| BackgroundCornea lesions including,corneal thinning and perforation is one of the sight-threatening complications of corneal diseases such as,severe corneal ulcers,chemical burns as well as corneal trauma which can ultimately results in blindness or even loss of eyeball.Corneal thinning is a medical condition with a decrease in total thickness of the cornea and in severe cases,it may ultimately lead to perforation.Most commonly corneal thinning is due to the primary causes including ocular surface disorders,ocular infection,trauma,burns,immune-mediated disease as well as surgical complications after recurrent pterygium,limbal dermoid and other diseases involving cornea;however certain systemic diseases are also associated.The corneal thinning can either be central or peripheral.Peripheral thinning is more common since the infection can spread from the adjacent limbus,ocular surface and sclera.Corneal thinning possibly will disturb the vision by causing severe astigmatism and advancement of the diseases with completely occupying the visual axis.Furthermore,anatomical integrity of the eyeball is compromised by spontaneous perforation or due to increased vulnerability to perforation even after minor injury or trauma.Corneal perforation is an ophthalmic emergency that needs immediate intervention.Besides,being a reason for ocular morbidity leading to a permanent loss of vision,they also symbolize a risk in the quality of life.The etiology for corneal perforation can either be traumatic(penetrating trauma,burns)or non-traumatic(bacterial,viral,fungal corneal infections,autoimmune keratitis).Amongst the infective causes,bacterial infection is regarded as the most common cause for perforation.The majority of corneal perforation is due to the trauma accounting for 76% and non-traumatic causes accounts for about 28% of patients.Occasionally inflammatory disorders such as,collagen vascular diseases,acne rosacea,Wegener's granulomatosis as well as idiopathic ulcer might cause a corneal ulcer later perforation.Corneal thinning if left untreated can lead to perforation,which ultimately results in various complications including,severe loss of anatomical integrity of the anterior segment,the spread of infection in the eyeball leading to,purulent uveitis,endophthalmitis,panuveitis,secondary glaucoma,retinal detachment,phthisis bulbi,irreversible vision loss.Corneal perforation is also associated with a sudden drop of intraocular pressure,ocular tissue prolapses,subluxation or anterior dislocation of lens,corneal fistula(if the perforation is not plugged by iris).Hence,timely diagnosis and proper intervention based on site,size and location of the corneal perforation is needed to prevent these complications.Early medical management is recommended in case of corneal thinning and for the deep/complicated corneal thinning the management is same as corneal perforation.Moreover,pathologic corneal thinning needs careful monitoring for advancement to recognize cases who might benefit from an amplifying the therapy.The treatment of corneal perforation varies from tissue adhesive,bandage contact lens to simple suturing of the cornea,conjunctival grafts,multilayer amniotic membrane transplantation(AMT)and therapeutic or tectonic cornea transplantation.In cases with small perforation(perforation less than 2-3mm or corneal thinning),bandage soft contact lens with or without tissue adhesive glue(cyanoacrylate glue)are the mainstay of treatment.Multilayered AMT is also useful in the management of patient with corneal perforation with less than 1.5 mm in diameter.However,in cases not responding to the above technique and those cases with large perforation,keratoplasty is the only option for the treatment.Corneal tissue is the utmost commonly transplanted organ in the world.According the Eye Bank Association of America's 2013 Eye Banking Statistical Report,72,736 corneal grafts were performed,including tissues sent overseas.Even though,keratoplasty is an effective and safe surgical approach for the management of corneal lesion,there are few limitations in developing nations including eye bank barrier,high cost for the donor cornea,huge shortage of corneal tissue.The records had shown that the cornea transplantation in China has increased in recent years from 5000 to more than 8000,still there a huge demand for the corneal tissue.In another data from India the number of corneal transplantation had tripled from 8014 to 23,050 over the past decades from 2003 to 2012,still there is a huge shortage for donor cornea and there is still a long waiting list.In contrast,almost in all developing nations the rate of corneal transplantation is increasing steady i.e.in Philippines about 1529 corneas were transplanted per year for the last 5 years,in Brazil the number of cornea transplantation was 6193 in 2001 and reached to 14,838 by 2011,and in Ethiopia the number has increased from 150-200 in recent 5 years.However,the lack for the donor cornea and high demand for the graft is the major limitation of keratoplasty in these nations.SMILE is an innovative femtosecond laser procedure used for the correction of myopia and myopic astigmatism.In this procedure,a single,thin and transparent corneal tissue is extracted from the patient through a small incision.The lenticule thus obtained is a small piece of corneal tissue which can be re-implanted for the treatment of various other ocular condition including hypermetropia,presbyopia,corneal dystrophy,corneal micro perforations,bullous keratopathy and corneal ulcers.Pradhan et al.described the first successful human implantation of the SMILE extracted lenticule from a myopic donor with in the patient with hyperopia and concluded that reimplantation of SMILE lenticule for the endokeratophakia is a viable procedure for the correction of hyperopia.There was no any adverse effect during the 1 year follow up.In our study,we performed tectonic keratoplasty(TK)using SMILE extracted lenticule in patient with corneal lesions.Tectonic keratoplasty is a surgical technique in which the diseased or damaged corneal tissue is replaced by healthy donor cornea.Furthermore,Wu et al.stated the use of SMILE lenticule as a patch graft in patient with corneal ulcer perforation in 6 patients and suggested that that the application of SMILE extracted lenticule may be a reliable and efficient surgical alternative for corneal perforation closure as well to maintain the anatomical structure of eyeball.ObjectiveThe main objective of this study is assess the effectiveness of SMILE extracted lenticule as a graft for tectonic keratoplasty in the management of corneal lesion.Furthermore,it also directs to find out an alternative option for the donor cornea for the keratoplasty in nations where the corneal demand and graft cost is very high.MethodsWe performed a non-comparative retrospective study on patients who were diagnosed to have corneal lesions secondary to ocular pathology and managed by tectonic keratoplasty using SMILE extracted lenticule in Department of Ophthalmology of First hospital of Jilin University,Changchun,China.Based on computer database registry search of First Hospital of Jilin University,from March 2017 to October 2018,a total of 18 patients(18 eyes)were managed by tectonic keratoplasty using SMILE extracted lenticule for the corneal thinning and perforation secondary to corneal ulcer,recurrent pterygium,blepharokeratoconjunctivitis,limbal dermoid,exposure keratitis and Pseudopterygium and were included in the study.From their medical register age,sex,diagnosis,status of cornea,localization and size of cornea defect,preoperative visual acuity,post-operative visual acuity,layer of lenticule used for translation,surgical procedure and additional medical history was recorded.Visual acuity was recorded based on Snellen's Chart decibel system.The size and localization of corneal defect was based on slit lamp examination or anterior segment optical coherence tomography(AS-OCT).Corneal perforation was assessed using slit lamp examination or by positive Seidel test using fluorescein staining.All the lenticule donor who go through SMILE procedure had provided written informed consent for the donation process.Collected data were analyses were conducted using SPSS18.0 software.Quantitative data were expressed as a mean ± standard deviation and qualitative data were expressed as constituent ratio.Because the number of patients was less than 40,the difference of VA before and after surgery was tested by Fisher exact probability.P value was calculated and P < 0.05 was considered statistically significant.ResultsConsidering the epidemic and medical data of the included 18 cases,10(55.6%)were males and 8(44.4%)were females.The mean age of the patient was 46.2±25.2 years with a range of 7-82 years.Moreover,7(38.9%)patients were farmers,6(33.3%)patients were students,and 5(27.8%)patients engaged in other occupations.On clinical analysis,the diseases eye was left and right in 7(38.9%)and 11(61.1%)patients,respectively.The predisposing diseases leading to corneal lesion was corneal ulcer(CU)in 11(61.1%)patient,blepharokeratoconjunctivitis(BKC)in 2(11.1%)patients,limbal dermoid in 2(11.1%)patients,recurrent pterygium in 1(5.6%)patient,exposure keratitis in 1(5.6%)patients and pseudo-pterygium in 1(5.6%)patients.In 13(72.2%)patients there was corneal thinning and in 5(27.8%)patients there was corneal perforation.Furthermore,the lesion was in infratemporal region in 8(44.4%)patients,central in 6(33.3%)patients,nasal in 2(11.1%)patients,supratemporal region in 1(5.6%)patients and infransal region in 1(5.6%)patients.Preoperative and post-operative data showed that,the ranges of pre-operative VA was PL to 1.00,and the mean preoperative VA was 0.2555±0.3326.Monolayer lenticule as a graft was used in 11(61.1%)patients,and double layer of lenticule was used in 7(38.9%)patients.The ranges of postoperative VA were PL to 1.0,and the mean postoperative VA was 0.3303±0.3487.After operation,postoperative VA remained unchanged in 11(61.1%)patients,while improved in 7(38.9%)patients.In 2(11.1%)patients the surgical outcome was poor and in one patient re-implantation of lenticule was done and another patient conjunctival flap surgery was performed to seal the perforation and preserve the anatomical structure of eyeball.The result suggested that status of cornea and localization of defect were the influence factors of VA(P < 0.05).After surgery,VA was found to be improved in patients with perforated cornea(P= 0.047)than the patient with corneal thinning and with infratemporal defect(P=0.010)than the patient with central,infranasal and nasal lesions.In regards to the status of cornea,there was significant difference in size of the defects.(P<0.05).Corneal perforation was found to be higher in patient with size of defects < 3 x 3 mm and corneal thinning was higher in patient with size of defects ? 3 x 3 mm(P= 0.044).ConclusionTectonic Keratoplasty using SMILE extracted lenticule is comparatively safe,effective and reliable alterative approach for the treatment of corneal lesion.Besides maintain the anatomical integrity of eyeball and visual rehabilitation,it is effective functionally and cosmetically.Furthermore,it can solve the problem of donor shortage,high cost of donor cornea in developing nations as well as can be used in emergency conditions. |
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