This was a prospective, randomised ,interventional clinical study , duly approved by the Institutional Ethics Committee (Ethical clearance certificate no. 29/MH/2015 dated 11 Aug 2015 of Military Hospital Jammu Cantt) and adheres to the tenets of the declaration of Helsinki.Two hundred and sixty four consecutive patients (264 eyes) with primary pterygium were enrolled in this study which was conducted between between Aug 2015 and Jan 2019. All consecutive cases of Primary nasal Pterygium were enrolled in the study. Exclusion criteria included ocular surface disorders , hypersensitivity to blood components and seropositivity to Hepatitis B, Hepatitis C and HIV (These patients were excluded as part of the norm followed by the Ethical committee of the institute).
Written informed consent was obtained from all the patients recruited in the study. This included consent for the images to be published. Comprehensive medical and ocular histories besides age, sex of the subjects was obtained. Thereafter, a detailed ocular examination was performed. Pterygia were graded into three grades based on classification given by Tan and coworkers17: T1 (episcleral vessels underlying the body of the pterygium seen unobscured and distinguished), T2 (episcleral vessels indistinctly seen or partially obscured) and T3 (epislceral vessels totally obscured by fibrovascular tissue). The Patients were divided into two groups by simple random sampling using lottery method: group I (133 eyes)underwent CAG with fibrin glue and group II (131 eyes) underwent mini-SLET. An allocation concealment and masking of the patients was done. Formula used for calculation of sample size is n= (Zα+z(1-β)2×(p1q1+p2q2)/ d2,n= sample size,Zα = Standard normal variate for α=0.05(95%CI),Z 1-β = Standard normal variate for 1-β=0.80(80%),P1 = proportion (%) in one gp; qi =100-p1 &p2…,d = p1-p2
Surgical Technique
All surgeries were performed under peribulbar anaesthesia (2 % lidocaine) by the same surgeon (AJ).Using the Westcott scissors horizontal incisions along the superior and inferior borders of the body of pterygium were made.Thereafter, an incision parallel to the limbus at the periphery of the pterygium 2mm nasal to the limbus was made. The pterygium was subsequently reflected centrally i.e. towards the limbus using Moore field’s conjunctival forceps. The remaining underlying fibrovascular tissues in the bulbar conjunctiva were dissected.
The area of the bare sclera was measured using a caliper. For group I a tenon-free supero-temporal conjunctival autograft one mm larger than the bare sclera in horizontal and vertical dimensions was obtained.Fibrin glue (Tisseel,Baxter) was applied to the bare and dried up sclera and the graft was transferred onto the bare sclera with correct orientation. The angled flat end of two iris repositors were utilized to iron out the graft. This was done superior- inferior axis(parallel to limbus) and nasal-temporal axis ,if required. This manoeuvre with iris spatulas has been termed as ‘cheese-spreading technique’ (video 1) not only leads to expansion of the graft to its maximum possible size but also ensures removal of excess glue on the sclera bed.
In group II, after performing 3mm or 1 clock hour of (10-11 o’clock for Right Eye and 1-2 o’clock for left Eye) peritomy, 2x 2 mm size limbal tissue was harvested with the help of a crescent blade commencing from the conjunctival side. This strip was then cut into 6 to 8 pieces, using Vannas scissors under higher magnification, i.e.X16. These pieces were placed and fixed with fibrin glue on the inlay AM closer to the limbus.Subsequently, the overlay AM was used to sandwich the limbal tissues.Freeze dried Amniotic membrane (Amnio-care, Biocover Labs), which is available in (3X3) cm size was used. A bandage contact lens was left in place.
The fibrin glue (Tisseel VH, Baxter AG) was prepared by reconstituting freeze-dried protein concentrate and thrombin in fibrinolysis inhibitor solution and calcium chloride solution, respectively, and were warmed for 20 min in a patented fibrinotherm device. Both fibrin and the thrombin were loaded in the separate syringes mounted with 26G needle.This was mainly done to be able to use one fibrin glue kit of 2ml for at least 10-15 cases(for both groups) to avoid any logistic wastage. To use the glue, equal number of drops of (fibrin) and (thrombin) were used to stick conjuctival autograft, Limbal tissues and Amniotic membrane. The operating time was noted for both the groups.
Both the groups were patched for 24 hours. Post-operatively all the patients were treated with1 % prednisolone acetate eye drops 4 hourly ,0.5 % Moxifloxacin eye drops 6 hourly in the first week, followed by application of only a topical steroid in tapering dosage over a period of 1 month.
The patients were reviewed on next day after surgery and then on day 3,7,14 and 30 and subsequently at third , sixth and ninth month. Each visit initially included a slit-lamp examination to check autograft/AM status, and complications like graft retraction, graft/AM displacement, corneal thinning and later on for recurrence.
Recurrence was recognised as any fibrovascular growth that crossed the limbus. The photographs were taken pre-operatively, intraoperatively and post-operatively on day 1, 30 & at 6 and 9 months for both the groups (Figure 1).
Statistical Analysis
The statistical software SPSS version 20 was used for the analysis for various variables. A p value of less than 0.05 was considered as significant. Variables like age and preoperative BCVA were compared using unpaired t test . Other baseline characteristics like gender, Laterality, grades of pterygium(I-III),Occupation and indication of surgery were expressed between the two groups using Pearson’s Chi-Square test. Comparison of operative time and the dimensions of graft between CAG and mini-SLET Conjunctivalautograft was done using unpaired t test.