein angiographic variables that have been shown to be prognostic of visual outcome. The new classification system for Eales' disease is unambiguous, consistent, simple and is useful in assessing the severity of the disease and monitoring the effect of medical, laser and/or surgical treatment.7
Visual outcome in Eales' disease was categorized according to this new classification system. Visual outcome based on the disease severity, was documented for the first time. Vitreous hemorrhage was observed to be the commonest presenting feature. Results were in accordance with the hypothesis. Median final visual acuity was found to be dependent upon the stage of presentation. Good visual outcome was achieved in Stages 1, 2 and 3. However, fair/poor and poor visual outcome was observed in Stage 4a and 4b, respectively. Statistically significant improvement in visual acuities was observed in the majority of stages of the disease. No improvement in visual acuity was observed in Stage 1a, since all the cases had excellent visual acuity at presentation, but treatment maintained visual acuity by not allowing further progression of the disease. Visual loss, most commonly, resulted from vitreous hemorrhage and retinal detachment.
Good visual outcome has been reported in cases of Eales' disease with venous occlusion.1213 Atmaca et al.,14 in a study from Turkey, also reported fair visual outcome in Eales' disease. Macula is not primarily involved despite extensive peripheral capillary non-perfusion in Eales' disease.15 Macular involvement is more common in the advanced stage of the disease. In the present study, macular involvement was observed in the form of epiretinal membrane (2.26%), macular non-perfusion (2.71%), macular edema (5.88%), retinal pigment epithelial abnormalities (9.56%) and intraretinal hemorrhages (11.76%). Macula-off retinal detachment was observed in 4.97% cases. Macular involvement contributes to decreased final visual acuity. Therefore, status of the macula should be ascertained in cases of Eales' disease.
Meticulous management was observed as the key factor resulting in good visual outcome. The new classification system for Eales' disease was found to be useful in monitoring the effect of medical, laser and/or surgical treatment.
The strengths of this study have been a valid study question, data collection, analysis and statistical interpretation. The limitation may be the retrospective nature of the study. Interpretation and implications in the context of the totality of evidence may be implied from this study. Since there is no systematic review of visual outcome to refer to, this one could be used for future. Since this study adds further to the available evidences in literature, it may have effects on patient care and health policy. Future research direction may be a prospective multi-center trial, incorporating the effect of treatment on the underlying mechanisms with clinical research.
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Conflict of Interest:
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