Dr. Sangeet Mittal, M09477
Abstract:
Methods: Retrospective review of records of 556 eyes who had undergone vitrectomy for complications of Diabetic Retinopathy from 1/1/2013 to 31/12/2015 was done. 17 eyes of 16 patients with plaque like sub-foveal hard exudates that underwent vitrectomy & ILM peeling using ICG dye were analysed. Main outcome measures evaluated included visual acuity, size of plaque and surgical complications. Results: Mean age was 51.6±8.7 years. There were 13 males & 4 females. Mean follow up was 15.5 months. The mean visual acuity improved from 20/250 to 20/90. Improvement in visual acuity was seen in 15/17 eyes. 6 patients had total resorption of hard exudates and 11 patients had partial absorption. One patient had retinal detachment during surgery for which silicon oil was injected. However complete resorption was seen in this patient also. Conclusions: Vitrectomy with ILM peeling is a simple & effective option in the management of exudative diabetic maculopathy with plaque like sub-foveal exudates.
Introduction:
Exudative diabetic maculopathy is a frequent cause of visual deterioration in patients with diabetic retinopathy. The deposition and accumulation of the large molecules within the exudative material causes a clinical picture of hard exudates.1
Hard exudates are composed of lipid and proteinaceous material, and settle in the outer retinal layers. Plaque-like hard exudates may deposit in the foveal region and often cause visual loss. The visual loss may be severe and irreversible. Subfoveal hard exudates usually respond poorly to focal laser treatment, but may slowly resolve leaving behind a retinal pigment epithelium (RPE) scar and subfoveal fibrosis with associated poor visual acuity.2
Unfavourable prognosis in eyes with subfoveal plaque-like hard exudates following a natural course encouraged the development of alternative treatment options, one of which is the surgical excision of plaque-like foveal exudate. Takagi et al3 and Sakuraba et al4 first performed excision of submacular hard exudates and reported promising short-term surgical outcomes with favourable prognosis. Takaya et al5 reported long-term results of surgical removal of hard exudates and noted that visual improvement could not be obtained.
In this study, we retrospectively reported an analysis of long-term results of vitrectomy with Internal Limiting Membrane (ILM) Peeling in patients with Diabetic Macular Edema (DME) with plaque-like hard exudates.
Material & Methods:
Retrospective review of records of 556 eyes which had undergone vitrectomy for complications of Diabetic Retinopathy from 1/1/2013 to 31/12/2015 was done. 17 eyes of 16 patients with plaque like sub-foveal hard exudates that underwent standard 3 port pars plana vitrectomy (25 Gauge) combined with ILM peeling using Indo-cyanine Green dye were analysed. All patients were under strict metabolic control for at least 6 weeks before the surgery. Only patients who had completed 6 months of follow up were included in the study. Main outcome measures evaluated included visual acuity, size of plaque like exudates and surgical complications.
Results:
The mean age of patients was 51.6+/-8.7 years. There were 13 males and 4 females. Mean follow up was 15.5 months. 11 patients had Non Proliferative Diabetic Retinopathy (NPDR) and 6 had Proliferative Diabetic Retinopathy (PDR). 7 eyes were phakic and 10 eyes were pseudophakic. Vitreofoveal traction was seen in 3 eyes on Optical Coherence Tomography. 4 eyes had not undergone any previous treatment. 1 eye has focal laser, 8 eyes had 1-3 injections of anti VEGF agents, 3 eyes had more than 3 injections and record was not available for 1 eye. Improvement in visual acuity was seen in 15 out of 17 eyes. Mean preoperative visual acuity improved to 6/24 from 5/60. Resorption of hardexudates was seen in all eyes. 6 eyes showed total resorption of hard exudates and 11 eyes had partial resorption. Mean plaque size decreased from 0.531 mm2 to 0.136 mm2. Largest decrease seen was 1.721 mm2. One eye had intra-operative Retinal Detachment. Silicon Oil tamponade was done in this eye, however total resorption was seen in this eye also. Transient IOP rise was seen in 3 eyes and hypotony was present in 1 eye. All these patients were controlled with medicines. 2 eyes developed macular scar postoperatively. 3 of the 7 phakic patients developed cataract and 2 of them needed cataract surgery within 6 months of vitreous surgery.
Discussion:
In our study, we presented results of vitrectomy with ILM peeling for subretinal plaque-like hard exudates in patients with exudative diabetic maculopathy. No serious intraocular complications occurred. All of the eyes benefited anatomically from surgery, and all except two eyes gained two or more lines visual acuity.
Although retinal hard exudate usually accompanies diabetic macular oedema, increasing amounts of exudate appear to be independently associated with increased risk of visual impairment. Hard exudates are assumed to appear primarily in the outer retinal layer. They can replace almost the entire retinal layer and continue to the subretinal space after longstanding and massive deposition.6
In cases in which foveolar massive hard exudates accumulate in the outer retinal layer, surgical removal has been claimed to result in damage to the neural retina, therefore functional success in these eyes will be very unlikely.3 On the other hand, subretinal hard exudates seem to block interaction between the neurosensory retina and retinal pigment epithelium, and will cause deterioration of visual acuity unless they are extracted or reabsorbed before the time that irreversible damage can occur.6 Therefore, the necessity of removal of subretinal hard exudates to restore the interaction may justify surgery for removal of exudates.
Recently, Takaya et al5 reported their long-term results of vitrectomy for removal of submacular hard exudates in patients with diabetic maculopathy. In their series, visual acuity improved in 7 of 13 eyes 1 year after surgery, but improvement of visual acuity was observed in only 5 eyes 3 years after surgery. They compared the visual results with those of eight eyes that underwent vitrectomy without extraction of hard exudates, and concluded that removing submacular hard exudates was not superior to vitrectomy alone. However, in the treatment group, they were confronted with complications of iatrogenic macular hole in three eyes, postoperative submacularhaemorrhage in one eye, and optic atrophy in one eye at the final examination, which worsened final visual acuity results. Vitrectomy and ILM peeling is a routine surgical procedure with lesser complications.
Vitrectomy and removal of the normal or thickened posterior hyaloid has considerable effects on diabetic macular oedema.7It helps in removal of tractional forces at the retinal surface which in some cases may be subtle or hidden. It reduces oxygen consumption of vitreous and hypoxia at the retinal surface. It removes the vitreous collagen over retinal surface and decrease VEGF load.
Yang8 reported that in his series of vitrectomy alone, obvious reduction of hard exudates was observed after approximately 3 months and marked resolution occurred within 12 months. Although visual acuity improved in 11 eyes and decreased in 2 eyes, none of the eyes improved more than 6/60. The advantage of surgical removal of the plaque exudates may be early cleaning of the exudates and protecting the fovea from harmful effects of exudates. In our series vitrectomy was combined with ILM peeling also. ILM peeling ensures complete removal of posterior hyaloid.9 Surgical trauma induced by ILM peeling results in overexpression of Glial Fibrotic Acidic Protien which helps to fight against the blood-retinal barrier breakdown & repairs the interruptions of axoplasmic flow. This also explains the slow improvement in DME after vitrectomy surgery. ILM peeling increase release of EGF-R (Epidermal Growth Factor receptor) which maintains homeostasis, reduces apoptosis and acts as inhibitory to VEGF. Reduction of hard exudates was observed as early as 6 weeks. Visual improvement was seen in 15/17 eyes. Best corrected post operative visual acuity was better than 6/60 in 10 eyes with 4 eyes improving to 6/12 or better. Probably early intervention in these eyes resulted in better visual Recovery.
The limitations of the study are that it is non comparative. Comparison with surgical excision and observation alone is needed. Also the sample size is small, thus probable complications may have been missed.
In conclusion, Vitrectomy with ILM peeling is a simple and effective option in the management of exudative diabetic maculopathy with plaque like sub-foveal hard exudates. Prospective randomized controlled trials are necessary to substantiate the above findings. Although Vitrectomy for subfoveal exudates is not yet a standard primary treatment option, it could be considered in cases resistant to alternative therapies before damage has occurred.
References:
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