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Siero autologo e sue applicazioni in oculistica

Conventional therapeutic options include intensive artificial tear supplements, punctal occlusion, contact lenses and appropriate management of adnexal disease. The most frequent therapy utilized to treat ocular surface disorders is artificial tear eye drops.

However, none of the commercially available artificial tear preparations includes essential tear components such as growth factors, vitamins, and immunoglobulins. Another drawback of artificial tears is the fact that they often contain preservatives, stabilizers, and other additives, which potentially induce toxic or allergic reactions. Despite maximal conventional therapy, there is a cohort of patients who still have persistent symptoms and signs. Such patients may have more serious ocular surface disorders with significant visual impairment and disability.

Autologous serum eye drops have been recommended for the treatment of several ocular surface disturbances, such as Sjögren's syndrome-related tear deficiency, non-Sjögren's tear deficiency associated with graft-versus-host disease, neurotrophic keratitis, persistent epithelial defects, superior limbic keratoconjunctivitis, as well as a supportive measure in ocular surface reconstruction.

Its utilization in ophthalmology arose out of the need of finding lacrimal substitutes which, in addition to lubricating the ocular surface, were able to provide other components of tears that are reduced in ocular surface disease.


Human serum properties

Human serum contains substances such as epidermal growth factor, vitamin A, transforming growth factor-β , fibronectin, and cytokines normally found in tears. These factors are important for maintaining a healthy corneal and conjunctival epithelium. The rationale for the topical use of autologous serum is based on the premise that chemotactic and growth factors present in tears are also present in patient's own serum. Moreover, the biochemical properties of the serum are similar to that of normal tears.

Of all human serum components, it is believed that the most important for ocular surface are: epithelial growth factor (EGF), transformer growth fibroblast β -factor (TGF-β ), vitamin A, fibronectin, albumin, α -2 macroglobulin, the platelet-derived growth factor (PDGF-AB), hepatocyte growth factor, neuropeptides such as substance P and the insulin-like growth factor.

Autologous serum contains neuronal factors such as substance P and insulin-1-type growth factor, which seem to play a role in the migration and adhesion of the corneal epithelium to its stroma. PDGF-AB is one of the 5 known isoforms of platelet-derivated growth factors and is activated intracellularly and secreted by the alpha granules of platelets after its activation, enhancing mitosis and scarring. In addition, autologous serum contains immunoglobulines such as IgG, IgA, lysozyme and supplemental factors that provide bactericide and bacteriostatic effects.


Preparation of serum and patient

Blood is extracted from patient's vein with vacuum extraction tubes without anticoagulant. Subsequently, the tubes are left in vertical position at 22°C for about 2 hours to allow coagulation. After blood clot is formed, supernatant is centrifuged to separate the serum from the solid components. A bottle of serum eye drops with the desired concentration, adequately identified and preserved from light is given to the patient. It is important to keep the eye drops away from light because some of its components (vitamin A) degrade quickly with light exposure. Most prepared all the autologous serum eye drops with fresh serum, giving the flasks to the patients for their utilization, recommending them to keep the one in use in the refrigerator at +4°C(5).

Regarding dispensation, some authors suggest a flask per day while others the same flask for one week(2,5). The remaining bottles should be stored frozen (ideally at -20°C) for up to 3 months(2). The number of applications varies from once every hour up to 3 times a day. Some authors believe that concentrations of 50% or 100% would have more effect on the eye surface(1,9). However, the most standardized dilution of autologous serum is at 20% which is based on the concentration of certain growth factors in tears(2,7).



  • severe dry eye
    Dry eye syndrome is recognized as a growing public health problem and one of the most frequent reasons for seeking eye care. The estimated prevalence for people > 50 year-old in the United States is 7.8% for women (approximately 3.2 million affected), and 4.7% for men (approximately 1.6 million affected)(10). Dry eye syndrome is characterized by a deficiency in the quality or quantity of tears, an unstable tear film, ocular surface damage, and bothersome symptoms such as ocular irritation, grittiness, fatigue, and fluctuating vision.
    1. Noble BA, Loh RS, MacLennan S, Pesudovs K, Reynolds A, Bridges LR et al. Comparison of autologous serum eye drops with conventional therapy in a randomized controlled crossover trial for ocular surface disease.
    Br J Ophthalmol. 2004;88(5):647-52.  Tananuvat N, Daniell M, Sullivan LJ, Yi Q, McKelvie P, McCarty DJ et al. Controlled study of the use of autologous serum in dry eye patients. Cornea. 2001;20(8):802-6.
    Kojima T, Ishida R, Dogru M, Goto E, Matsumoto Y, Kaido M, Tsubota K. The effect of autologous serum eye drops in the treatment of severe dry eye disease: a prospective randomized case-control study. Am J Ophthalmol. 2005;139(2):242-6.
    Hyon JY, Lee YJ, Yun PY. Management of ocular surface inflammation in Sjögren syndrome. Cornea. 2007;26(9 Suppl 1):S13-15.  
  • persistent epithelial corneal defect
    Severe dry eye and neurotrophic ulcers present the most severe types of persistent epithelial defect (PED). Desiccation itself can be compensated by the frequent use of preservative-free artificial tears combined with the use of moisture chamber glasses, punctal plugs, or both. However, the lack of tear production results in the deprivation of essential tear components such as epidermal growth factor and vitamin A to the ocular surface epithelium.
    Tsubota K, Goto E, Shimmura S, Shimazaki J. Treatment of persistent corneal epithelial defect by autologous serum application. Ophthalmology. 1999;106(10):1984-9.
    Young AL, Cheng AC, Ng HK, Cheng LL, Leung GY, Lam DS. The use of autologous serum tears in persistent corneal epithelial defects. Eye. 2004; 18(6):609-14.
    Alvarado Valero MC, Martínez Toldos JJ, Borras Blasco J, Almiñana Almiñana A, Pérez Ramos JM. Treatment of persistent epithelial defects using autologous serum application. Arch Soc Esp Oftalmol. 2004;79(11):537-42.
    Schrader S, Wedel T, Moll R, Geerling G. Combination of serum eye drops with hydrogel bandage contact lenses in the treatment of persistent epithelial defects. Graefes Arch Clin Exp Ophthalmol. 2006;244(10):1345-9.
  • recurrent corneal erosion
    Corneal erosions can be an extremely painful condition for many patients. The pathogenic mechanism is linked to abnormalities of the adhesion complex between the corneal epithelium and the stromal layer. The etiologies for erosions are very wide and include trauma, dry eye, corneal dystrophies, and eyelid diseases that occur after infection or spontaneously(21). Holzer et al.(22) evaluated the clinical outcomes after transepithelial phototherapeutic keratectomy (t-PTK) using an excimer laser and postoperative administration of 20% autologous serum eye drops to treat 25 eyes of 25 patients with 3 to 12 recurrent erosions. Postoperatively, autologous serum eye drops were administrated 6 times a day for 6 weeks. Twenty eyes (80%) recovered without further corneal erosion in a follow-up period of 15.5 months (range 6 to 20 months). Five eyes had 1 further erosion, which was treated in 4 cases with autologous serum without additional excimer laser treatment. One patient requested additional t-PTK treatment and recovered without further complications thereafter.
    Del Castillo et al.(studied the effect of 20% autologous serum in the treatment of recurrent corneal erosions in 11 eyes of 11 patients. Mean follow-up time was 9.4 ± 3.7 months (range, 4 to 16). Treatments prior to the use of autologous serum had failed to avoid recurrences in all patients, with the mean recurrence rate being 2.2 recurrences per month of follow-up. After the onset of serum treatment, only a single recurrence was recorded in 3 of the patients. Thus, the use of autologous serum for the treatment of patients with recurrent corneal erosion appears to be effective and safe in reducing the number of recurrences experienced by patients.
  • neurotrophic keratopathy
    Numerous ocular and systemic diseases, including viral keratitis, chemical or thermal burns of the ocular surface, fifth nerve palsy after removal of acoustic neuroma or radiation, drug toxicity, corneal surgery, multiple sclerosis, and diabetes, may lead to neurotrophic keratopathy (NK). This presents with a broad spectrum of corneal findings, including superficial punctate keratitis, epithelial defects, ulceration, and perforation. In neurotrophic ulcers, neural factors such as acetylcholine or substance P are depleted from the cornea. Nishida et al.(24) emphasized the importance of substance P and insulin-like growth factor for a normal wound-healing response. Matsumoto et al.(25) reported the treatment of 14 eyes of 11 patients with NK with application of 20% autologous serum eye drops 5 to 10 times daily until the defect healed. The epithelial defect healed completely in all eyes within 6 to 32 days (mean, 17.1 ± 8.0 days), with a decrease in corneal scarring. Corneal sensitivity, as measured by Cochet-Bonnet esthesiometer, increased from a pretreatment level of 11.8 mm to 30.0 mm after treatment at the last follow-up, and 5 eyes achieved normal corneal sensitivity with treatment.
  • filtering blebs after trabeculectomy
    Aqueous leakage from filtering blebs is not a rare condition after trabeculectomy with antimetabolites, which can pose a potential risk for bleb-related complication. Although the effects of serum on the conjunctiva have not been fully studied, vitamin A and epidermal growth factor are reported to have roles in maintaining the normal histology in the conjunctiva. Matsuo et al.(26) evaluated the efficacy of 20% topical autologous serum application to stop aqueous oozing or point-leak through filtering bleb after trabeculectomy. A total of 21 eyes with oozing and 21 eyes with a point-leak through a functional bleb after trabeculectomy with 5-fluoracil or mitomycin C were enrolled in this randomized case-control study. The serum was topically applied 4 times a day for up to 12 weeks. In the serum and control groups, oozing stopped in 62.5% and 0% of eyes, respectively (P=0.003), and point-leaks stopped in 27.3 and 18.2%, respectively (P>0.9). These findings suggest that autologous serum application was significantly effective to stop aqueous oozing but not point-leaks.
  • superior limbic keratoconjunctivitis
    Superior limbic keratoconjunctivitis (SLK) is a relatively uncommon ocular surface disorder, and mild clinical findings can cause a significant patient discomfort. Fine punctate rose bengal and fluorescein staining of the superior cornea and limbus are sometimes the only clinical signs detected. Its etiology is not completely understood, and various causes, such as eye rubbing, viral infection, and autoimmune diseases have been proposed, as well as a diverse range of possible treatments. Goto et al.(27) assessed the efficacy of autologous serum drops in the treatment of SLK. Twenty two eyes of 11 SLK patients were treated with 20% autologous serum 10 times a day in addition to ongoing treatment of dry eye. Previous therapies, including artificial tears, topical corticosteroids, and topical vitamin A, were ineffective. Nine of the 11 patients reported subjective improvement (81.8%), and all eyes showed objective improvement (100%) by rose bengal or fluorescein staining. Despite the good results obtained in this study, the authors proposed that punctal occlusion be considered the first choice of therapy for SLK, and if conventional treatment is ineffective, autologous serum drops should be added to the regime.
  • graft-versus-host disease
    Allogeneic haematopoietic stem cell transplantation (SCT) is considered a curative treatment for various hematological malignancies. However, chronic graft-versus-host disease (GVHD) remains a major complication after SCT, and is the largest factor in impairing the quality of life of transplant recipients. Dry eye is one of the major symptoms of GVHD. Although several therapies have been used to minimize the symptoms of dry eyes associated with GVHD, an effective treatment has not been established. In 2000, Rocha et al.(28) reported the first two cases of GVHD with severe dry eyes treated with autologous serum, which proved to be safe during the 10 months of treatment. Ogawa et al.(29), in 2003, utilized autologous serum eye drops to treat 14 patients with severe dry eye associated with GVHD.
  • refractive surgery
    One of the most common complications of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) is dry eye syndrome. Although dry eye after refractive surgery is usually transient, some patients complain of severe symptoms, which may negatively influence their satisfaction with the outcome of the procedure. Both keratorefractive procedures have been reported to perturb the ocular surface homeostasis by causing a decrease in corneal sensitivity, tear film instability, decreased aqueous tear production, and corneal and conjunctival epitheliopathy.
    Noda-Tsuruya T, Asano-Kato N, Toda I, Tsubota K. Autologous serum eye drops for dry eye after LASIK. J Refract Surg. 2006;22(1):61-6.
    Toda I, Asano-Kato N, Hori-Komai Y, Tsubota K. Ocular surface treatment before laser in situ keratomileusis in patients with severe dry eye. J Refract Surg. 2004;20(3):270-5.
  • aniridic keratopathy
    Keratopathy occurs in 20% to 90% of patients with aniridia and is caused by a primary dysfunction of the limbal stem cells. Corneal changes include recurrent erosions and ulcerations of corneal epithelium, tear film instability, dry eye, chronic pain, corneal vascularization, progressive corneal opacification, and blindness. López-García et al.(34) studied the effect of 20% autologous serum eye drops in a prospective case series of 26 eyes of 13 patients with aniridic keratopathy. The mean age of the patients was 26 ± 9.5 years (range 9 to 48 years). There were no local side effects from autologous serum treatment, and all patients showed a subjective improvement of keratopathy symptoms after the serum application. The corneal reepithelialization, corneal epithelial cell squamous metaplasia, and tear stability improved significantly with the treatment, but visual acuity, regression of vascular pannus, and subepithelial scarring showed only slight improvement.
  • ocular surface reconstruction
    Ocular cicatricial pemphigoid and Stevens-Johnson syndrome are severe ocular surface diseases of unknown origin that often result in bilateral blindness, despite such treatment as immunosuppression. Although penetrating keratoplasty is an established procedure for the accompanying conditions, including severe dry eye, lack of corneal stem cells, trichiasis, and persistent ocular surface inflammation, make these diseases refractory to treatment. Tsubota et al.(35) evaluated 14 eyes of 11 patients with cicatricial keratoconjunctivitis (7 patients with cicatricial pemphigoid and 4 with Stevens-Johnson syndrome). The patients were treated with a combination of allograft limbal transplantation, amniotic membrane transplantation, and tarsorrhaphy, followed every 15 minutes by 20% autologous serum eye drops. Eight patients required concomitant penetrating or lamellar keratoplasty because of corneal opacity. With a mean follow-up of 143 days (range 10 to 608 days), the authors achieved successful ocular surface reconstruction in 12 eyes (86%), with minimal recurrence of symblepharon. However, failure occurred in 2 eyes that developed corneal infiltrations and vascularization.
  • mooren's ulcer
    Mooren's ulcer is an uncommon, inflammatory keratopathy characterized by severe pain, conjunctival and episcleral injection, and peripheral corneal ulceration. The corneal changes may expand centrally or peripherally producing dramatic corneal thinning, often with an overhanging edge of superficial cornea. One or both eyes may be affected and recurrences are common. Most cases resolve with stromal thinning and scarring, although a minority of cases advance to perforation. Its clinical course and eventual prognosis is variable and usually these ulcers respond poorly to conventional therapy. Mavrakanas et al.(36) reported a case of Mooren's ulcer treated with antibiotic, corticosteroid and cyclosporine therapy. The patient did not respond well to initial treatment, but reepithelialization occurred and the corneal deficit improved after the introduction of 20% autologous serum eye drops. Therefore, autologous serum appears to be an effective supplementary treatment in Mooren's ulcer, by providing enhanced conditions for epithelial healing and by modulating the corneal inflammatory and immune response.



Regarding stability, Tsubota et al. reported that the concentration of growth factors, vitamin A, and fibronectin in 100% and 20% serum diluted with NaCl stored at +4°C remained unchanged for 1 month and at -20°C for at least 3 months. However, no more detailed published evidence is available to clarify the minimum freezer temperature required for several months of storage. Leite et al.(37) analyzed viability of autologous serum by the presence of insulin and protein levels. The authors found insulin levels in autologous serum of 2.30 ± 0.60 (n= 9) at day 0 and 1.60 ± 0.70 ng/ml (n=5) at day 30 (P=0.84). The protein levels were 51.10 ± 2.70 at day 0 (n=9) and 50.70 ± 4.60 ng/ml at day 30 (n=5) (P=0.47).


Drawbacks of serum eye drops treatment

Since autologous serum preparation is a body fluid, it is able to transmit infections(2). Another drawback of autologous serum treatment lies in the frequent blood extractions, mainly in the groups requiring prolonged treatment. In these cases, it is important to pay attention because not all patients can be treated due to systemic difficulties and in some occasions it is even necessary to provide an iron sulphate supplement to prevent anemia(5). Autologous serum contains no preservatives, which avoids the risk of preservative toxicity, however, there is a potential risk of inducing infections because of microbial contamination of the dropper bottle(16). Leite et al.(37) analyzed 11 autologous serum samples after 30 days of use by the patients, in which 6 of them were contaminated by single or multiple microorganisms such as: Klebsiella pneumoniae (4/6), Streptococcus viridans (3/6), Candida sp (1/6), Pseudomonas aeruginosa (1/6), Bacillus sp (1/6), Staphylococcus aureus (1/6), Micrococcus sp (1/6).



The literature describes some complications such as the deposit of immunoglobulins in the cornea and the presence of corneal peripheral infiltrates with 100% autologous serum treatment in one patient*. The literature does not describe either side effect when utilized for long periods of time. Autologous serum treatment is usually well tolerated and most patients report improvement of discomfort sensation. Although uncommon, some patients may experience increased discomfort, slight epitheliopathy, bacterial conjunctivitis or eyelid eczema, according to some reports(**).

McDonnell PJ, Schanzlin DJ, Rao NA. Immunoglobulin deposition in the cornea after application of autologous serum. Arch Ophthalmol. 1988;106(10): 1423-5

López-García JS, García-Lozano I, Rivas L, Martínez-Garchitorena J. Use of autologous serum in ophthalmic practice. Arch Soc Esp Oftalmol. 2007; 82(1):9-20.


Standardizing the production of serum eye drops

Neither production nor application of serum have been standardized so far. It also remains unclear whether the serum should be filter-sterilized to remove any corpuscular blood components. The variable efficacy of serum eye drops suggests that the parameters for their production should be standardized and optimized before any meaningful placebo controlled randomized clinical trial can evaluate the real potential of this therapy

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